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HomeMy WebLinkAboutBLOCK 23 MORNINGSTAR - FDP200027 - - STORMWATER MANAGEMENT PLAN (3) STORMWATER MANAGEMENT PLAN (SWMP) MORNINGSTAR/BLOCK 23 Fort Collins, CO December 16, 2020 Prepared for: Hazeldon/Morningstar Fort Collins, LLC 300 North Mason Street Fort Collins, CO 80524 Prepared by: 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 1024-004  This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double -sided printing. December 16, 2020 Hazeldon/Morningstar Fort Collins, LLC 300 North Mason Street Fort Collins, CO 80524 RE: Stormwater Management Plan Morningstar/Block 23 To Whom It May Concern: Northern Engineering Services, Inc. is pleased to submit this Stormwater Management Plan for the Morningstar/Block 23 project. This report outlines Best Management Practices (BMPs) to be implemented with the proposed construction in order to minimize potential pollutants in stormwater discharges. We have prepared this report to accompany the Colorado Department of Public Health and Environment General Permit for Stormwater Discharge Associated with Construction Activities (aka, Stormwater Discharge Permit or SDP). The General Permit No. for this SDP is (to be filled-in by permittee) and the Certification No. for this SDP is (to be filled-in by permittee). The Permit Certification is Effective beginning (to be filled-in by permittee), and initial certification expires (to be filled-in by permittee). A copy of the issuance cover letter can be found in the Appendix D of this document (to be provided by permittee). Please note: this Stormwater Management plan (including the Site Maps) is not a static document. It is a dynamic device that should be kept current and logged as construction takes place. As such, this version was prepared to facilitate initial plan approvals and permitting, but does not necessarily reflect the final version, or the transitions throughout the construction process. As the site develops and changes, the Contractor is expected and encouraged to make changes to what is contained herein so that the SWMP works as effectively and efficiently as possible. It shall be the responsibility of the SWMP Administrator and/or the permit holder (or applicant thereof) to ensure the plan is properly maintained and followed. If you should have any questions or comments as you review this report, please feel free to contact us at your convenience. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Frederick S. Wegert, PE Project Engineer Morningstar/Block 23 Stormwater Management Plan TABLE OF CONTENTS Vicinity Map 1.0 General Requirements ................................................................................................ 1 1.1 Objectives .................................................................................................................. 1 1.2 SMWP Availability ...................................................................................................... 1 1.3 Definitions.................................................................................................................. 1 1.4 Additional Permitting ................................................................................................... 1 2.0 Narrative Site Description ........................................................................................... 2 2.1 Existing Site Description .............................................................................................. 2 2.2 Nature of Construction Activity ..................................................................................... 2 2.3 Sequence of Major Activities ......................................................................................... 2 2.4 Site Disturbance ......................................................................................................... 2 2.5 Existing Data .............................................................................................................. 2 2.6 Existing Vegetation ...................................................................................................... 2 2.7 Potential Pollution Sources ........................................................................................... 2 2.8 Non-stormwater discharges .......................................................................................... 3 2.9 Receiving Waters ........................................................................................................ 3 3.0 Stormwater Management Controls ............................................................................... 4 3.1 SWMP Administrator ................................................................................................... 4 3.2 Best Management Practices (BMP’s) for Stormwater Pollution Prevention.......................... 4 3.3 Structural Practices for Erosion and Sediment Control ..................................................... 4 3.4 Non-Structural Practices for Erosion and Sediment Control .............................................. 7 3.5 Phased BMP Installation .............................................................................................. 9 3.6 Material Handling and Spill Prevention ........................................................................ 10 3.7 Dedicated Concrete or Asphalt Batch Plant .................................................................. 11 3.8 Vehicle Tracking Control ............................................................................................ 11 3.9 Waste Management and Disposal ............................................................................... 11 3.10 Groundwater and Stormwater Dewatering .................................................................... 11 4.0 Final Stabilization and Long-Term Stormwater Management ........................................ 12 4.1 Final Stabilization ..................................................................................................... 12 4.2 Long-Term Stormwater Management ........................................................................... 12 4.3 BMP Inspection ........................................................................................................ 12 4.4 BMP Maintenance .................................................................................................... 13 4.5 Record Keeping ........................................................................................................ 13 5.0 Additional SWMP and BMP Resources ....................................................................... 15 References 16 Morningstar/Block 23 Stormwater Management Plan LIST OF TABLES: Table 1 – Preliminary Permit and Construction Schedule ........................................................ 10 Table 2 - Native Grass Seed Mix ......................................................................................... 12 APPENDICES: APPENDIX A – Site Maps APPENDIX B – Erosion Control Details APPENDIX C – Landscape Plan APPENDIX D – Copies of Permits/Applications APPENDIX E – Inspection Logs APPENDIX F – Contractor Inserts (as needed) APPENDIX G – Contractor Inserts (as needed) Morningstar/Block 23 Stormwater Management Plan 1 1.0 General Requirements 1.1 Objectives The objective of a Stormwater Management Plan (SWMP) is to identify all potential sources of pollution likely to occur as a result of construction activity associated with the site construction, and to describe the practices that will be used to reduce the pollutants in stormwater discharges from the site. The SWMP must be completed and implemented at the time the project breaks ground, and revised as necessary as construction proceeds to accurately reflect the conditions and practices at the site. This report summarizes the Stormwater Management Plan for the construction activity that will occur with Morningstar/Block 23 in Fort Collins, CO. This plan has been prepared according to regulations of the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division. 1.2 SMWP Availability This report is intended to remain on the aforementioned construction site to allow for maintenance and inspection updates, and for review during inspection. 1.3 Definitions BMP – Best Management Practice encompassing a wide range of erosion and sediment control practices, both structural and non-structural in nature, which are intended to reduce or eliminate any possible water quality impacts from stormwater leaving a construction site. Erosion Control BMPs – Practices that PREVENT the erosion of soil, such as minimizing the amount of disturbed area through phasing, temporary stabilization, and preserving existing vegetation. Sediment Control BMP’s – Practices to REMOVE sediment from runoff, such as sediment basins, silt fence, or inlet protection. Non-structural BMP’s – The implementation of methods, practices, and procedures to minimize water quality impacts, such as the preservation of natural vegetation, preventive maintenance and spill response procedures. Structural BMP’s – Physical devices that prevent or minimize water quality impacts, such as sediment basins, inlet protection, or silt fence. 1.4 Additional Permitting As mentioned above, this Stormwater Management Plan is associated with the Colorado Department of Public Health and Environment Stormwater Permit that is issued by the Water Quality Control Division of the CDPHE. Additional Environmental permitting not described in this report may be required as a part of this project. An example is the Construction Dewatering Permit for groundwater. Another example is the Air Pollution Emission Notice (APEN). The CDPHE website contains links to both of these permits, as well as many other potential permits. The Contractor is responsible for ensuring the proper permits are acquired. Morningstar/Block 23 Stormwater Management Plan 2 2.0 Narrative Site Description 2.1 Existing Site Description The project is located at the northwest corner of Maple Street and College Avenue being part of Section 11, Township 7 North, Range 69 West of the 6th P.M., City of Fort Collins, County of Larimer, State of Colorado. In particular, the project is bordered to the north by Cherry Street; to the south by Maple Street; to the east by College Avenue; to the west by Old Town Flats Subdivision; and to the northwest by the Burlington Northern Railroad and the intersection of Mason and Cherry Streets. 2.2 Nature of Construction Activity The proposed project consists of the construction of a long-term care facility, commercial units, and a parking structure. Other proposed improvements include new asphalt within a north-south alley bisecting the project site, landscaping planters, new sidewalks, and storm sewer improvements. The project will maintain historic flow patterns and rates. 2.3 Sequence of Major Activities To complete the project, many basic categories of construction activity will take place. The first part will be the removal of the existing infrastructure. Existing buildings, parking lots, and utility infrastructure will be removed. This includes the removal of topsoil, weeds, and native vegetation. Once the existing infrastructure is removed, overlot grading and site preparation of vertical construction will begin followed by the installation of utilities. Construction will then proceed with vertical construction of the multi-use facility and parking garage. New curb/gutter, paving, and sidewalks are expected to begin after utility installation and will occur concurrent with vertical construction. Finally, landscaping will be installed. The aforementioned sequencing is an initial best guess and is subject to change at the Contractor’s discretion. 2.4 Site Disturbance The site disturbance will occur across roughly 3.29 acres. It is recommended that existing site condition photos be taken prior to the demolition. 2.5 Existing Data In order to complete the associated construction plans, a topographical survey of the site was completed. This survey consisted of field measurements made by Northern Engineering in June 2019. 2.6 Existing Vegetation The existing site vegetation consists of native grasses and invasive weeds. It is highly recommended that pre-construction photos be taken to clearly document vegetative conditions prior any disturbance activities. 2.7 Potential Pollution Sources As is typical with most construction sites, there are a number of potential pollution sources which could affect water quality. It is not possible for this report to identify all materials that will be used or stored on the construction site. It is the sole responsibility of the Contractor to identify and properly handle all materials that are potential pollution sources. The following are some common Morningstar/Block 23 Stormwater Management Plan 3 examples of potential pollution sources: • Exposed and stored soils • Management of contaminated soils • Off-site tracking of soils and sediment • Loading and unloading operations • Outdoor storage of building materials, fertilizers, chemicals, etc. • Vehicle and equipment maintenance and fueling • Significant dust or particulate generating processes • Routine maintenance activities involving fertilizers, pesticides, detergents, fuels, solvents, oils, etc. • On-site waste disposal practices (waste piles, dumpsters, etc.) • Concrete truck/equipment washing • Non-industrial waste sources that may be significant, such as worker trash and portable toilets • Uncovered trash bins • Other areas or procedures where potential spills can occur • Stockpiling of materials that can be transported to receiving waterway(s) Management of Contaminated Soils: We are not aware of on-site contaminated soils. Loading and Unloading Operations: As site development and building construction progresses, space constraints will limit the number of on-site locations for loading and unloading activities to the site from Maple Street. The contractor will be responsible for the proper handling and management of pollution sources during loading and unloading operations. Dedicated Asphalt and Concrete Batch Plants: Neither a dedicated asphalt or concrete batch plant will be constructed on-site. 2.8 Non-stormwater discharges The Stormwater Construction Permit only covers discharges composed entirely of stormwater. Emergency firefighting water is the only authorized exception. Concrete Washout water can NOT be discharged to surface waters or to storm sewer systems without separate permit coverage. The discharge of Concrete Washout water to the ground, under specific conditions, may be allowed by the Stormwater Construction Permit when appropriate BMPs are implemented. The discharge of pumped stormwater, ONLY, from excavations, ponds, depressions, etc. to surface waters, or to a municipal storm sewer system is allowed by the Stormwater Construction Permit, as long as the dewatering activity and associated BMPs are identified in the Stormwater Management Plan (SWMP) and are implemented in accordance with the SWMP. Aside from the exceptions noted above, non-stormwater discharges must be addressed in a separate permit issued for that discharge. If groundwater is encountered, and dewatering is required, a Construction Dewatering Permit must be acquired from the Colorado Department of Public Health and Environment. 2.9 Receiving Waters The proposed development is in the City of Fort Collins Old Town Basin. The property historically drains radially inward to existing inlets located onsite. The outer ring of the project site generally drains into the surrounding curb and gutter for Cherry Street, Maple Street, and College Avenue. The entire site, both the existing onsite inlets and the surrounding streets, drain towards an existing Type-R inlet located within College Avenue in the northeast corner of the project. Ultimately, this Morningstar/Block 23 Stormwater Management Plan 4 Type-R drains, via the Fort Collins storm sewer system, into the Cache La Poudre River. 3.0 Stormwater Management Controls 3.1 SWMP Administrator A SWMP Administrator must be designated in conjunction with the Stormwater Permit. This person shall be responsible for developing, implementing, maintaining, and revising the SWMP. The SWMP Administrator will also be the contact for all SWMP-related issues and will be the person responsible for the accuracy, completeness, and implementation of the SWMP. The Administrator should be a person with authority to adequately manage and direct d ay-to-day stormwater quality management activities at the site. The SWMP Administrator for this site is: Name: (to be filled-in by permittee) Company: (to be filled-in by permittee) Phone: (to be filled-in by permittee) E-mail: (to be filled-in by permittee) 3.2 Best Management Practices (BMP’s) for Stormwater Pollution Prevention Beginning from mobilization, and throughout the entire construction of the project, erosion control devices shall be installed to ensure minimal pollutant migration. These erosion control devices may be installed in phases, or not at all, depending on actual conditions encountered at the site. It is the responsibility of the Contractor to make the determination as to what practices should be employed and when. In the event that a review agency deems BMPs to be insufficient, it shall be the responsibility of the contractor to implement modifications as directed. Best Management Practices (BMPs) are loosely defined as a method, activity, maintenance procedure, or other management practice for reducing the amount of pollution entering a water body. The term originated from rules and regulations in Section 208 of the Clean Water Act. Details for Structural and Non-Structural BMPs have been included in Appendix B. These details should be used for additional information on installation and maintenance of BMPs specified in this report. It is also intended to serve as a resource for additional BMPs that may be appropriate for the site that have not specifically been mentioned in the report. 3.3 Structural Practices for Erosion and Sediment Control Structural BMPs are physical devices that are implemented to prevent erosion from happening or to limit erosion once it occurs. These devices can be temporary or permanent, and installation of individual components will vary depending on the stage of construction. A table depicting construction sequence and BMP application/removal has been placed on the “Dynamic Site Plan” to help document the implementation of these BMPs. Refer to the Stormwater Management Plan Static Site Plan in the Appendix for the assumed location of all BMPs. Construction Details for Temporary BMPs are located in the Appendix for reference. Again, the final determination for which BMP’s will be installed, where they will be located, and when they will be installed shall be made by the Contractor, along with all documentation throughout the construction process. Morningstar/Block 23 Stormwater Management Plan 5 Construction Fencing with Rock Socks (Phase I) Construction fencing with rock socks shall be provided to prevent migration of sediment off-site or into adjacent properties. All construction fencing with rock socks shall be installed prior to any land disturbing activity (demolition, stockpiling, stripping, grading, etc.). Construction fencing with rock socks is to be installed prior to site excavation or earthwork activities. Inspections of the construction fencing should identify tears or holes in the material. Rock socks should inspected for excess sedimentation and slumping or undercut areas that allow flows to bypass the rock socks. Sediment should be removed prior to reaching half the height of the log. It is suggested the construction fencing with rock socks be located along the entire project boundary except at the entrances onto the site off Maple Street. Refer to the Erosion Control Plan (Sheet EC1) for additional clarification. Sediment Control Log – aka “Straw Wattles” and “Rock Socks” (Phase I & II) A Sediment Control Log is a linear roll made of natural materials, such as gravel, straw, coconut fiber, or other fibrous material trenched into the ground and held with a wooden stake. Sediment Control Logs can be used in many instances. Examples include perimeter control for stockpiles, as part of inlet protection designs, as check dams in small drainage ways, on disturbed slopes to shorten flow lengths, or in lieu of silt fencing (where appropriate). Sediment Control Logs should be inspected for excess sediment accumulation. Sediment should be removed prior to reaching half the height of the log. At a minimum, Sediment Control Logs should be used as part of the perimeter construction fencing, check dams in curb and gutter, and at all stormwater discharge locations other than inlets. There are four curb inlets and four area inlets within the project site that will need to be protected via rock socks. Refer to the Erosion Control Plan (Sheet EC1) for additional clarification. Vehicle Tracking Control Pads (Phase I) Vehicle tracking control pads shall be provided to minimize tracking of mud and sediment onto paved surfaces and neighboring roadways. All vehicle tracking control pads shall be installed prior to any land disturbing activity (demolition – as necessary, stockpiling, stripping, grading, etc.). Location of vehicle tracking control pads will be located at any and all existing and future vehicle accesses being used during any of the construction phases. These locations will primarily be dictated by gates or openings in the temporary construction fencing that is expected to be installed. Vehicle tracking control pads are to be installed prior to demolition (as appropriate), site excavation or earthwork activities. Vehicle tracking pads should be inspected for degradation and aggregate material should be replaced as needed. If the area becomes clogged with water, excess sediment should be removed. Aggregate material should remain rough, and at no point should aggregate be allowed to compact in a manner that causes the tracking pad to stop working as intended. Suggested locations for vehicle tracking pads are at the proposed accesses off Maple Street. Refer to the Erosion Control Plan (Sheet EC1) for additional clarification. Inlet Protection (Phase I & II) Inlet protection shall be provided for existing inlets to prevent sediment transport from adjacent earthwork disturbance. Installation of these filters shall occur before adjacent earth disturbing activities (Phase I implementation). Wattle type filters are to be implemented for new and existing Morningstar/Block 23 Stormwater Management Plan 6 inlets where asphalt does not exist. For these inlets, if pavement is constructed adjacent to the structure or if the area adjacent to the inlet is changed such that the wattle type filter is no longer effective, it shall be the responsibility of the Contractor to ensure that an appropriate method is used instead. For example, the wattle filter could be reused, or a gravel-block inlet filter may be installed. It will be left to the discretion of the Contractor as to whether replacement of any inlet filter is necessary. Inlet protection should be inspected regularly for tears that can result in sediment entering an inlet. Inlet protection should also be inspected for sediment accumulation upstream of the inlet, and sediment should be removed when the less than half of the capacity is available, or per manufacturer specifications. The Contractor shall provide inlet protection for all proposed inlets (eight in total) as they are installed (Phase II implementation). Refer to the Erosion Control Plan (Sheet EC1) for additional clarification. Erosion Control Blankets (Phase II) A temporary degradable rolled erosion control product composed of natural flexible fibers shall be used on all seeded slopes 3:1 and greater (excluding mulched shrub bed areas). Erosion control blankets should be utilized to provide erosion control and to facilitate vegetation establishment. During installation, it is important to ensure that no gaps or voids exist under the material and that all corners of the material are secured using stakes and trenching. Stakes should be made of materials that are biodegradable. Continuous contact between the product and the soil is necessary to avoid failure. Erosion Control Blankets should be inspected regularly for signs of erosion, including beneath the mat. If voids are apparent, they should be filled with suitable soil. Inspections should also identify loose or damaged stakes, as well as loose portions of the blanket. If deficiencies are found, they should be repaired or replaced. Concrete Washout Area (Phase II) A concrete washout should be provided on the site. The washout can be lined or unlined excavated pits in the ground, commercially manufactured prefabricated containers, or aboveground holding areas. The concrete washout must be located a minimum of 400 feet from any natural drainage way or body of water, and at least 1000 feet from any wells or drinking water sources. Washout areas should not be located in an area where shallow groundwater may be present. Contractor shall clearly show the desired location and access to the Concrete Washout Area on the Stormwater Management Plan - Dynamic Site Plan. Contractor shall place a Vehicle Tracking Pad if the selected location for the Concrete Washout Area is detached from pavement. Clear signage identifying the concrete washout should also be provided. The Concrete Washout Area should be inspected regularly. Particular attention should be paid to signage to ensure that the area is clearly marked. Confirmation that the washout is being used should also be noted to ensure that other undesignated areas of the site are not being used incorrectly as a concrete washout. It is suggested the Contractor build a concrete wash out pit for this project. It is recommended that the concrete wash out pit be placed next to the vehicle tracking pad at the proposed access off Maple Street. This location is only a suggestion and can be relocated at the discretion of the Contractor. Morningstar/Block 23 Stormwater Management Plan 7 Permanent/Established Vegetation (Phase IV) Permanent or established vegetation and landscaping is considered a permanent form of sediment and erosion control for common open spaces, steep slopes and areas not exposed to prolonged scour velocities, or acute incipient motion bed shear stresses that will create soil erosion, rill formation and subsequent sediment transport. Areas where the previous conditions apply will contain sufficient permanent BMPs, such as riprap or cobble mulch. Permanent vegetation shall conform to the approved Landscape Plan prepared by The Birdsall Group. Permanent/Established vegetation and hardscape defines Phase IV of development. 3.4 Non-Structural Practices for Erosion and Sediment Control Non-Structural BMPs are practices or activities that are implemented to prevent erosion from happening or to limit erosion once it occurs. These BMPs can be a practice resulting in physical change to the site, such as mulching or slope stabilization. They can also result in behavioral changes on the site, such as changes to construction phasing to minimize exposure to weather elements, or increased employee awareness gained through training. Protection of Existing Vegetation (Phases I-IV) Protection of existing vegetation on a construction site can be accomplished through installation of a construction fence around the area requiring protection. In cases where up-gradient areas are disturbed, it may also be necessary to install perimeter controls to minimize sediment loading to sensitive areas such as wetlands. Trees that are to remain after construction is complete must be protected. Most tree roots grow within the top 12”-18” of soil, and soil compaction is a significant threat to tree health. As such, particular care should be taken to avoid activities within the drip-line of the tree. Direct equipment damage should also be prevented. The most effective way to ensure the health of trees is to establish a protection zone at the drip-line of the tree to prevent unintended activity in the area directly surrounding the tree. Fencing should be inspected and repaired when needed. If damage occurs to a tree, an arborist should be consulted on how to care for the tree. If a tree is damage beyond repair, the City Forester should be consulted on remediation measures. At a minimum, protection to all trees identified for retention on the plans by The Birdsall Group. Stockpile Management (Phases I-III) Stockpile management should be utilized to minimize erosion and sediment transport from soil stockpiles. In general, soil stockpiles should be located a minimum of 100 feet from any drainage way and 50 feet from any storm sewer inlets. Where practical, choose a stockpile location that will remain undisturbed for the longest period of time as the phases of construction progress. Sediment control BMPs should be placed around the perimeter of the stockpile, and a designated access point on the upstream side of the stockpile should be identified. BMPs such as surface roughening, temporary seeding, mulching, erosion control blankets, or soil binders should be used to stabilize the stockpile surface. As a part of stockpile management, regular inspections of the perimeter controls should be completed. If BMPs have been utilized to stabilize the surface of the stockpile, they should be inspected and repaired as needed. Morningstar/Block 23 Stormwater Management Plan 8 While soil stockpiles are not expected with this project, it is possible that foundation excavation or the delivery landscaping material may generate temporary stockpiles. The location of any such stockpiles shall be the responsibility of the SWMP Administrator. Mulching (Phase I-III) Mulching helps reduce erosion by protecting bare soil from rainfall impact, increasing infiltration, and reducing runoff. Although often applied in conjunction with temporary or permanent seeding, it can also be used for temporary stabilization of areas that cannot be reseeded due to seasonal constraints. The most common type of mulch used is hay or grass that is crimped into the soil to keep it secure. However, crimping may not be practical on slopes steeper than three to one (3H:1V). The Contractor shall mulch all planted areas within twenty-four (24) hours after planting. Only weed-free and seed-free straw mulch may be used. Straw mulch should be applied at two (2) tons per acre, and shall be adequately secured by crimping, tackifier, netting or blankets. Hydraulic mulching may also be used on steep slopes or where access is limited. In the case that hydraulic mulching is utilized, the Contractor shall use wood cellulose fibers mixed with water at two thousands to two thousand five hundred (2,000-2,500) pounds per acre and organic tackifier at one hundred to four hundred (100-400) pounds per acre. The Contractor is responsible in applying wood chip mulch to all planted trees and shrubs as shown on the Landscape Plan prepared by The Birdsall Group. Wind Erosion/Dust Control (Phase I-IV) Wind Erosion and Dust Control BMP’s help to keep soil particles from entering the air as a result of land disturbing construction activities. Attached at the end of the Appendix B is the Fort Collins Dust Prevention and Control Manual. The purpose of this manual is to establish minimum requirements consistent with nationally recognize BMP’s for controlling fugitive dust emissions and to describe applicable best management practices to prevent, minimize, and mitigate off-property transport or off-vehicle transport of fugitive dust emissions pursuant to Chapter 12, Article X of the Fort Collins City Code (§12-150 et. seq) for specific dust generating activities and sources. Examples include use of a water truck or irrigation/sprinkler system to wet the top layer of disturbed soil, seeding and mulching, soil binders, or wind fences. Please refer to the last three pages of Appendix B for the Dust Control Plan. A Dust Control Plan is required for all development projects or construction sites with greater than five (5) acres in size. Street Sweeping (Phases I -IV) Street sweeping should be used to remove sediment that has been tracked onto adjacent road ways. Roadways should be inspected at least once a day, and sediment should be removed as needed. A check of the area inlet protection should be completed after sweeping to ensure nothing was displaced during sweeping operations. Street sweeping can reduce the sediment washed into the existing storm drain system. Street sweeping may be necessary on the existing hardscape areas which receive runoff from the disturbed areas. Saw Cutting Pollution Prevention (Phase I) The following protocol is recommended to prevent dust and slurry from asphalt and concrete saw cutting activities from migrating into the existing storm drain system. • Slurry and cuttings shall be vacuumed during cutting and surfacing operations Morningstar/Block 23 Stormwater Management Plan 9 • Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight • Slurry and cuttings shall not drain to any natural or constructed drainage conveyance • Collected slurry and cuttings shall be disposed of in a manner that does not violate groundwater or surface water standards Good Housekeeping Practices (All phases) Good housekeeping practices that will prevent pollution associated with solid, liquid, and hazardous construction-related materials and wastes should be implemented throughout the project. Examples of good housekeeping include providing an appropriate location for waste management containers, establishing proper building material staging areas, designating paint and concrete washout areas, establishing proper equipment/vehicle fueling and maintenance practices. Development of a spill prevention and response plan is another example of Good Housekeeping practices that should be used on the project. The following items are detailed examples of some of the good housekeeping practices that should be utilized throughout the project. It should be noted that a complete list of practices and detailed discussion regarding good housekeeping has been included with Appendix B. Street Sweeping and Vacuuming – Street sweeping and vacuuming should be used to remove sediment that has been tracked onto adjacent roadways. Roadways should be inspected at least once a day, and sediment should be removed as needed. A check of inlet protection should be completed after sweeping to ensure nothing was displaced during sweeping operations. Waste Management – Designate trash and bulk waste collection areas on-site. When possible, materials should be recycled. Hazardous material waste should be segregated from other solid waste. Waste collection areas should be located away from streets, gutters, watercourses, and storm drains. Dumpsters should be located near site entrances to minimize traffic on disturbed soils, and they should be placed on a level soil surface. Establish Proper Building Material Handling and Staging areas – Clearly designate site areas for staging and storage of building materials. Provide appropriate BMPs to ensure that spills or leaks are contained. Establish Proper Equipment/Vehicle Fueling and Maintenance Practices – If needed, create a clearly designated on-site fueling and maintenance area that is clean and dry. Provide appropriate BMPs to ensure that spills or leaks are contained. 3.5 Phased BMP Installation It is important to recognize the four (4) major Development Phases as defined by the State of Colorado’s Stormwater Discharge Permit (SDP). These four development phases (referred to as Sequencing by the City of Fort Collins) have been distinguished to aid in the appropriate timing of installation/implementation of BMPs at different stages of the construction process. These phases are described as follows: Phase I – Grading Stage; BMPs for initial installation of perimeter controls Phase II – Infrastructure Stage; BMPs for utility, paving and curb installation Phase III – Vertical Construction Stage; BMPs for individual building construction. Morningstar/Block 23 Stormwater Management Plan 10 Phase IV – Permanent BMPs and final site stabilization. The following is a rough estimate of the anticipated construction sequence for site improvements. The schedule outlined below is subject to change as the project progresses and as determined by the General Contractor. Table 1 – Preliminary Permit and Construction Schedule TASK BEGINNING DATE ENDING DATE "BMP-PHASE OF DEVELOPMENT" Development Construction Permit Issued by City of Fort Collins April 2021 April 2021 I Overlot Grading (Demolition) April 2021 April 2021 I Utility Installation April 2021 May 2021 II Building Construction May 2021 January 2022 III Final Stabilization December 2021 January 2022 IV Included in the back map pockets are two Site Plans: a “Static” Site Plan and a “Dynamic” Site Plan. The “Static” plan serves to display the overall management plan all at once. However, proper implementation of BMPs does not occur at once, and certain BMPs may move location in the construction process; therefore, the “Dynamic” Site Plan is intended for the Contractor to write in the BMP symbols to document the location and time the BMPs are installed and maintained throughout the entire construction process. 3.6 Material Handling and Spill Prevention Potential pollution sources, as discussed in earlier sections, are to be to be identified by the Contractor. Spill prevention procedures are to be determined and put in place prior to construction by the Contractor. A spill and flooding response procedure must also be determined and put in place prior to construction by the Contractor. Additionally, steps should be taken to reduce the potential for leaks and spills to come in contact with stormwater runoff, such as storing and handling toxic materials in covered areas or by storing chemicals within berms or other secondary containment devices. A notification procedure must be put in place by the Contractor, by which workers would first notify the site construction superintendent, who would then notify the SWMP Administrator. Depending on the severity of the spill, the site construction superintendent and SWMP Administrator would possibly notify the Colorado Department of Public Health and Environment - Water Quality Control Division, downstream water users, or other appropriate agencies. The release of any chemical, oil, petroleum product, sewage, etc., which enter waters of the State of Colorado (which include surface water, ground water, and dry gullies or storm sewers leading to surface water) must be reported immediately to the Division’s emergency spill reporting line at (877) 518-5608. All spills that will require cleanup, even if the spill is minor and does not need to be reported to the state, should still be reported to the City of Fort Collins Utilities office at 970-221-6700. While not expected with this project, it will be the responsibility of the Contractor to designate a fueling area and take the necessary precautions to ensure that no stormwater pollution occurs in the event that a fueling area is needed. Fueling areas shall be located a minimum 100 feet from all drainage courses. A 12-inch high compacted earthen ridge capable of retaining potential spills Morningstar/Block 23 Stormwater Management Plan 11 shall enclose fueling areas. Other secondary containment devices can be used instead of the earthen ridge. The area shall be covered with a non-porous lining to prevent soil contamination. Printed instructions for cleanup procedures shall be posted in the fueling area and appropriate fuel absorbents shall be available along with containers for used absorbents within the fueling area. 3.7 Dedicated Concrete or Asphalt Batch Plant There are not any dedicated concrete or asphalt batch plants anticipated with this project. In the event that a plant is needed, the Contractor should be aware that additional permitting will be required. In particular, an Air Pollutant Emission Notice (APEN) will need to be obtained from the CDPHE. 3.8 Vehicle Tracking Control In addition to the vehicle tracking pads discussed previously, additional measures can be taken to minimize and control sediment discharges from the site due to vehicle tracking. These measures can include fencing around the site to control access points. Regular street sweeping can also be used to minimize the transmission of sediment from the site due to vehicles leaving the site. The use of gravel parking areas and wash racks can also be implemented to ensure minimal vehicle tracking from the site. 3.9 Waste Management and Disposal It will be the responsibility of the Contractor to designate a concrete truck chute washout area and to clearly identify that area. Detailed information about the design and maintenance of the Concrete Washout can be found under the Structural Practices section of this report. At no time should untreated wash water be allowed to discharge from the site or to enter a storm drain system or stream. Upon completion of construction activities the concrete washout material shall be removed and properly disposed of prior to the area being restored. Any waste material that currently exists on the site or that is generated by construction will be disposed of in such a manner as to not cause pollutants in stormwater discharges. If waste is to be stored on-site, it shall be in an area located a minimum of 100 feet from all drainage courses. Whenever waste is not stored in a non-porous container, it shall be in an area enclosed by a 12- inch high compacted earthen ridge or some other approved secondary containment device. The area shall be covered with a non-porous lining to prevent soil contamination. Whenever precipitation is predicted, the waste shall be covered with a non-porous cover, anchored on all sides to prevent its removal by wind, in order to prevent precipitation from leaching out potential pollutants from the waste. On-site waste disposal practices, such as dumpsters, should be covered or otherwise contained as to prevent dispersion of waste materials from wind. It shall also be the responsibility of the Contractor to maintain a clean jobsite as to prevent dispersion of waste material and potential pollutants into adjacent properties or waterways. This project is not known to have hazardous soil and groundwater on site. The location of, and protective measures for, temporary restroom facilities shall be the responsibility of the SWMP Administrator. 3.10 Groundwater and Stormwater Dewatering The BMPs selected for construction dewatering vary depending on the site-specific features, such as soils, topography, discharge quantities, and discharge location. Typically, dewatering involves Morningstar/Block 23 Stormwater Management Plan 12 pumping water from an inundated area to a BMP, prior to the water being released downstream into a receiving waterway, sediment basin, or well-vegetated area. Acceptable BMPs included discharging water into a sediment trap or basin, using a dewatering filter bag, or using a series of sediment logs. A settlement tank or an active treatment system can also be utilized. Another commonly used method to handle the pumped water is the “sprinkler method ,” which involves applying the water to vegetated areas through a perforated discharge hose. Dispersal from a water truck for dust control can also be used to disperse the pumped water. Per the Subsurface Exploration Report; Block 23 Development; Northwest Corner of North College Avenue and Maple Street prepared by Earth Engineering Consultants, LLC, groundwater was encountered roughly 12 to 18.5 feet below existing surface. 4.0 Final Stabilization and Long-Term Stormwater Management 4.1 Final Stabilization All disturbed areas will be seeded, crimped and mulched. Soil amendments such as compost, peat, aged manure, or other similar materials, shall also be utilized. Soil amendments shall be tilled into the soil to a minimum depth of 6”, and should comply with the requirements found in City Code Section 12-132 (refer also to Land Use Code 3.8.21). As defined by the Colorado Department of Public Health and Environment (CDPHE) in the General Permit Application for Stormwater Discharges, “Final stabilization is reached when all soil disturbing activities at the site have been completed, and uniform vegetative cover has been established with a density of at least 70 percent of pre-disturbance levels or equivalent permanent, physical erosion reduction methods have been employed.” Table 2 - Native Grass Seed Mix Preferred Varieties Seeded Rate (lbs. per acre, drilled) PLS Seeded/acre Leymus Cinereus Great Basin Wilrye Mangar 3 285,000 Nassella Viridula Green Needlegrass Lodorm 2 362,000 Chnatherum Hymenoides Indian Ricegrass Paloma, Nezpar 1 188,000 Elymus Trachycaulus Slender Wheatgrass Primar, Revenue 2 320,000 Elymus Lanceolatus Thickspike Wheatgrass Critana 3 580,500 Pascopyrum Smithii Western Wheatgrass Arriba, Barton 4 504,000 Totals 15 2,239,500 Species 4.2 Long-Term Stormwater Management All stormwater is being collected via curb and gutter, inlets, and proposed storm sewer, and is being discharged into an existing storm sewer within College Avenue so no rip-rap or erosion control matting is needed. There will be two separate water quality and detention systems for the site. The east half of the site will consist of small planters with a biomedia subsurface and underground water quality and detention chambers. The west half of the site will consist of a sand filter vault and a detention vault. 4.3 BMP Inspection All temporary erosion control facilities shall be inspected at a minimum of once every two (2) weeks and after each significant storm event or snowmelt. Repairs or reconstruction of BMPs, as Morningstar/Block 23 Stormwater Management Plan 13 necessary, shall occur as soon as possible in order to ensure the continued performance of their intended function. It is the responsibility of the SWMP Administrator to conduct bi-weekly inspections, maintain BMPs if needed, to keep records of site conditions and inspections, and to update the SWMP as necessary. The construction site perimeter, disturbed areas, all applicable/installed erosion and sediment control measures, and areas used for material storage that are exposed to precipitation shall be inspected for evidence of, or the potential for, pollutants entering the drainage system. Erosion and sediment control measures identified in the SWMP shall be observed to ensure that they are operating correctly. Attention should be paid to areas that have a significant potential for stormwater pollution, such as demolition areas, concrete washout locations, and vehicle entries to the site. The inspection must be documented to ensure compliance with the permit requirements. 4.4 BMP Maintenance Any BMP’s not operating in accordance with the SWMP must be addressed as soon as possible, immediately in most cases, to prevent the discharge of pollutants. If modifications are necessary, such modifications shall be documented so that the SWMP accurately reflects on-site conditions. The SWMP needs to accurately represent field conditions at all times. Uncontrolled releases of mud, muddy water, or measurable amounts of sediment found off-site will be recorded with a brief explanation of the measures taken to clean-up the sediment that has left the site, as well as the measures taken to prevent future releases. This record shall be made available to the appropriate public agencies (Colorado Department of Public Health and Environment, Water Quality Control Division; Environmental Protection Agency; City of Fort Collins; etc.) upon request. Preventative maintenance of all temporary and permanent erosion control BMPs shall be provided in order to ensure the continued performance of their intended function. Temporary erosion control measures are to be removed after the site has been sufficiently stabilized as determined by the City of Fort Collins. Maintenance activities and actions to correct problems shall be noted and recorded during inspections. Inspection and maintenance procedures specific to each BMP identified with this SWMP are discussed in Section 3. Details have also been included with Appendix B. 4.5 Record Keeping Documentation of site inspections must be maintained. The following items are to be recorded and kept with the SWMP: • Date of Inspection • Name(s) and title(s) of personnel making the inspection • Location(s) of sediment discharges or other pollutants from the site • Location(s) of BMP’s that need to be maintained • Location(s) of BMP’s that failed to operate as designed or proved inadequate • Locations(s) where additional BMP’s are needed that were not in place at the time of inspection • Deviations from the minimum inspection schedule • Descriptions of corrective action taken to remedy deficiencies that have been identified • The report shall contain a signed statement indicating the site is in compliance with the permit to the best of the signer’s knowledge and belief after corrective actions have been taken. Morningstar/Block 23 Stormwater Management Plan 14 Provided within Appendix E of this SWMP is an Example Inspection Log to aid in the record keeping of BMP inspections and maintenance. Photographs, field notebooks, drawings and maps should be included by the SWMP Administrator when appropriate. In addition to the Inspection Log, records should be kept documenting: • BMP maintenance and operation • Stormwater contamination • Contacts with suppliers • Notes on the need for and performance of preventive maintenance and other repairs • Implementation of specific items in the SWMP • Training events (given or attended) • Events involving materials handling and storage • Contacts with regulatory agencies and personnel • Notes of employee activities, contact, notifications, etc. Records of spills, leaks, or overflows that result in the discharge of pollutants must be documented and maintained. A record of other spills that are responded to, even if they do not result in a discharge of pollutants, should be made. Information that should be recorded for all occurrences includes the time and date, weather conditions, reasons for the spill, etc. Some spills may need to be reported to authorities immediately. Specifically, a release of any chemical, oil, petroleum product, sewage, etc., which may enter waters of the State of Colorado (which include s urface water, ground water and dry gullies or storm sewers leading to surface water) must be reported to the CDPHE. Additionally, the “Dynamic Site Plan” is intended to be a “living” document where the SWMP Administrator can hand write the location of BMPs as they are installed to appropriately reflect the current site conditions. Also on the “Dynamic Site Plan” is a “Table of Construction Sequence and BMP Application/Removal” that the SWMP Administrator can use to document when BMPs were installed or removed in conjunction with construction activities. These items have been included as an aid to the SWMP Administrator, and other methods of record keeping are at his or her discretion. This Stormwater Management Plan (both the text and map) is not a static document. It is a dynamic device intended to be kept current and logged as construction takes place. It shall be the responsibility of the SWMP Administrator and/or the permit holder (or applicant thereof) to ensure the plan is properly maintained and followed. Diligent administration is critical, including processing the Notice to Proceed and noting on the Stormwater Management Plan the dates that various construction activities occur and respective BMPs are installed and/or removed. Morningstar/Block 23 Stormwater Management Plan 15 5.0 Additional SWMP and BMP Resources Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual - Volume 3 “Best Management Practices” Colorado Department of Transportation Erosion Control and Stormwater Quality Guide BMP Field Academy EPA Menu of BMP’s Construction Site Storm Water Runoff Control International Stormwater Best Management (BMP) Database Rocky Mountain Education Center Rocky Mountain Education Center Red Rocks Community College, Lakewood Keep It Clean Partnership Boulder Morningstar/Block 23 Stormwater Management Plan 16 References 1. Final Drainage Report Morningstar/Block 23 Northern Engineering Services, December 16, 2020 (NE Project No. 1024-001) 2. Soil Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 3. Subsurface Exploration Report Block 23 Development Northwest Corner of North College Avenue and Maple Street, Earth Engineering Consultants LLC, August 5, 2019 (Project No. 1192054) 4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Water Resources Publications, LLC., Denver, Colorado, Updated November 2010. APPENDIX A SITE MAPS UDUDUDUDUDGUDFUDUDUDFDC T S T S G CONTROL IRR CONTROL IRR CONTROL IRRCC C CCCCCCEE CHERRY ST N COLLEGE AVEMAPLE STN MASON STPARKING GARAGE OLD TOWN FLATS LLC 310 N MASON ST FORT COLLINS, CO 80524 UNION PACIFIC RAILROADBURLINGTON NORTHERN RAILROAD30' RAILROAD EASEMENT REC. NO. 89053240 6' SIDEWALK6' SIDEWALK COURTYARD COURTYARD OFFSITE PERMEABLE PAVERS (SEE EROSION CONTROL NOTES 18 & 20) SheetBLOCK 23 - MORNINGSTARThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 26 DYN EROSION CONTROL PLANDYNAMIC PLAN NORTH ( IN FEET ) 0 1 INCH = 30 FEET 30 30 60 90 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY CONSTRUCTION FENCE ROCK SOCK 1.CONTRACTOR SHALL IMMEDIATELY STABILIZE ALL DISTURBED SLOPES BY CRIMP MULCHING OR SIMILAR METHODS. 2.SWMP ADMINISTRATOR: Contact ________________________________ Company ________________________________ Address ________________________________ Phone________________________________ 3.CONTRACTOR TO PROVIDE VEHICLE TRACKING CONTROL FOR CONCRETE WASHOUT AREA IF ACCESS IS OFF PAVEMENT. 4.REFER TO THE FINAL DRAINAGE REPORT FOR BLOCK 23, DATED BY NORTHERN ENGINEERING FOR ADDITIONAL INFORMATION. GENERAL NOTES: WATTLE DIKE CONCRETE WASH AREA LEGEND: INLET PROTECTION VEHICLE TRACKING CONTROL PAD CF TABLE OF CONSTRUCTION SEQUENCE AND BMP APPLICATION/REMOVAL Project: MORNINGSTAR/BLOCK 23 Date: 12/16/20 Contractor to utilize this table to indicate when construction activities occur and when each associated BMP is installed or removed. CONSTRUCTION PHASE (Monthly)1 2 3 4 5 6 7 8 9 10 11 12 Comments Grading Overlot Swales, Drainageways Pipeline Installation Stormwater Concrete Installation Building Structure Miscellaneous Hardscape Amenities BEST MANAGEMENT PRACTICES Temporary Contour Furrows and Diversion Dikes (Ripping/Disking) Inlet Protection (IP) Vehicle Tracking Control (VTC) Flow Barriers (Bales, Wattles, Etc) (WD) Concrete Washout Area (CWA) Preventative Maintenance Activities/Meetings/ etc. Permanent Mulching/Sealant Permanent Seed Planting Water Service Sanitary Sewer Service Curb and Gutter Concrete Parking and Drive Aisle EROSION CONTROL NOTES: 1.IT SHOULD BE NOTED THAT ANY EROSION CONTROL PLAN SERVES ONLY AS A GUIDELINE TO THE CONTRACTOR. STAGING AND/OR PHASING OF BEST MANAGEMENT PRACTICES (BMPs) IS EXPECTED. ADDITIONAL AND/OR DIFFERENT BMPs FROM THOSE ORIGINALLY DEPICTED MAY BE NECESSARY DURING CONSTRUCTION DUE TO CHANGING SITE CONDITIONS OR AS REQUIRED BY LOCAL AUTHORITIES. 2.THIS EROSION CONTROL PLAN IS SCHEMATIC IN NATURE. AS SUCH, GRAPHICAL SYMBOLS MAY NOT BE TO SCALE, NOR ARE THEY NECESSARILY SHOWN IN THEIR EXACT LOCATION. 3.THE CONTRACTOR SHALL BE RESPONSIBLE FOR ALL PERMITTING (CITY, STATE DISCHARGE PERMIT, ETC.) AND COMPLIANCE WITH GOVERNING AUTHORITIES. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR (OR PERMIT HOLDER) TO ENSURE EROSION CONTROL MEASURES ARE PROPERLY MAINTAINED AND FOLLOWED. 4.CONTRACTOR SHALL IMPLEMENT THE APPROPRIATE EROSION CONTROL MEASURES ACCORDING THE THE CONSTRUCTION SEQUENCING AND LEVEL OF SITE STABILIZATION. 5.CONTRACTOR SHALL IMPLEMENT APPROPRIATE INLET PROTECTION FOR ALL STORM DRAINS, SWALES, PONDS AND RAIN GARDENS UNTIL SITE IS FULLY STABILIZED. 6.CONTRACTOR SHALL IMPLEMENT APPROPRIATE INLET PROTECTION FOR DOWNSPOUT CONNECTIONS, TO THE STORM DRAIN SYSTEM, UNTIL CONNECTION IS ESTABLISHED WITH DOWNSPOUT. 7.INLET PROTECTION SHALL BE ADAPTED, AS NECESSARY, TO THE SURROUNDING SURFACE TYPE AND CONDITION (i.e., STAKE-DRIVEN WATTLES FOR BARE SOIL, GRAVEL SOCKS FOR PAVEMENT, ETC.) 8.CONTRACTOR IS RESPONSIBLE FOR STABILIZING ALL SLOPES, PARTICULARLY THOSE STEEPER THAN 6:1. CRIMP MULCHING, HYDRO MULCHING, EROSION MATS, TEMPORARY IRRIGATION, AND ADDITIONAL WATTLES OR SILT FENCING MAY BE NECESSARY TO ESTABLISH VEGETATIVE COVER AND STABILIZE THE SLOPE. 9.CONTRACTOR IS RESPONSIBLE FOR PREVENTING SEDIMENT FROM UNSTABILIZED LANDSCAPE AREAS FROM MIGRATING ONTO AND ENTERING THE PERMEABLE PAVER SYSTEMS UNTIL UPGRADIENT TRIBUTARY AREAS ARE FULLY STABILIZED. 10.ADDITIONAL WATTLES, SILT FENCE, OR OTHER MEASURES, MAY BE NECESSARY TO ENSURE THAT EACH BUILDING PAD IS STABILIZED THROUGHOUT CONSTRUCTION. WATTLES SHALL BE PROVIDED AROUND BUILDING PAD SIDES TO ENSURE AT NO TIME SHALL SEDIMENT BE ALLOWED TO CROSS THE PUBLIC SIDEWALKS. 11.CONTRACTOR SHALL IMPLEMENT APPROPRIATE PERIMETER PROTECTION FOR AREAS DIRECTING DRAINAGE OFFSITE. PERIMETER PROTECTION SHALL BE ADAPTED, AS NECESSARY, TO THE SURROUNDING SURFACE TYPE AND CONDITION (i.e., STAKE-DRIVEN SEDIMENT CONTROL LOGS OR SILT FENCE FOR BARE SOIL, GRAVEL SOCKS FOR PAVEMENT, ETC.) 12.FUELING FACILITIES SHALL BE LOCATED AT LEAST ONE HUNDRED (100) FEET FROM NATURAL BODY OF WATER, WETLAND, NATURAL DRAINAGE WAY OR MANMADE DRAINAGE WAY. THE FUEL TANKS AND FUELING AREA MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW A FUEL SPILL TO DIRECTLY FLOW, SEEP, RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY. 13.CONSTRUCTION WASTE STORAGE (DUMPSTERS) AND PORTABLE SANITATION UNITS (CONSTRUCTION TOILETS) SHALL BE LOCATED AT LEAST FIFTY (50) FEET FROM ANY STORMWATER INLET, WETLAND, OR DRAINAGE WAY. SAID FACILITIES MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW POLLUTANTS TO DIRECTLY FLOW, SEEP, RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY. DUMPSTERS SHALL BE LOCATED ON FLAT, STABLE GROUND, AND CONSTRUCTION TOILETS SHALL BE STAKED DOWN. 14.THE CONTRACTOR AND ALL SUBCONTRACTORS WILL COOPERATE WITH THE CITY'S CONSTRUCTION INSPECTORS BY CEASING OPERATIONS WHEN WINDS ARE OF SUFFICIENT VELOCITY TO CREATE BLOWING DUST WHICH, IN THE INSPECTOR'S OPINION, IS HAZARDOUS TO THE PUBLIC HEALTH AND WELFARE. 15.WHERE SEASONAL CONSTRAINTS (E.G., DURING SUMMER AND WINTER MONTHS) INHIBIT PERMANENT SEEDING OPERATIONS, DISTURBED AREAS WILL BE TREATED WITH MULCH AND MULCH TACKIFIER OR OTHER MATERIALS APPROVED BY EROSION CONTROL STAFF TO PREVENT EROSION. 16.CONTRACTOR SHALL EXERCISE CAUTION TO PROTECT RAIN GARDENS AND MODIFIED RAIN GARDEN FROM SEDIMENTATION. THIS INCLUDES EDUCATING SUBCONTRACTORS ON-SITE. 17.SEE LANDSCAPE PLANS FOR ADDITIONAL INFORMATION ON PLANTING, REVEGETATION, HARDSCAPE AND OTHER PERMANENT SITE STABILIZATION METHODS. 18.THE SITE MUST BE SWEPT AND MAINTAINED TO PREVENT DIRT, SEDIMENT, SAW CUTTINGS, CONCRETE WASH, TRASH & DEBRIS, LANDSCAPE MATERIALS AND OTHER POLLUTANTS FROM ENTERING STORM SEWER AT ALL TIMES. DIRT, DEBRIS, AND MUD FROM CONSTRUCTION ACTIVITIES SHALL NOT BE TRACKED ON TO CITY STREETS AND ALLEYS, AND THE SITE SHALL BE CLEANED NIGHTLY OR AT THE SUGGESTION OF THE CITY'S EROSION CONTROL INSPECTOR. CONTRACTOR SHALL TAKE EXTRA PRECAUTION TO PREVENT SEDIMENT, DEBRIS, AND DIRT FROM ENTERING OFFSITE PERMEABLE PAVERS, INCLUDING COVERING THE PERMEABLE PAVERS, LOCATED ON ADJACENT PROPERTIES (SEE EROSION CONTROL NOTE 20). 19.CONTRACTOR SHALL KEEP CONSTRUCTION VEHICLES ENTERING AND EXITING SITE TO A MINIMUM. 20.THE CONTRACTOR SHALL, AT ALL TIMES DURING AND AFTER SYSTEM INSTALLATION, PREVENT SEDIMENT, DEBRIS, AND DIRT FROM ANY SOURCE FROM ENTERING THE PERMEABLE PAVEMENT SYSTEM. LOOSE MATERIALS SHALL NOT BE STORED ON THE PERMEABLE PAVEMENT AREA. MUD AND SEDIMENT-LADEN RUNOFF SHOULD BE KEPT AWAY FROM THE PAVEMENT AREA. TEMPORARILY DIVERT RUNOFF OR INSTALL SEDIMENT CONTROL MEASURES AS NECESSARY TO REDUCE THE AMOUNT OF SEDIMENT RUN-ON TO THE PAVEMENT. SURFACE PROTECTION COULD INCLUDE COVERING AREAS OF THE PAVEMENT, PROVIDING ALTERNATIVE CONSTRUCTION VEHICLE ACCESS, AND PROVIDING EDUCATION TO ALL PARTIES WORKING ONSITE. UDUDUDUDUDGUDFUDUDUDFDC T S T S G CONTROL IRR CONTROL IRR CONTROL IRRCC C CCCCCCEECHERRY ST N COLLEGE AVEMAPLE STN MASON STPARKING GARAGE OLD TOWN FLATS LLC 310 N MASON ST FORT COLLINS, CO 80524 UNION PACIFIC RAILROADBURLINGTON NORTHERN RAILROAD30' RAILROAD EASEMENT REC. NO. 89053240 6' SIDEWALK6' SIDEWALK COURTYARD COURTYARD CF CF CFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCFCF CF CF CF CF CF CFCFCFCFCFCFCFCF CF CF CF CF CF OFFSITE PERMEABLE PAVERS (SEE EROSION CONTROL NOTES 18 & 20) SheetBLOCK 23 - MORNINGSTARThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 26 STATEROSION CONTROL PLANSTATIC PLAN NORTH ( IN FEET ) 0 1 INCH = 30 FEET 30 30 60 90 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY CONSTRUCTION FENCE ROCK SOCK 1.CONTRACTOR SHALL IMMEDIATELY STABILIZE ALL DISTURBED SLOPES BY CRIMP MULCHING OR SIMILAR METHODS. 2.SWMP ADMINISTRATOR: Contact ________________________________ Company ________________________________ Address ________________________________ Phone________________________________ 3.CONTRACTOR TO PROVIDE VEHICLE TRACKING CONTROL FOR CONCRETE WASHOUT AREA IF ACCESS IS OFF PAVEMENT. 4.REFER TO THE FINAL DRAINAGE REPORT FOR BLOCK 23, DATED BY NORTHERN ENGINEERING FOR ADDITIONAL INFORMATION. GENERAL NOTES: WATTLE DIKE CONCRETE WASH AREA LEGEND: INLET PROTECTION VEHICLE TRACKING CONTROL PAD CF TABLE OF CONSTRUCTION SEQUENCE AND BMP APPLICATION Project: MORNINGSTAR/BLOCK 23 CONSTRUCTION PHASE MOBILIZATION DEMOLITION GRADING BEST MANAGEMENT PRACTICES (BMPS) Structural "Installation" Flow Barriers (Bales, Wattles, etc.) (RS) UTILITIES INSTALLATION FLAT WORK INSTALLATION VERTICAL INSTALLATION LANDSCAPE DEMOBILIZATION Concrete Washout Area (CWA) * All Temporary BMPs to be Removed once Construction is Complete Vehicle Tracking Pad * (VTC) Construction Fence (CF) EROSION CONTROL NOTES: 1.IT SHOULD BE NOTED THAT ANY EROSION CONTROL PLAN SERVES ONLY AS A GUIDELINE TO THE CONTRACTOR. STAGING AND/OR PHASING OF BEST MANAGEMENT PRACTICES (BMPs) IS EXPECTED. ADDITIONAL AND/OR DIFFERENT BMPs FROM THOSE ORIGINALLY DEPICTED MAY BE NECESSARY DURING CONSTRUCTION DUE TO CHANGING SITE CONDITIONS OR AS REQUIRED BY LOCAL AUTHORITIES. 2.THIS EROSION CONTROL PLAN IS SCHEMATIC IN NATURE. AS SUCH, GRAPHICAL SYMBOLS MAY NOT BE TO SCALE, NOR ARE THEY NECESSARILY SHOWN IN THEIR EXACT LOCATION. 3.THE CONTRACTOR SHALL BE RESPONSIBLE FOR ALL PERMITTING (CITY, STATE DISCHARGE PERMIT, ETC.) AND COMPLIANCE WITH GOVERNING AUTHORITIES. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR (OR PERMIT HOLDER) TO ENSURE EROSION CONTROL MEASURES ARE PROPERLY MAINTAINED AND FOLLOWED. 4.CONTRACTOR SHALL IMPLEMENT THE APPROPRIATE EROSION CONTROL MEASURES ACCORDING THE THE CONSTRUCTION SEQUENCING AND LEVEL OF SITE STABILIZATION. 5.CONTRACTOR SHALL IMPLEMENT APPROPRIATE INLET PROTECTION FOR ALL STORM DRAINS, SWALES, PONDS AND RAIN GARDENS UNTIL SITE IS FULLY STABILIZED. 6.CONTRACTOR SHALL IMPLEMENT APPROPRIATE INLET PROTECTION FOR DOWNSPOUT CONNECTIONS, TO THE STORM DRAIN SYSTEM, UNTIL CONNECTION IS ESTABLISHED WITH DOWNSPOUT. 7.INLET PROTECTION SHALL BE ADAPTED, AS NECESSARY, TO THE SURROUNDING SURFACE TYPE AND CONDITION (i.e., STAKE-DRIVEN WATTLES FOR BARE SOIL, GRAVEL SOCKS FOR PAVEMENT, ETC.) 8.CONTRACTOR IS RESPONSIBLE FOR STABILIZING ALL SLOPES, PARTICULARLY THOSE STEEPER THAN 6:1. CRIMP MULCHING, HYDRO MULCHING, EROSION MATS, TEMPORARY IRRIGATION, AND ADDITIONAL WATTLES OR SILT FENCING MAY BE NECESSARY TO ESTABLISH VEGETATIVE COVER AND STABILIZE THE SLOPE. 9.CONTRACTOR IS RESPONSIBLE FOR PREVENTING SEDIMENT FROM UNSTABILIZED LANDSCAPE AREAS FROM MIGRATING ONTO AND ENTERING THE PERMEABLE PAVER SYSTEMS UNTIL UPGRADIENT TRIBUTARY AREAS ARE FULLY STABILIZED. 10.ADDITIONAL WATTLES, SILT FENCE, OR OTHER MEASURES, MAY BE NECESSARY TO ENSURE THAT EACH BUILDING PAD IS STABILIZED THROUGHOUT CONSTRUCTION. WATTLES SHALL BE PROVIDED AROUND BUILDING PAD SIDES TO ENSURE AT NO TIME SHALL SEDIMENT BE ALLOWED TO CROSS THE PUBLIC SIDEWALKS. 11.CONTRACTOR SHALL IMPLEMENT APPROPRIATE PERIMETER PROTECTION FOR AREAS DIRECTING DRAINAGE OFFSITE. PERIMETER PROTECTION SHALL BE ADAPTED, AS NECESSARY, TO THE SURROUNDING SURFACE TYPE AND CONDITION (i.e., STAKE-DRIVEN SEDIMENT CONTROL LOGS OR SILT FENCE FOR BARE SOIL, GRAVEL SOCKS FOR PAVEMENT, ETC.) 12.FUELING FACILITIES SHALL BE LOCATED AT LEAST ONE HUNDRED (100) FEET FROM NATURAL BODY OF WATER, WETLAND, NATURAL DRAINAGE WAY OR MANMADE DRAINAGE WAY. THE FUEL TANKS AND FUELING AREA MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW A FUEL SPILL TO DIRECTLY FLOW, SEEP, RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY. 13.CONSTRUCTION WASTE STORAGE (DUMPSTERS) AND PORTABLE SANITATION UNITS (CONSTRUCTION TOILETS) SHALL BE LOCATED AT LEAST FIFTY (50) FEET FROM ANY STORMWATER INLET, WETLAND, OR DRAINAGE WAY. SAID FACILITIES MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW POLLUTANTS TO DIRECTLY FLOW, SEEP, RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY. DUMPSTERS SHALL BE LOCATED ON FLAT, STABLE GROUND, AND CONSTRUCTION TOILETS SHALL BE STAKED DOWN. 14.THE CONTRACTOR AND ALL SUBCONTRACTORS WILL COOPERATE WITH THE CITY'S CONSTRUCTION INSPECTORS BY CEASING OPERATIONS WHEN WINDS ARE OF SUFFICIENT VELOCITY TO CREATE BLOWING DUST WHICH, IN THE INSPECTOR'S OPINION, IS HAZARDOUS TO THE PUBLIC HEALTH AND WELFARE. 15.WHERE SEASONAL CONSTRAINTS (E.G., DURING SUMMER AND WINTER MONTHS) INHIBIT PERMANENT SEEDING OPERATIONS, DISTURBED AREAS WILL BE TREATED WITH MULCH AND MULCH TACKIFIER OR OTHER MATERIALS APPROVED BY EROSION CONTROL STAFF TO PREVENT EROSION. 16.CONTRACTOR SHALL EXERCISE CAUTION TO PROTECT RAIN GARDENS AND MODIFIED RAIN GARDEN FROM SEDIMENTATION. THIS INCLUDES EDUCATING SUBCONTRACTORS ON-SITE. 17.SEE LANDSCAPE PLANS FOR ADDITIONAL INFORMATION ON PLANTING, REVEGETATION, HARDSCAPE AND OTHER PERMANENT SITE STABILIZATION METHODS. 18.THE SITE MUST BE SWEPT AND MAINTAINED TO PREVENT DIRT, SEDIMENT, SAW CUTTINGS, CONCRETE WASH, TRASH & DEBRIS, LANDSCAPE MATERIALS AND OTHER POLLUTANTS FROM ENTERING STORM SEWER AT ALL TIMES. DIRT, DEBRIS, AND MUD FROM CONSTRUCTION ACTIVITIES SHALL NOT BE TRACKED ON TO CITY STREETS AND ALLEYS, AND THE SITE SHALL BE CLEANED NIGHTLY OR AT THE SUGGESTION OF THE CITY'S EROSION CONTROL INSPECTOR. CONTRACTOR SHALL TAKE EXTRA PRECAUTION TO PREVENT SEDIMENT, DEBRIS, AND DIRT FROM ENTERING OFFSITE PERMEABLE PAVERS, INCLUDING COVERING THE PERMEABLE PAVERS, LOCATED ON ADJACENT PROPERTIES (SEE EROSION CONTROL NOTE 20). 19.CONTRACTOR SHALL KEEP CONSTRUCTION VEHICLES ENTERING AND EXITING SITE TO A MINIMUM. 20.THE CONTRACTOR SHALL, AT ALL TIMES DURING AND AFTER SYSTEM INSTALLATION, PREVENT SEDIMENT, DEBRIS, AND DIRT FROM ANY SOURCE FROM ENTERING THE PERMEABLE PAVEMENT SYSTEM. LOOSE MATERIALS SHALL NOT BE STORED ON THE PERMEABLE PAVEMENT AREA. MUD AND SEDIMENT-LADEN RUNOFF SHOULD BE KEPT AWAY FROM THE PAVEMENT AREA. TEMPORARILY DIVERT RUNOFF OR INSTALL SEDIMENT CONTROL MEASURES AS NECESSARY TO REDUCE THE AMOUNT OF SEDIMENT RUN-ON TO THE PAVEMENT. SURFACE PROTECTION COULD INCLUDE COVERING AREAS OF THE PAVEMENT, PROVIDING ALTERNATIVE CONSTRUCTION VEHICLE ACCESS, AND PROVIDING EDUCATION TO ALL PARTIES WORKING ONSITE. APPENDIX B EROSION CONTROL DETAILS SheetBLOCK 23 - MORNINGSTARThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 26 EC2 EROSION CONTROL DETAILS19 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R VTC ROCK SOCK SECTION ROCK SOCK PLAN ROCK SOCK JOINTING GRADATION TABLE SIEVE SIZE MASS PERCENT PASSING SQUARE MESH SIEVES NO. 4 2"100 1-1/2"90-100 1"20-55 3/4"0-15 3/8"0-5 MATCHES SPECIFICATIONS FOR NO. 4 COARSE AGGREGATE FOR CONCRETE PER AASHTO M43. ALL ROCK SHALL BE FRACTURED FACE, ALL SIDES RS 001 CONCRETE WASHOUT AREA 002 ROCK SOCK 003 VEHICLE TRACKING PAD 004 CONSTRUCTION FENCE w/ ROCK SOCKS TEMPORARY CHAIN-LINK FENCE ROCK SOCK TEMPORARY CHAIN-LINK FENCE ROCK SOCK SIDE VIEW CF CWA 005 WD 006 CURB INLET PROTECTION IP SWALE WATTLE DIKE Chapter 7 Construction BMPs November 2010 Urban Drainage and Flood Control District 7-13 Urban Storm Drainage Criteria Manual Volume 3 Final Stabilization ▪Revegetate Site ▪Activate Post Construction BMPs (e.g., convert sediment basin to extended detention basin) ▪Remove Temporary BMPs ▪Closeout State and Local Stormwater Permits Construction Phase Representative Phases: ▪Clearing and Grubbing ▪Rough Grading ▪Road Construction ▪Utility and Infrastructure Installation ▪Vertical Construction (Buildings) ▪Final Grading Management Practices: ▪Phase Construction Activities to Minimize Disturbed Area at a Given Time ▪Sequence Contruction within Phases to Avoid Idle Disturbed Areas ▪Install, Inspect and Proactively Maintain BMPs Appropriate for Each Phase of Construction ▪Maintain and Update SWMP as Construction Progresses Pre-Construction ▪Develop Site Plan ▪Obtain Site Survey, Hydrology and Soils Information ▪Prepare SWMP ▪Obtain Stormwater Construction Permits (State and Local) ▪Obtain Other Relevant Permits (e.g., 404 , Floodplain, Dewatering) Figure 7-2. Construction Stormwater Management Construction BMPs Construction BMPs 7-14 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Functions Erosion Control Sediment Control Site/Material Management Surface Roughening Yes No No Temporary/Permanent Seeding Yes No No Soil Binders Yes No Moderate Mulching Yes Moderate No Compost Blankets and Filter Berms Yes Moderate No Rolled Erosion Control Products Yes No No Temporary Slope Drains Yes No No Temporary Outlet Protection Yes Moderate No Rough Cut Street Control Yes Moderate No Earth Dikes / Drainage Swales Yes Moderate No Terracing Yes Moderate No Check Dams Yes Moderate No Streambank Stabilization Yes No No Wind Erosion / Dust Control Yes No Moderate Silt Fence No Yes No Sediment Control Log Moderate Yes No Straw Bale Barrier No Moderate No Brush Barrier Moderate Moderate No Rock Sock (perimeter control)No Yes No Inlet Protection (various forms)No Yes No Sediment Basins No Yes No Sediment Traps No Yes No Vegetative Buffers Moderate Yes Yes Chemical Treatment Moderate Yes No Concrete Washout Area No No Yes Stockpile Management Yes Yes Yes Good Houskeeping (multiple practices)No No Yes Construction Phasing Moderate Moderate Yes Protection of Existing Vegetation Yes Moderate Yes Construction Fence No No Yes Vehicle Tracking Control Moderate Yes Yes Stabilized Construction Roadway Yes Moderate Yes Stabilized Staging Area Yes Moderate Yes Street Sweeping / Vacuuming No Yes Yes Temporary Diversion Channel Yes No No Dewatering Operations Moderate Yes Yes Temporary Stream Crossing Yes Yes No Temporary Batch Plants No No Yes Paving and Grinding Operations No No Yes Site Management and Other Specific Practices Sediment Control BMPs Erosion Control BMPs Materials Management Table 7-2. Overview of Construction BMPs Surface Roughening (SR) EC-1 November 2010 Urban Drainage and Flood Control District SR-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SR-1. Surface roughening via imprinting for temporary stabilization. Description Surface roughening is an erosion control practice that involves tracking, scarifying, imprinting, or tilling a disturbed area to provide temporary stabilization of disturbed areas. Surface roughening creates variations in the soil surface that help to minimize wind and water erosion. Depending on the technique used, surface roughening may also help establish conditions favorable to establishment of vegetation. Appropriate Uses Surface roughening can be used to provide temporary stabilization of disturbed areas, such as when revegetation cannot be immediately established due to seasonal planting limitations. Surface roughening is not a stand-alone BMP, and should be used in conjunction with other erosion and sediment controls. Surface roughening is often implemented in conjunction with grading and is typically performed using heavy construction equipment to track the surface. Be aware that tracking with heavy equipment will also compact soils, which is not desirable in areas that will be revegetated. Scarifying, tilling, or ripping are better surface roughening techniques in locations where revegetation is planned. Roughening is not effective in very sandy soils and cannot be effectively performed in rocky soil. Design and Installation Typical design details for surfacing roughening on steep and mild slopes are provided in Details SR-1 and SR-2, respectively. Surface roughening should be performed either after final grading or to temporarily stabilize an area during active construction that may be inactive for a short time period. Surface roughening should create depressions 2 to 6 inches deep and approximately 6 inches apart. The surface of exposed soil can be roughened by a number of techniques and equipment. Horizontal grooves (running parallel to the contours of the land) can be made using tracks from equipment treads, stair-step grading, ripping, or tilling. Fill slopes can be constructed with a roughened surface. Cut slopes that have been smooth graded can be roughened as a subsequent operation. Roughening should follow along the contours of the slope. The tracks left by truck mounted equipment working perpendicular to the contour can leave acceptable horizontal depressions; however, the equipment will also compact the soil. Surface Roughening Functions Erosion Control Yes Sediment Control No Site/Material Management No EC-1 Surface Roughening (SR) SR-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Maintenance and Removal Care should be taken not to drive vehicles or equipment over areas that have been surface roughened. Tire tracks will smooth the roughened surface and may cause runoff to collect into rills and gullies. Because surface roughening is only a temporary control, additional treatments may be necessary to maintain the soil surface in a roughened condition. Areas should be inspected for signs of erosion. Surface roughening is a temporary measure, and will not provide long-term erosion control. Surface Roughening (SR) EC-1 November 2010 Urban Drainage and Flood Control District SR-3 Urban Storm Drainage Criteria Manual Volume 3 EC-1 Surface Roughening (SR) SR-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Temporary and Permanent Seeding (TS/PS) EC-2 November 2010 Urban Drainage and Flood Control District TS/PS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph TS/PS -1. Equipment used to drill seed. Photo courtesy of Douglas County. Description Temporary seeding can be used to stabilize disturbed areas that will be inactive for an extended period. Permanent seeding should be used to stabilize areas at final grade that will not be otherwise stabilized. Effective seeding includes preparation of a seedbed, selection of an appropriate seed mixture, proper planting techniques, and protection of the seeded area with mulch, geotextiles, or other appropriate measures. Appropriate Uses When the soil surface is disturbed and will remain inactive for an extended period (typically 30 days or longer), proactive stabilization measures should be implemented. If the inactive period is short-lived (on the order of two weeks), techniques such as surface roughening may be appropriate. For longer periods of inactivity, temporary seeding and mulching can provide effective erosion control. Permanent seeding should be used on finished areas that have not been otherwise stabilized. Typically, local governments have their own seed mixes and timelines for seeding. Check jurisdictional requirements for seeding and temporary stabilization. Design and Installation Effective seeding requires proper seedbed preparation, selection of an appropriate seed mixture, use of appropriate seeding equipment to ensure proper coverage and density, and protection with mulch or fabric until plants are established. The USDCM Volume 2 Revegetation Chapter contains detailed seed mix, soil preparations, and seeding and mulching recommendations that may be referenced to supplement this Fact Sheet. Drill seeding is the preferred seeding method. Hydroseeding is not recommended except in areas where steep slopes prevent use of drill seeding equipment, and even in these instances it is preferable to hand seed and mulch. Some jurisdictions do not allow hydroseeding or hydromulching. Seedbed Preparation Prior to seeding, ensure that areas to be revegetated have soil conditions capable of supporting vegetation. Overlot grading can result in loss of topsoil, resulting in poor quality subsoils at the ground surface that have low nutrient value, little organic matter content, few soil microorganisms, rooting restrictions, and conditions less conducive to infiltration of precipitation. As a result, it is typically necessary to provide stockpiled topsoil, compost, or other Temporary and Permanent Seeding Functions Erosion Control Yes Sediment Control No Site/Material Management No EC-2 Temporary and Permanent Seeding (TS/PS) TS/PS-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 soil amendments and rototill them into the soil to a depth of 6 inches or more. Topsoil should be salvaged during grading operations for use and spread on areas to be revegetated later. Topsoil should be viewed as an important resource to be utilized for vegetation establishment, due to its water-holding capacity, structure, texture, organic matter content, biological activity, and nutrient content. The rooting depth of most native grasses in the semi-arid Denver metropolitan area is 6 to 18 inches. At a minimum, the upper 6 inches of topsoil should be stripped, stockpiled, and ultimately respread across areas that will be revegetated. Where topsoil is not available, subsoils should be amended to provide an appropriate plant-growth medium. Organic matter, such as well digested compost, can be added to improve soil characteristics conducive to plant growth. Other treatments can be used to adjust soil pH conditions when needed. Soil testing, which is typically inexpensive, should be completed to determine and optimize the types and amounts of amendments that are required. If the disturbed ground surface is compacted, rip or rototill the surface prior to placing topsoil. If adding compost to the existing soil surface, rototilling is necessary. Surface roughening will assist in placement of a stable topsoil layer on steeper slopes, and allow infiltration and root penetration to greater depth. Prior to seeding, the soil surface should be rough and the seedbed should be firm, but neither too loose nor compacted. The upper layer of soil should be in a condition suitable for seeding at the proper depth and conducive to plant growth. Seed-to-soil contact is the key to good germination. Seed Mix for Temporary Vegetation To provide temporary vegetative cover on disturbed areas which will not be paved, built upon, or fully landscaped or worked for an extended period (typically 30 days or more), plant an annual grass appropriate for the time of planting and mulch the planted areas. Annual grasses suitable for the Denver metropolitan area are listed in Table TS/PS-1. These are to be considered only as general recommendations when specific design guidance for a particular site is not available. Local governments typically specify seed mixes appropriate for their jurisdiction. Seed Mix for Permanent Revegetation To provide vegetative cover on disturbed areas that have reached final grade, a perennial grass mix should be established. Permanent seeding should be performed promptly (typically within 14 days) after reaching final grade. Each site will have different characteristics and a landscape professional or the local jurisdiction should be contacted to determine the most suitable seed mix for a specific site. In lieu of a specific recommendation, one of the perennial grass mixes appropriate for site conditions and growth season listed in Table TS/PS-2 can be used. The pure live seed (PLS) rates of application recommended in these tables are considered to be absolute minimum rates for seed applied using proper drill-seeding equipment. If desired for wildlife habitat or landscape diversity, shrubs such as rubber rabbitbrush (Chrysothamnus nauseosus), fourwing saltbush (Atriplex canescens) and skunkbrush sumac (Rhus trilobata) could be added to the upland seedmixes at 0.25, 0.5 and 1 pound PLS/acre, respectively. In riparian zones, planting root stock of such species as American plum (Prunus americana), woods rose (Rosa woodsii), plains cottonwood (Populus sargentii), and willow (Populus spp.) may be considered. On non-topsoiled upland sites, a legume such as Ladak alfalfa at 1 pound PLS/acre can be included as a source of nitrogen for perennial grasses. Temporary and Permanent Seeding (TS/PS) EC-2 November 2010 Urban Drainage and Flood Control District TS/PS-3 Urban Storm Drainage Criteria Manual Volume 3 Seeding dates for the highest success probability of perennial species along the Front Range are generally in the spring from April through early May and in the fall after the first of September until the ground freezes. If the area is irrigated, seeding may occur in summer months, as well. See Table TS/PS-3 for appropriate seeding dates. Table TS/PS-1. Minimum Drill Seeding Rates for Various Temporary Annual Grasses Speciesa (Common name) Growth Seasonb Pounds of Pure Live Seed (PLS)/acrec Planting Depth (inches) 1. Oats Cool 35 - 50 1 - 2 2. Spring wheat Cool 25 - 35 1 - 2 3. Spring barley Cool 25 - 35 1 - 2 4. Annual ryegrass Cool 10 - 15 ½ 5. Millet Warm 3 - 15 ½ - ¾ 6. Sudangrass Warm 5–10 ½ - ¾ 7. Sorghum Warm 5–10 ½ - ¾ 8. Winter wheat Cool 20–35 1 - 2 9. Winter barley Cool 20–35 1 - 2 10. Winter rye Cool 20–35 1 - 2 11. Triticale Cool 25–40 1 - 2 a Successful seeding of annual grass resulting in adequate plant growth will usually produce enough dead-plant residue to provide protection from wind and water erosion for an additional year. This assumes that the cover is not disturbed or mowed closer than 8 inches. Hydraulic seeding may be substituted for drilling only where slopes are steeper than 3:1 or where access limitations exist. When hydraulic seeding is used, hydraulic mulching should be applied as a separate operation, when practical, to prevent the seeds from being encapsulated in the mulch. b See Table TS/PS-3 for seeding dates. Irrigation, if consistently applied, may extend the use of cool season species during the summer months. c Seeding rates should be doubled if seed is broadcast, or increased by 50 percent if done using a Brillion Drill or by hydraulic seeding. EC-2 Temporary and Permanent Seeding (TS/PS) TS/PS-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Table TS/PS-2. Minimum Drill Seeding Rates for Perennial Grasses Commona Name Botanical Name Growth Seasonb Growth Form Seeds/ Pound Pounds of PLS/acre Alakali Soil Seed Mix Alkali sacaton Sporobolus airoides Cool Bunch 1,750,000 0.25 Basin wildrye Elymus cinereus Cool Bunch 165,000 2.5 Sodar streambank wheatgrass Agropyron riparium 'Sodar' Cool Sod 170,000 2.5 Jose tall wheatgrass Agropyron elongatum 'Jose' Cool Bunch 79,000 7.0 Arriba western wheatgrass Agropyron smithii 'Arriba' Cool Sod 110,000 5.5 Total 17.75 Fertile Loamy Soil Seed Mix Ephriam crested wheatgrass Agropyron cristatum 'Ephriam' Cool Sod 175,000 2.0 Dural hard fescue Festuca ovina 'duriuscula' Cool Bunch 565,000 1.0 Lincoln smooth brome Bromus inermis leyss 'Lincoln' Cool Sod 130,000 3.0 Sodar streambank wheatgrass Agropyron riparium 'Sodar' Cool Sod 170,000 2.5 Arriba western wheatgrass Agropyron smithii 'Arriba' Cool Sod 110,000 7.0 Total 15.5 High Water Table Soil Seed Mix Meadow foxtail Alopecurus pratensis Cool Sod 900,000 0.5 Redtop Agrostis alba Warm Open sod 5,000,000 0.25 Reed canarygrass Phalaris arundinacea Cool Sod 68,000 0.5 Lincoln smooth brome Bromus inermis leyss 'Lincoln' Cool Sod 130,000 3.0 Pathfinder switchgrass Panicum virgatum 'Pathfinder' Warm Sod 389,000 1.0 Alkar tall wheatgrass Agropyron elongatum 'Alkar' Cool Bunch 79,000 5.5 Total 10.75 Transition Turf Seed Mixc Ruebens Canadian bluegrass Poa compressa 'Ruebens' Cool Sod 2,500,000 0.5 Dural hard fescue Festuca ovina 'duriuscula' Cool Bunch 565,000 1.0 Citation perennial ryegrass Lolium perenne 'Citation' Cool Sod 247,000 3.0 Lincoln smooth brome Bromus inermis leyss 'Lincoln' Cool Sod 130,000 3.0 Total 7.5 Temporary and Permanent Seeding (TS/PS) EC-2 November 2010 Urban Drainage and Flood Control District TS/PS-5 Urban Storm Drainage Criteria Manual Volume 3 Table TS/PS-2. Minimum Drill Seeding Rates for Perennial Grasses (cont.) Common Name Botanical Name Growth Seasonb Growth Form Seeds/ Pound Pounds of PLS/acre Sandy Soil Seed Mix Blue grama Bouteloua gracilis Warm Sod-forming bunchgrass 825,000 0.5 Camper little bluestem Schizachyrium scoparium 'Camper' Warm Bunch 240,000 1.0 Prairie sandreed Calamovilfa longifolia Warm Open sod 274,000 1.0 Sand dropseed Sporobolus cryptandrus Cool Bunch 5,298,000 0.25 Vaughn sideoats grama Bouteloua curtipendula 'Vaughn' Warm Sod 191,000 2.0 Arriba western wheatgrass Agropyron smithii 'Arriba' Cool Sod 110,000 5.5 Total 10.25 Heavy Clay, Rocky Foothill Seed Mix Ephriam crested wheatgrassd Agropyron cristatum 'Ephriam' Cool Sod 175,000 1.5 Oahe Intermediate wheatgrass Agropyron intermedium 'Oahe' Cool Sod 115,000 5.5 Vaughn sideoats gramae Bouteloua curtipendula 'Vaughn' Warm Sod 191,000 2.0 Lincoln smooth brome Bromus inermis leyss 'Lincoln' Cool Sod 130,000 3.0 Arriba western wheatgrass Agropyron smithii 'Arriba' Cool Sod 110,000 5.5 Total 17.5 a All of the above seeding mixes and rates are based on drill seeding followed by crimped hay or straw mulch. These rates should be doubled if seed is broadcast and should be increased by 50 percent if the seeding is done using a Brillion Drill or is applied through hydraulic seeding. Hydraulic seeding may be substituted for drilling only where slopes are steeper than 3:1. If hydraulic seeding is used, hydraulic mulching should be done as a separate operation. b See Table TS/PS-3 for seeding dates. c If site is to be irrigated, the transition turf seed rates should be doubled. d Crested wheatgrass should not be used on slopes steeper than 6H to 1V. e Can substitute 0.5 lbs PLS of blue grama for the 2.0 lbs PLS of Vaughn sideoats grama. EC-2 Temporary and Permanent Seeding (TS/PS) TS/PS-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Table TS/PS-3. Seeding Dates for Annual and Perennial Grasses Annual Grasses (Numbers in table reference species in Table TS/PS-1) Perennial Grasses Seeding Dates Warm Cool Warm Cool January 1–March 15   March 16–April 30 4 1,2,3   May 1–May 15 4  May 16–June 30 4,5,6,7 July 1–July 15 5,6,7 July 16–August 31 September 1–September 30 8,9,10,11 October 1–December 31   Mulch Cover seeded areas with mulch or an appropriate rolled erosion control product to promote establishment of vegetation. Anchor mulch by crimping, netting or use of a non-toxic tackifier. See the Mulching BMP Fact Sheet for additional guidance. Maintenance and Removal Monitor and observe seeded areas to identify areas of poor growth or areas that fail to germinate. Reseed and mulch these areas, as needed. An area that has been permanently seeded should have a good stand of vegetation within one growing season if irrigated and within three growing seasons without irrigation in Colorado. Reseed portions of the site that fail to germinate or remain bare after the first growing season. Seeded areas may require irrigation, particularly during extended dry periods. Targeted weed control may also be necessary. Protect seeded areas from construction equipment and vehicle access. Soil Binders (SB) EC-3 November 2010 Urban Drainage and Flood Control District SB-1 Urban Storm Drainage Criteria Manual Volume 3 Description Soil binders include a broad range of treatments that can be applied to exposed soils for temporary stabilization to reduce wind and water erosion. Soil binders may be applied alone or as tackifiers in conjunction with mulching and seeding applications. Acknowledgement: This BMP Fact Sheet has been adapted from the 2003 California Stormwater Quality Association (CASQA) Stormwater BMP Handbook: Construction (www.cabmphandbooks.com). Appropriate Uses Soil binders can be used for short-term, temporary stabilization of soils on both mild and steep slopes. Soil binders are often used in areas where work has temporarily stopped, but is expected to resume before revegetation can become established. Binders are also useful on stockpiled soils or where temporary or permanent seeding has occurred. Prior to selecting a soil binder, check with the state and local jurisdiction to ensure that the chemicals used in the soil binders are allowed. The water quality impacts of some types of soil binders are relatively unknown and may not be allowed due to concerns about potential environmental impacts. Soil binders must be environmentally benign (non-toxic to plant and animal life), easy to apply, easy to maintain, economical, and should not stain paved or painted surfaces. Soil binders should not be used in vehicle or pedestrian high traffic areas, due to loss in effectiveness under these conditions. Site soil type will dictate appropriate soil binders to be used. Be aware that soil binders may not function effectively on silt or clay soils or highly compacted areas. Check manufacturer's recommendations for appropriateness with regard to soil conditions. Some binders may not be suitable for areas with existing vegetation. Design and Installation Properties of common soil binders used for erosion control are provided in Table SB-1. Design and installation guidance below are provided for general reference. Follow the manufacturer's instructions for application rates and procedures. Soil Binders Functions Erosion Control Yes Sediment Control No Site/Material Management Moderate Photograph SB-1. Tackifier being applied to provide temporary soil stabilization. Photo courtesy of Douglas County. EC-3 Soil Binders (SB) SB-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Table SB-1. Properties of Soil Binders for Erosion Control (Source: CASQA 2003) Evaluation Criteria Binder Type Plant Material Based (short lived) Plant Material Based (long lived) Polymeric Emulsion Blends Cementitious- Based Binders Resistance to Leaching High High Low to Moderate Moderate Resistance to Abrasion Moderate Low Moderate to High Moderate to High Longevity Short to Medium Medium Medium to Long Medium Minimum Curing Time before Rain 9 to 18 hours 19 to 24 hours 0 to 24 hours 4 to 8 hours Compatibility with Existing Vegetation Good Poor Poor Poor Mode of Degradation Biodegradable Biodegradable Photodegradable/ Chemically Degradable Photodegradable/ Chemically Degradable Specialized Application Equipment Water Truck or Hydraulic Mulcher Water Truck or Hydraulic Mulcher Water Truck or Hydraulic Mulcher Water Truck or Hydraulic Mulcher Liquid/Powder Powder Liquid Liquid/Powder Powder Surface Crusting Yes, but dissolves on rewetting Yes Yes, but dissolves on rewetting Yes Clean Up Water Water Water Water Erosion Control Application Rate Varies Varies Varies 4,000 to 12,000 lbs/acre Typ. Soil Binders (SB) EC-3 November 2010 Urban Drainage and Flood Control District SB-3 Urban Storm Drainage Criteria Manual Volume 3 Factors to consider when selecting a soil binder generally include:  Suitability to situation: Consider where the soil binder will be applied, if it needs a high resistance to leaching or abrasion, and whether it needs to be compatible with existing vegetation. Determine the length of time soil stabilization will be needed, and if the soil binder will be placed in an area where it will degrade rapidly. In general, slope steepness is not a discriminating factor.  Soil types and surface materials: Fines and moisture content are key properties of surface materials. Consider a soil binder's ability to penetrate, likelihood of leaching, and ability to form a surface crust on the surface materials.  Frequency of application: The frequency of application can be affected by subgrade conditions, surface type, climate, and maintenance schedule. Frequent applications could lead to high costs. Application frequency may be minimized if the soil binder has good penetration, low evaporation, and good longevity. Consider also that frequent application will require frequent equipment clean up. An overview of major categories of soil binders, corresponding to the types included in Table SB-1 follows. Plant-Material Based (Short Lived) Binders  Guar: A non-toxic, biodegradable, natural galactomannan-based hydrocolloid treated with dispersant agents for easy field mixing. It should be mixed with water at the rate of 11 to 15 lbs per 1,000 gallons. Recommended minimum application rates are provided in Table SB-2. Table SB-2. Application Rates for Guar Soil Stabilizer Slope (H:V) Flat 4:1 3:1 2:1 1:1 Application Rate (lb/acre) 40 45 50 60 70  Psyllium: Composed of the finely ground muciloid coating of plantago seeds that is applied as a wet slurry to the surface of the soil. It dries to form a firm but rewettable membrane that binds soil particles together but permits germination and growth of seed. Psyllium requires 12 to 18 hours drying time. Application rates should be from 80 to 200 lbs/acre, with enough water in solution to allow for a uniform slurry flow.  Starch: Non-ionic, cold-water soluble (pre-gelatinized) granular cornstarch. The material is mixed with water and applied at the rate of 150 lb/acre. Approximate drying time is 9 to 12 hours. Plant-Material Based (Long Lived) Binders  Pitch and Rosin Emulsion: Generally, a non-ionic pitch and rosin emulsion has a minimum solids content of 48 percent. The rosin should be a minimum of 26 percent of the total solids content. The soil stabilizer should be a non-corrosive, water dilutable emulsion that upon application cures to a water insoluble binding and cementing agent. For soil erosion control applications, the emulsion is diluted and should be applied as follows: o For clayey soil: 5 parts water to 1 part emulsion EC-3 Soil Binders (SB) SB-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 o For sandy soil: 10 parts water to 1 part emulsion Application can be by water truck or hydraulic seeder with the emulsion and product mixture applied at the rate specified by the manufacturer. Polymeric Emulsion Blend Binders  Acrylic Copolymers and Polymers: Polymeric soil stabilizers should consist of a liquid or solid polymer or copolymer with an acrylic base that contains a minimum of 55 percent solids. The polymeric compound should be handled and mixed in a manner that will not cause foaming or should contain an anti-foaming agent. The polymeric emulsion should not exceed its shelf life or expiration date; manufacturers should provide the expiration date. Polymeric soil stabilizer should be readily miscible in water, non-injurious to seed or animal life, non-flammable, should provide surface soil stabilization for various soil types without inhibiting water infiltration, and should not re-emulsify when cured. The applied compound should air cure within a maximum of 36 to 48 hours. Liquid copolymer should be diluted at a rate of 10 parts water to 1 part polymer and the mixture applied to soil at a rate of 1,175 gallons/acre.  Liquid Polymers of Methacrylates and Acrylates: This material consists of a tackifier/sealer that is a liquid polymer of methacrylates and acrylates. It is an aqueous 100 percent acrylic emulsion blend of 40 percent solids by volume that is free from styrene, acetate, vinyl, ethoxylated surfactants or silicates. For soil stabilization applications, it is diluted with water in accordance with manufacturer's recommendations, and applied with a hydraulic seeder at the rate of 20 gallons/acre. Drying time is 12 to 18 hours after application.  Copolymers of Sodium Acrylates and Acrylamides: These materials are non-toxic, dry powders that are copolymers of sodium acrylate and acrylamide. They are mixed with water and applied to the soil surface for erosion control at rates that are determined by slope gradient, as summarized in Table SB-3. Table SB-3. Application Rates for Copolymers of Sodium Acrylates and Acrylamides Slope (H:V) Flat to 5:1 5:1 to 3:1 2:2 to 1:1 Application Rate (lb/acre) 3.0-5.0 5.0-10.0 10.0-20.0  Polyacrylamide and Copolymer of Acrylamide: Linear copolymer polyacrylamide is packaged as a dry flowable solid. When used as a stand-alone stabilizer, it is diluted at a rate of 11 lb/1,000 gal. of water and applied at the rate of 5.0 lb/acre.  Hydrocolloid Polymers: Hydrocolloid Polymers are various combinations of dry flowable polyacrylamides, copolymers, and hydrocolloid polymers that are mixed with water and applied to the soil surface at rates of 55 to 60 lb/acre. Drying times are 0 to 4 hours. Cementitious-Based Binders  Gypsum: This formulated gypsum based product readily mixes with water and mulch to form a thin protective crust on the soil surface. It is composed of high purity gypsum that is ground, calcined and processed into calcium sulfate hemihydrate with a minimum purity of 86 percent. It is mixed in a hydraulic seeder and applied at rates 4,000 to 12,000 lb/acre. Drying time is 4 to 8 hours. Soil Binders (SB) EC-3 November 2010 Urban Drainage and Flood Control District SB-5 Urban Storm Drainage Criteria Manual Volume 3 Installation After selecting an appropriate soil binder, the untreated soil surface must be prepared before applying the soil binder. The untreated soil surface must contain sufficient moisture to assist the agent in achieving uniform distribution. In general, the following steps should be followed:  Follow manufacturer's written recommendations for application rates, pre-wetting of application area, and cleaning of equipment after use.  Prior to application, roughen embankment and fill areas.  Consider the drying time for the selected soil binder and apply with sufficient time before anticipated rainfall. Soil binders should not be applied during or immediately before rainfall.  Avoid over spray onto roads, sidewalks, drainage channels, sound walls, existing vegetation, etc.  Soil binders should not be applied to frozen soil, areas with standing water, under freezing or rainy conditions, or when the temperature is below 40°F during the curing period.  More than one treatment is often necessary, although the second treatment may be diluted or have a lower application rate.  Generally, soil binders require a minimum curing time of 24 hours before they are fully effective. Refer to manufacturer's instructions for specific cure time.  For liquid agents: o Crown or slope ground to avoid ponding. o Uniformly pre-wet ground at 0.03 to 0.3 gal/yd2 or according to manufacturer's recommendations. o Apply solution under pressure. Overlap solution 6 to 12 in. o Allow treated area to cure for the time recommended by the manufacturer, typically at least 24 hours. o Apply second treatment before first treatment becomes ineffective, using 50 percent application rate. o In low humidity, reactivate chemicals by re-wetting with water at 0.1 to 0.2 gal/yd2. Maintenance and Removal Soil binders tend to break down due to natural weathering. Weathering rates depend on a variety of site- specific and product characteristics. Consult the manufacturer for recommended reapplication rates and reapply the selected soil binder as needed to maintain effectiveness. Soil binders can fail after heavy rainfall events and may require reapplication. In particular, soil binders will generally experience spot failures during heavy rainfall events. If runoff penetrates the soil at the top of a slope treated with a soil binder, it is likely that the runoff will undercut the stabilized soil layer and discharge at a point further down slope. EC-3 Soil Binders (SB) SB-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Areas where erosion is evident should be repaired and soil binder or other stabilization reapplied, as needed. Care should be exercised to minimize the damage to protected areas while making repairs. Most binders biodegrade after exposure to sun, oxidation, heat and biological organisms; therefore, removal of the soil binder is not typically required. Mulching (MU) EC-4 November 2010 Urban Drainage and Flood Control District MU-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph MU-1. An area that was recently seeded, mulched, and crimped. Description Mulching consists of evenly applying straw, hay, shredded wood mulch, bark or compost to disturbed soils and securing the mulch by crimping, tackifiers, netting or other measures. Mulching helps reduce erosion by protecting bare soil from rainfall impact, increasing infiltration, and reducing runoff. Although often applied in conjunction with temporary or permanent seeding, it can also be used for temporary stabilization of areas that cannot be reseeded due to seasonal constraints. Mulch can be applied either using standard mechanical dry application methods or using hydromulching equipment that hydraulically applies a slurry of water, wood fiber mulch, and often a tackifier. Appropriate Uses Use mulch in conjunction with seeding to help protect the seedbed and stabilize the soil. Mulch can also be used as a temporary cover on low to mild slopes to help temporarily stabilize disturbed areas where growing season constraints prevent effective reseeding. Disturbed areas should be properly mulched and tacked, or seeded, mulched and tacked promptly after final grade is reached (typically within no longer than 14 days) on portions of the site not otherwise permanently stabilized. Standard dry mulching is encouraged in most jurisdictions; however, hydromulching may not be allowed in certain jurisdictions or may not be allowed near waterways. Do not apply mulch during windy conditions. Design and Installation Prior to mulching, surface-roughen areas by rolling with a crimping or punching type roller or by track walking. Track walking should only be used where other methods are impractical because track walking with heavy equipment typically compacts the soil. A variety of mulches can be used effectively at construction sites, including the following types: Mulch Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-4 Mulching (MU) MU-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3  Clean, weed- and seed-free, long-stemmed grass hay (preferred) or cereal grain straw. Hay is preferred because it is less susceptible to removal by wind. Mulch should be applied evenly at a rate of 2 tons per acre and must be tacked or fastened by an approved method suitable for the type of mulch used. At least 50 percent of the grass hay mulch, by weight, should be 10 inches or more in length.  Grass hay mulch must be anchored and not merely placed on the surface. This can be accomplished mechanically by crimping or with the aid of tackifiers or nets. Anchoring with a crimping implement is preferred, and is the recommended method for areas flatter than 3:1. Mechanical crimpers must be capable of tucking the long mulch fibers into the soil to a depth of 3 inches without cutting them. An agricultural disk, while not an ideal substitute, may work if the disk blades are dull or blunted and set vertically; however, the frame may have to be weighted to afford proper soil penetration.  On small areas sheltered from the wind and heavy runoff, spraying a tackifier on the mulch is satisfactory for holding it in place. For steep slopes and special situations where greater control is needed, erosion control blankets anchored with stakes should be used instead of mulch.  Hydraulic mulching consists of wood cellulose fibers mixed with water and a tackifying agent and should be applied at a rate of no less than 1,500 pounds per acre (1,425 lbs of fibers mixed with at least 75 lbs of tackifier) with a hydraulic mulcher. For steeper slopes, up to 2000 pounds per acre may be required for effective hydroseeding. Hydromulch typically requires up to 24 hours to dry; therefore, it should not be applied immediately prior to inclement weather. Application to roads, waterways and existing vegetation should be avoided.  Erosion control mats, blankets, or nets are recommended to help stabilize steep slopes (generally 3:1 and steeper) and waterways. Depending on the product, these may be used alone or in conjunction with grass or straw mulch. Normally, use of these products will be restricted to relatively small areas. Biodegradable mats made of straw and jute, straw-coconut, coconut fiber, or excelsior can be used instead of mulch. (See the ECM/TRM BMP for more information.)  Some tackifiers or binders may be used to anchor mulch. Check with the local jurisdiction for allowed tackifiers. Manufacturer's recommendations should be followed at all times. (See the Soil Binder BMP for more information on general types of tackifiers.)  Rock can also be used as mulch. It provides protection of exposed soils to wind and water erosion and allows infiltration of precipitation. An aggregate base course can be spread on disturbed areas for temporary or permanent stabilization. The rock mulch layer should be thick enough to provide full coverage of exposed soil on the area it is applied. Maintenance and Removal After mulching, the bare ground surface should not be more than 10 percent exposed. Reapply mulch, as needed, to cover bare areas. Compost Blanket and Filter Berm (CB) EC-5 November 2010 Urban Drainage and Flood Control District CB-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph CB-1. Application of a compost blanket to a disturbed area. Photo courtesy of Caltrans. Description A compost blanket is a layer of compost uniformly applied to the soil in disturbed areas to control erosion, facilitate revegetation, and retain sediment resulting from sheet-flow runoff. A compost filter berm is a dike of compost or a compost product that is placed perpendicular to runoff to control erosion in disturbed areas and retain sediment. Compost berms can be placed at regular intervals to help reduce the formation of rill and gully erosion when a compost blanket is stabilizing a slope. Appropriate Uses Compost blankets can be used as an alternative to erosion control blankets and mulching to help stabilize disturbed areas where sheet flow conditions are present. Compost blankets should not be used in areas of concentrated flows. Compost provides an excellent source of nutrients for plant growth, and should be considered for use in areas that will be permanently vegetated. Design and Installation See Detail CB-1 for design details and notes. Do not place compost in areas where it can easily be transported into drainage pathways or waterways. When using a compost blanket on a slope, berms should be installed periodically to reduce the potential for concentrated flow and rilling. Seeding should be completed before an area is composted or incorporated into the compost. Compost quality is an important consideration when selecting compost blankets or berms. Representative compost quality factors include pH, salinity, moisture content, organic matter content, stability (maturity), and physical contaminants. The compost should meet all local, state, and federal quality requirements. Biosolids compost must meet the Standards for Class A biosolids outlined in 40 CFR Part 503. The U.S. Composting Council (USCC) certifies compost products under its Seal of Testing Assurance (STA) Program. Compost producers whose products have been certified through the STA Program provide customers with a standard product label that allows comparison between compost products. Only STA certified, Class I compost should be used. Compost Blankets and Berms Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-5 Compost Blanket and Filter Berm (CB) CB-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Maintenance and Removal When rills or gullies develop in an area that has been composted, fill and cover the area with additional compost and install berms as necessary to help reduce erosion. Weed control can be a maintenance challenge in areas using compost blankets. A weed control strategy may be necessary, including measures such as mechanical removal and spot application of targeted herbicides by licensed applicators. For compost berms, accumulated sediments should be removed from behind the berm when the sediments reach approximately one third the height of the berm. Areas that have been washed away should be replaced. If the berm has experienced significant or repeated washouts, a compost berm may not be the appropriate BMP for this area. Compost blankets and berms biodegrade and do not typically require removal following site stabilization. Compost Blanket and Filter Berm (CB) EC-5 November 2010 Urban Drainage and Flood Control District CB-3 Urban Storm Drainage Criteria Manual Volume 3 EC-5 Compost Blanket and Filter Berm (CB) CB-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC-6 November 2010 Urban Drainage and Flood Control District RECP-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph RECP-1. Erosion control blanket protecting the slope from erosion and providing favorable conditions for revegetation. Description Rolled Erosion Control Products (RECPs) include a variety of temporary or permanently installed manufactured products designed to control erosion and enhance vegetation establishment and survivability, particularly on slopes and in channels. For applications where natural vegetation alone will provide sufficient permanent erosion protection, temporary products such as netting, open weave textiles and a variety of erosion control blankets (ECBs) made of biodegradable natural materials (e.g., straw, coconut fiber) can be used. For applications where natural vegetation alone will not be sustainable under expected flow conditions, permanent rolled erosion control products such as turf reinforcement mats (TRMs) can be used. In particular, turf reinforcement mats are designed for discharges that exert velocities and sheer stresses that exceed the typical limits of mature natural vegetation. Appropriate Uses RECPs can be used to control erosion in conjunction with revegetation efforts, providing seedbed protection from wind and water erosion. These products are often used on disturbed areas on steep slopes, in areas with highly erosive soils, or as part of drainageway stabilization. In order to select the appropriate RECP for site conditions, it is important to have a general understanding of the general types of these products, their expected longevity, and general characteristics. The Erosion Control Technology Council (ECTC 2005) characterizes rolled erosion control products according to these categories:  Mulch control netting: A planar woven natural fiber or extruded geosynthetic mesh used as a temporary degradable rolled erosion control product to anchor loose fiber mulches.  Open weave textile: A temporary degradable rolled erosion control product composed of processed natural or polymer yarns woven into a matrix, used to provide erosion control and facilitate vegetation establishment.  Erosion control blanket (ECB): A temporary degradable rolled erosion control product composed of processed natural or polymer fibers which are mechanically, structurally or chemically bound together to form a continuous matrix to provide erosion control and facilitate vegetation establishment. ECBs can be further differentiated into rapidly degrading single-net and double-net types or slowly degrading types. Rolled Erosion Control Products Functions Erosion Control Yes Sediment Control No Site/Material Management No EC-6 Rolled Erosion Control Products (RECP) RECP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3  Turf Reinforcement Mat (TRM): A rolled erosion control product composed of non-degradable synthetic fibers, filaments, nets, wire mesh, and/or other elements, processed into a permanent, three- dimensional matrix of sufficient thickness. TRMs, which may be supplemented with degradable components, are designed to impart immediate erosion protection, enhance vegetation establishment and provide long-term functionality by permanently reinforcing vegetation during and after maturation. Note: TRMs are typically used in hydraulic applications, such as high flow ditches and channels, steep slopes, stream banks, and shorelines, where erosive forces may exceed the limits of natural, unreinforced vegetation or in areas where limited vegetation establishment is anticipated. Tables RECP-1 and RECP-2 provide guidelines for selecting rolled erosion control products appropriate to site conditions and desired longevity. Table RECP-1 is for conditions where natural vegetation alone will provide permanent erosion control, whereas Table RECP-2 is for conditions where vegetation alone will not be adequately stable to provide long-term erosion protection due to flow or other conditions. Rolled Erosion Control Products (RECP) EC-6 November 2010 Urban Drainage and Flood Control District RECP-3 Urban Storm Drainage Criteria Manual Volume 3 Table RECP-1. ECTC Standard Specification for Temporary Rolled Erosion Control Products (Adapted from Erosion Control Technology Council 2005) Product Description Slope Applications* Channel Applications* Minimum Tensile Strength1 Expected Longevity Maximum Gradient C Factor2,5 Max. Shear Stress3,4,6 Mulch Control Nets 5:1 (H:V) ≤0.10 @ 5:1 0.25 lbs/ft2 (12 Pa) 5 lbs/ft (0.073 kN/m) Up to 12 months Netless Rolled Erosion Control Blankets 4:1 (H:V) ≤0.10 @ 4:1 0.5 lbs/ft2 (24 Pa) 5 lbs/ft (0.073 kN/m) Single-net Erosion Control Blankets & Open Weave Textiles 3:1 (H:V) ≤0.15 @ 3:1 1.5 lbs/ft2 (72 Pa) 50 lbs/ft (0.73 kN/m) Double-net Erosion Control Blankets 2:1 (H:V) ≤0.20 @ 2:1 1.75 lbs/ft2 (84 Pa) 75 lbs/ft (1.09 kN/m) Mulch Control Nets 5:1 (H:V) ≤0.10 @ 5:1 0.25 lbs/ft2 (12 Pa) 25 lbs/ft (0.36 kN/m) 24 months Erosion Control Blankets & Open Weave Textiles (slowly degrading) 1.5:1 (H:V) ≤0.25 @ 1.5:1 2.00 lbs/ft2 (96 Pa) 100 lbs/ft (1.45 kN/m) 24 months Erosion Control Blankets & Open Weave Textiles 1:1 (H:V) ≤0.25 @ 1:1 2.25 lbs/ft2 (108 Pa) 125 lbs/ft (1.82 kN/m) 36 months * C Factor and shear stress for mulch control nettings must be obtained with netting used in conjunction with pre-applied mulch material. (See Section 5.3 of Chapter 7 Construction BMPs for more information on the C Factor.) 1 Minimum Average Roll Values, Machine direction using ECTC Mod. ASTM D 5035. 2 C Factor calculated as ratio of soil loss from RECP protected slope (tested at specified or greater gradient, H:V) to ratio of soil loss from unprotected (control) plot in large-scale testing. 3 Required minimum shear stress RECP (unvegetated) can sustain without physical damage or excess erosion (> 12.7 mm (0.5 in) soil loss) during a 30-minute flow event in large-scale testing. 4 The permissible shear stress levels established for each performance category are based on historical experience with products characterized by Manning's roughness coefficients in the range of 0.01 - 0.05. 5 Acceptable large-scale test methods may include ASTM D 6459, or other independent testing deemed acceptable by the engineer. 6 Per the engineer’s discretion. Recommended acceptable large-scale testing protocol may include ASTM D 6460, or other independent testing deemed acceptable by the engineer. EC-6 Rolled Erosion Control Products (RECP) RECP-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Table RECP-2. ECTC Standard Specification for Permanent1 Rolled Erosion Control Products (Adapted from: Erosion Control Technology Council 2005) Product Type Slope Applications Channel Applications TRMs with a minimum thickness of 0.25 inches (6.35 mm) per ASTM D 6525 and UV stability of 80% per ASTM D 4355 (500 hours exposure). Maximum Gradient Maximum Shear Stress4,5 Minimum Tensile Strength2,3 0.5:1 (H:V) 6.0 lbs/ft2 (288 Pa) 125 lbs/ft (1.82 kN/m) 0.5:1 (H:V) 8.0 lbs/ft2 (384 Pa) 150 lbs/ft (2.19 kN/m) 0.5:1 (H:V) 10.0 lbs/ft2 (480 Pa) 175 lbs/ft (2.55 kN/m) 1 For TRMs containing degradable components, all property values must be obtained on the non- degradable portion of the matting alone. 2 Minimum Average Roll Values, machine direction only for tensile strength determination using ASTM D 6818 (Supersedes Mod. ASTM D 5035 for RECPs) 3 Field conditions with high loading and/or high survivability requirements may warrant the use of a TRM with a tensile strength of 44 kN/m (3,000 lb/ft) or greater. 4 Required minimum shear stress TRM (fully vegetated) can sustain without physical damage or excess erosion (> 12.7 mm (0.5 in.) soil loss) during a 30-minute flow event in large scale testing. 5 Acceptable large-scale testing protocols may include ASTM D 6460, or other independent testing deemed acceptable by the engineer. Design and Installation RECPs should be installed according to manufacturer’s specifications and guidelines. Regardless of the type of product used, it is important to ensure no gaps or voids exist under the material and that all corners of the material are secured using stakes and trenching. Continuous contact between the product and the soil is necessary to avoid failure. Never use metal stakes to secure temporary erosion control products. Often wooden stakes are used to anchor RECPs; however, wood stakes may present installation and maintenance challenges and generally take a long time to biodegrade. Some local jurisdictions have had favorable experiences using biodegradable stakes. This BMP Fact Sheet provides design details for several commonly used ECB applications, including: ECB-1 Pipe Outlet to Drainageway ECB-2 Small Ditch or Drainageway ECB-3 Outside of Drainageway Rolled Erosion Control Products (RECP) EC-6 November 2010 Urban Drainage and Flood Control District RECP-5 Urban Storm Drainage Criteria Manual Volume 3 Staking patterns are also provided in the design details according to these factors:  ECB type  Slope or channel type For other types of RECPs including TRMs, these design details are intended to serve as general guidelines for design and installation; however, engineers should adhere to manufacturer’s installation recommendations. Maintenance and Removal Inspection of erosion control blankets and other RECPs includes:  Check for general signs of erosion, including voids beneath the mat. If voids are apparent, fill the void with suitable soil and replace the erosion control blanket, following the appropriate staking pattern.  Check for damaged or loose stakes and secure loose portions of the blanket. Erosion control blankets and other RECPs that are biodegradable typically do not need to be removed after construction. If they must be removed, then an alternate soil stabilization method should be installed promptly following removal. Turf reinforcement mats, although generally resistant to biodegradation, are typically left in place as a dense vegetated cover grows in through the mat matrix. The turf reinforcement mat provides long-term stability and helps the established vegetation resist erosive forces. EC-6 Rolled Erosion Control Products (RECP) RECP-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC-6 November 2010 Urban Drainage and Flood Control District RECP-7 Urban Storm Drainage Criteria Manual Volume 3 EC-6 Rolled Erosion Control Products (RECP) RECP-8 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rolled Erosion Control Products (RECP) EC-6 November 2010 Urban Drainage and Flood Control District RECP-9 Urban Storm Drainage Criteria Manual Volume 3 Temporary Slope Drains (TSD) EC-7 November 2010 Urban Drainage and Flood Control District SD-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph TSD-1. A temporary slope drain installed to convey runoff down a slope during construction. Photo courtesy of the City of Aurora. Description A temporary slope drain is a pipe or culvert used to convey water down a slope where there is a high potential for erosion. A drainage channel or swale at the top of the slope typically directs upgradient runoff to the pipe entrance for conveyance down the slope. The pipe outlet must be equipped with outlet protection. Appropriate Uses Use on long, steep slopes when there is a high potential of flow concentration or rill development. Design and Installation Effective use of temporary slope drains involves design of an effective collection system to direct flows to the pipe, proper sizing and anchoring of the pipe, and outlet protection. Upgradient of the temporary slope drain, a temporary drainage ditch or swale should be constructed to collect surface runoff from the drainage area and convey it to the drain entrance. The temporary slope drain must be sized to safely convey the desired flow volume. At a minimum, it should be sized to convey the 2-year, 24-hour storm. Temporary slope drains may be constructed of flexible or rigid pipe, riprap, or heavy (30 mil) plastic lining. When piping is used, it must be properly anchored by burying it with adequate cover or by using an anchor system to secure it to the ground. The discharge from the slope drain must be directed to a stabilized outlet, temporary or permanent channel, and/or sedimentation basin. See Detail TSD-1 for additional sizing and design information. Temporary Slope Drains Functions Erosion Control Yes Sediment Control No Site/Material Management No EC-7 Temporary Slope Drains (TSD) SD-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Maintenance and Removal Inspect the entrance for sediment accumulation and remove, as needed. Clogging as a result of sediment deposition at the entrance can lead to ponding upstream causing flooding or overtopping of the slope drain. Inspect the downstream outlet for signs of erosion and stabilize, as needed. It may also be necessary to remove accumulated sediment at the outfall. Inspect pipe anchors to ensure that they are secure. If the pipe is secured by ground cover, ensure erosion has not compromised the depth of cover. Slope drains should be removed when no longer needed or just prior to installation of permanent slope stabilization measures that cannot be installed with the slope drain in place. When slope drains are removed, the disturbed areas should be covered with topsoil, seeded, mulched or otherwise stabilized as required by the local jurisdiction. Temporary Slope Drains (TSD) EC-7 November 2010 Urban Drainage and Flood Control District SD-3 Urban Storm Drainage Criteria Manual Volume 3 EC-7 Temporary Slope Drains (TSD) SD-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Temporary Outlet Protection (TOP) EC-8 November 2010 Urban Drainage and Flood Control District TOP-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph TOP-1. Riprap outlet protection. Description Outlet protection helps to reduce erosion immediately downstream of a pipe, culvert, slope drain, rundown or other conveyance with concentrated, high- velocity flows. Typical outlet protection consists of riprap or rock aprons at the conveyance outlet. Appropriate Uses Outlet protection should be used when a conveyance discharges onto a disturbed area where there is potential for accelerated erosion due to concentrated flow. Outlet protection should be provided where the velocity at the culvert outlet exceeds the maximum permissible velocity of the material in the receiving channel. Note: This Fact Sheet and detail are for temporary outlet protection, outlets that are intended to be used for less than 2 years. For permanent, long-term outlet protection, see the Major Drainage chapter of Volume 1. Design and Installation Design outlet protection to handle runoff from the largest drainage area that may be contributing runoff during construction (the drainage area may change as a result of grading). Key in rock, around the entire perimeter of the apron, to a minimum depth of 6 inches for stability. Extend riprap to the height of the culvert or the normal flow depth of the downstream channel, whichever is less. Additional erosion control measures such as vegetative lining, turf reinforcement mat and/or other channel lining methods may be required downstream of the outlet protection if the channel is susceptible to erosion. See Design Detail OP-1 for additional information. Maintenance and Removal Inspect apron for damage and displaced rocks. If rocks are missing or significantly displaced, repair or replace as necessary. If rocks are continuously missing or displaced, consider increasing the size of the riprap or deeper keying of the perimeter. Remove sediment accumulated at the outlet before the outlet protection becomes buried and ineffective. When sediment accumulation is noted, check that upgradient BMPs, including inlet protection, are in effective operating condition. Outlet protection may be removed once the pipe is no longer draining an upstream area, or once the downstream area has been sufficiently stabilized. If the drainage pipe is permanent, outlet protection can be left in place; however, permanent outlet protection should be designed and constructed in accordance with the requirements of the Major Drainage chapter of Volume 2. Outlet Protection Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-8 Temporary Outlet Protection (TOP) TOP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Temporary Outlet Protection (TOP) EC-8 November 2010 Urban Drainage and Flood Control District TOP-3 Urban Storm Drainage Criteria Manual Volume 3 Rough Cut Street Control (RCS) EC-9 November 2010 Urban Drainage and Flood Control District RCS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph RCS-1. Rough cut street controls. Description Rough cut street controls are rock or earthen berms placed along dirt roadways that are under construction or used for construction access. These temporary berms intercept sheet flow and divert runoff from the roadway, and control erosion by minimizing concentration of flow and reducing runoff velocity. Appropriate Uses Appropriate uses include:  Temporary dirt construction roadways that have not received roadbase.  Roadways under construction that will not be paved within 14 days of final grading, and that have not yet received roadbase. Design and Installation Rough cut street controls are designed to redirect sheet flow off the dirt roadway to prevent water from concentrating and eroding the soil. These controls consist of runoff barriers that are constructed at intervals along the road. These barriers are installed perpendicular to the longitudinal slope from the outer edge of the roadside swale to the crown of the road. The barriers are positioned alternately from the right and left side of the road to allow construction traffic to pass in the lane not barred. If construction traffic is expected to be congested and a vehicle tracking control has been constructed, rough-cut street controls may be omitted for 400 feet from the entrance. Runoff from the controls should be directed to another stormwater BMP such as a roadside swale with check dams once removed from the roadway. See Detail RCS-1 for additional information. Maintenance and Removal Inspect street controls for erosion and stability. If rills are forming in the roadway or cutting through the control berms, place the street controls at shorter intervals. If earthen berms are used, periodic recompaction may be necessary. When rock berms are used, repair and/or replace as necessary when damaged. Street controls may be removed 14 days prior to road surfacing and paving. Rough Cut Street Control Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-9 Rough Cut Street Control (RCS) RCS-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rough Cut Street Control (RCS) EC-9 November 2010 Urban Drainage and Flood Control District RCS-3 Urban Storm Drainage Criteria Manual Volume 3 Earth Dikes and Drainage Swales (ED/DS) EC-10 November 2010 Urban Drainage and Flood Control District ED/DS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph ED/DS-1. Example of an earth dike used to divert flows at a construction site. Photo courtesy of CDOT. Description Earth dikes and drainage swales are temporary storm conveyance channels constructed either to divert runoff around slopes or to convey runoff to additional sediment control BMPs prior to discharge of runoff from a site. Drainage swales may be lined or unlined, but if an unlined swale is used, it must be well compacted and capable of resisting erosive velocities. Appropriate Uses Earth dikes and drainage swales are typically used to control the flow path of runoff at a construction site by diverting runoff around areas prone to erosion, such as steep slopes. Earth dikes and drainage swales may also be constructed as temporary conveyance features. This will direct runoff to additional sediment control treatment BMPs, such as sediment traps or basins. Design and Installation When earth dikes are used to divert water for slope protection, the earth dike typically consists of a horizontal ridge of soil placed perpendicular to the slope and angled slightly to provide drainage along the contour. The dike is used in conjunction with a swale or a small channel upslope of the berm to convey the diverted water. Temporary diversion dikes can be constructed by excavation of a V-shaped trench or ditch and placement of the fill on the downslope side of the cut. There are two types of placement for temporary slope diversion dikes:  A dike located at the top of a slope to divert upland runoff away from the disturbed area and convey it in a temporary or permanent channel.  A diversion dike located at the base or mid-slope of a disturbed area to intercept runoff and reduce the effective slope length. Depending on the project, either an earth dike or drainage swale may be more appropriate. If there is a need for cut on the project, then an excavated drainage swale may be better suited. When the project is primarily fill, then a conveyance constructed using a berm may be the better option. All dikes or swales receiving runoff from a disturbed area should direct stormwater to a sediment control BMP such as a sediment trap or basin. Earth Dikes and Drainage Swales Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-10 Earth Dikes and Drainage Swales (ED/DS) ED/DS-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Unlined dikes or swales should only be used for intercepting sheet flow runoff and are not intended for diversion of concentrated flows. Details with notes are provided for several design variations, including: ED-1. Unlined Earth Dike formed by Berm DS-1. Unlined Excavated Swale DS-2. Unlined Swale Formed by Cut and Fill DS-3. ECB-lined Swale DS-4. Synthetic-lined Swale DS-5. Riprap-lined Swale The details also include guidance on permissible velocities for cohesive channels if unlined approaches will be used. Maintenance and Removal Inspect earth dikes for stability, compaction, and signs of erosion and repair. Inspect side slopes for erosion and damage to erosion control fabric. Stabilize slopes and repair fabric as necessary. If there is reoccurring extensive damage, consider installing rock check dams or lining the channel with riprap. If drainage swales are not permanent, remove dikes and fill channels when the upstream area is stabilized. Stabilize the fill or disturbed area immediately following removal by revegetation or other permanent stabilization method approved by the local jurisdiction. Earth Dikes and Drainage Swales (ED/DS) EC-10 November 2010 Urban Drainage and Flood Control District ED/DS-3 Urban Storm Drainage Criteria Manual Volume 3 EC-10 Earth Dikes and Drainage Swales (ED/DS) ED/DS-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Earth Dikes and Drainage Swales (ED/DS) EC-10 November 2010 Urban Drainage and Flood Control District ED/DS-5 Urban Storm Drainage Criteria Manual Volume 3 Terracing (TER) EC-11 November 2010 Urban Drainage and Flood Control District TER-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph TER-1. Use of a terrace to reduce erosion by controlling slope length on a long, steep slope. Photo courtesy of Douglas County. Description Terracing involves grading steep slopes into a series of relatively flat sections, or terraces, separated at intervals by steep slope segments. Terraces shorten the uninterrupted flow lengths on steep slopes, helping to reduce the development of rills and gullies. Retaining walls, gabions, cribbing, deadman anchors, rock-filled slope mattresses, and other types of soil retention systems can be used in terracing. Appropriate Uses Terracing techniques are most typically used to control erosion on slopes that are steeper than 4:1. Design and Installation Design details with notes are provided in Detail TER-1. The type, number, and spacing of terraces will depend on the slope, slope length, and other factors. The Revised Universal Soil Loss Equation (RUSLE) may be helpful in determining spacing of terraces on slopes. Terracing should be used in combination with other stabilization measures that provide cover for exposed soils such as mulching, seeding, surface roughening, or other measures. Maintenance and Removal Repair rill erosion on slopes and remove accumulated sediment, as needed. Terracing may be temporary or permanent. If terracing is temporary, the slope should be topsoiled, seeded, and mulched when the slope is graded to its final configuration and terraces are removed. Due to the steepness of the slope, once terraces are graded, erosion control blankets or other stabilization measures are typically required. If terraces are permanent, vegetation should be established on slopes and terraces as soon as practical. Terracing Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-11 Terracing (TER) TER-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Check Dams (CD) EC-12 November 2010 Urban Drainage and Flood Control District CD-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph CD-1. Rock check dams in a roadside ditch. Photo courtesy of WWE. Description Check dams are temporary grade control structures placed in drainage channels to limit the erosivity of stormwater by reducing flow velocity. Check dams are typically constructed from rock, gravel bags, sand bags, or sometimes, proprietary devices. Reinforced check dams are typically constructed from rock and wire gabion. Although the primary function of check dams is to reduce the velocity of concentrated flows, a secondary benefit is sediment trapping upstream of the structure. Appropriate Uses Use as a grade control for temporary drainage ditches or swales until final soil stabilization measures are established upstream and downstream. Check dams can be used on mild or moderately steep slopes. Check dams may be used under the following conditions:  As temporary grade control facilities along waterways until final stabilization is established.  Along permanent swales that need protection prior to installation of a non-erodible lining.  Along temporary channels, ditches or swales that need protection where construction of a non- erodible lining is not practicable.  Reinforced check dams should be used in areas subject to high flow velocities. Design and Installation Place check dams at regularly spaced intervals along the drainage swale or ditch. Check dams heights should allow for pools to develop upstream of each check dam, extending to the downstream toe of the check dam immediately upstream. When rock is used for the check dam, place rock mechanically or by hand. Do not dump rocks into the drainage channel. Where multiple check dams are used, the top of the lower dam should be at the same elevation as the toe of the upper dam. When reinforced check dams are used, install erosion control fabric under and around the check dam to prevent erosion on the upstream and downstream sides. Each section of the dam should be keyed in to reduce the potential for washout or undermining. A rock apron upstream and downstream of the dam may be necessary to further control erosion. Check Dams Functions Erosion Control Yes Sediment Control Moderate Site/Material Management No EC-12 Check Dams (CD) CD-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Design details with notes are provided for the following types of check dams:  Rock Check Dams (CD-1)  Reinforced Check Dams (CD-2) Sediment control logs may also be used as check dams; however, silt fence is not appropriate for use as a check dam. Many jurisdictions also prohibit or discourage use of straw bales for this purpose. Maintenance and Removal Replace missing rocks causing voids in the check dam. If gravel bags or sandbags are used, replace or repair torn or displaced bags. Remove accumulated sediment, as needed to maintain BMP effectiveness, typically before the sediment depth upstream of the check dam is within ½ of the crest height. Remove accumulated sediment prior to mulching, seeding, or chemical soil stabilization. Removed sediment can be incorporated into the earthwork with approval from the Project Engineer, or disposed of at an alternate location in accordance with the standard specifications. Check dams constructed in permanent swales should be removed when perennial grasses have become established, or immediately prior to installation of a non-erodible lining. All of the rock and accumulated sediment should be removed, and the area seeded and mulched, or otherwise stabilized. Check Dams (CD) EC-12 November 2010 Urban Drainage and Flood Control District CD-3 Urban Storm Drainage Criteria Manual Volume 3 EC-12 Check Dams (CD) CD-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Check Dams (CD) EC-12 November 2010 Urban Drainage and Flood Control District CD-5 Urban Storm Drainage Criteria Manual Volume 3 EC-12 Check Dams (CD) CD-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Streambank Stabilization (SS) EC-13 November 2010 Urban Drainage and Flood Control District SS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SS-1. Streambank stabilization using geotextiles following installation of a permanent in-stream grade control structure. Description Streambank stabilization involves a combination of erosion and sediment control practices to protect streams, banks, and in-stream habitat from accelerated erosion. BMPs associated with streambank stabilization may include protection of existing vegetation, check dams/grade control, temporary and permanent seeding, outlet protection, rolled erosion control products, temporary diversions, dewatering operations and bioengineering practices such as brush layering, live staking and fascines. Appropriate Uses Streambank stabilization may be a construction activity in and of itself, or it may be in conjunction with a broader construction project that discharges to a waterway that is susceptible to accelerated erosion due to increases in the rate and volume of stormwater runoff. Depending on the health of the stream, water quality sampling and testing may be advisable prior to and/or during construction to evaluate health and stability of the stream and potential effects from adjacent construction activities. Design and Installation Streambank stabilization consists of protecting the stream in a variety of ways to minimize negative effects to the stream environment. The following lists the minimum requirements necessary for construction streambank stabilization:  Protect existing vegetation along the stream bank in accordance with the Vegetated Buffers and Protection of Existing Vegetation Fact Sheets. Preserving a riparian buffer along the streambank will help to remove sediment and decrease runoff rates from the disturbed area.  Outside the riparian buffer, provide sediment control in the form of a silt fence or equivalent sediment control practice along the entire length of the stream that will receive runoff from the area of disturbance. In some cases, a double-layered perimeter control may be justified adjacent to sensitive receiving waters and wetlands to provide additional protection.  Stabilize all areas that will be draining to the stream. Use rolled erosion control products, temporary or permanent seeding, or other appropriate measures.  Ensure all point discharges entering the stream are adequately armored with a velocity dissipation device and appropriate outlet protection. See individual design details and notes for the various BMPs referenced in this practice. Additional information on bioengineering techniques for stream stabilization can be Streambank Stabilization Functions Erosion Control Yes Sediment Control No Site/Material Management No EC-13 Streambank Stabilization (SS) SS-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 found in the Major Drainage chapter of Volume 1 and additional guidance on BMPs for working in waterways can be found in UDFCD’s Best Management Practices for Construction in Waterways Training Manual. Maintenance and Removal Inspect BMPs protecting the stream for damage on a daily basis. Maintain, repair, or replace damaged BMPs following the guidance provided in individual BMP Fact Sheets for practices that are implemented. Some streambank stabilization BMPs are intended to remain in place as vegetation matures (e.g. erosion control blankets protecting seeded stream banks and turf reinforcement mats). For BMPs that are not to remain in place as a part of final stabilization such as silt fence and other temporary measures, BMPs should be removed when all land disturbing activities have ceased and areas have been permanently stabilized. Wind Erosion/Dust Control (DC) EC-14 November 2010 Urban Drainage and Flood Control District DC-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph DC-1. Water truck used for dust suppression. Photo courtesy of Douglas County. Description Wind erosion and dust control BMPs help to keep soil particles from entering the air as a result of land disturbing construction activities. These BMPs include a variety of practices generally focused on either graded disturbed areas or construction roadways. For graded areas, practices such as seeding and mulching, use of soil binders, site watering, or other practices that provide prompt surface cover should be used. For construction roadways, road watering and stabilized surfaces should be considered. Appropriate Uses Dust control measures should be used on any site where dust poses a problem to air quality. Dust control is important to control for the health of construction workers and surrounding waterbodies. Design and Installation The following construction BMPs can be used for dust control:  An irrigation/sprinkler system can be used to wet the top layer of disturbed soil to help keep dry soil particles from becoming airborne.  Seeding and mulching can be used to stabilize disturbed surfaces and reduce dust emissions.  Protecting existing vegetation can help to slow wind velocities across the ground surface, thereby limiting the likelihood of soil particles to become airborne.  Spray-on soil binders form a bond between soil particles keeping them grounded. Chemical treatments may require additional permitting requirements. Potential impacts to surrounding waterways and habitat must be considered prior to use.  Placing rock on construction roadways and entrances will help keep dust to a minimum across the construction site.  Wind fences can be installed on site to reduce wind speeds. Install fences perpendicular to the prevailing wind direction for maximum effectiveness. Maintenance and Removal When using an irrigation/sprinkler control system to aid in dust control, be careful not to overwater. Overwatering will cause construction vehicles to track mud off-site. Wind Erosion Control/ Dust Control Functions Erosion Control Yes Sediment Control No Site/Material Management Moderate Concrete Washout Area (CWA) MM-1 November 2010 Urban Drainage and Flood Control District CWA-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph CWA-1. Example of concrete washout area. Note gravel tracking pad for access and sign. Description Concrete waste management involves designating and properly managing a specific area of the construction site as a concrete washout area. A concrete washout area can be created using one of several approaches designed to receive wash water from washing of tools and concrete mixer chutes, liquid concrete waste from dump trucks, mobile batch mixers, or pump trucks. Three basic approaches are available: excavation of a pit in the ground, use of an above ground storage area, or use of prefabricated haul- away concrete washout containers. Surface discharges of concrete washout water from construction sites are prohibited. Appropriate Uses Concrete washout areas must be designated on all sites that will generate concrete wash water or liquid concrete waste from onsite concrete mixing or concrete delivery. Because pH is a pollutant of concern for washout activities, when unlined pits are used for concrete washout, the soil must have adequate buffering capacity to result in protection of state groundwater standards; otherwise, a liner/containment must be used. The following management practices are recommended to prevent an impact from unlined pits to groundwater:  The use of the washout site should be temporary (less than 1 year), and  The washout site should be not be located in an area where shallow groundwater may be present, such as near natural drainages, springs, or wetlands. Design and Installation Concrete washout activities must be conducted in a manner that does not contribute pollutants to surface waters or stormwater runoff. Concrete washout areas may be lined or unlined excavated pits in the ground, commercially manufactured prefabricated washout containers, or aboveground holding areas constructed of berms, sandbags or straw bales with a plastic liner. Although unlined washout areas may be used, lined pits may be required to protect groundwater under certain conditions. Do not locate an unlined washout area within 400 feet of any natural drainage pathway or waterbody or within 1,000 feet of any wells or drinking water sources. Even for lined concrete washouts, it is advisable to locate the facility away from waterbodies and drainage paths. If site constraints make these Concrete Washout Area Functions Erosion Control No Sediment Control No Site/Material Management Yes MM-1 Concrete Washout Area (CWA) CWA-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 setbacks infeasible or if highly permeable soils exist in the area, then the pit must be installed with an impermeable liner (16 mil minimum thickness) or surface storage alternatives using prefabricated concrete washout devices or a lined aboveground storage area should be used. Design details with notes are provided in Detail CWA-1 for pits and CWA-2 for aboveground storage areas. Pre-fabricated concrete washout container information can be obtained from vendors. Maintenance and Removal A key consideration for concrete washout areas is to ensure that adequate signage is in place identifying the location of the washout area. Part of inspecting and maintaining washout areas is ensuring that adequate signage is provided and in good repair and that the washout area is being used, as opposed to washout in non-designated areas of the site. Remove concrete waste in the washout area, as needed to maintain BMP function (typically when filled to about two-thirds of its capacity). Collect concrete waste and deliver offsite to a designated disposal location. Upon termination of use of the washout site, accumulated solid waste, including concrete waste and any contaminated soils, must be removed from the site to prevent on-site disposal of solid waste. If the wash water is allowed to evaporate and the concrete hardens, it may be recycled. Photograph CWA-3. Earthen concrete washout. Photo courtesy of CDOT. Photograph CWA-2. Prefabricated concrete washout. Photo courtesy of CDOT. Concrete Washout Area (CWA) MM-1 November 2010 Urban Drainage and Flood Control District CWA-3 Urban Storm Drainage Criteria Manual Volume 3 MM-1 Concrete Washout Area (CWA) CWA-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Stockpile Management (SP) MM-2 November 2010 Urban Drainage and Flood Control District SP-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SP-1. A topsoil stockpile that has been partially revegetated and is protected by silt fence perimeter control. Description Stockpile management includes measures to minimize erosion and sediment transport from soil stockpiles. Appropriate Uses Stockpile management should be used when soils or other erodible materials are stored at the construction site. Special attention should be given to stockpiles in close proximity to natural or manmade storm systems. Design and Installation Locate stockpiles away from all drainage system components including storm sewer inlets. Where practical, choose stockpile locations that that will remain undisturbed for the longest period of time as the phases of construction progress. Place sediment control BMPs around the perimeter of the stockpile, such as sediment control logs, rock socks, silt fence, straw bales and sand bags. See Detail SP-1 for guidance on proper establishment of perimeter controls around a stockpile. For stockpiles in active use, provide a stabilized designated access point on the upgradient side of the stockpile. Stabilize the stockpile surface with surface roughening, temporary seeding and mulching, erosion control blankets, or soil binders. Soils stockpiled for an extended period (typically for more than 60 days) should be seeded and mulched with a temporary grass cover once the stockpile is placed (typically within 14 days). Use of mulch only or a soil binder is acceptable if the stockpile will be in place for a more limited time period (typically 30-60 days). Timeframes for stabilization of stockpiles noted in this fact sheet are "typical" guidelines. Check permit requirements for specific federal, state, and/or local requirements that may be more prescriptive. Stockpiles should not be placed in streets or paved areas unless no other practical alternative exists. See the Stabilized Staging Area Fact Sheet for guidance when staging in roadways is unavoidable due to space or right-of-way constraints. For paved areas, rock socks must be used for perimeter control and all inlets with the potential to receive sediment from the stockpile (even from vehicle tracking) must be protected. Maintenance and Removal Inspect perimeter controls and inlet protection in accordance with their respective BMP Fact Sheets. Where seeding, mulch and/or soil binders are used, reseeding or reapplication of soil binder may be necessary. When temporary removal of a perimeter BMP is necessary to access a stockpile, ensure BMPs are reinstalled in accordance with their respective design detail section. Stockpile Management Functions Erosion Control Yes Sediment Control Yes Site/Material Management Yes MM-2 Stockpile Management (SM) SP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 When the stockpile is no longer needed, properly dispose of excess materials and revegetate or otherwise stabilize the ground surface where the stockpile was located. Stockpile Management (SP) MM-2 November 2010 Urban Drainage and Flood Control District SP-3 Urban Storm Drainage Criteria Manual Volume 3 MM-2 Stockpile Management (SM) SP-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Stockpile Management (SP) MM-2 November 2010 Urban Drainage and Flood Control District SP-5 Urban Storm Drainage Criteria Manual Volume 3 MM-2 Stockpile Management (SM) SP-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Good Housekeeping Practices (GH) MM-3 November 2010 Urban Drainage and Flood Control District GH-1 Urban Storm Drainage Criteria Manual Volume 3 Photographs GH-1 and GH-2. Proper materials storage and secondary containment for fuel tanks are important good housekeeping practices. Photos courtesy of CDOT and City of Aurora. Description Implement construction site good housekeeping practices to prevent pollution associated with solid, liquid and hazardous construction-related materials and wastes. Stormwater Management Plans (SWMPs) should clearly specify BMPs including these good housekeeping practices:  Provide for waste management.  Establish proper building material staging areas.  Designate paint and concrete washout areas.  Establish proper equipment/vehicle fueling and maintenance practices.  Control equipment/vehicle washing and allowable non- stormwater discharges.  Develop a spill prevention and response plan. Acknowledgement: This Fact Sheet is based directly on EPA guidance provided in Developing Your Stormwater Pollution Prevent Plan (EPA 2007). Appropriate Uses Good housekeeping practices are necessary at all construction sites. Design and Installation The following principles and actions should be addressed in SWMPs:  Provide for Waste Management. Implement management procedures and practices to prevent or reduce the exposure and transport of pollutants in stormwater from solid, liquid and sanitary wastes that will be generated at the site. Practices such as trash disposal, recycling, proper material handling, and cleanup measures can reduce the potential for stormwater runoff to pick up construction site wastes and discharge them to surface waters. Implement a comprehensive set of waste-management practices for hazardous or toxic materials, such as paints, solvents, petroleum products, pesticides, wood preservatives, acids, roofing tar, and other materials. Practices should include storage, handling, inventory, and cleanup procedures, in case of spills. Specific practices that should be considered include: Solid or Construction Waste o Designate trash and bulk waste-collection areas on- site. Good Housekeeping Functions Erosion Control No Sediment Control No Site/Material Management Yes MM-3 Good Housekeeping Practices (GH) GH-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Photograph GH-3. Locate portable toilet facilities on level surfaces away from waterways and storm drains. Photo courtesy of WWE. o Recycle materials whenever possible (e.g., paper, wood, concrete, oil). o Segregate and provide proper disposal options for hazardous material wastes. o Clean up litter and debris from the construction site daily. o Locate waste-collection areas away from streets, gutters, watercourses, and storm drains. Waste- collection areas (dumpsters, and such) are often best located near construction site entrances to minimize traffic on disturbed soils. Consider secondary containment around waste collection areas to minimize the likelihood of contaminated discharges. o Empty waste containers before they are full and overflowing. Sanitary and Septic Waste o Provide convenient, well-maintained, and properly located toilet facilities on-site. o Locate toilet facilities away from storm drain inlets and waterways to prevent accidental spills and contamination of stormwater. o Maintain clean restroom facilities and empty portable toilets regularly. o Where possible, provide secondary containment pans under portable toilets. o Provide tie-downs or stake-downs for portable toilets. o Educate employees, subcontractors, and suppliers on locations of facilities. o Treat or dispose of sanitary and septic waste in accordance with state or local regulations. Do not discharge or bury wastewater at the construction site. o Inspect facilities for leaks. If found, repair or replace immediately. o Special care is necessary during maintenance (pump out) to ensure that waste and/or biocide are not spilled on the ground. Hazardous Materials and Wastes o Develop and implement employee and subcontractor education, as needed, on hazardous and toxic waste handling, storage, disposal, and cleanup. o Designate hazardous waste-collection areas on-site. o Place all hazardous and toxic material wastes in secondary containment. Good Housekeeping Practices (GH) MM-3 November 2010 Urban Drainage and Flood Control District GH-3 Urban Storm Drainage Criteria Manual Volume 3 o Hazardous waste containers should be inspected to ensure that all containers are labeled properly and that no leaks are present.  Establish Proper Building Material Handling and Staging Areas. The SWMP should include comprehensive handling and management procedures for building materials, especially those that are hazardous or toxic. Paints, solvents, pesticides, fuels and oils, other hazardous materials or building materials that have the potential to contaminate stormwater should be stored indoors or under cover whenever possible or in areas with secondary containment. Secondary containment measures prevent a spill from spreading across the site and may include dikes, berms, curbing, or other containment methods. Secondary containment techniques should also ensure the protection of groundwater. Designate staging areas for activities such as fueling vehicles, mixing paints, plaster, mortar, and other potential pollutants. Designated staging areas enable easier monitoring of the use of materials and clean up of spills. Training employees and subcontractors is essential to the success of this pollution prevention principle. Consider the following specific materials handling and staging practices: o Train employees and subcontractors in proper handling and storage practices. o Clearly designate site areas for staging and storage with signs and on construction drawings. Staging areas should be located in areas central to the construction site. Segment the staging area into sub-areas designated for vehicles, equipment, or stockpiles. Construction entrances and exits should be clearly marked so that delivery vehicles enter/exit through stabilized areas with vehicle tracking controls (See Vehicle Tracking Control Fact Sheet). o Provide storage in accordance with Spill Protection, Control and Countermeasures (SPCC) requirements and plans and provide cover and impermeable perimeter control, as necessary, for hazardous materials and contaminated soils that must be stored on site. o Ensure that storage containers are regularly inspected for leaks, corrosion, support or foundation failure, or other signs of deterioration and tested for soundness. o Reuse and recycle construction materials when possible.  Designate Concrete Washout Areas. Concrete contractors should be encouraged to use the washout facilities at their own plants or dispatch facilities when feasible; however, concrete washout commonly occurs on construction sites. If it is necessary to provide for concrete washout areas on- site, designate specific washout areas and design facilities to handle anticipated washout water. Washout areas should also be provided for paint and stucco operations. Because washout areas can be a source of pollutants from leaks or spills, care must be taken with regard to their placement and proper use. See the Concrete Washout Area Fact Sheet for detailed guidance. Both self-constructed and prefabricated washout containers can fill up quickly when concrete, paint, and stucco work are occurring on large portions of the site. Be sure to check for evidence that contractors are using the washout areas and not dumping materials onto the ground or into drainage facilities. If the washout areas are not being used regularly, consider posting additional signage, relocating the facilities to more convenient locations, or providing training to workers and contractors. When concrete, paint, or stucco is part of the construction process, consider these practices which will help prevent contamination of stormwater. Include the locations of these areas and the maintenance and inspection procedures in the SWMP. MM-3 Good Housekeeping Practices (GH) GH-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 o Do not washout concrete trucks or equipment into storm drains, streets, gutters, uncontained areas, or streams. Only use designated washout areas. o Establish washout areas and advertise their locations with signs. Ensure that signage remains in good repair. o Provide adequate containment for the amount of wash water that will be used. o Inspect washout structures daily to detect leaks or tears and to identify when materials need to be removed. o Dispose of materials properly. The preferred method is to allow the water to evaporate and to recycle the hardened concrete. Full service companies may provide dewatering services and should dispose of wastewater properly. Concrete wash water can be highly polluted. It should not be discharged to any surface water, storm sewer system, or allowed to infiltrate into the ground in the vicinity of waterbodies. Washwater should not be discharged to a sanitary sewer system without first receiving written permission from the system operator.  Establish Proper Equipment/Vehicle Fueling and Maintenance Practices. Create a clearly designated on-site fueling and maintenance area that is clean and dry. The on-site fueling area should have a spill kit, and staff should know how to use it. If possible, conduct vehicle fueling and maintenance activities in a covered area. Consider the following practices to help prevent the discharge of pollutants to stormwater from equipment/vehicle fueling and maintenance. Include the locations of designated fueling and maintenance areas and inspection and maintenance procedures in the SWMP. o Train employees and subcontractors in proper fueling procedures (stay with vehicles during fueling, proper use of pumps, emergency shutoff valves, etc.). o Inspect on-site vehicles and equipment regularly for leaks, equipment damage, and other service problems. o Clearly designate vehicle/equipment service areas away from drainage facilities and watercourses to prevent stormwater run-on and runoff. o Use drip pans, drip cloths, or absorbent pads when replacing spent fluids. o Collect all spent fluids, store in appropriate labeled containers in the proper storage areas, and recycle fluids whenever possible.  Control Equipment/Vehicle Washing and Allowable Non-Stormwater Discharges. Implement practices to prevent contamination of surface and groundwater from equipment and vehicle wash water. Representative practices include: o Educate employees and subcontractors on proper washing procedures. o Use off-site washing facilities, when available. o Clearly mark the washing areas and inform workers that all washing must occur in this area. o Contain wash water and treat it using BMPs. Infiltrate washwater when possible, but maintain separation from drainage paths and waterbodies. Good Housekeeping Practices (GH) MM-3 November 2010 Urban Drainage and Flood Control District GH-5 Urban Storm Drainage Criteria Manual Volume 3 o Use high-pressure water spray at vehicle washing facilities without detergents. Water alone can remove most dirt adequately. o Do not conduct other activities, such as vehicle repairs, in the wash area. o Include the location of the washing facilities and the inspection and maintenance procedures in the SWMP.  Develop a Spill Prevention and Response Plan. Spill prevention and response procedures must be identified in the SWMP. Representative procedures include identifying ways to reduce the chance of spills, stop the source of spills, contain and clean up spills, dispose of materials contaminated by spills, and train personnel responsible for spill prevention and response. The plan should also specify material handling procedures and storage requirements and ensure that clear and concise spill cleanup procedures are provided and posted for areas in which spills may potentially occur. When developing a spill prevention plan, include the following: o Note the locations of chemical storage areas, storm drains, tributary drainage areas, surface waterbodies on or near the site, and measures to stop spills from leaving the site. o Provide proper handling and safety procedures for each type of waste. Keep Material Safety Data Sheets (MSDSs) for chemical used on site with the SWMP. o Establish an education program for employees and subcontractors on the potential hazards to humans and the environment from spills and leaks. o Specify how to notify appropriate authorities, such as police and fire departments, hospitals, or municipal sewage treatment facilities to request assistance. Emergency procedures and contact numbers should be provided in the SWMP and posted at storage locations. o Describe the procedures, equipment and materials for immediate cleanup of spills and proper disposal. o Identify personnel responsible for implementing the plan in the event of a spill. Update the spill prevention plan and clean up materials as changes occur to the types of chemicals stored and used at the facility. MM-3 Good Housekeeping Practices (GH) GH-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Spill Prevention, Control, and Countermeasure (SPCC) Plan Construction sites may be subject to 40 CFR Part 112 regulations that require the preparation and implementation of a SPCC Plan to prevent oil spills from aboveground and underground storage tanks. The facility is subject to this rule if it is a non-transportation-related facility that:  Has a total storage capacity greater than 1,320 gallons or a completely buried storage capacity greater than 42,000 gallons.  Could reasonably be expected to discharge oil in quantities that may be harmful to navigable waters of the United States and adjoining shorelines. Furthermore, if the facility is subject to 40 CFR Part 112, the SWMP should reference the SPCC Plan. To find out more about SPCC Plans, see EPA's website on SPPC at www.epa.gov/oilspill/spcc.htm. Reporting Oil Spills In the event of an oil spill, contact the National Response Center toll free at 1-800-424- 8802 for assistance, or for more details, visit their website: www.nrc.uscg.mil. Maintenance and Removal Effective implementation of good housekeeping practices is dependent on clear designation of personnel responsible for supervising and implementing good housekeeping programs, such as site cleanup and disposal of trash and debris, hazardous material management and disposal, vehicle and equipment maintenance, and other practices. Emergency response "drills" may aid in emergency preparedness. Checklists may be helpful in good housekeeping efforts. Staging and storage areas require permanent stabilization when the areas are no longer being used for construction-related activities. Construction-related materials, debris and waste must be removed from the construction site once construction is complete. Design Details See the following Fact Sheets for related Design Details: MM-1 Concrete Washout Area MM-2 Stockpile Management SM-4 Vehicle Tracking Control Design details are not necessary for other good housekeeping practices; however, be sure to designate where specific practices will occur on the appropriate construction drawings. Silt Fence (SF) SC-1 November 2010 Urban Drainage and Flood Control District SF-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SF-1. Silt fence creates a sediment barrier, forcing sheet flow runoff to evaporate or infiltrate. Description A silt fence is a woven geotextile fabric attached to wooden posts and trenched into the ground. It is designed as a sediment barrier to intercept sheet flow runoff from disturbed areas. Appropriate Uses A silt fence can be used where runoff is conveyed from a disturbed area as sheet flow. Silt fence is not designed to receive concentrated flow or to be used as a filter fabric. Typical uses include:  Down slope of a disturbed area to accept sheet flow.  Along the perimeter of a receiving water such as a stream, pond or wetland.  At the perimeter of a construction site. Design and Installation Silt fence should be installed along the contour of slopes so that it intercepts sheet flow. The maximum recommended tributary drainage area per 100 lineal feet of silt fence, installed along the contour, is approximately 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1. Longer and steeper slopes require additional measures. This recommendation only applies to silt fence installed along the contour. Silt fence installed for other uses, such as perimeter control, should be installed in a way that will not produce concentrated flows. For example, a "J-hook" installation may be appropriate to force runoff to pond and evaporate or infiltrate in multiple areas rather than concentrate and cause erosive conditions parallel to the silt fence. See Detail SF-1 for proper silt fence installation, which involves proper trenching, staking, securing the fabric to the stakes, and backfilling the silt fence. Properly installed silt fence should not be easily pulled out by hand and there should be no gaps between the ground and the fabric. Silt fence must meet the minimum allowable strength requirements, depth of installation requirement, and other specifications in the design details. Improper installation of silt fence is a common reason for silt fence failure; however, when properly installed and used for the appropriate purposes, it can be highly effective. Silt Fence Functions Erosion Control No Sediment Control Yes Site/Material Management No SC-1 Silt Fence (SF) SF-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Photograph SF-2. When silt fence is not installed along the contour, a "J-hook" installation may be appropriate to ensure that the BMP does not create concentrated flow parallel to the silt fence. Photo courtesy of Tom Gore. Maintenance and Removal Inspection of silt fence includes observing the material for tears or holes and checking for slumping fence and undercut areas bypassing flows. Repair of silt fence typically involves replacing the damaged section with a new section. Sediment accumulated behind silt fence should be removed, as needed to maintain BMP effectiveness, typically before it reaches a depth of 6 inches. Silt fence may be removed when the upstream area has reached final stabilization. Silt Fence (SF) SC-1 November 2010 Urban Drainage and Flood Control District SF-3 Urban Storm Drainage Criteria Manual Volume 3 SC-1 Silt Fence (SF) SF-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Control Log (SCL) SC-2 November 2010 Urban Drainage and Flood Control District SCL-1 Urban Storm Drainage Criteria Manual Volume 3 Photographs SCL-1 and SCL-2. Sediment control logs used as 1) a perimeter control around a soil stockpile; and, 2) as a "J-hook" perimeter control at the corner of a construction site. Description A sediment control log is a linear roll made of natural materials such as straw, coconut fiber, or other fibrous material trenched into the ground and held with a wooden stake. Sediment control logs are also often referred to as "straw wattles." They are used as a sediment barrier to intercept sheet flow runoff from disturbed areas. Appropriate Uses Sediment control logs can be used in the following applications to trap sediment:  As perimeter control for stockpiles and the site.  As part of inlet protection designs.  As check dams in small drainage ditches. (Sediment control logs are not intended for use in channels with high flow velocities.)  On disturbed slopes to shorten flow lengths (as an erosion control).  As part of multi-layered perimeter control along a receiving water such as a stream, pond or wetland. Sediment control logs work well in combination with other layers of erosion and sediment controls. Design and Installation Sediment control logs should be installed along the contour to avoid concentrating flows. The maximum allowable tributary drainage area per 100 lineal feet of sediment control log, installed along the contour, is approximately 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1. Longer and steeper slopes require additional measures. This recommendation only applies to sediment control logs installed along the contour. When installed for other uses, such as perimeter control, it should be installed in a way that will not produce concentrated flows. For example, a "J-hook" installation may be appropriate to force runoff to pond and evaporate or infiltrate in multiple areas rather than concentrate and cause erosive conditions parallel to the BMP. Sediment Control Log Functions Erosion Control Moderate Sediment Control Yes Site/Material Management No SC-2 Sediment Control Log (SCL) SCL-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Although sediment control logs initially allow runoff to flow through the BMP, they can quickly become a barrier and should be installed is if they are impermeable. Design details and notes for sediment control logs are provided in Detail SCL-1. Sediment logs must be properly trenched and staked into the ground to prevent undercutting, bypassing and displacement. When installed on slopes, sediment control logs should be installed along the contours (i.e., perpendicular to flow). Improper installation can lead to poor performance. Be sure that sediment control logs are properly trenched, anchored and tightly jointed. Maintenance and Removal Be aware that sediment control logs will eventually degrade. Remove accumulated sediment before the depth is one-half the height of the sediment log and repair damage to the sediment log, typically by replacing the damaged section. Once the upstream area is stabilized, remove and properly dispose of the logs. Areas disturbed beneath the logs may need to be seeded and mulched. Sediment control logs that are biodegradable may occasionally be left in place (e.g., when logs are used in conjunction with erosion control blankets as permanent slope breaks). However, removal of sediment control logs after final stabilization is typically recommended when used in perimeter control, inlet protection and check dam applications. Sediment Control Log (SCL) SC-2 November 2010 Urban Drainage and Flood Control District SCL-3 Urban Storm Drainage Criteria Manual Volume 3 SC-2 Sediment Control Log (SCL) SCL-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Control Log (SCL) SC-2 November 2010 Urban Drainage and Flood Control District SCL-5 Urban Storm Drainage Criteria Manual Volume 3 Brush Barrier (BB) SC-4 November 2010 Urban Drainage and Flood Control District BB-1 Urban Storm Drainage Criteria Manual Volume 3 Description A brush barrier is a perimeter sediment control constructed with stacked shrubs, tree limbs, and bushy vegetation that has been cleared from a construction area. Brush barriers reduce sediment loads by intercepting and slowing sheet flow from disturbed areas. Appropriate Uses A brush barrier is an appropriate BMP at sites where there is adequate brush from the clearing and grubbing of the construction site to construct an effective brush barrier. Brush barriers are typically used at the toe of slopes and should be implemented in combination with other BMPs such as surface roughening and reseeding. Brush barriers should be considered short-term, supplemental BMPs because they are constructed of materials that naturally decompose. Brush barriers are not acceptable as a sole means of perimeter control, but they may be used internally within a site to reduce slope length or at the site perimeter in combination with other perimeter control BMPs for multi-layered protection. Brush barriers are not appropriate for high-velocity flow areas. A large amount of material is needed to construct a useful brush barrier; therefore, alternative perimeter controls such as a fabric silt fence may be more appropriate for sites with little material from clearing. Design and Installation The drainage area for brush barriers should be no greater than 0.25 acre per 100 feet of barrier length. Additionally, the drainage slope leading down to a brush barrier must be no greater than 3:1 and no longer than 150 feet. To construct an effective brush barrier, use only small shrubs and limbs with diameters of 6 inches or less. Larger materials (such as a tree stump) can create void spaces in the barrier, making it ineffective. The brush barrier mound should be at least 3 feet high and 5 feet wide at its base. In order to avoid significant movement of the brush and improve effectiveness, a filter fabric can be placed over the top of the brush pile, keyed in on the upstream side, and anchored on the downstream side. On the upgradient side, the filter fabric cover should be buried in a trench 4 inches deep and 6 inches wide. Brush Barrier Functions Erosion Control Moderate Sediment Control Moderate Site/Material No Photograph BB-1. Brush barrier constructed with chipped wood. Photo courtesy of EPA. SC-4 Brush Barrier (BB) BB-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Maintenance and Removal Inspect the brush barrier for voids where concentrated flow or erosion is occurring. Voids in the brush barrier should be filled with additional brush. Accumulated sediment should be removed from the uphill side of the barrier when sediment height reaches one-third of the height of the barrier. If filter fabric is used, inspect the filter fabric for damage; replace and properly secure it, as needed. Once the upstream area has been vegetated or stabilized, the brush barrier should be removed and the underlying area revegetated. Rock Sock (RS) SC-5 November 2010 Urban Drainage and Flood Control District RS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph RS-1. Rock socks placed at regular intervals in a curb line can help reduce sediment loading to storm sewer inlets. Rock socks can also be used as perimeter controls. Description A rock sock is constructed of gravel that has been wrapped by wire mesh or a geotextile to form an elongated cylindrical filter. Rock socks are typically used either as a perimeter control or as part of inlet protection. When placed at angles in the curb line, rock socks are typically referred to as curb socks. Rock socks are intended to trap sediment from stormwater runoff that flows onto roadways as a result of construction activities. Appropriate Uses Rock socks can be used at the perimeter of a disturbed area to control localized sediment loading. A benefit of rock socks as opposed to other perimeter controls is that they do not have to be trenched or staked into the ground; therefore, they are often used on roadway construction projects where paved surfaces are present. Use rock socks in inlet protection applications when the construction of a roadway is substantially complete and the roadway has been directly connected to a receiving storm system. Design and Installation When rock socks are used as perimeter controls, the maximum recommended tributary drainage area per 100 lineal feet of rock socks is approximately 0.25 acres with disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1. A rock sock design detail and notes are provided in Detail RS-1. Also see the Inlet Protection Fact Sheet for design and installation guidance when rock socks are used for inlet protection and in the curb line. When placed in the gutter adjacent to a curb, rock socks should protrude no more than two feet from the curb in order for traffic to pass safely. If located in a high traffic area, place construction markers to alert drivers and street maintenance workers of their presence. Maintenance and Removal Rock socks are susceptible to displacement and breaking due to vehicle traffic. Inspect rock socks for damage and repair or replace as necessary. Remove sediment by sweeping or vacuuming as needed to maintain the functionality of the BMP, typically when sediment has accumulated behind the rock sock to one-half of the sock's height. Once upstream stabilization is complete, rock socks and accumulated sediment should be removed and properly disposed. Rock Sock Functions Erosion Control No Sediment Control Yes Site/Material Management No SC-5 Rock Sock (RS) RS-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Rock Sock (RS) SC-5 November 2010 Urban Drainage and Flood Control District RS-3 Urban Storm Drainage Criteria Manual Volume 3 Inlet Protection (IP) SC-6 November 2010 Urban Drainage and Flood Control District IP-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph IP-1. Inlet protection for a curb opening inlet. Description Inlet protection consists of permeable barriers installed around an inlet to filter runoff and remove sediment prior to entering a storm drain inlet. Inlet protection can be constructed from rock socks, sediment control logs, silt fence, block and rock socks, or other materials approved by the local jurisdiction. Area inlets can also be protected by over-excavating around the inlet to form a sediment trap. Appropriate Uses Install protection at storm sewer inlets that are operable during construction. Consider the potential for tracked-out sediment or temporary stockpile areas to contribute sediment to inlets when determining which inlets must be protected. This may include inlets in the general proximity of the construction area, not limited to downgradient inlets. Inlet protection is not Design and Installation a stand-alone BMP and should be used in conjunction with other upgradient BMPs. To function effectively, inlet protection measures must be installed to ensure that flows do not bypass the inlet protection and enter the storm drain without treatment. However, designs must also enable the inlet to function without completely blocking flows into the inlet in a manner that causes localized flooding. When selecting the type of inlet protection, consider factors such as type of inlet (e.g., curb or area, sump or on-grade conditions), traffic, anticipated flows, ability to secure the BMP properly, safety and other site-specific conditions. For example, block and rock socks will be better suited to a curb and gutter along a roadway, as opposed to silt fence or sediment control logs, which cannot be properly secured in a curb and gutter setting, but are effective area inlet protection measures. Several inlet protection designs are provided in the Design Details. Additionally, a variety of proprietary products are available for inlet protection that may be approved for use by local governments. If proprietary products are used, design details and installation procedures from the manufacturer must be followed. Regardless of the type of inlet protection selected, inlet protection is most effective when combined with other BMPs such as curb socks and check dams. Inlet protection is often the last barrier before runoff enters the storm sewer or receiving water. Design details with notes are provided for these forms of inlet protection: IP-1. Block and Rock Sock Inlet Protection for Sump or On-grade Inlets IP-2. Curb (Rock) Socks Upstream of Inlet Protection, On-grade Inlets Inlet Protection (various forms) Functions Erosion Control No Sediment Control Yes Site/Material Management No SC-6 Inlet Protection (IP) IP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 IP-3. Rock Sock Inlet Protection for Sump/Area Inlet IP-4. Silt Fence Inlet Protection for Sump/Area Inlet IP-5. Over-excavation Inlet Protection IP-6. Straw Bale Inlet Protection for Sump/Area Inlet CIP-1. Culvert Inlet Protection Propriety inlet protection devices should be installed in accordance with manufacturer specifications. More information is provided below on selecting inlet protection for sump and on-grade locations. Inlets Located in a Sump When applying inlet protection in sump conditions, it is important that the inlet continue to function during larger runoff events. For curb inlets, the maximum height of the protective barrier should be lower than the top of the curb opening to allow overflow into the inlet during larger storms without excessive localized flooding. If the inlet protection height is greater than the curb elevation, particularly if the filter becomes clogged with sediment, runoff will not enter the inlet and may bypass it, possibly causing localized flooding, public safety issues, and downstream erosion and damage from bypassed flows. Area inlets located in a sump setting can be protected through the use of silt fence, concrete block and rock socks (on paved surfaces), sediment control logs/straw wattles embedded in the adjacent soil and stacked around the area inlet (on pervious surfaces), over-excavation around the inlet, and proprietary products providing equivalent functions. Inlets Located on a Slope For curb and gutter inlets on paved sloping streets, block and rock sock inlet protection is recommended in conjunction with curb socks in the gutter leading to the inlet. For inlets located along unpaved roads, also see the Check Dam Fact Sheet. Maintenance and Removal Inspect inlet protection frequently. Inspection and maintenance guidance includes:  Inspect for tears that can result in sediment directly entering the inlet, as well as result in the contents of the BMP (e.g., gravel) washing into the inlet.  Check for improper installation resulting in untreated flows bypassing the BMP and directly entering the inlet or bypassing to an unprotected downstream inlet. For example, silt fence that has not been properly trenched around the inlet can result in flows under the silt fence and directly into the inlet.  Look for displaced BMPs that are no longer protecting the inlet. Displacement may occur following larger storm events that wash away or reposition the inlet protection. Traffic or equipment may also crush or displace the BMP.  Monitor sediment accumulation upgradient of the inlet protection. Inlet Protection (IP) SC-6 November 2010 Urban Drainage and Flood Control District IP-3 Urban Storm Drainage Criteria Manual Volume 3  Remove sediment accumulation from the area upstream of the inlet protection, as needed to maintain BMP effectiveness, typically when it reaches no more than half the storage capacity of the inlet protection. For silt fence, remove sediment when it accumulates to a depth of no more than 6 inches. Remove sediment accumulation from the area upstream of the inlet protection as needed to maintain the functionality of the BMP.  Propriety inlet protection devices should be inspected and maintained in accordance with manufacturer specifications. If proprietary inlet insert devices are used, sediment should be removed in a timely manner to prevent devices from breaking and spilling sediment into the storm drain. Inlet protection must be removed and properly disposed of when the drainage area for the inlet has reached final stabilization. SC-6 Inlet Protection (IP) IP-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Inlet Protection (IP) SC-6 November 2010 Urban Drainage and Flood Control District IP-5 Urban Storm Drainage Criteria Manual Volume 3 SC-6 Inlet Protection (IP) IP-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Inlet Protection (IP) SC-6 November 2010 Urban Drainage and Flood Control District IP-7 Urban Storm Drainage Criteria Manual Volume 3 Sediment Basin (SB) SC-7 November 2010 Urban Drainage and Flood Control District SB-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SB-1. Sediment basin at the toe of a slope. Photo courtesy of WWE. Description A sediment basin is a temporary pond built on a construction site to capture eroded or disturbed soil transported in storm runoff prior to discharge from the site. Sediment basins are designed to capture site runoff and slowly release it to allow time for settling of sediment prior to discharge. Sediment basins are often constructed in locations that will later be modified to serve as post-construction stormwater basins. Appropriate Uses Most large construction sites (typically greater than 2 acres) will require one or more sediment basins for effective management of construction site runoff. On linear construction projects, sediment basins may be impractical; instead, sediment traps or other combinations of BMPs may be more appropriate. Sediment basins should not be used as stand-alone sediment controls. Erosion and other sediment controls should also be implemented upstream. When feasible, the sediment basin should be installed in the same location where a permanent post- construction detention pond will be located. Design and Installation The design procedure for a sediment basin includes these steps:  Basin Storage Volume: Provide a storage volume of at least 3,600 cubic feet per acre of drainage area. To the extent practical, undisturbed and/or off-site areas should be diverted around sediment basins to prevent “clean” runoff from mixing with runoff from disturbed areas. For undisturbed areas (both on-site and off-site) that cannot be diverted around the sediment basin, provide a minimum of 500 ft3/acre of storage for undeveloped (but stable) off-site areas in addition to the 3,600 ft3/acre for disturbed areas. For stable, developed areas that cannot be diverted around the sediment basin, storage volume requirements are summarized in Table SB-1.  Basin Geometry: Design basin with a minimum length-to-width ratio of 2:1 (L:W). If this cannot be achieved because of site space constraints, baffling may be required to extend the effective distance between the inflow point(s) and the outlet to minimize short-circuiting.  Dam Embankment: It is recommended that embankment slopes be 4:1 (H:V) or flatter and no steeper than 3:1 (H:V) in any location. Sediment Basins Functions Erosion Control No Sediment Control Yes Site/Material Management No SC-7 Sediment Basin (SB) SB-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3  Inflow Structure: For concentrated flow entering the basin, provide energy dissipation at the point of inflow. Table SB-1. Additional Volume Requirements for Undisturbed and Developed TributaryAreas Draining through Sediment Basins Imperviousness (%) Additional Storage Volume (ft3) Per Acre of Tributary Area Undeveloped 500 10 800 20 1230 30 1600 40 2030 50 2470 60 2980 70 3560 80 4360 90 5300 100 6460  Outlet Works: The outlet pipe shall extend through the embankment at a minimum slope of 0.5 percent. Outlet works can be designed using one of the following approaches: o Perforated Riser/Plate: Follow the design criteria for Full Spectrum Detention outlets in the EDB BMP Fact Sheet provided in Chapter 4 of this manual for sizing of outlet perforations with an emptying time of approximately 72 hours. In lieu of the well-screen trash rack, pack uniformly sized 1½ - to 2-inch gravel in front of the plate. This gravel will need to be cleaned out frequently during the construction period as sediment accumulates within it. The gravel pack will need to be removed and disposed of following construction to reclaim the basin for use as a permanent detention facility. If the basin will be used as a permanent extended detention basin for the site, a well-screen trash rack will need to be installed once contributing drainage areas have been stabilized and the gravel pack and accumulated sediment have been removed. o Floating Skimmer: If a floating skimmer is used, install it using manufacturer’s recommendations. Illustration SB-1 provides an illustration of a Faircloth Skimmer Floating Outlet™, one of the more commonly used floating skimmer outlets. A skimmer should be designed to release the design volume in no less than 48 hours. The use of a floating skimmer outlet can increase the sediment capture efficiency of a basin significantly. A floating outlet continually decants cleanest water off the surface of the pond and releases cleaner water than would discharge from a perforated riser pipe or plate. Sediment Basin (SB) SC-7 November 2010 Urban Drainage and Flood Control District SB-3 Urban Storm Drainage Criteria Manual Volume 3 Illustration SB-1. Outlet structure for a temporary sediment basin - Faircloth Skimmer Floating Outlet. Illustration courtesy of J. W. Faircloth & Sons, Inc., FairclothSkimmer.com. o Outlet Protection: Outlet protection should be provided where the velocity of flow will exceed the maximum permissible velocity of the material of the waterway into which discharge occurs. This may require the use of a riprap apron at the outlet location and/or other measures to keep the waterway from eroding. o Emergency Spillway: Provide a stabilized emergency overflow spillway for rainstorms that exceed the capacity of the sediment basin volume and its outlet. Protect basin embankments from erosion and overtopping. If the sediment basin will be converted to a permanent detention basin, design and construct the emergency spillway(s) as required for the permanent facility. If the sediment basin will not become a permanent detention basin, it may be possible to substitute a heavy polyvinyl membrane or properly bedded rock cover to line the spillway and downstream embankment, depending on the height, slope, and width of the embankments. Maintenance and Removal Maintenance activities include the following: • Dredge sediment from the basin, as needed to maintain BMP effectiveness, typically when the design storage volume is no more than one-third filled with sediment. • Inspect the sediment basin embankments for stability and seepage. • Inspect the inlet and outlet of the basin, repair damage, and remove debris. Remove, clean and replace the gravel around the outlet on a regular basis to remove the accumulated sediment within it and keep the outlet functioning. • Be aware that removal of a sediment basin may require dewatering and associated permit requirements. • Do not remove a sediment basin until the upstream area has been stabilized with vegetation. SC-7 Sediment Basin (SB) SB-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Final disposition of the sediment basin depends on whether the basin will be converted to a permanent post-construction stormwater basin or whether the basin area will be returned to grade. For basins being converted to permanent detention basins, remove accumulated sediment and reconfigure the basin and outlet to meet the requirements of the final design for the detention facility. If the sediment basin is not to be used as a permanent detention facility, fill the excavated area with soil and stabilize with vegetation. Sediment Basin (SB) SC-7 November 2010 Urban Drainage and Flood Control District SB-5 Urban Storm Drainage Criteria Manual Volume 3 SC-7 Sediment Basin (SB) SB-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Basin (SB) SC-7 November 2010 Urban Drainage and Flood Control District SB-7 Urban Storm Drainage Criteria Manual Volume 3 Sediment Trap (ST) SC-8 November 2010 Urban Drainage and Flood Control District ST-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph ST-1. Sediment traps are used to collect sediment-laden runoff from disturbed area. Photo courtesy of EPA Menu of BMPs. Description Sediment traps are formed by excavating an area or by placing an earthen embankment across a low area or drainage swale. Sediment traps are designed to capture drainage from disturbed areas less than one acre and allow settling of sediment. Appropriate Uses Sediment traps can be used in combination with other layers of erosion and sediment controls to trap sediment from small drainage areas (less than one acre) or areas with localized high sediment loading. For example, sediment traps are often provided in conjunction with vehicle tracking controls and wheel wash facilities. Design and Installation A sediment trap consists of a small excavated basin with an earthen berm and a riprap outlet. The berm of the sediment trap may be constructed from the excavated material and must be compacted to 95 percent of the maximum density in accordance with ASTM D698. An overflow outlet must be provided at an elevation at least 6 inches below the top of the berm. See Detail ST-1 for additional design and installation information. Maintenance and Removal Inspect the sediment trap embankments for stability and seepage. Remove accumulated sediment as needed to maintain the effectiveness of the sediment trap, typically when the sediment depth is approximately one-half the height of the outflow embankment. Inspect the outlet for debris and damage. Repair damage to the outlet, and remove all obstructions. A sediment trap should not be removed until the upstream area is sufficiently stabilized. Upon removal of the trap, the disturbed area should be covered with topsoil and stabilized. Sediment Trap Functions Erosion Control No Sediment Control Yes Site/Material Management No SC-8 Sediment Trap (ST) ST-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Sediment Trap (ST) SC-8 November 2010 Urban Drainage and Flood Control District ST-3 Urban Storm Drainage Criteria Manual Volume 3 Vegetated Buffers (VB) SC-9 November 2010 Urban Drainage and Flood Control District VB-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph VB-1. A vegetated buffer is maintained between the area of active construction and the drainage swale. Photo courtesy of WWE. Description Buffer strips of preserved natural vegetation or grass help protect waterways and wetlands from land disturbing activities. Vegetated buffers improve stormwater runoff quality by straining sediment, promoting infiltration, and slowing runoff velocities. Appropriate Uses Vegetated buffers can be used to separate land disturbing activities and natural surface waters or conveyances. In many jurisdictions, local governments require some type of setback from natural waterways. Concentrated flow should not be directed through a buffer; instead, runoff should be in the form of sheet flow. Vegetated buffers are typically used in combination with other perimeter control BMPs such as sediment control logs or silt fence for multi- layered protection. Design and Installation Minimum buffer widths may vary based on local regulations. Clearly delineate the boundary of the natural buffer area using construction fencing, silt fence, or a comparable technique. In areas that have been cleared and graded, vegetated buffers such as sod can also be installed to create or restore a vegetated buffer around the perimeter of the site. Maintenance and Removal Inspect buffer areas for signs of erosion such as gullies or rills. Stabilize eroding areas, as needed. If erosion is due to concentrated flow conditions, it may be necessary to install a level spreader or other technique to restore sheet flow conditions. Inspect perimeter controls delineating the vegetative buffer and repair or replace as needed. Vegetated Buffers Functions Erosion Control Moderate Sediment Control Yes Site/Material Management Yes Chemical Treatment (CT) SC-10 November 2010 Urban Drainage and Flood Control District CT-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph CT-1. Proprietary chemical treatment system being used on a construction site with sensitive receiving waters. Photo courtesy of WWE. Description Chemical treatment for erosion and sediment control can take several forms: 1. Applying chemicals to disturbed surfaces to reduce erosion (these uses are discussed in the Soil Binders Fact Sheet). 2. Adding flocculants to sedimentation ponds or tanks to enhance sediment removal prior. 3. Using proprietary barriers or flow- through devices containing flocculants (e.g., "floc logs"). The use of flocculants as described in No. 2 and No. 3 above will likely require special permitting. Check with the state permitting agency. See the Soil Binder BMP Fact Sheet for information on surface application of chemical treatments, as described in No. 1. Appropriate Uses At sites with fine-grained materials such as clays, chemical addition to sedimentation ponds or tanks can enhance settling of suspended materials through flocculation. Prior to selecting and using chemical treatments, it is important to check state and local permit requirements related to their use. Design and Installation Due to variations among proprietary chemical treatment methods, design details are not provided for this BMP. Chemical feed systems for sedimentation ponds, settling tanks and dewatering bags should be installed and operated in accordance with manufacturer's recommendations and applicable regulations. Alum and chitosan are two common chemicals used as flocculants. Because the potential long-term impact of these chemicals to natural drainageways is not yet fully understood, the state does not currently allow chemical addition under the CDPS General Stormwater Construction Discharge Permit. Additional permitting may be necessary, which may include sampling requirements and numeric discharge limits. Any devices or barriers containing chemicals should be installed following manufacturer's guidelines. Check for state and local jurisdiction usage restrictions and requirements before including these practices in the SWMP and implementing them onsite. Chemical Treatment Functions Erosion Control Moderate Sediment Control Yes Site/Material Management No SC-10 Chemical Treatment (CT) CT-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Maintenance and Removal Chemical feed systems for sedimentation ponds or tanks should be maintained in accordance with manufacturer's recommendations and removed when the systems are no longer being used. Accumulated sediment should be dried and disposed of either at a landfill or in accordance with applicable regulations. Barriers and devices containing chemicals should be removed and replaced when tears or other damage to the devices are observed. These barriers should be removed and properly disposed of when the site has been stabilized. Construction Phasing/Sequencing (CP) SM-1 November 2010 Urban Drainage and Flood Control District CP-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph CP-1. Construction phasing to avoid disturbing the entire area at one time. Photo courtesy of WWE. Description Effective construction site management to minimize erosion and sediment transport includes attention to construction phasing, scheduling, and sequencing of land disturbing activities. On most construction projects, erosion and sediment controls will need to be adjusted as the project progresses and should be documented in the SWMP. Construction phasing refers to disturbing only part of a site at a time to limit the potential for erosion from dormant parts of a site. Grading activities and construction are completed and soils are effectively stabilized on one part of a site before grading and construction begins on another portion of the site. Construction sequencing or scheduling refers to a specified work schedule that coordinates the timing of land disturbing activities and the installation of erosion and sediment control practices. Appropriate Uses All construction projects can benefit from upfront planning to phase and sequence construction activities to minimize the extent and duration of disturbance. Larger projects and linear construction projects may benefit most from construction sequencing or phasing, but even small projects can benefit from construction sequencing that minimizes the duration of disturbance. Typically, erosion and sediment controls needed at a site will change as a site progresses through the major phases of construction. Erosion and sediment control practices corresponding to each phase of construction must be documented in the SWMP. Design and Installation BMPs appropriate to the major phases of development should be identified on construction drawings. In some cases, it will be necessary to provide several drawings showing construction-phase BMPs placed according to stages of development (e.g., clearing and grading, utility installation, active construction, final stabilization). Some municipalities in the Denver area set maximum sizes for disturbed area associated with phases of a construction project. Additionally, requirements for phased construction drawings vary among local governments within the UDFCD boundary. Some local governments require separate erosion and sediment control drawings for initial BMPs, interim conditions (in active construction), and final stabilization. Construction Scheduling Functions Erosion Control Moderate Sediment Control Moderate Site/Material Management Yes SM-1 Construction Phasing/Sequencing (CP) CP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Typical construction phasing BMPs include:  Limit the amount of disturbed area at any given time on a site to the extent practical. For example, a 100-acre subdivision might be constructed in five phases of 20 acres each.  If there is carryover of stockpiled material from one phase to the next, position carryover material in a location easily accessible for the pending phase that will not require disturbance of stabilized areas to access the stockpile. Particularly with regard to efforts to balance cut and fill at a site, careful planning for location of stockpiles is important. Typical construction sequencing BMPs include:  Sequence construction activities to minimize duration of soil disturbance and exposure. For example, when multiple utilities will occupy the same trench, schedule installation so that the trench does not have to be closed and opened multiple times.  Schedule site stabilization activities (e.g., landscaping, seeding and mulching, installation of erosion control blankets) as soon as feasible following grading.  Install initial erosion and sediment control practices before construction begins. Promptly install additional BMPs for inlet protection, stabilization, etc., as construction activities are completed. Table CP-1 provides typical sequencing of construction activities and associated BMPs. Maintenance and Removal When the construction schedule is altered, erosion and sediment control measures in the SWMP and construction drawings should be appropriately adjusted to reflect actual "on the ground" conditions at the construction site. Be aware that changes in construction schedules can have significant implications for site stabilization, particularly with regard to establishment of vegetative cover. Construction Phasing/Sequencing (CP) SM-1 November 2010 Urban Drainage and Flood Control District CP-3 Urban Storm Drainage Criteria Manual Volume 3 Table CP -1. Typical Phased BMP Installation for Construction Projects Project Phase BMPs Pre- disturbance, Site Access  Install sediment controls downgradient of access point (on paved streets this may consist of inlet protection).  Establish vehicle tracking control at entrances to paved streets. Fence as needed.  Use construction fencing to define the boundaries of the project and limit access to areas of the site that are not to be disturbed. Note: it may be necessary to protect inlets in the general vicinity of the site, even if not downgradient, if there is a possibility that sediment tracked from the site could contribute to the inlets. Site Clearing and Grubbing  Install perimeter controls as needed on downgradient perimeter of site (silt fence, wattles, etc).  Limit disturbance to those areas planned for disturbance and protect undisturbed areas within the site (construction fence, flagging, etc).  Preserve vegetative buffer at site perimeter.  Create stabilized staging area.  Locate portable toilets on flat surfaces away from drainage paths. Stake in areas susceptible to high winds.  Construct concrete washout area and provide signage.  Establish waste disposal areas.  Install sediment basins.  Create dirt perimeter berms and/or brush barriers during grubbing and clearing.  Separate and stockpile topsoil, leave roughened and/or cover.  Protect stockpiles with perimeter control BMPs. Stockpiles should be located away from drainage paths and should be accessed from the upgradient side so that perimeter controls can remain in place on the downgradient side. Use erosion control blankets, temporary seeding, and/or mulch for stockpiles that will be inactive for an extended period.  Leave disturbed area of site in a roughened condition to limit erosion. Consider temporary revegetation for areas of the site that have been disturbed but that will be inactive for an extended period.  Water to minimize dust but not to the point that watering creates runoff. SM-1 Construction Phasing/Sequencing (CP) CP-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Project Phase BMPs Utility And Infrastructure Installation In Addition to the Above BMPs:  Close trench as soon as possible (generally at the end of the day).  Use rough-cut street control or apply road base for streets that will not be promptly paved.  Provide inlet protection as streets are paved and inlets are constructed.  Protect and repair BMPs, as necessary.  Perform street sweeping as needed. Building Construction In Addition to the Above BMPs:  Implement materials management and good housekeeping practices for home building activities.  Use perimeter controls for temporary stockpiles from foundation excavations.  For lots adjacent to streets, lot-line perimeter controls may be necessary at the back of curb. Final Grading In Addition to the Above BMPs:  Remove excess or waste materials.  Remove stored materials. Final Stabilization In Addition to the Above BMPs:  Seed and mulch/tackify.  Seed and install blankets on steep slopes.  Remove all temporary BMPs when site has reached final stabilization. Protection of Existing Vegetation (PV) SM-2 November 2010 Urban Drainage and Flood Control District PV-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph PV-1. Protection of existing vegetation and a sensitive area. Photo courtesy of CDOT. Description Protection of existing vegetation on a construction site can be accomplished through installation of a construction fence around the area requiring protection. In cases where upgradient areas are disturbed, it may also be necessary to install perimeter controls to minimize sediment loading to sensitive areas such as wetlands. Existing vegetation may be designated for protection to maintain a stable surface cover as part of construction phasing, or vegetation may be protected in areas designated to remain in natural condition under post-development conditions (e.g., wetlands, mature trees, riparian areas, open space). Appropriate Uses Existing vegetation should be preserved for the maximum practical duration on a construction site through the use of effective construction phasing. Preserving vegetation helps to minimize erosion and can reduce revegetation costs following construction. Protection of wetland areas is required under the Clean Water Act, unless a permit has been obtained from the U.S. Army Corps of Engineers (USACE) allowing impacts in limited areas. If trees are to be protected as part of post-development landscaping, care must be taken to avoid several types of damage, some of which may not be apparent at the time of injury. Potential sources of injury include soil compaction during grading or due to construction traffic, direct equipment-related injury such as bark removal, branch breakage, surface grading and trenching, and soil cut and fill. In order to minimize injuries that may lead to immediate or later death of the tree, tree protection zones should be developed during site design, implemented at the beginning of a construction project, as well as continued during active construction. Design and Installation General Once an area has been designated as a preservation area, there should be no construction activity allowed within a set distance of the area. Clearly mark the area with construction fencing. Do not allow stockpiles, equipment, trailers or parking within the protected area. Guidelines to protect various types of existing vegetation follow. Protection of Existing Vegetation Functions Erosion Control Yes Sediment Control Moderate Site/Material Management Yes SM-2 Protection of Existing Vegetation (PV) PV-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Surface Cover During Phased Construction Install construction fencing or other perimeter controls around areas to be protected from clearing and grading as part of construction phasing. Maintaining surface cover on steep slopes for the maximum practical duration during construction is recommended. Open Space Preservation Where natural open space areas will be preserved as part of a development, it is important to install construction fencing around these areas to protect them from compaction. This is particularly important when areas with soils with high infiltration rates are preserved as part of LID designs. Preserved open space areas should not be used for staging and equipment storage. Wetlands and Riparian Areas Install a construction fence around the perimeter of the wetland or riparian (streamside vegetation) area to prevent access by equipment. In areas downgradient of disturbed areas, install a perimeter control such as silt fence, sediment control logs, or similar measure to minimize sediment loading to the wetland. Tree Protection 1  Before beginning construction operations, establish a tree protection zone around trees to be preserved by installing construction fences. Allow enough space from the trunk to protect the root zone from soil compaction and mechanical damage, and the branches from mechanical damage (see Table PV-1). If low branches will be kept, place the fence outside of the drip line. Where this is not possible, place fencing as far away from the trunk as possible. In order to maintain a healthy tree, be aware that about 60 percent of the tree's root zone extends beyond the drip line. Table PV-1 Guidelines for Determining the Tree Protection Zone (Source: Matheny and Clark, 1998; as cited in GreenCO and WWE 2008) Distance from Trunk (ft) per inch of DBH Species Tolerance to Damage Young Mature Over mature Good 0.5' 0.75' 1.0' Moderate 0.75' 1.0' 1.25' Poor 1.0' 1.25' 1.5' Notes: DBH = diameter at breast height (4.5 ft above grade); Young = <20% of life expectancy; Mature = 20%-80% of life expectancy; Over mature =>80% of life expectancy  Most tree roots grow within the top 12 to 18 inches of soil. Grade changes within the tree protection zone should be avoided where possible because seemingly minor grade changes can either smother 1 Tree Protection guidelines adapted from GreenCO and WWE (2008). Green Industry Best Management Practices (BMPs) for the Conservation and Protection of Water Resources in Colorado: Moving Toward Sustainability, Third Release. See www.greenco.org for more detailed guidance on tree preservation. Protection of Existing Vegetation (PV) SM-2 November 2010 Urban Drainage and Flood Control District PV-3 Urban Storm Drainage Criteria Manual Volume 3 roots (in fill situations) or damage roots (in cut situations). Consider small walls where needed to avoid grade changes in the tree protection zone.  Place and maintain a layer of mulch 4 to 6-inch thick from the tree trunk to the fencing, keeping a 6-inch space between the mulch and the trunk. Mulch helps to preserve moisture and decrease soil compaction if construction traffic is unavoidable. When planting operations are completed, the mulch may be reused throughout planting areas.  Limit access, if needed at all, and appoint one route as the main entrance and exit to the tree protection zone. Within the tree protection zone, do not allow any equipment to be stored, chemicals to be dumped, or construction activities to take place except fine grading, irrigation system installation, and planting operations. These activities should be conducted in consultation with a landscaping professional, following Green Industry BMPs.  Be aware that soil compaction can cause extreme damage to tree health that may appear gradually over a period of years. Soil compaction is easier to prevent than repair. Maintenance and Removal Repair or replace damaged or displaced fencing or other protective barriers around the vegetated area. If damage occurs to a tree, consult an arborist for guidance on how to care for the tree. If a tree in a designated preservation area is damaged beyond repair, remove and replace with a 2-inch diameter tree of the same or similar species. Construction equipment must not enter a wetland area, except as permitted by the U.S. Army Corps of Engineers (USACE). Inadvertent placement of fill in a wetland is a 404 permit violation and will require notification of the USACE. If damage to vegetation occurs in a protected area, reseed the area with the same or similar species, following the recommendations in the USDCM Revegetation chapter. Construction Fence (CF) SM-3 November 2010 Urban Drainage and Flood Control District CF-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph CF-1. A construction fence helps delineate areas where existing vegetation is being protected. Photo courtesy of Douglas County. Description A construction fence restricts site access to designated entrances and exits, delineates construction site boundaries, and keeps construction out of sensitive areas such as natural areas to be preserved as open space, wetlands and riparian areas. Appropriate Uses A construction fence can be used to delineate the site perimeter and locations within the site where access is restricted to protect natural resources such as wetlands, waterbodies, trees, and other natural areas of the site that should not be disturbed. If natural resource protection is an objective, then the construction fencing should be used in combination with other perimeter control BMPs such as silt fence, sediment control logs or similar measures. Design and Installation Construction fencing may be chain link or plastic mesh and should be installed following manufacturer’s recommendations. See Detail CF-1 for typical installations. Do not place construction fencing in areas within work limits of machinery. Maintenance and Removal  Inspect fences for damage; repair or replace as necessary.  Fencing should be tight and any areas with slumping or fallen posts should be reinstalled.  Fencing should be removed once construction is complete. Construction Fence Functions Erosion Control No Sediment Control No Site/Material Management Yes SM-3 Construction Fence (CF) CF-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Construction Fence (CF) SM-3 November 2010 Urban Drainage and Flood Control District CF-3 Urban Storm Drainage Criteria Manual Volume 3 Vehicle Tracking Control (VTC) SM-4 November 2010 Urban Drainage and Flood Control District VTC-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph VTC-1. A vehicle tracking control pad constructed with properly sized rock reduces off-site sediment tracking. Description Vehicle tracking controls provide stabilized construction site access where vehicles exit the site onto paved public roads. An effective vehicle tracking control helps remove sediment (mud or dirt) from vehicles, reducing tracking onto the paved surface. Appropriate Uses Implement a stabilized construction entrance or vehicle tracking control where frequent heavy vehicle traffic exits the construction site onto a paved roadway. An effective vehicle tracking control is particularly important during the following conditions:  Wet weather periods when mud is easily tracked off site.  During dry weather periods where dust is a concern.  When poorly drained, clayey soils are present on site. Although wheel washes are not required in designs of vehicle tracking controls, they may be needed at particularly muddy sites. Design and Installation Construct the vehicle tracking control on a level surface. Where feasible, grade the tracking control towards the construction site to reduce off-site runoff. Place signage, as needed, to direct construction vehicles to the designated exit through the vehicle tracking control. There are several different types of stabilized construction entrances including: VTC-1. Aggregate Vehicle Tracking Control. This is a coarse-aggregate surfaced pad underlain by a geotextile. This is the most common vehicle tracking control, and when properly maintained can be effective at removing sediment from vehicle tires. VTC-2. Vehicle Tracking Control with Construction Mat or Turf Reinforcement Mat. This type of control may be appropriate for site access at very small construction sites with low traffic volume over vegetated areas. Although this application does not typically remove sediment from vehicles, it helps protect existing vegetation and provides a stabilized entrance. Vehicle Tracking Control Functions Erosion Control Moderate Sediment Control Yes Site/Material Management Yes SM-4 Vehicle Tracking Control (VTC) VTC-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Photograph VTC-2. A vehicle tracking control pad with wheel wash facility. Photo courtesy of Tom Gore. VTC-3. Stabilized Construction Entrance/Exit with Wheel Wash. This is an aggregate pad, similar to VTC-1, but includes equipment for tire washing. The wheel wash equipment may be as simple as hand-held power washing equipment to more advance proprietary systems. When a wheel wash is provided, it is important to direct wash water to a sediment trap prior to discharge from the site. Vehicle tracking controls are sometimes installed in combination with a sediment trap to treat runoff. Maintenance and Removal Inspect the area for degradation and replace aggregate or material used for a stabilized entrance/exit as needed. If the area becomes clogged and ponds water, remove and dispose of excess sediment or replace material with a fresh layer of aggregate as necessary. With aggregate vehicle tracking controls, ensure rock and debris from this area do not enter the public right-of-way. Remove sediment that is tracked onto the public right of way daily or more frequently as needed. Excess sediment in the roadway indicates that the stabilized construction entrance needs maintenance. Ensure that drainage ditches at the entrance/exit area remain clear. A stabilized entrance should be removed only when there is no longer the potential for vehicle tracking to occur. This is typically after the site has been stabilized. When wheel wash equipment is used, be sure that the wash water is discharged to a sediment trap prior to discharge. Also inspect channels conveying the water from the wash area to the sediment trap and stabilize areas that may be eroding. When a construction entrance/exit is removed, excess sediment from the aggregate should be removed and disposed of appropriately. The entrance should be promptly stabilized with a permanent surface following removal, typically by paving. Vehicle Tracking Control (VTC) SM-4 November 2010 Urban Drainage and Flood Control District VTC-3 Urban Storm Drainage Criteria Manual Volume 3 SM-4 Vehicle Tracking Control (VTC) VTC-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Vehicle Tracking Control (VTC) SM-4 November 2010 Urban Drainage and Flood Control District VTC-5 Urban Storm Drainage Criteria Manual Volume 3 SM-4 Vehicle Tracking Control (VTC) VTC-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Stabilized Construction Roadway (SCR) SM-5 November 2010 Urban Drainage and Flood Control District SCR-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SCR-1. Stabilized construction roadway. Description A stabilized construction roadway is a temporary method to control sediment runoff, vehicle tracking, and dust from roads during construction activities. Appropriate Uses Use on high traffic construction roads to minimize dust and erosion. Stabilized construction roadways are used instead of rough-cut street controls on roadways with frequent construction traffic. Design and Installation Stabilized construction roadways typically involve two key components: 1) stabilizing the road surface with an aggregate base course of 3-inch-diameter granular material and 2) stabilizing roadside ditches, if applicable. Early application of road base is generally suitable where a layer of coarse aggregate is specified for final road construction. Maintenance and Removal Apply additional gravel as necessary to ensure roadway integrity. Inspect drainage ditches along the roadway for erosion and stabilize, as needed, through the use of check dams or rolled erosion control products. Gravel may be removed once the road is ready to be paved. Prior to paving, the road should be inspected for grade changes and damage. Regrade and repair as necessary. Stabilized Construction Roadway Functions Erosion Control Yes Sediment Control Moderate Site/Material Management Yes Stabilized Staging Area (SSA) SM-6 November 2010 Urban Drainage and Flood Control District SSA-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SSA-1. Example of a staging area with a gravel surface to prevent mud tracking and reduce runoff. Photo courtesy of Douglas County. Description A stabilized staging area is a clearly designated area where construction equipment and vehicles, stockpiles, waste bins, and other construction-related materials are stored. The contractor office trailer may also be located in this area. Depending on the size of the construction site, more than one staging area may be necessary. Appropriate Uses Most construction sites will require a staging area, which should be clearly designated in SWMP drawings. The layout of the staging area may vary depending on the type of construction activity. Staging areas located in roadways due to space constraints require special measures to avoid materials being washed into storm inlets. Design and Installation Stabilized staging areas should be completed prior to other construction activities beginning on the site. Major components of a stabilized staging area include:  Appropriate space to contain storage and provide for loading/unloading operations, as well as parking if necessary.  A stabilized surface, either paved or covered, with 3-inch diameter aggregate or larger.  Perimeter controls such as silt fence, sediment control logs, or other measures.  Construction fencing to prevent unauthorized access to construction materials.  Provisions for Good Housekeeping practices related to materials storage and disposal, as described in the Good Housekeeping BMP Fact Sheet.  A stabilized construction entrance/exit, as described in the Vehicle Tracking Control BMP Fact Sheet, to accommodate traffic associated with material delivery and waste disposal vehicles. Over -sizing the stabilized staging area may result in disturbance of existing vegetation in excess of that required for the project. This increases costs, as well as requirements for long-term stabilization following the construction period. When designing the stabilized staging area, minimize the area of disturbance to the extent practical. Stabilized Staging Area Functions Erosion Control Yes Sediment Control Moderate Site/Material Yes SM-6 Stabilized Staging Area (SSA) SSA-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 See Detail SSA-1 for a typical stabilized staging area and SSA-2 for a stabilized staging area when materials staging in roadways is required. Maintenance and Removal Maintenance of stabilized staging areas includes maintaining a stable surface cover of gravel, repairing perimeter controls, and following good housekeeping practices. When construction is complete, debris, unused stockpiles and materials should be recycled or properly disposed. In some cases, this will require disposal of contaminated soil from equipment leaks in an appropriate landfill. Staging areas should then be permanently stabilized with vegetation or other surface cover planned for the development. Minimizing Long-Term Stabilization Requirements  Utilize off-site parking and restrict vehicle access to the site.  Use construction mats in lieu of rock when staging is provided in an area that will not be disturbed otherwise.  Consider use of a bermed contained area for materials and equipment that do not require a stabilized surface.  Consider phasing of staging areas to avoid disturbance in an area that will not be otherwise disturbed. Stabilized Staging Area (SSA) SM-6 November 2010 Urban Drainage and Flood Control District SSA-3 Urban Storm Drainage Criteria Manual Volume 3 SM-6 Stabilized Staging Area (SSA) SSA-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Street Sweeping and Vacuuming (SS) SM-7 November 2010 Urban Drainage and Flood Control District SS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph SS-1. A street sweeper removes sediment and potential pollutants along the curb line at a construction site. Photo courtesy of Tom Gore. Description Street sweeping and vacuuming remove sediment that has been tracked onto roadways to reduce sediment transport into storm drain systems or a surface waterway. Appropriate Uses Use this practice at construction sites where vehicles may track sediment offsite onto paved roadways. Design and Installation Street sweeping or vacuuming should be conducted when there is noticeable sediment accumulation on roadways adjacent to the construction site. Typically, this will be concentrated at the entrance/exit to the construction site. Well-maintained stabilized construction entrances, vehicle tracking controls and tire wash facilities can help reduce the necessary frequency of street sweeping and vacuuming. On smaller construction sites, street sweeping can be conducted manually using a shovel and broom. Never wash accumulated sediment on roadways into storm drains. Maintenance and Removal  Inspect paved roads around the perimeter of the construction site on a daily basis and more frequently, as needed. Remove accumulated sediment, as needed.  Following street sweeping, check inlet protection that may have been displaced during street sweeping.  Inspect area to be swept for materials that may be hazardous prior to beginning sweeping operations. Street Sweeping/ Vacuuming Functions Erosion Control No Sediment Control Yes Site/Material Management Yes Temporary Diversion Channel (TDC) SM-8 August 2011 Urban Drainage and Flood Control District TDC-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph TDC-1. Use of a temporary diversion channel (right side) to enable installation of a grade control structure (left side). Photo courtesy of WWE. Description A temporary diversion channel diverts water from a stream to allow for construction activities to take place underneath or in the stream. Diversion channels are often required during the construction of detention ponds, dams, in-stream grade control structures, utility installation and other activities that require working in waterways. Appropriate Uses Temporary diversion channels vary with the size of the waterway that is being diverted. For large streams, a temporary diversion may consist of berms or coffer dams constructed in the stream to confine flow to one side of the stream while work progresses on the dry side of the berm. For smaller streams and often for construction of dams and detention basins, a temporary diversion channel may divert the entire waterway, as illustrated in Figure TDC-1. For very short duration projects (typically less than 4 weeks) during dry periods with low base flows, a pump and bypass pipe may serve as a temporary diversion. Whenever a temporary diversion is used, construction should be scheduled during drier times of the year if possible (October 1 through April 1), and construction in the waterway should progress as quickly as possible to reduce the risk of exceeding the temporary diversion channel capacity. Some construction activities within a waterway are very short lived, namely a few hours or days in duration, and are minor in nature. These are typically associated with maintenance of utilities and stream crossings and minor repairs to outfalls and eroded banks. In these cases, construction of temporary diversion channels can often cause more soil disturbance and sediment movement than the maintenance activity itself. If it can be reasonably determined based on area and duration of disturbance that channel work will result in less disturbance and movement of sediment than would be done through installation of a temporary diversion channel, it is reasonable to exempt these activities from the requirement to construct a temporary diversion. Design and Installation Temporary Diversion Channel sizing procedures typically include the following steps:  Using the tributary area, A (in acres), determine the design peak flow rate according to Figure TDC-2. Note: For long duration projects, or where the consequences of diversion failure warrant, a larger design flow may be necessary.  Determine depth of flow, 1-foot maximum for flows less than 20 cfs and 3 feet maximum for flows less than 100 cfs. (Flows in excess of 100 cfs should be designed in accordance with the Major Drainage chapter in Volume 1). Temporary Diversion Channel Functions Erosion Control Yes Sediment Control No Site/Material Management No SM-8 Temporary Diversion Channel (TDC) TDC-2 Urban Drainage and Flood Control District August 2011 Urban Storm Drainage Criteria Manual Volume 3  Determine channel slope based on existing and proposed site conditions.  Perform initial channel sizing calculations using Manning's Equation. Determine maximum permissible velocities based on lining material.  Determine the channel geometry and check the capacity using Manning's Equation and the "n" value given in Table TDC-1. The steepest side slope allowable for a temporary channel is two horizontal to one vertical (2:1), unless vertical walls are installed using sheet piling, concrete or stacked stone. Temporary diversion channels should have a minimum freeboard of 0.5 feet above the design water surface elevation. Figure TDC-2 may be used to estimate the design discharge for the sizing of temporary diversion channels and pipes. The curves in this figure were developed using annual peak flow data collected from 17 watersheds within the UDFCD boundary. These data were collected over extended periods of time (up to eleven years) and, as a result, provide a sound statistical basis for the figure. The data supporting Figure TDC-2 were taken during the high flood potential period of April through September. The values from Figure TDC-2 represent approximately the 95th percentile event that can occur, on the average, any given year, which means that it is likely that about 95 percent of runoff peaks during an average year will be less than values from this chart. This may not be the case in wetter-than-average seasons. Figure TDC-2 provides estimated 2-year peak flow rates based on watershed imperviousness for small waterways (< 12 square miles). Because Figure TDC-2 was developed using data from small watersheds, it is not appropriate to extrapolate from this figure for larger, more complex watersheds. For larger waterways (e.g., South Platte River, Sand Creek, Bear Creek, etc.), including ones controlled by flood control reservoirs (e.g. Chatfield Dam, Cherry Creek Dam, etc.), site specific risk assessment may be necessary to evaluate the appropriate level of protection to be provided by the temporary diversion. It is also important to recognize that larger floods can and do occur. It is the responsibility of the designer and the contractor to assess their risk of having the temporary diversion being exceeded and to evaluate the damages such an event may cause to the project, adjacent properties and others. Consider larger capacity diversions to protect a project if it will require a temporary diversion for more than one year. Because temporary diversion channels typically are not in service long enough to establish adequate vegetative lining, they must be designed to be stable for the design flow with the channel shear stress less than the critical tractive shear stress for the channel lining material. This stability criterion applies not only to diversion channels, but also to the stream-side of berms when berms are used to isolate a work area within a stream. Unlined channels should not be used. Table TDC-1 gives Manning's "n" values for lining materials. Design procedures for temporary channels are described in detail in the Hydraulic Engineering Circular No. 15 published by the Federal Highway Administration. The methods presented in this Fact Sheet are greatly simplified and are based on information developed using the most commonly used erosion control materials. Temporary Diversion Channel (TDC) SM-8 August 2011 Urban Drainage and Flood Control District TDC-3 Urban Storm Drainage Criteria Manual Volume 3 Figure TDC-1. Typical Temporary Diversion Channel Former Location of Stream Bank Former Location of Stream Bank SM-8 Temporary Diversion Channel (TDC) TDC-4 Urban Drainage and Flood Control District August 2011 Urban Storm Drainage Criteria Manual Volume 3 52.4% 40.2% 46.5%43.3% 33.3% 15.5% 18.0% 55.4% 24.3% 46.1% 39.1% 10.1% 60.9% 26.8% 29.8% 0 100 200 300 400 500 600 700 800 900 1000 0 2 4 6 8 10 12 TRIBUTARY AREA (SQUARE MILES)FLOW (CFS)Imp. = 40% Imp. = 30% Imp. = 20% Imp. = 60% Figure TDC-2. Temporary Diversion Facility Sizing Nomograph Based on 2-year Peak Flows - Denver Metropolitan and Adjacent Areas Temporary Diversion Channel (TDC) SM-8 August 2011 Urban Drainage and Flood Control District TDC-5 Urban Storm Drainage Criteria Manual Volume 3 Table TDC-1. Temporary Diversion Channel Design Criteria Lining Material Manning's n for Flow Depth 0 ft to 1.0 ft Manning's n for Flow Depth 1.0 ft to 3.0 ft Manning's n for Flow Depth 3.0 ft to 5.0 ft Plastic Membrane 0.011 0.010 0.009 Straw or Curled Wood Mats 0.035 0.025 0.020 Riprap, Type VL 0.070 0.045 0.035 Riprap, Type L 0.100 0.070 0.040 Riprap, Type M 0.125 0.075 0.045 Notes: Use manufacturer's Manning's n when available. See the Major Drainage chapter of Volume 1 for riprap gradation. Erosion protection should extend a minimum of 0.5 feet above the design water depth. Maintenance and Removal Because temporary diversion channels are one of the most critical BMPs for work in waterways, they must be inspected and maintained frequently to remain in effective operating condition. Flow barriers should be inspected at the start and end of each workday and at any time that excess water is noted in dry work areas. The diversion channel itself should be inspected for signs of erosion, and the lining should be repaired or replaced if there are signs of failure. Check armoring at the diversion return point to the waterway, and add additional armoring if erosion is noted. Water should not be allowed to flow back through the natural stream until all construction is completed. After redirecting the flow through the natural channel, lining materials should be removed from the temporary diversion channel. The diversion channel should then be backfilled and stabilized. Points of tie-in to the natural channel should be protected with riprap sized in accordance with the Major Drainage chapter in Volume 1. SM-8 Temporary Diversion Channel (TDC) TDC-6 Urban Drainage and Flood Control District August 2011 Urban Storm Drainage Criteria Manual Volume 3 Temporary Diversion Channel (TDC) SM-8 August 2011 Urban Drainage and Flood Control District TDC-7 Urban Storm Drainage Criteria Manual Volume 3 Dewatering Operations (DW) SM-9 November 2010 Urban Drainage and Flood Control District DW-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph DW-1. A relatively small dewatering operation using straw bales and a dewatering bag. Photograph DW-2. Dewatering bags used for a relatively large dewatering operation. Description The BMPs selected for construction dewatering vary depending on site- specific features such as soils, topography, anticipated discharge quantities, and discharge location. Dewatering typically involves pumping water from an inundated area to a BMP, and then downstream to a receiving waterway, sediment basin, or well- vegetated area. Dewatering typically involves use of several BMPs in sequence. Appropriate Uses Dewatering operations are used when an area of the construction site needs to be dewatered as the result of a large storm event, groundwater, or existing ponding conditions. This can occur during deep excavation, utility trenching, and wetland or pond excavation. Design and Installation Dewatering techniques will vary depending on site conditions. However, all dewatering discharges must be treated to remove sediment before discharging from the construction site. Discharging water into a sediment trap or basin is an acceptable treatment option. Water may also be treated using a dewatering filter bag, and a series of straw bales or sediment logs. If these previous options are not feasible due to space or the ability to passively treat the discharge to remove sediment, then a settling tank or an active treatment system may need to be utilized. Settling tanks are manufactured tanks with a series of baffles to promote settling. Flocculants can also be added to the tank to induce more rapid settling. This is an approach sometimes used on highly urbanized construction sites. Contact the state agency for special requirements prior to using flocculents and land application techniques. Some commonly used methods to handle the pumped water without surface discharge include land application to vegetated areas through a perforated discharge hose (i.e., the "sprinkler method") or dispersal from a water truck for dust control. Dewatering Operations Functions Erosion Control Moderate Sediment Control Yes Site/Material Management Yes SM-9 Dewatering Operations (DW) DW-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Dewatering discharges to non-paved areas must minimize the potential for scour at the discharge point either using a velocity dissipation device or dewatering filter bag. Design Details are provided for these types of dewatering situations: DW-1. Dewatering for Pond Already Filled with Water DW-2 Dewatering Sump for Submersed Pump DW-3 Sump Discharge Settling Basin DW-4 Dewatering Filter Bag Maintenance and Removal When a sediment basin or trap is used to enable settling of sediment from construction dewatering discharges, inspect the basin for sediment accumulation. Remove sediment prior to the basin or trap reaching half full. Inspect treatment facilities prior to any dewatering activity. If using a sediment control practice such as a sediment trap or basin, complete all maintenance requirements as described in the fact sheets prior to dewatering. Properly dispose of used dewatering bags, as well as sediment removed from the dewatering BMPs. Depending on the size of the dewatering operation, it may also be necessary to revegetate or otherwise stabilize the area where the dewatering operation was occurring. Dewatering Operations (DW) SM-9 November 2010 Urban Drainage and Flood Control District DW-3 Urban Storm Drainage Criteria Manual Volume 3 SM-9 Dewatering Operations (DW) DW-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Dewatering Operations (DW) SM-9 November 2010 Urban Drainage and Flood Control District DW-5 Urban Storm Drainage Criteria Manual Volume 3 Temporary Stream Crossing (TSC) SM-10 November 2010 Urban Drainage and Flood Control District TSC-1 Urban Storm Drainage Criteria Manual Volume 3 Description Where an actively flowing watercourse must be crossed regularly by construction vehicles, a temporary crossing should be provided. Three primary methods are available:  Culvert crossing  Stream ford  Temporary bridge Culvert crossings and fords are the most commonly used methods. Due to the expense associated with a temporary bridge, these are used primarily on long- term projects. Appropriate Uses Construction vehicles shall be kept out of waterways to the maximum extent practicable. Use a temporary stream crossing when it is absolutely necessary to cross a stream on a construction site. Construct a temporary crossing even if the stream or drainageway is typically dry. Multiple stream crossings should be avoided to minimize environmental impacts. A permit is required for placement of fill in a waterway under Section 404 of the Clean Water Act. The local office of the U.S. Army Corps of Engineers (USACE) should be contacted concerning the requirements for obtaining a 404 permit. In addition, a permit from the U.S. Fish and Wildlife Service (USFWS) may be needed if endangered species are of concern in the work area. Typically, the USFWS issues are addressed by a 404 permit, if one is required. The municipality of jurisdiction should also be consulted, and can provide assistance. Other permits to be obtained may include a floodplain development permit from the local jurisdiction. Design and Installation Design details are provided for these types of stream crossings: TSC-1. Culvert Crossing TSC-2. Ford Crossing TSC-3. Flume Crossing Temporary Stream Crossing Functions Erosion Control Yes Sediment Control Yes Site/Material Management No Photograph TSC-1. A temporary stream crossing using culverts. Photo courtesy of Tom Gore. SM-10 Temporary Stream Crossing (TSC) TSC-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 A culvert crossing should be designed to pass at least the 2-year design flow. Use Figure DC-2 from the Temporary Channel Diversion Fact Sheet to determine the 2-year peak flow rate. Culvert sizing must account for the headwater and tailwater controls to properly size the culvert. For additional discussion on design of box culverts and pipes, see the Major Drainage chapter in Volume 1. The designer also needs to confirm that the riprap selected is appropriate for the conditions in the channel being crossed. When a ford must be used, namely when a culvert is not practical or the best solution, the ford should be lined with at least a 12-inch thick layer of Type VL (D50 = 6 inches) or Type L (D50 = 9 inches) riprap with void spaces filed with 1-1/2 inch diameter rock. Ford crossings are recommended primarily for crossings of ephemeral (i.e. intermittently, briefly flowing) streams. For a temporary bridge crossing, consult with a structural and/or geotechnical engineer for temporary bridge design or consider pre-fabricated alternatives. Maintenance and Removal Inspect stream for bank erosion and in-stream degradation. If bank erosion is occurring, stabilize banks using erosion control practices such as erosion control blankets. If in-stream degradation is occurring, armor the culvert outlet(s) with riprap to dissipate energy (see Outlet Protection Fact Sheet). If sediment is accumulating upstream of the crossing, remove excess sediment as needed to maintain the functionality of the crossing. Remove the temporary crossing when it is no longer needed for construction. Take care to minimize the amount of sediment lost into the stream upon removal. Once the crossing has been removed, stabilize the stream banks with seed and erosion control blankets. Temporary Stream Crossing (TSC) SM-10 November 2010 Urban Drainage and Flood Control District TSC-3 Urban Storm Drainage Criteria Manual Volume 3 SM-10 Temporary Stream Crossing (TSC) TSC-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Temporary Stream Crossing (TSC) SM-10 November 2010 Urban Drainage and Flood Control District TSC-5 Urban Storm Drainage Criteria Manual Volume 3 SM-10 Temporary Stream Crossing (TSC) TSC-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Temporary Batch Plant (TBP) SM-11 November 2010 Urban Drainage and Flood Control District TBP-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph TBP-1. Effective stormwater management at temporary batch plants requires implementation of multiple BMPs. Photo courtesy of California Stormwater BMP Handbook. Description Temporary batch plant management includes implementing multiple BMPs such as perimeter controls, concrete washout area, stabilized construction access, good housekeeping, and other practices designed to reduce polluted runoff from the batch plant area. Appropriate Uses Implement this BMP at temporary batch plants and identify the location of the batch plant in the SWMP. Additional permitting may be required for the operation of batch plants depending on their duration and location. Design and Installation The following lists temporary management strategies to mitigate runoff from batch plant operations:  When stockpiling materials, follow the Stockpile Management BMP.  Locate batch plants away from storm drains and natural surface waters.  A perimeter control should be installed around the temporary batch plant.  Install run-on controls where feasible.  A designated concrete washout should be located within the perimeter of the site following the procedures in the Concrete Washout Area BMP.  Follow the Good Housekeeping BMP, including proper spill containment measures, materials storage, and waste storage practices.  A stabilized construction entrance or vehicle tracking control pad should be installed at the plant entrance, in accordance with the Vehicle Tracking Control BMP. Maintenance and Removal Inspect the batch plant for proper functioning of the BMPs, with attention to material and waste storage areas, integrity of perimeter BMPs, and an effective stabilized construction entrance. Temporary Batch Plants Functions Erosion Control No Sediment Control No Site/Material Management Yes SM-11 Temporary Batch Plant (TBP) TBP-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 After the temporary batch plant is no longer needed, remove stockpiled materials and equipment, regrade the site as needed, and revegetate or otherwise stabilize the area. Paving and Grinding Operations (PGO) SM-12 November 2010 Urban Drainage and Flood Control District PGO-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph PGO-1. Paving operations on a Colorado highway. Photo courtesy of CDOT. Description Manage runoff from paving and grinding operations to reduce pollutants entering storm drainage systems and natural drainageways. Appropriate Uses Use runoff management practices during all paving and grinding operations such as surfacing, resurfacing, and saw cutting. Design and Installation There are a variety of management strategies that can be used to manage runoff from paving and grinding operations:  Establish inlet protection for all inlets that could potentially receive runoff.  Schedule paving operations when dry weather is forecasted.  Keep spill kits onsite for equipment spills and keep drip pans onsite for stored equipment.  Install perimeter controls when asphalt material is used on embankments or shoulders near waterways, drainages, or inlets.  Do not wash any paved surface into receiving storm drain inlets or natural drainageways. Instead, loose material should be swept or vacuumed following paving and grinding operations.  Store materials away from drainages or waterways.  Recycle asphalt and pavement material when feasible. Material that cannot be recycled must be disposed of in accordance with applicable regulations. See BMP Fact Sheets for Inlet Protection, Silt Fence and other perimeter controls selected for use during paving and grinding operations. Maintenance and Removal Perform maintenance and removal of inlet protection and perimeter controls in accordance with their respective fact sheets. Promptly respond to spills in accordance with the spill prevention and control plan. Paving and Grinding Operations Functions Erosion Control No Sediment Control No Site/Material Management Yes Grass Buffer T-1 November 2010 Urban Drainage and Flood Control District GB-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph GB-1. A flush curb allows roadway runoff to sheet flow through the grass buffer. Flows are then further treated by the grass swale. Photo courtesy of Muller Engineering. Description Grass buffers are densely vegetated strips of grass designed to accept sheet flow from upgradient development. Properly designed grass buffers play a key role in LID, enabling infiltration and slowing runoff. Grass buffers provide filtration (straining) of sediment. Buffers differ from swales in that they are designed to accommodate overland sheet flow rather than concentrated or channelized flow. Site Selection Grass buffers can be incorporated into a wide range of development settings. Runoff can be directly accepted from a parking lot, roadway, or the roof of a structure, provided the flow is distributed in a uniform manner over the width of the buffer. This can be achieved through the use of flush curbs, slotted curbs, or level spreaders where needed. Grass buffers are often used in conjunction with grass swales. They are well suited for use in riparian zones to assist in stabilizing channel banks adjacent to major drainageways and receiving waters. These areas can also sometimes serve multiple functions such as recreation. Hydrologic Soil Groups A and B provide the best infiltration capacity for grass buffers. For Type C and D soils, buffers still serve to provide filtration (straining) although infiltration rates are lower. Designing for Maintenance Recommended ongoing maintenance practices for all BMPs are provided in Chapter 6 of this manual. During design the following should be considered to ensure ease of maintenance over the long-term:  Where appropriate (where vehicle safety would not be impacted), install the top of the buffer 1 to 3 inches below the adjacent pavement so that growth of vegetation and accumulation of sediment at the edge of the strip does not prevent runoff from entering the buffer. Alternatively, a sloped edge can be used adjacent to vehicular traffic areas.  Amend soils to encourage deep roots and reduce irrigation requirements, as well as promote infiltration. Grass Buffer Functions LID/Volume Red. Yes WQCV Capture No WQCV+Flood Control No Fact Sheet Includes EURV Guidance No Typical Effectiveness for Targeted Pollutants3 Sediment/Solids Good Nutrients Moderate Total Metals Good Bacteria Poor Other Considerations Life-cycle Costs Low 3 Based primarily on data from the International Stormwater BMP Database (www.bmpdatabase.org). T-1 Grass Buffer GB-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Benefits  Filters (strains) sediment and trash.  Reduces directly connected impervious area. (See Chapter 3 for quantifying benefits.)  Can easily be incorporated into a treatment train approach.  Provides green space available for multiple uses including recreation and snow storage.  Straightforward maintenance requirements when the buffer is protected from vehicular traffic. Limitations  Frequently damaged by vehicles when adjacent to roadways and unprotected.  A thick vegetative cover is needed for grass buffers to be effective.  Nutrient removal in grass buffers is typically low.  High loadings of coarse solids, trash, and debris require pretreatment.  Space for grass buffers may not be available in ultra urban areas (lot-line-to-lot-line).  Design and adjust the irrigation system (temporary or permanent) to provide water in amounts appropriate for the selected vegetation. Irrigation needs will change from month to month and year to year.  Protect the grass buffer from vehicular traffic when using this BMP adjacent to roadways. This can be done with a slotted curb (or other type of barrier) or by constructing a reinforced grass shoulder (see Fact Sheet T-10.5). Design Procedure and Criteria The following steps outline the grass buffer design procedure and criteria. Figure GB-1 is a schematic of the facility and its components: 1. Design Discharge: Use the hydrologic procedures described in the Runoff chapter of Volume 1 to determine the 2-year peak flow rate (Q2) of the area draining to the grass buffer. 2. Minimum Width: The width (W), normal to flow of the buffer, is typically the same as the contributing basin (see Figure GB-1). An exception to this is where flows become concentrated. Concentrated flows require a level spreader to distribute flows evenly across the width of the buffer. The minimum width should be: 𝑊𝑊=𝑄𝑄20.05 Equation GB-1 Where: W = width of buffer (ft) Q2 = 2-year peak runoff (cfs) 3. Length: The recommended length (L), the distance along the sheet flow direction, should be a minimum of 14 feet. This value is based on the findings of Barrett et al. 2004 in Stormwater Pollutant Removal in Roadside Vegetated Strips and is appropriate for buffers with greater than 80% vegetative cover and slopes up to 10%. The study found that pollutant removal continues throughout a length of 14 feet. Beyond this length, a point of diminishing returns in pollutant reduction was found. It is important to note that shorter lengths or slightly steeper slopes will also provide some level of removal where site constraints dictate the geometry of the buffer. Grass Buffer T-1 November 2010 Urban Drainage and Flood Control District GB-3 Urban Storm Drainage Criteria Manual Volume 3 Photograph GB-2. This level spreader carries concentrated flows into a slotted pipe encased in concrete to distribute flows evenly to the grass buffer shown left in the photo. Photo courtesy of Bill Wenk. Use of Grass Buffers Sheet flow of stormwater through a grassed area provides some benefit in pollutant removal and volume reduction even when the geometry of the BMP does not meet the criteria provided in this Fact Sheet. These criteria provide a design procedure that should be used when possible; however, when site constraints are limiting, this treatment concept is still encouraged. 4. Buffer Slope: The design slope of a grass buffer in the direction of flow should not exceed 10%. Generally, a minimum slope of 2% or more in turf is adequate to facilitate positive drainage. For slopes less than 2%, consider including an underdrain system to mitigate nuisance drainage. 5. Flow Characteristics (sheet or concentrated): Concentrated flows can occur when the width of the watershed differs from that of the grass buffer. Additionally, when the product of the watershed flow length and the interface slope (the slope of the watershed normal to flow at the grass buffer) exceeds approximately one, flows may become concentrated. Use the following equations to determine flow characteristics: Sheet Flow: FL(SI) ≤ 1 Equation GB-2 Concentrated Flow: FL(SI) > 1 Equation GB-3 Where: FL = watershed flow length (ft) SI = interface slope (normal to flow) (ft/ft) 6. Flow Distribution: Flows delivered to a grass buffer must be sheet flows. Slotted or flush curbing, permeable pavements, or other devices can be used to spread flows. The grass buffer should have relatively consistent slopes to avoid concentrating flows within the buffer. A level spreader should be used when flows are concentrated. A level spreader can be a slotted drain designed to discharge flow through the slot as shown in Photo GB-2. It could be an exfiltration trench filled with gravel, which allows water to infiltrate prior to discharging over a level concrete or rock curb. There are many ways to design and construct a level spreader. They can also be used in series when the length of the buffer allows flows to re- concentrate. See Figure GB-2 for various level spreader sections. T-1 Grass Buffer GB-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Photograph GB-3. This level spreader includes the added benefit of a sedimentation basin prior to even distribution of concentrated flows from the roadway into the grass buffer. Photo courtesy of Bill Wenk. Photograph GB-4. Maintenance access is provided via the ramp located at the end of the basin. Photo courtesy of Bill Wenk. Photos GB-3 and GB-4 show a level spreader that includes a basin for sedimentation. Concentrated flows enter the basin via stormsewer. The basin is designed to drain slowly while overflow is spread evenly to the downstream vegetation. A small notch, orifice, or pipe can be used to drain the level spreader completely. The opening should be small to encourage frequent flows to overtop the level spreader but not so small that it is frequently clogged. 7. Soil Preparation: In order to encourage establishment and long- term health of the selected vegetation, it is essential that soil conditions be properly prepared prior to installation. Following site grading, poor soil conditions often exist. When possible, remove, strip, stockpile, and reuse on-site topsoil. If the site does not contain topsoil, the soils should be amended prior to vegetation. Typically 3 to 5 cubic yards of soil amendment (compost) per 1,000 square feet, tilled 6 inches into the soil is required in order for vegetation to thrive, as well as to enable infiltration of runoff. Additionally, inexpensive soil tests can be conducted to determine required soil amendments. (Some local governments may also require proof of soil amendment in landscaped areas for water conservation reasons.) 8. Vegetation: This is the most critical component for treatment within a grass buffer. Select durable, dense, and drought tolerant grasses to vegetate the buffer. Also consider the size of the watershed as larger watersheds will experience more frequent flows. The goal is to provide a dense mat of vegetative cover. Grass buffer performance falls off rapidly as the vegetation coverage declines below 80% (Barrett et al.2004). Grass Buffer T-1 November 2010 Urban Drainage and Flood Control District GB-5 Urban Storm Drainage Criteria Manual Volume 3 Turf grasses such as Kentucky bluegrass are often selected due to these qualities1 9. Irrigation: Grass buffers should be equipped with irrigation systems to promote establishment and survival in Colorado's semi-arid environment. Systems may be temporary or permanent, depending on the type of vegetation selected. Irrigation application rates and schedules should be developed and adjusted throughout the establishment and growing season to meet the needs of the selected plant species. Initially, native grasses require the same irrigation requirements as bluegrass. After the grass is established, irrigation requirements for native grasses can be reduced. Irrigation practices have a significant effect on the function of the grass buffer. Overwatering decreases the permeability of the soil, reducing the infiltration capacity and contributing to nuisance baseflows. Conversely, under watering may result in delays in establishment of the vegetation in the short term and unhealthy vegetation that provides less filtering and increased susceptibility to erosion and rilling over the long term. . Dense native turf grasses may also be selected where a more natural look is desirable. Once established, these provide the benefit of lower irrigation requirements. See the Revegetation chapter in Volume 2 of this manual with regard to seed mix selection, planting and ground preparation. Depending on soils and anticipated flows, consider erosion control measures until vegetation has been established. 10. Outflow Collection: Provide a means for downstream conveyance. A grass swale can be used for this purpose, providing additional LID benefits. Construction Considerations Success of grass buffers depends not only on a good design and long-term maintenance, but also on installing the facility in a manner that enables the BMP to function as designed. Construction considerations include:  The final grade of the buffer is critical. Oftentimes, following soil amendment and placement of sod, the final grade is too high to accept sheet flow. The buffer should be inspected prior to placement of seed or sod to ensure appropriate grading.  Perform soil amending, fine grading, and seeding only after tributary areas have been stabilized and utility work crossing the buffer has been completed.  When using sod tiles stagger the ends of the tiles to prevent the formation of channels along the joints. Use a roller on the sod to ensure there are no air pockets between the sod and soil.  Avoid over compaction of soils in the buffer area during construction to preserve infiltration capacities.  Erosion and sediment control measures on upgradient disturbed areas must be maintained to prevent excessive sediment loading to grass buffer. 1 Although Kentucky bluegrass has relatively high irrigation requirements to maintain a lush, green aesthetic, it also withstands drought conditions by going dormant. Over-irrigation of Kentucky bluegrass is a common problem along the Colorado Front Range, and it can be healthy, although less lush, with much less irrigation than is typically applied. T-1 Grass Buffer GB-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 PLAN PROFILE Figure GB-1. Typical Grass Buffer Graphic by Adia Davis. Grass Buffer T-1 November 2010 Urban Drainage and Flood Control District GB-7 Urban Storm Drainage Criteria Manual Volume 3 Figure GB-2. Typical Level Spreader Details Grass Swale T-2 November 2010 Urban Drainage and Flood Control District GS-1 Urban Storm Drainage Criteria Manual Volume 3 Photograph GS-1. This grass swale provides treatment of roadway runoff in a residential area. Photo courtesy of Bill Ruzzo. Description Grass swales are densely vegetated trapezoidal or triangular channels with low-pitched side slopes designed to convey runoff slowly. Grass swales have low longitudinal slopes and broad cross-sections that convey flow in a slow and shallow manner, thereby facilitating sedimentation and filtering (straining) while limiting erosion. Berms or check dams may be incorporated into grass swales to reduce velocities and encourage settling and infiltration. When using berms, an underdrain system should be provided. Grass swales are an integral part of the Low Impact Development (LID) concept and may be used as an alternative to a curb and gutter system. Site Selection Grass swales are well suited for sites with low to moderate slopes. Drop structures or other features designed to provide the same function as a drop structures (e.g., a driveway with a stabilized grade differential at the downstream end) can be integrated into the design to enable use of this BMP at a broader range of site conditions. Grass swales provide conveyance so they can also be used to replace curb and gutter systems making them well suited for roadway projects. Designing for Maintenance Recommended ongoing maintenance practices for all BMPs are provided in Chapter 6 of this manual. During design, the following should be considered to ensure ease of maintenance over the long-term:  Consider the use and function of other site features so that the swale fits into the landscape in a natural way. This can encourage upkeep of the area, which is particularly important in residential areas where a loss of aesthetics and/or function can lead to homeowners filling in and/or piping reaches of this BMP. Grass Swale Functions LID/Volume Red. Yes WQCV Capture No WQCV+Flood Control No Fact Sheet Includes EURV Guidance No Typical Effectiveness for Targeted Pollutants3 Sediment/Solids Good Nutrients Moderate Total Metals Good Bacteria Poor Other Considerations Life-cycle Costs Low 3 Based primarily on data from the International Stormwater BMP Database (www.bmpdatabase.org). T-2 Grass Swale GS-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3  Provide access to the swale for mowing equipment and design sideslopes flat enough for the safe operation of equipment.  Design and adjust the irrigation system (temporary or permanent) to provide appropriate water for the selected vegetation.  An underdrain system will reduce excessively wet areas, which can cause rutting and damage to the vegetation during mowing operations.  When using an underdrain, do not put a filter sock on the pipe. This is unnecessary and can cause the slots or perforations in the pipe to clog. Design Procedure and Criteria The following steps outline the design procedure and criteria for stormwater treatment in a grass swale. Figure GS-1 shows trapezoidal and triangular swale configurations. 1. Design Discharge: Determine the 2-year flow rate to be conveyed in the grass swale under fully developed conditions. Use the hydrologic procedures described in the Runoff Chapter in Volume 1. 2. Hydraulic Residence Time: Increased hydraulic residence time in a grass swale improves water quality treatment. Maximize the length of the swale when possible. If the length of the swale is limited due to site constraints, the slope can also be decreased or the cross-sectional area increased to increase hydraulic residence time. 3. Longitudinal Slope: Establish a longitudinal slope that will meet Froude number, velocity, and depth criteria while ensuring that the grass swale maintains positive drainage. Positive drainage can be achieved with a minimum 2% longitudinal slope or by including an underdrain system (see step 8). Use drop structures as needed to accommodate site constraints. Provide for energy dissipation downstream of each drop when using drop structures. 4. Swale Geometry: Select geometry for the grass swale. The cross section should be either trapezoidal or triangular with side slopes not exceeding 4:1 (horizontal: vertical), preferably flatter. Increase the wetted area of the swale to reduce velocity. Lower velocities result in improved pollutant removal efficiency and greater volume reduction. If one or both sides of the grass swale are also to be used as a grass buffer, follow grass buffer criteria. Benefits  Removal of sediment and associated constituents through filtering (straining)  Reduces length of storm sewer systems in the upper portions of a watershed  Provides a less expensive and more attractive conveyance element  Reduces directly connected impervious area and can help reduce runoff volumes. Limitations  Requires more area than traditional storm sewers.  Underdrains are recommended for slopes under 2%.  Erosion problems may occur if not designed and constructed properly. Grass Swale T-2 November 2010 Urban Drainage and Flood Control District GS-3 Urban Storm Drainage Criteria Manual Volume 3 Native grasses provide a more natural aesthetic and require less water once established. Use of Grass Swales Vegetated conveyance elements provide some benefit in pollutant removal and volume reduction even when the geometry of the BMP does not meet the criteria provided in this Fact Sheet. These criteria provide a design procedure that should be used when possible; however, when site constraints are limiting, vegetated conveyance elements designed for stability are still encouraged. 5. Vegetation: Select durable, dense, and drought tolerant grasses. Turf grasses, such as Kentucky bluegrass, are often selected due to these qualities1 once established. Turf grass is a general term for any grasses that will form a turf or mat as opposed to bunch grass, which will grow in clumplike fashion. Grass selection should consider both short-term (for establishment) and long-term maintenance requirements, given that some varieties have higher maintenance requirements than others. Follow criteria in the Revegetation Chapter of Volume 2, with regard to seed mix selection, planting, and ground preparation. . Native turf grasses may also be selected where a more natural look is desirable. This will also provide the benefit of lower irrigation requirements, 6. Design Velocity: Maximum flow velocity in the swale should not exceed one foot per second. Use the Soil Conservation Service (now the NRCS) vegetal retardance curves for the Manning coefficient (Chow 1959). Determining the retardance coefficient is an iterative process that the UD-BMP workbook automates. When starting the swale vegetation from sod, curve "D" (low retardance) should be used. When starting vegetation from seed, use the "E" curve (very low vegetal retardance). 7. Design Flow Depth: Maximum flow depth should not exceed one foot at the 2-year peak flow rate. Check the conditions for the 100-year flow to ensure that drainage is being handled without flooding critical areas, structures, or adjacent streets. Table GS-1. Grass Swale Design Summary for Water Quality 1 Although Kentucky bluegrass has relatively high irrigation requirements to maintain a lush, green aesthetic, it also withstands drought conditions by going dormant. Over-irrigation of Kentucky bluegrass is a common problem along the Colorado Front Range. It can be healthy, although less lush, with much less irrigation than is typically applied. Design Flow Maximum Froude Number Maximum Velocity Maximum Flow Depth 2-year event 0.5 1 ft/s 1 ft T-2 Grass Swale GS-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 8. Underdrain: An underdrain is necessary for swales with longitudinal slopes less than 2.0%. The underdrain can drain directly into an inlet box at the downstream end of the swale, daylight through the face of a grade control structure or continue below grade through several grade control structures as shown in Figure GS-1. The underdrain system should be placed within an aggregate layer. If no underdrain is required, this layer is not required. The aggregate layer should consist of an 8-inch thick layer of CDOT Class C filter material meeting the gradation in Table GS-2. Use of CDOT Class C Filter material with a slotted pipe that meets the slot dimensions provided in Table GS-3 will eliminate the need for geotextile fabrics. Previous versions of this manual detailed an underdrain system that consisted of a 3- to 4-inch perforated HDPE pipe in a one-foot trench section of AASHTO #67 coarse aggregate surrounded by geotextile fabric. If desired, this system continues to provide an acceptable alternative for use in grass swales. Selection of the pipe size may be a function of capacity or of maintenance equipment. Provide cleanouts at approximately 150 feet on center. Table GS-2. Gradation Specifications for Class C Filter Material (Source: CDOT Table 703-7) Sieve Size Mass Percent Passing Square Mesh Sieves 19.0 mm (3/4") 100 4.75 mm (No. 4) 60 – 100 300 µm (No. 50) 10 – 30 150 µm (No. 100) 0 – 10 75 µm (No. 200) 0 - 3 Table GS-3. Dimensions for Slotted Pipe Pipe Diameter Slot Length1 Maximum Slot Width Slot Centers1 Open Area1 (per foot) 4” 1-1/16” 0.032” 0.413” 1.90 in2 6” 1-3/8” 0.032” 0.516” 1.98 in2 1 Some variation in these values is acceptable and is expected from various pipe manufacturers. Be aware that both increased slot length and decreased slot centers will be beneficial to hydraulics but detrimental to the structure of the pipe. Grass Swale T-2 November 2010 Urban Drainage and Flood Control District GS-5 Urban Storm Drainage Criteria Manual Volume 3 Photograph GS-2. This community used signage to mitigate compaction of soils post- construction. Photo courtesy of Nancy Styles. 9. Soil preparation: Poor soil conditions often exist following site grading. When the section includes an underdrain, provide 4 inches of sandy loam at the invert of the swale extending up to the 2-year water surface elevation. This will improve infiltration and reduce ponding. For all sections, encourage establishment and long-term health of the bottom and side slope vegetation by properly preparing the soil. If the existing site provides a good layer of topsoil, this should be striped, stockpiled, and then replaced just prior to seeding or placing sod. If not available at the site, topsoil can be imported or the existing soil may be amended. Inexpensive soil tests can be performed following rough grading, to determine required soil amendments. Typically, 3 to 5 cubic yards of soil amendment per 1,000 square feet, tilled 4 to 6 inches into the soil is required in order for vegetation to thrive, as well as to enable infiltration of runoff. 10. Irrigation: Grass swales should be equipped with irrigation systems to promote establishment and survival in Colorado's semi-arid environment. Systems may be temporary or permanent, depending on the type of grass selected. Irrigation practices have a significant effect on the function of the grass swale. Overwatering decreases the permeability of the soil, reducing the infiltration capacity of the soil and contributing to nuisance baseflows. Conversely, under watering may result in delays in establishment of the vegetation in the short term and unhealthy vegetation that provides less filtering (straining) and increased susceptibility to erosion and riling over the long term. Construction Considerations Success of grass swales depends not only on a good design and maintenance, but also on construction practices that enable the BMP to function as designed. Construction considerations include:  Perform fine grading, soil amendment, and seeding only after upgradient surfaces have been stabilized and utility work crossing the swale has been completed.  Avoid compaction of soils to preserve infiltration capacities.  Provide irrigation appropriate to the grass type.  Weed the area during the establishment of vegetation by hand or mowing. Mechanical weed control is preferred over chemical weed killer.  Protect the swale from other construction activities.  When using an underdrain, ensure no filter sock is placed on the pipe. This is unnecessary and can cause the slots or perforations in the pipe to clog. T-2 Grass Swale GS-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Figure GS-1. Grass Swale Profile and Sections Design Example The UD-BMP workbook, designed as a tool for both designer and reviewing agency is available at www.udfcd.org. This section provides a completed design form from this workbook as an example. Bioretention T-3 November 2010 Urban Drainage and Flood Control District B-1 Urban Storm Drainage Criteria Manual Volume 3 Terminology The term bioretention refers to the treatment process although it is also frequently used to describe a BMP that provides biological uptake and retention of the pollutants found in stormwater runoff. This BMP is frequently referred to as a porous landscape detention (PLD) area or rain garden. Photograph B-1. This recently constructed rain garden provides bioretention of pollutants, as well as an attractive amenity for a residential building. Treatment should improve as vegetation matures. Description A BMP that utilizes bioretention is an engineered, depressed landscape area designed to capture and filter or infiltrate the water quality capture volume (WQCV). BMPs that utilize bioretention are frequently referred to as rain gardens or porous landscape detention areas (PLDs). The term PLD is common in the Denver metropolitan area as this manual first published the BMP by this name in 1999. In an effort to be consistent with terms most prevalent in the stormwater industry, this document generally refers to the treatment process as bioretention and to the BMP as a rain garden. The design of a rain garden may provide detention for events exceeding that of the WQCV. There are generally two ways to achieve this. The design can provide the flood control volume above the WQCV water surface elevation, with flows bypassing the filter usually by overtopping into an inlet designed to restrict the peak flow for a larger event (or events). Alternatively, the design can provide and slowly release the flood control volume in an area downstream of one or more rain gardens. This infiltrating BMP requires consultation with a geotechnical engineer when proposed near a structure. A geotechnical engineer can assist with evaluating the suitability of soils, identifying potential impacts, and establishing minimum distances between the BMP and structures. Bioretention (Rain Garden) Functions LID/Volume Red. Yes WQCV Capture Yes WQCV+Flood Control Yes Fact Sheet Includes EURV Guidance No Typical Effectiveness for Targeted Pollutants3 Sediment/Solids Very Good1 Nutrients Moderate Total Metals Good Bacteria Moderate Other Considerations Life-cycle Costs4 Moderate 1 Not recommended for watersheds with high sediment yields (unless pretreatment is provided). 3 Based primarily on data from the International Stormwater BMP Database (www.bmpdatabase.org). 4 Based primarily on BMP-REALCOST available at www.udfcd.org. Analysis based on a single installation (not based on the maximum recommended watershed tributary to each BMP). T-3 Bioretention B-2 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Site Selection Bioretention can be provided in a variety of areas within new developments, or as a retrofit within an existing site. This BMP allows the WQCV to be treated within areas designated for landscape (see design step 7 for appropriate vegetation). In this way, it is an excellent alternative to extended detention basins for small sites. A typical rain garden serves a tributary area of one impervious acre or less, although they can be designed for larger tributary areas. Multiple installations can be used within larger sites. Rain gardens should not be used when a baseflow is anticipated. They are typically small and installed in locations such as:  Parking lot islands  Street medians  Landscape areas between the road and a detached walk  Planter boxes that collect roof drains Bioretention requires a stable watershed. Retrofit applications are typically successful for this reason. When the watershed includes phased construction, sparsely vegetated areas, or steep slopes in sandy soils, consider another BMP or provide pretreatment before runoff from these areas reaches the rain garden. The surface of the rain garden should be flat. For this reason, rain gardens can be more difficult to incorporate into steeply sloping terrain; however, terraced applications of these facilities have been successful in other parts of the country. When bioretention (and other BMPs used for infiltration) are located adjacent to buildings or pavement areas, protective measures should be implemented to avoid adverse impacts to these structures. Oversaturated subgrade soil underlying a structure can cause the structure to settle or result in moisture-related problems. Wetting of expansive soils or bedrock can cause swelling, resulting in structural movements. A geotechnical engineer should evaluate the potential impact of the BMP on adjacent structures based on an evaluation of the subgrade soil, groundwater, and bedrock conditions at the site. Additional minimum requirements include:  In locations where subgrade soils do not allow infiltration, the growing medium should be underlain by an underdrain system.  Where infiltration can adversely impact adjacent structures, the filter layer should be underlain by an underdrain system designed to divert water away from the structure.  In locations where potentially expansive soils or bedrock exist, placement of a rain garden adjacent to structures and pavement should only be considered if the BMP includes an underdrain designed to divert water away from the structure and is lined with an essentially impermeable geomembrane liner designed to restrict seepage. Benefits  Bioretention uses multiple treatment processes to remove pollutants, including sedimentation, filtering, adsorption, evapotranspiration, and biological uptake of constituents.  Volumetric stormwater treatment is provided within portions of a site that are already reserved for landscaping.  There is a potential reduction of irrigation requirements by taking advantage of site runoff. Limitations  Additional design and construction steps are required for placement of any ponding or infiltration area near or upgradient from a building foundation and/or when expansive (low to high swell) soils exist. This is discussed in the design procedure section.  In developing or otherwise erosive watersheds, high sediment loads can clog the facility. Bioretention T-3 November 2010 Urban Drainage and Flood Control District B-3 Urban Storm Drainage Criteria Manual Volume 3 Designing for Maintenance Recommended maintenance practices for all BMPs are in Chapter 6 of this manual. During design, the following should be considered to ensure ease of maintenance over the long-term:  Do not put a filter sock on the underdrain. This is not necessary and can cause the BMP to clog.  The best surface cover for a rain garden is full vegetation. Do not use rock mulch within the rain garden because sediment build-up on rock mulch tends to inhibit infiltration and require frequent cleaning or removal and replacement. Wood mulch handles sediment build-up better than rock mulch; however, wood mulch floats and may clog the overflow depending on the configuration of the outlet, settle unevenly, or be transported downstream. Some municipalities may not allow wood mulch for this reason.  Consider all potential maintenance requirements such as mowing (if applicable) and replacement of the growing medium. Consider the method and equipment for each task required. For example, in a large rain garden where the use of hand tools is not feasible, does the shape and configuration of the rain garden allow for removal of the growing medium using a backhoe?  Provide pre-treatment when it will reduce the extent and frequency of maintenance necessary to maintain function over the life of the BMP. For example, if the site is larger than 2 impervious acres, prone to debris or the use of sand for ice control, consider a small forebay.  Make the rain garden as shallow as possible. Increasing the depth unnecessarily can create erosive side slopes and complicate maintenance. Shallow rain gardens are also more attractive.  Design and adjust the irrigation system (temporary or permanent) to provide appropriate water for the establishment and maintenance of selected vegetation. Design Procedure and Criteria The following steps outline the design procedure and criteria, with Figure B-1 providing a corresponding cross-section. 1. Basin Storage Volume: Provide a storage volume based on a 12-hour drain time.  Find the required WQCV (watershed inches of runoff). Using the imperviousness of the tributary area (or effective imperviousness where LID elements are used upstream), use Figure 3-2 located in Chapter 3 of this manual to determine the WQCV based on a 12-hour drain time.  Calculate the design volume as follows: 𝑉𝑉 = �WQCV12�𝐴𝐴 Equation B-1 Where: V= design volume (ft3) Is Pretreatment Needed Designing the inflow gutter to the rain garden at a minimal slope of 0.5% can facilitate sediment and debris deposition prior to flows entering the BMP. Be aware, this will reduce maintenance of the BMP, but may require more frequent sweeping of the gutter to ensure that the sediment does not impede flow into the rain garden. T-3 Bioretention B-4 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Benefits of Shredded Paper in Rain Garden Growing Media  Shredded paper, similar to other woody materials, captures nutrients from the compost and slowly releases them as the paper decomposes. Compost alone will leach more nutrients than desired.  As the paper decomposes, nutrients stored in the material are available to the vegetation.  Paper temporarily slows the infiltration rate of the media and retains moisture, providing additional time for a young root system to benefit from moisture in the growing media. A = area of watershed tributary to the rain garden (ft2) 2. Basin Geometry: A maximum WQCV ponding depth of 12 inches is recommended to maintain vegetation properly. Provide an inlet or other means of overflow at this elevation. Depending on the type of vegetation planted, a greater depth may be utilized to detain larger (more infrequent) events. The bottom surface of the rain garden, also referred to here as the filter area, should be flat. Sediment will reside on the filter area of the rain garden; therefore, if the filter area is too small, it may clog prematurely. Increasing the filter area will reduce clogging and decrease the frequency of maintenance. Equation B-2 provides a minimum filter area allowing for some of the volume to be stored beyond the area of the filter (i.e., above the sideslopes of the rain garden). Note that the total surcharge volume provided by the design must also equal or exceed the design volume. Use vertical walls or slope the sides of the basin to achieve the required volume. Use the rain garden growing medium described in design step 3 only on the filter area because this material is more erosive than typical site soils. Sideslopes should be no steeper than 4:1 (horizontal:vertical). 𝐴𝐴≥(2/3)V 1 foot Equation B-2 Where: V= design volume (ft3) A = minimum filter area (flat surface area) (ft2) The one-foot dimension in this equation represents the maximum recommended WQCV depth in the rain garden. The actual design depth may differ; however, it is still appropriate to use a value of one foot when calculating the minimum filter area. 3. Growing Medium: For partial and no infiltration sections, provide a minimum of 18 inches of growing medium to enable establishment of the roots of the vegetation (see Figure B-1). Previous versions of this manual recommended a mix of 85% sand and 15% peat (by volume). Peat is a material that typically requires import to Colorado and mining peat has detrimental impacts to the environment (Mazerolle 2002). UDFCD partnered with the University of Colorado to perform a study to find a sustainable material to replace peat. The study was successful in finding a replacement that performed well for filtering ability, clogging characteristics, as well as seed germination. This mixture consists of 85% coarse sand and a 15% compost/shredded paper mixture (by volume). The study used thin (approximately 1/4 inch) strips of loosely packed shredded paper mixed with an equal volume of compost. Based on conversations with local suppliers, compost Bioretention T-3 November 2010 Urban Drainage and Flood Control District B-5 Urban Storm Drainage Criteria Manual Volume 3 containing shredded paper is not an uncommon request, although not typically provided in the proportions recommended in this BMP Fact Sheet. Compost suppliers have access to shredded paper through document destruction companies and can provide a mixture of Class 1 compost and shredded paper. The supplier should provide the rain garden compost mixture premixed with coarse sand. On- site mixing is not recommended. Rain Garden Compost Mixture (by volume)  50% Class 1 STA registered compost (approximate bulk density 1000 lbs/CY)  50% loosely packed shredded paper (approximate bulk density 50 to 100 lbs/CY) When using diamond cut shredded paper or tightly packed paper, use the bulk densities provided to mix by weight. The supplier should premix the rain garden compost mixture (above) with coarse sand, in the following proportions, prior to delivery to the site: Rain Garden Growing Medium  15% rain garden compost mixture described above (by volume)  85% coarse sand (either Class C Filter Material per Table B-2 or sand meeting ASTM C-33) (by volume) Table B-1 provides detailed information on Class 1 compost. Be aware, regular testing is not required to allow a compost supplier to refer to a product as a specific STA class. However, regular testing is required and performed through the United States Compost Council (USCC) Seal of Testing Assurance (STA) Program to be a STA registered compost. To ensure Class 1 characteristics, look for a Class 1 STA registered compost. Other Rain Garden Growing Medium Amendments The growing medium described above is designed for filtration ability, clogging characteristics, and vegetative health. It is important to preserve the function provided by the rain garden growing medium when considering additional materials for incorporation into the growing medium or into the standard section shown in Figure B-1. When desired, amendments may be included to improve water quality or to benefit vegetative health as long as they do not add nutrients, pollutants, or modify the infiltration rate. For example, a number of products, including steel wool, capture and retain dissolved phosphorus (Erickson 2009). When phosphorus is a target pollutant, proprietary materials with similar characteristics may be considered. Do not include amendments such as top soil, sandy loam, and additional compost. Full Infiltration Sections A full infiltration section retains the WQCV onsite. For this section, it is not necessary to use the prescribed rain garden growing medium. Amend the soils to provide adequate nutrients to establish vegetation. Typically, 3 to 5 cubic yards of soil amendment (compost) per 1,000 square feet, tilled 6 inches into the soil, is required for vegetation to thrive. Additionally, inexpensive soil tests can be conducted to determine required soil amendments. (Some local governments may also require proof of soil amendment in landscaped areas for water conservation reasons.) T-3 Bioretention B-6 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Table B-1. Class 1 Compost Characteristic Criteria Minimum Stability Indicator (Respirometry) Stable to Very Stable Maturity Indicator Expressed as Ammonia N / Nitrate N Ratio < 4 Maturity Indicator Expressed as Carbon to Nitrogen Ratio < 12 Maturity Indicator Expressed as Percentage of Germination/Vigor 80+ / 80+ pH – Acceptable Range 6.0 – 8.4 Soluble Salts – Acceptable Range (1:5 by weight) 0 – 5 mmhos/cm Testing and Test Report Submittal Requirement Seal of Testing Assurance (STA)/Test Methods for the Examination of Composting and Compost (TMECC) Chemical Contaminants Equal or better than US EPA Class A Standard, 40 CFR 503.13, Tables 1 & 3 levels Pathogens Meet or exceed US EPA Class A standard, 40 CFR 503.32(a) levels Bioretention T-3 November 2010 Urban Drainage and Flood Control District B-7 Urban Storm Drainage Criteria Manual Volume 3 4. Underdrain System: Underdrains are often necessary and should be provided if infiltration tests show percolation drawdown rates slower than 2 times the rate needed to drain the WQCV over 12 hours, or where required to divert water away from structures as determined by a professional engineer. Percolation tests should be performed or supervised by a licensed professional engineer and conducted at a minimum depth equal to the bottom of the bioretention facility. Additionally, underdrains are required where impermeable membranes are used. Similar to the terminology used for permeable pavement sections, there are three basic sections for bioretention facilities:  No-Infiltration Section: This section includes an underdrain and an impermeable liner that does not allow for any infiltration of stormwater into the subgrade soils. It is appropriate to use a no- infiltration system when either of the following is true: o Land use or activities could contaminate groundwater when stormwater is allowed to infiltrate, or o The BMP is located over potentially expansive soils or bedrock and is adjacent (within 10 feet) to structures.  Partial Infiltration Section: This section does not include an impermeable liner and, therefore; allows for some infiltration. Stormwater that does not infiltrate will be collected and removed by an underdrain system.  Full Infiltration Section: This section is designed to infiltrate all of the water stored into the subgrade below. Overflows are managed via perimeter drainage to a downstream conveyance element. UDFCD recommends a minimum infiltration rate of 2 times the rate needed to drain the WQCV over 12 hours. When using an underdrain system, provide a control orifice sized to drain the design volume in 12 hours or more (see Equation B-3). Use a minimum orifice size of 3/8 inch to avoid clogging. This will provide detention and slow release of the WQCV, providing water quality benefits and reducing impacts to downstream channels. Space underdrain pipes a maximum of 20 feet on center. Provide cleanouts to enable maintenance of the underdrain. Cleanouts can also be used to conduct an inspection (by camera) of the underdrain system to Important Design Considerations The potential for impacts to adjacent buildings can be significantly reduced by locating the bioretention area at least 10 feet away from the building, beyond the limits of backfill placed against the building foundation walls, and by providing positive surface drainage away from the building. The BMP should not restrict surface water from flowing away from the buildings. This can occur if the top of the perimeter wall for the BMP impedes flow away from the building. Always adhere to the slope recommendations provided in the geotechnical report. In the absence of a geotechnical report, the following general recommendations should be followed for the first 10 feet from a building foundation. 1) Where feasible, provide a slope of 10% for a distance of 10 feet away from a building foundation. 2) In locations where non-expansive soil or bedrock conditions exist, the slope for the surface within 10 feet of the building should be at least 5% away from the building for unpaved (landscaped) surfaces. 3) In locations where potentially expansive soil or bedrock conditions exist, the design slope should be at least 10% away from the building for unpaved (landscaped) surfaces. 4) For paved surfaces, a slope of at least 2% away from the building is adequate. Where accessibility requirements or other design constraints do not apply, use an increased minimum design slope for paved areas (2.5% where non- expansive soil or bedrock conditions exist). T-3 Bioretention B-8 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 ensure that the pipe was not crushed or disconnected during construction. Calculate the diameter of the orifice for a 12-hour drain time using Equation B-3 (Use a minimum orifice size of 3/8 inch to avoid clogging.): 𝐷𝐷12 hour drain time =�𝑉𝑉1414 𝑦𝑦0.41 Equation B-3 Where: D = orifice diameter (in) y = distance from the lowest elevation of the storage volume (i.e., surface of the filter) to the center of the orifice (ft) V = volume (WQCV or the portion of the WQCV in the rain garden) to drain in 12 hours (ft3) In previous versions of this manual, UDFCD recommended that the underdrain be placed in an aggregate layer and that a geotextile (separator fabric) be placed between this aggregate and the growing medium. This version of the manual replaces that section with materials that, when used together, eliminate the need for a separator fabric. The underdrain system should be placed within an 6-inch-thick section of CDOT Class C filter material meeting the gradation in Table B-2. Use slotted pipe that meets the slot dimensions provided in Table B-3. Table B-2. Gradation Specifications for CDOT Class C Filter Material (Source: CDOT Table 703-7) Sieve Size Mass Percent Passing Square Mesh Sieves 19.0 mm (3/4”) 100 4.75 mm (No. 4) 60 – 100 300 µm (No. 50) 10 – 30 150 µm (No. 100) 0 – 10 75 µm (No. 200) 0 - 3 Bioretention T-3 November 2010 Urban Drainage and Flood Control District B-9 Urban Storm Drainage Criteria Manual Volume 3 Table B-3. Dimensions for Slotted Pipe Pipe Diameter Slot Length1 Maximum Slot Width Slot Centers1 Open Area1 (per foot) 4” 1-1/16” 0.032” 0.413” 1.90 in2 6” 1-3/8” 0.032” 0.516” 1.98 in2 1 Some variation in these values is acceptable and is expected from various pipe manufacturers. Be aware that both increased slot length and decreased slot centers will be beneficial to hydraulics but detrimental to the structure of the pipe. 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric: For no-infiltration sections, install a 30 mil (minimum) PVC geomembrane liner, per Table B-5, on the bottom and sides of the basin, extending up at least to the top of the underdrain layer. Provide at least 9 inches (12 inches if possible) of cover over the membrane where it is attached to the wall to protect the membrane from UV deterioration. The geomembrane should be field-seamed using a dual track welder, which allows for non-destructive testing of almost all field seams. A small amount of single track and/or adhesive seaming should be allowed in limited areas to seam around pipe perforations, to patch seams removed for destructive seam testing, and for limited repairs. The liner should be installed with slack to prevent tearing due to backfill, compaction, and settling. Place CDOT Class B geotextile separator fabric above the geomembrane to protect it from being punctured during the placement of the filter material above the liner. If the subgrade contains angular rocks or other material that could puncture the geomembrane, smooth-roll the surface to create a suitable surface. If smooth-rolling the surface does not provide a suitable surface, also place the separator fabric between the geomembrane and the underlying subgrade. This should only be done when necessary because fabric placed under the geomembrane can increase seepage losses through pinholes or other geomembrane defects. Connect the geomembrane to perimeter concrete walls around the basin perimeter, creating a watertight seal between the geomembrane and the walls using a continuous batten bar and anchor connection (see Figure B-3). Where the need for the impermeable membrane is not as critical, the membrane can be attached with a nitrile-based vinyl adhesive. Use watertight PVC boots for underdrain pipe penetrations through the liner (see Figure B-2). T-3 Bioretention B-10 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 Table B-4. Physical Requirements for Separator Fabric1 Table B-5. Physical Requirements for Geomembrane Property Thickness 0.76 mm (30 mil) Test Method Thickness, % Tolerance ±5 ASTM D 1593 Tensile Strength, kN/m (lbs/in) width 12.25 (70) ASTM D 882, Method B Modulus at 100% Elongation, kN/m (lbs/in) 5.25 (30) ASTM D 882, Method B Ultimate Elongation, % 350 ASTM D 882, Method A Tear Resistance, N (lbs) 38 (8.5) ASTM D 1004 Low Temperature Impact, °C (°F) -29 (-20) ASTM D 1790 Volatile loss, % max. 0.7 ASTM D 1203, Method A Pinholes, No. Per 8 m2 (No. per 10 sq. yds.) max. 1 N/A Bonded Seam Strength, % of tensile strength 80 N/A Property Class B Test Method Elongation < 50%2 Elongation > 50%2 Grab Strength, N (lbs) 800 (180) 510 (115) ASTM D 4632 Puncture Resistance, N (lbs) 310 (70) 180 (40) ASTM D 4833 Trapezoidal Tear Strength, N (lbs) 310 (70) 180 (40) ASTM D 4533 Apparent Opening Size, mm (US Sieve Size) AOS < 0.3mm (US Sieve Size No. 50) ASTM D 4751 Permittivity, sec-1 0.02 default value, must also be greater than that of soil ASTM D 4491 Permeability, cm/sec k fabric > k soil for all classes ASTM D 4491 Ultraviolet Degradation at 500 hours 50% strength retained for all classes ASTM D 4355 1 Strength values are in the weaker principle direction 2 As measured in accordance with ASTM D 4632 Bioretention T-3 November 2010 Urban Drainage and Flood Control District B-11 Urban Storm Drainage Criteria Manual Volume 3 Designing for Flood Protection Provide the WQCV in rain gardens that direct excess flow into to a landscaped area providing the flood control volume. Design the flood control outlet to meter the major event (100-year event) and slowly release the difference in volume between the EURV and the WQCV. (This assumes that the runoff treated by the rain gardens is routed directly into the outlet or infiltrates.) Providing treatment in this manner will reduce inundation in the landscaped area to a few times per year, resulting in an area better suited for multipurpose uses. 6. Inlet/Outlet Control: In order to provide the proper drain time, the bioretention area can be designed without an underdrain (provided it meets the requirements in step 4) or the outlet can be controlled by an orifice plate. Equation B-3 is a simplified equation for sizing an orifice plate for a 12-hour drain time. 7. How flow enters and exits the BMP is a function of the overall drainage concept for the site. Inlets at each rain garden may or may not be needed. Curb cuts can be designed to both allow stormwater into the rain garden as well as to provide release of stormwater in excess of the WQCV. Roadside rain gardens located on a steep site might pool and overflow into downstream cells with a single curb cut, level spreader, or outlet structure located at the most downstream cell. When selecting the type and location of the outlet structure, ensure that the runoff will not short-circuit the rain garden. This is a frequent problem when using a curb inlet located outside the rain garden for overflow. For rain gardens with concentrated points of inflow, provide for energy dissipation. When rock is used, provide separator fabric between the rock and growing medium to minimize subsidence. 8. Vegetation: UDFCD recommends that the filter area be vegetated with drought tolerant species that thrive in sandy soils. Table B-6 provides a suggested seed mix for sites that will not need to be irrigated after the grass has been established. All seed must be well mixed and broadcast, followed by hand raking to cover seed and then mulched. Hydromulching can be effective for large areas. Do not place seed when standing water or snow is present or if the ground is frozen. Weed control is critical in the first two to three years, especially when starting with seed. Do not use conventional sod. Conventional sod is grown in clay soil that will seal the filter area, greatly reducing overall function of the BMP. Several successful local installations have started with seed. Photograph B-2. The curb cut shown allows flows to enter this rain garden while excess flows bypass the facility. Note: trees are not recommended inside a rain garden T-3 Bioretention B-12 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 When using an impermeable liner, select plants with diffuse (or fibrous) root systems, not taproots. Taproots can damage the liner and/or underdrain pipe. Avoid trees and large shrubs that may interfere with restorative maintenance. Trees and shrubs can be planted outside of the area of growing medium. Use a cutoff wall to ensure that roots do not grow into the underdrain or place trees and shrubs a conservative distance from the underdrain. 9. Irrigation: Provide spray irrigation at or above the WQCV elevation or place temporary irrigation on top of the rain garden surface. Do not place sprinkler heads on the flat surface. Remove temporary irrigation when vegetation is established. If left in place this will become buried over time and will be damaged during maintenance operations. Irrigation schedules should be adjusted during the growing season to provide the minimum water necessary to maintain plant health and to maintain the available pore space for infiltration. Adopted by Ordinance No. 44, 2016 Dust Prevention and Control Manual Dust Prevention and Control Manual Page i CONTENTS 1.0 Introduction 1 1.1 Title 1 1.2 Purpose of Manual 1 1.3 Applicability 1 1.4 Definitions 2 2.0 Fugitive Dust and the Problems it Causes 5 2.1 What is Fugitive Dust, Generally? 5 2.2 Why is the City Addressing Fugitive Dust? 5 2.3 Health and Environmental Effects 6 2.4 Nuisance and Aesthetics 6 2.5 Safety Hazard and Visibility 6 3.0 Best Management Practices 7 3.1 Earthmoving Activities 8 3.2 Demolition and Renovation 10 3.3 Stockpiles 12 3.4 Street Sweeping 14 3.5 Track-out / Carry-out 15 3.6 Bulk Materials Transport 16 3.7 Unpaved Roads and Haul Roads 18 3.8 Parking Lots 19 3.9 Open Areas and Vacant Lots 21 3.10 Saw Cutting and Grinding 22 3.11 Abrasive Blasting 24 3.12 Mechanical Blowing 26 4.0 Dust Control Plan for Land Development Greater Than Five Acres 28 Dust Prevention and Control Checklist 31 5.0 Resources 32 5.1 Cross Reference to Codes, Standards, Regulations, and Policies 32 5.2 City of Fort Collins Manuals and Policies 35 5.3 References for Dust Control 35 Dust Prevention and Control Manual Page 1 1.0 Introduction 1.1 Title The contents of this document shall be known as the Dust Prevention and Control Manual (“the Manual”). 1.2 Purpose of Manual The purpose of the Manual is to establish minimum requirements consistent with nationally recognized best management practices for controlling fugitive dust emissions and to describe applicable best management practices to prevent, minimize, and mitigate off-property transport or off-vehicle transport of fugitive dust emissions pursuant to Chapter 12, Article X of the Fort Collins City Code (§§12-150 et. seq) for specific dust generating activities and sources. The purpose of Chapter 12, Article X of the Code is to protect the health, safety, and welfare of the public, including prevention of adverse impacts to human health, property, sensitive vegetation and areas, waters of the state, and other adverse environmental impacts and to prevent visibility impairment and safety hazards caused by emissions of particulate matter into the air from human activities. 1.3 Applicability This Manual applies to any person who conducts, or is an owner or operator of, a dust generating activity or source, as defined in the Code and described in this Manual, within the City of Fort Collins, subject to the exclusion set forth in Code §12-150(b)(3). Dust Prevention and Control Manual Page 2 1.4 Definitions Abrasive blasting shall mean a process to smooth rough surfaces; roughen smooth surfaces; and remove paint, dirt, grease, and other coatings from surfaces. Abrasive blasting media may consist of sand; glass, plastic or metal beads; aluminum oxide; corn cobs; or other materials. Additional best management practice shall mean using at least one additional measure if the required best management practices are ineffective at preventing off-property transport of particulate matter. Additional requirements shall mean when applicable, any measure that is required, e.g., a dust control plan when project sites are over 5 acres in size. Best management practice shall mean any action or process that is used to prevent or mitigate the emission of fugitive dust into the air. Bulk materials transport shall mean the carrying, moving, or conveying of loose materials including, but not limited to, earth, rock, silt, sediment, sand, gravel, soil, fill, aggregate, dirt, mud, construction or demolition debris, and other organic or inorganic material containing particulate matter onto a public road or right-of-way in an unenclosed trailer, truck bed, bin, or other container. Code shall mean the Fort Collins City Code, as amended from time to time. Cover shall mean the installation of a temporary cover material on top of disturbed soil surfaces or stockpiles, such as netting, mulch, wood chips, gravel or other materials capable of preventing wind erosion. Dust control measure shall mean any action or process that is used to prevent or mitigate the emission of fugitive dust into the air, including but not limited to the best management practices identified in this Manual. Dust generating activity or source shall mean a process, operation, action, or land use that creates emissions of fugitive dust or causes off-property or off-vehicle transport. Dust generating activity or source shall include a paved parking lot containing an area of more than one half (1/2) acre. Earthmoving shall mean any process that involves land clearing, disturbing soil surfaces, or moving, loading, or handling of earth, dirt, soil, sand, aggregate, or similar materials. Fugitive dust shall mean solid particulate matter emitted into the air by mechanical processes or natural forces but is not emitted through a stack, chimney, or vent Local wind speed shall mean the current or forecasted wind speed for the Fort Collins area as measured at the surface weather observation station KFNL located at the Fort Collins Loveland Municipal Airport or at Colorado State University’s Fort Collins or Christman Field weather stations or as measured onsite with a portable or hand-held anemometer. The City will use anemometers whenever practicable. Dust Prevention and Control Manual Page 3 Maximum speed limit shall mean the speed limit on public rights-of-way adopted by the City pursuant to Fort Collins Traffic Code adopted pursuant to City Code Section 28-16 for private roadways, a speed limit shall be established as appropriate to minimize off-site transportation of. Mechanical blower shall mean any portable machine powered with an internal combustion or electric-powered engine used to blow leaves, clippings, dirt or other debris off sidewalks, driveways, lawns, medians, and other surfaces including, but not limited to, hand-held, back- pack and walk-behind units, as well as blower- vacuum units. Off-property transport shall mean the visible emission of fugitive dust beyond the property line of the property on which the emission originates or the project boundary when the emission originates in the public right-of-way or on public property. Off-vehicle transport shall mean the visible emission of fugitive dust from a vehicle that is transporting dust generating materials on a public road or right-of-way. On-tool local exhaust ventilation shall mean a vacuum dust collection system attached to a construction tool that includes a dust collector (hood or shroud), tubing, vacuum, and a high efficiency particulate air (HEPA) filter. On-tool wet dust suppression shall mean the operation of nozzles or sprayers attached to a construction tool that continuously apply water or other liquid to the grinding or cutting area by a pressurized container or other water source. Open area shall mean any area of undeveloped land greater than one-half acre that contains less than 70 percent vegetation. This includes undeveloped lots, vacant or idle lots, natural areas, parks, or other non-agricultural areas. Recreational and multi-use trails maintained by the City are not included as an open area. Operator or owner shall mean any person who has control over a dust generating source either by operating, supervising, controlling, or maintaining ownership of the activity or source including, but not limited to, a contractor, lessee, or other responsible party of an activity, operation, or land use that is a dust generating activity or source. Particulate matter shall mean any material that is emitted into the air as finely divided solid or liquid particles, other than uncombined water, and includes dust, smoke, soot, fumes, aerosols and mists. Required best management practices shall mean specific measures that are required to be implemented if a dust generating activity is occurring. Sensitive area shall mean a specific area that warrants special protection from adverse impacts due to the deposition of fugitive dust, such as natural areas (excluding buffer zones), sources of water supply, wetlands, critical wildlife habitat, or wild and scenic river corridors. Soil retention shall mean the stabilization of disturbed surface areas that will remain exposed and inactive for 30 days or more or while vegetation is being established using mulch, compost, soil mats, or other methods. Stockpile shall mean any accumulation of bulk materials that contain particulate matter being stored for future use or disposal. This includes backfill materials and storage piles for soil, sand, dirt, mulch, aggregate, straw, chaff, or other materials that produce dust. Storm drainage facility shall mean those improvements designed, constructed or used to convey or control stormwater runoff and to remove pollutants from stormwater runoff after precipitation. Dust Prevention and Control Manual Page 4 Surface roughening shall mean to modify the soil surface to resist wind action and reduce dust emissions from wind erosion by creating grooves, depressions, ridges or furrows perpendicular to the predominant wind direction using tilling, ripping, discing, or other method. Track-out shall mean the carrying of mud, dirt, soil, or debris on vehicle wheels, sides, or undercarriages from a private, commercial, or industrial site onto a public road or right-of- way. Vegetation shall mean the planting or seeding of appropriate grasses, plants, bushes, or trees to hold soil or to create a wind break. All seeded areas must be mulched, and the mulch should be adequately crimped and or tackified. If hydro-seeding is conducted, mulching must be conducted as a separate, second operation. All planted areas must be mulched within twenty- four (24) hours after planting. Wet suppression shall mean the application of water by spraying, sprinkling, or misting to maintain optimal moisture content or to form a crust in dust generating materials and applied at a rate that prevents runoff from entering any public right-of-way, storm drainage facility or watercourse. Wind barrier shall mean an obstruction at least five feet high erected to assist in preventing the blowing of fugitive dust, comprised of a solid board fence, chain link and fabric fence, vertical wooden slats, hay bales, earth berm, bushes, trees, or other materials installed perpendicular to the predominant wind direction or upwind of an adjacent residential, commercial, industrial, or sensitive area that would be negatively impacted by fugitive dust. Dust Prevention and Control Manual Page 5 2.0 Fugitive Dust and the Problems it Causes 2.1 What is Fugitive Dust, Generally? Dust, also known as particulate matter, is made up of solid particles in the air that consist primarily of dirt and soil but can also contain ash, soot, salts, pollen, heavy metals, asbestos, pesticides, and other materials. “Fugitive” dust means particulate matter that has become airborne by wind or human activities and has not been emitted from a stack, chimney, or vent. The Colorado Department of Public Health and Environment (CDPHE) estimates that more than 4,300 tons of particulate matter are emitted into the air in Larimer County annually. The primary sources of this particulate matter include construction activities, paved and unpaved roads, and agricultural operations. The quantity of dust emitted from a particular activity or area and the materials in it can depend on the soil type (sand, clay, silt), moisture content (dry or damp), local wind speed, and the current or past uses of the site (industrial, farming, construction). 2.2 Why is the City Addressing Fugitive Dust? Colorado state air regulations and Larimer County air quality standards generally require owners and operators of dust generating activities or sources to use all available and practical methods that are technologically feasible and economically reasonable in order to prevent fugitive dust emissions. However, state regulations and permitting requirements typically apply to larger stationary sources rather than to activities that generate dust. Larimer County fugitive dust standards apply only to land development. Although state and county requirements apply to many construction activities, they do not address many sources of dust emissions and City code compliance officers do not have authority to enforce state or county regulations. Fort Collins is experiencing rapid growth and development that has contributed to local man-made dust emissions. The City has established Chapter 12, Article X of the Code (§§12-150- 12-159) to address dust generating activities and sources that negatively impact citizens in Fort Collins. Dust Prevention and Control Manual Page 6 2.3 Health and Environmental Effects Dust particles are very small and can be easily inhaled. They can enter the respiratory system and increase susceptibility to respiratory infections, and aggravate cardio-pulmonary disease. Even short-term exposure to dust can cause wheezing, asthma attacks and allergic reactions, and may cause increases in hospital admissions and emergency department visits for heart and lung related diseases. Fugitive dust emissions can cause significant environmental impacts as well as health effects. When dust from wind erosion or human activity deposits out of the air, it may impact vegetation, adversely affect nearby soils and waterways, and cause damage to cultural resources. Wind erosion can result in the loss of valuable top soil, reduce crop yields, and stunt plant growth. According to the Environmental Protection Agency (EPA), studies have linked particulate matter exposure to health problems and environmental impacts such as: •Health Impacts: o Irritation of the airways, coughing, and difficulty breathing o Reduced lung function and lung cancer o Aggravated asthma and chronic bronchitis o Irregular heartbeat and increases in heart attacks •Environmental Impacts: o Haze and reduced visibility o Reduced levels of nutrients in soil 2.4 Nuisance and Aesthetics Dust, dirt and debris that become airborne eventually settle back down to the surface. How far it travels and where it gets deposited depends on the size and type of the particles as well as wind speed and direction. When this material settles, it can be deposited on homes, cars, lawns, pools and ponds, and other property. The small particles can get trapped in machinery and electronics causing abrasion, corrosion, and malfunctions. The deposited dust can damage painted surfaces, clog filtration systems, stain materials and cause other expensive clean-up projects. 2.5 Safety Hazard and Visibility Blowing dust can be a safety hazard at construction sites and on roads and highways. Dust can obstruct visibility and can cause accidents between vehicles and bikes, pedestrians, or site workers. Dust plumes can also decrease visibility across a natural area or scenic vistas. The “brown cloud”, often visible along the Front Range during the winter months, and the brilliant red sunsets that occur are often caused by particulate matter and other pollutants in the air. Dust Prevention and Control Manual Page 7 3.0 Best Management Practices This Manual describes established best management practices for controlling dust emissions that are practical and used in common practice to prevent or mitigate impacts to air quality from dust generating activities and sources occurring within Fort Collins. The objective of the dust control measures included in this Manual is to reduce dust emissions from human activities and to prevent those emissions from impacting others and is based on the following principles: Prevent – avoid creating dust emissions through good project planning and modifying or replacing dust generating activities. Minimize – reduce dust emissions with methods that capture, collect, or contain emissions. Mitigate – when preventing fugitive dust or minimizing the impacts are not feasible, the Manual provides specific measures to mitigate dust. More specifically, the Manual establishes the following procedures for each dust generating activity outlined in this Chapter: 1. Required Best Management Practices – this section includes the specific measures that are required to be implemented if the dust generating activity is occurring. For example, high wind restrictions (temporarily halting work when wind speeds exceed 30 mph) are required best management practices for earthmoving, demolition/renovation, saw cutting or grind, abrasive blasting, and leaf blowing. 2. Additional Best Management Practices – this section includes additional measures if the required best management practices are ineffective at preventing off-property transport of particulate matter. At least one of the additional best management practices outlined in the Manual must be implemented on the site to be in compliance with the Manual and Code. 3. Additional Requirements – When applicable, additional measures are also required, e.g., a dust control plan when project sites are over 5 acres in size. The Dust Prevention and Control Checklist included on page 31 of this Manual provides a “quick guide” to dust control BMPs covered in the following sections of the Manual. Dust Prevention and Control Manual Page 8 3.1 Earthmoving Activities Above: This figure illustrates earthmoving, which is an activity that can generate dust. Dust emissions from earthmoving activities depend on the type and extent of activity being conducted, the amount of exposed surface area, wind conditions, and soil type and moisture content, including:  Site preparation (clearing, grubbing, scraping)  Road construction  Grading and overlot grading  Excavating, trenching, backfilling and compacting  Loading and unloading dirt, soil, gravel, or other earth materials  Dumping of dirt, soil, gravel, or other earth materials into trucks, piles, or receptacles  Screening of dirt, soil, gravel, or other earth materials Best Management Practices to Control Dust (a) Required Best Management Practices: Any person, owner, or operator who conducts earthmoving that is a dust generating activity or source shall implement the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Minimize disturbed area: plan the project or activity so that the minimum amount of disturbed soil or surface area is exposed to wind or vehicle traffic at any one time. (ii) Reduce vehicle speeds: establish a maximum speed limit or install traffic calming devices to reduce speeds to a rate to mitigate off-property transport of dust entrained by vehicles. (iii) Minimize drop height: Drivers and operators shall unload truck beds and loader or excavator buckets slowly, and minimize drop height of materials to the lowest height possible, including screening operations. (iv) High winds restriction: temporarily halt work activities during high wind events greater than 30 mph if operations would result in off-property transport. (v) Restrict access: restrict access to the work area to only authorized vehicles and personnel. Dust Prevention and Control Manual Page 9 (b) Additional Best Management Practices: In the event 3.1(a)(i)-(v) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Wet suppression: apply water to disturbed soil surfaces, backfill materials, screenings, and other dust generating operations as necessary and appropriate considering current weather conditions, and prevent water used for dust control from entering any public right-of-way, stormwater drainage facility, or watercourse. (ii) Wind barrier: construct a fence or other type of wind barrier to prevent wind erosion of top soils. (iii) Vegetation: plant vegetation appropriate for retaining soils or creating a wind break. (iv) Surface roughening: stabilize an active construction area during periods of inactivity or when vegetation cannot be immediately established. (v) Cover: install cover materials during periods of inactivity and properly anchor the cover. (vi) Soil retention: stabilize disturbed or exposed soil surface areas that will be inactive for more than 30 days or while vegetation is being established. (c) Additional requirements: Any person, owner, or operator who conducts earthmoving that is a dust generating activity or source at a construction site or land development project with a lot size equal to or greater than five (5) acres also shall implement the following measures: (i) Dust Control Plan: submit a plan that describes all potential sources of fugitive dust and methods that will be employed to control dust emissions with the development construction permit application or development review application (see Chapter 4 of this Manual). A copy of the Dust Control Plan must be onsite at all times and one copy must be provided to all contractors and operators engaged in dust generating activities at the site. (ii) Construction sequencing: include sequencing or phasing in the project plan to minimize the amount of disturbed area at any one time. Sites greater than 25 acres in size may be asked to provide additional justification, revise the sequencing plan, or include additional best management practices. Dust Prevention and Control Manual Page 10 3.2 Demolition and Renovation Above: This photo illustrates restricting access (a required best management practice) and a wind barrier (an additional best management practice) for demolition and renovation activities. Dust generated from demolition activities may contain significant levels of silica, lead, asbestos, and particulate matter. Inhalation of silica and asbestos is known to cause lung cancer, and exposure to even small quantities of lead dust can result in harm to children and the unborn. In addition to complying with the dust control measures below, any person engaged in demolition or renovation projects must comply with applicable state and federal regulations for asbestos and lead containing materials and notification and inspection requirements under the State of Colorado Air Quality Control Commission's Regulation No. 8, Part B Control of Hazardous Air pollutants. Best Management Practices to Control Dust (a) Required Best Management Practices: Any person, owner, or operator who conducts demolition or renovation that is a dust generating activity or source shall implement the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Asbestos and lead containing materials: demolition and renovation activities that involve asbestos or lead containing materials must be conducted in accordance with 2012 International Building Code (IBC), as adopted by the Code Sec. 5-26 and amended by Code Sec. 5-27 (59) (amending IBC §3602.1.1) and all other state and local regulations; (ii) Restrict access: restrict access to the demolition area to only authorized vehicles and personnel; (iii) High winds restriction: temporarily halt work activities during high wind events greater than 30 mph if operations would result in off-property transport; and (iv) Minimize drop height: Drivers and operators shall unload truck beds and loader or excavator buckets slowly, and minimize drop height of materials to the lowest height possible, including screening operations. Dust Prevention and Control Manual Page 11 (b) Additional Best Management Practices: In the event 3.2(a)(i)-(iv) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Wet suppression: apply water to demolished materials or pre-wet materials to be demolished as necessary. Prevent water used for dust control from entering any public right-of- way, storm drainage facility, or watercourse. (ii) Wind barrier: construct a fence or other type of wind barrier to prevent onsite dust generating materials from blowing offsite. (c) Additional requirements: (i) Building permit compliance: comply with all conditions and requirements under any building required pursuant to the Code and/or the Land Use Code. Above: This photo illustrates reducing drop height, a required best management practice. Dust Prevention and Control Manual Page 12 3.3 Stockpiles Above: This photo illustrates wet suppression, an additional best management practice for stockpiles. Stockpiles are used for both temporary and long-term storage of soil, fill dirt, sand, aggregate, woodchips, mulch, asphalt and other industrial feedstock, construction and landscaping materials. Fugitive dust can be emitted from stockpiles while working the active face of the pile or when wind blows across the pile. The quantity of emissions depends on pile height and exposure to wind, moisture content and particle size of the pile material, surface roughness of the pile, and frequency of pile disturbance. Best Management Practices to Control Dust (a) Required Best Management Practices: Any owner or operator of a stockpile that is a dust generating activity or source shall implement the following best management practices to prevent off property transport of fugitive dust emissions: (i) Minimize drop height: Drivers and operators shall unload truck beds and loader or excavator buckets slowly, and minimize drop height of materials to the lowest height possible, including screening operations. (b) Additional Best Management Practices: In the event 3.3(a)(i) is ineffective to prevent off-property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Wet suppression: Apply water to the active face when working the pile or to the entire pile during periods of inactivity. Prevent water used for dust control from entering any public right- of-way, storm drainage facility, or watercourse. (ii) Cover: install cover materials during periods of inactivity and anchor the cover. (iii) Surface roughening: stabilize a stockpile during periods of inactivity or when vegetation cannot be immediately established. Dust Prevention and Control Manual Page 13 (iv) Stockpile location: locate stockpile at a distance equal to ten times the pile height from property boundaries that abut residential areas. (v) Vegetation: seed and mulch any stockpile that will remain inactive for 30 days or more. (vi) Enclosure: construct a three-sided structure equal to or greater than the height of the pile to shelter the pile from the predominant winds. (c) Additional requirements: (i) Stockpile permit compliance: comply with all conditions and requirements under any stockpile permit required under the Code or the Land Use Code. (ii) Erosion control plan compliance: implement and comply with all conditions and requirements of the “Fort Collins Stormwater Criteria Manual, as adopted in Code Sec. §26-500; specifically, Volume 3 Chapter 7 “Construction BMPs”. The Stormwater Criteria Manual may require the use of Erosion Control Materials, soil stockpile height limit of ten feet, watering, surface roughening, vegetation, silt fence and other control measures. Dust Prevention and Control Manual Page 14 3.4 Street Sweeping Left: This figure illustrates the use of a wet suppression and vacuum system, an additional best management practice for street sweeping. Street sweeping is an effective method for removing dirt and debris from streets and preventing it from entering storm drains or becoming airborne. Regenerative air sweepers and mechanical sweepers with water spray can also be effective at removing particulate matter from hard surfaces. Best Management Practices to Control Dust (a) Required Best Management Practices: Any owner or operator that conducts sweeping operations or services on paved or concrete roads, parking lots, rights-of-way, pedestrian ways, plazas or other solid surfaces, and whose operations are a dust generating activity or source shall implement the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Uncontrolled sweeping prohibited: the use of rotary brushes, power brooms, or other mechanical sweeping for the removal of dust, dirt, mud, or other debris from a paved public road, right-of-way, or parking lot without the use of water, vacuum system with filtration, or other equivalent dust control method is prohibited. Mechanical or manual sweeping that occurs between lifts of asphalt paving operations or due to preparation for pavement markings are excluded from this prohibition, due to engineering requirements associated with these operations. (b) Additional Best Management Practices: In the event 3.4(a)(i) is ineffective to prevent off-property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Wet suppression: use a light spray of water or wetting agent applied directly to work area or use equipment with water spray system while operating sweeper or power broom. Prevent water used for dust control from entering any storm drainage facility or watercourse. (ii) Vacuum system: use sweeper or power broom equipped with a vacuum collection and filtration system. (iii) Other method: use any other method to control dust emissions that has a demonstrated particulate matter control efficiency of 80 percent or more. Dust Prevention and Control Manual Page 15 3.5 Track-out / Carry-out Above: This figure illustrates an installed grate (left) and a gravel bed (right), both of which are additional best management practices associated with track-out/carry-out. Mud, dirt, and other debris can be carried from a site on the wheels or undercarriage of equipment and vehicles onto public roads. When this material dries, it can become airborne by wind activity or when other vehicles travel on it. This is a health concern and can cause visibility issues and safety hazards. Best Management Practices to Control Dust (a) Required Best Management Practices: Any owner or operator of any operation that has the potential to result in track-out of mud, dirt, dust, or debris on public roads and rights-of-way and whose operation is a dust generating activity or source shall implement the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Contracts and standards: comply with track-out prevention requirements and construction best management practices as set forth in the Code, City regulations or policies, as specified in applicable contract documents, and as set forth in the Fort Collins Stormwater Criteria Manual. (ii) Remove deposition: promptly remove any deposition that occurs on public roads or rights- of-way as a result of the owner’s or operator’s operations. Avoid over-watering and prevent runoff into any storm drainage facility or watercourse. (b) Additional Best Management Practices: In the event 3.5(a)(i)-(ii) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Install rails, pipes, grate, or similar track-out control device. (ii) Install a gravel bed track-out apron that extends at least 50 feet from the intersection with a public road or right-of-way. (iii) Install gravel bed track-out apron with steel cattle guard or concrete wash rack. (iv) Install and utilize on-site vehicle and equipment washing station. (v) Install a paved surface that extends at least 100 feet from the intersection with a public road or right-of-way. (vi) Manually remove mud, dirt, and debris from equipment and vehicle wheels, tires and undercarriage. Dust Prevention and Control Manual Page 16 3.6 Bulk Materials Transport Above: This figure illustrates covered loads, a required best management practice for bulk materials transport. Haul trucks are used to move bulk materials, such as dirt, rock, demolition debris, or mulch to and from construction sites, material suppliers and storage yards. Dust emissions from haul trucks, if uncontrolled, can be a safety hazard by impairing visibility or by depositing debris on roads, pedestrians, bicyclists, or other vehicles. Best Management Practices to Control Dust (a) Required Best Management Practices: Any owner or operator of a dust generating activity or source for which vehicles used to transport bulk materials to and from a site within the City on a public or private road or on a public right-of-way shall prevent off-vehicle transport of fugitive dust emissions. To prevent off-vehicle transport of fugitive dust to and from the site, the owner or operator shall implement the following measures: (i) Cover Loads: Loads shall be completely covered or all material enclosed in a manner that prevents the material from blowing, dropping, sifting, leaking, or otherwise escaping from the vehicle. This includes the covering of hot asphalt and asphalt patching material with a tarp or other impermeable material. (ii) Minimize drop height: Drivers and operators shall load and unload truck beds and loader or excavator buckets slowly, and minimize drop height of materials to the lowest height possible, including screening operations. Dust Prevention and Control Manual Page 17 (b) Additional Best Management Practices: In the event 3.6(a)(i)-(ii) are ineffective to prevent off- vehicle transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Wet suppression: apply water to bulk materials loaded for transport as necessary to prevent fugitive dust emissions and deposition of materials on roadways. Prevent water used for dust control from entering any public right-of-way, storm drainage facility, or watercourse. (ii) Other technology: use other equivalent technology that effectively eliminates off-vehicle transport, such as limiting the load size to provide at least three inches of freeboard to prevent spillage. Above: This figure illustrates minimizing drop heights, a required best management practice for bulk materials transport. Dust Prevention and Control Manual Page 18 3.7 Unpaved Roads and Haul Roads Left: This figure illustrates surface improvements on an unpaved road, an additional best management practice. Road dust from unpaved roads is caused by particles lifted by and dropped from rolling wheels traveling on the road surface and from wind blowing across the road surface. Road dust can aggravate heart and lung conditions as well as cause safety issues such as decreased driver visibility and other safety hazards. Best Management Practices to Control Dust (a) Required Best Management Practices: Any owner or operator of an unpaved road located on a construction site greater than five acres on private property or an unpaved road used as a public right- of-way shall implement the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Reduce vehicle speeds: establish a maximum speed limit or install traffic calming devices to reduce speeds to a rate that prevents off-property transport of dust entrained by vehicles. (ii) Restrict access: restrict travel on unpaved roads by limiting access to only authorized vehicle use. (b) Additional Best Management Practices: In the event 3.7(a)(i)-(ii) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Wet suppression: apply water to unpaved road surface as necessary and appropriate considering current weather conditions, and prevent water used for dust control from entering any public right-of-way, storm drainage facility, or watercourse. (ii) Surface improvements: install gravel or similar materials with sufficient depth to reduce dust or pave high traffic areas. (iii) Access road location: locate site access roads away from residential or other populated areas. Dust Prevention and Control Manual Page 19 3.8 Parking Lots Above: This figure illustrates an unpaved parking lot in Fort Collins. This section applies to paved and unpaved areas where vehicles are parked or stored on a routine basis and includes parking areas for shopping, recreation, or events; automobile or vehicle storage yards; and animal staging areas. Best Management Practices to Control Dust- Unpaved Parking Lots (a) Required Best Management Practices: Any owners or operator of an unpaved parking lot greater than one-half acre shall use at least one of the following best management practices to prevent off- property transport of fugitive dust emissions (i) Surface improvements: install gravel or similar materials with sufficient depth to reduce dust or pave high traffic areas. (ii) Vegetation: plant vegetation appropriate for retaining soils or creating a wind break. (iii) Wet suppression: apply water as necessary and appropriate considering current weather conditions to prevent off-property transport of fugitive dust emissions. Prevent water used for dust control from entering any public right-of-way, storm drainage facility, or watercourse. (iv) Wind barrier: construct a fence or other type of wind barrier. (v) Reduce vehicle speeds: establish a maximum speed limit or install traffic calming devices to reduce speeds to a rate that prevents off-property transport of dust entrained by vehicles. (vi) Restrict access: restrict travel in parking lots to only those vehicles with essential duties and limit access to hours of operation or specific events. Dust Prevention and Control Manual Page 20 Best Management Practices to Control Dust- Paved Parking Lots (a) Required Best Management Practices: An owner or operator of a paved parking lot greater than one-half acre and shall use at least one of the following best management practices to prevent off- property transport of fugitive dust emissions. (i) Maintenance: repair potholes and cracks and maintain surface improvements. (ii) Mechanical sweeping: Sweep lot with a vacuum sweeper and light water spray as necessary to remove dirt and debris. Avoid overwatering and prevent runoff from entering any public right-of-way, storm drainage facility, or watercourse. (iii) Reduce vehicle speeds: establish a maximum speed limit or install traffic calming devices to reduce speeds to a rate that prevents off-property transport of dust entrained by vehicles. (iv) Restrict access: restrict travel in parking lots to only those vehicles with essential duties and limit access to hours of operation or specific events. Above: This photo represents improving the surface of a parking area, which is one measure to comply with the Manual. Dust Prevention and Control Manual Page 21 3.9 Open Areas and Vacant Lots Left: This photo represents adding vegetation by hydroseeding, which is one measure to comply with the Manual. Open areas are typically not a significant source of wind-blown dust emissions if the coverage of vegetation is sufficient or soil crusts are intact. However, if soils in open areas are disturbed by vehicle traffic, off-highway vehicle use, bicycling or grazing, or if they have become overpopulated by prairie dogs, dust emissions can become a problem. Best Management Practices to Control Dust (a) Required Best Management Practices: Any owner or operator of an open area greater than one-half acre shall use at least one of the following best management practices to stabilize disturbed or exposed soil surface areas that are intended to or remain exposed for 30 days or more and to prevent off- property transport of fugitive dust emissions: (i) Vegetation: plant vegetation appropriate for retaining soils or creating a wind break. (ii) Cover: install cover materials over exposed areas during periods of inactivity and properly anchor the cover. (iii) Surface roughening: stabilize an exposed area during periods of inactivity or when vegetation cannot be immediately established. (iv) Soil retention: stabilize disturbed or exposed soil surface areas that will be inactive for more than 30 days or while vegetation is being established, using mulch, compost, soil mats, or other methods. (v) Wet suppression: apply water to disturbed soil surfaces as necessary and appropriate considering current weather to prevent off-property transport of fugitive dust emissions. Prevent water used for dust control from entering any public right-of-way, storm drainage facility, or watercourse. (vi) Wind barrier: construct a fence or other type of wind barrier to prevent wind erosion of top soils. Dust Prevention and Control Manual Page 22 3.10 Saw Cutting and Grinding Above: This photo illustrates concrete cutting and how the activity can generate dust. Cutting and grinding of asphalt, concrete and other masonry materials can be a significant short-term source of fugitive dust that may expose workers and the public to crystalline silica. Inhalation of silica can cause lung disease known as silicosis and has been linked to other diseases such as tuberculosis and lung cancer. Using additional best management practices during cutting and grinding operations can significantly reduce dust emissions. Best Management Practices to Control Dust (a) Required Best Management Practices: Any person, owner, or operator that cuts or grinds asphalt, concrete, brick, tile, stone, or other masonry materials and whose operations are a dust generating activity or source shall use the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Restrict access: prevent the public from entering the area where dust emissions occur. (ii) High winds restriction: temporarily halt work activities during high wind events greater than 30 mph if operations would result in off-property transport. (iii) Equipment and work area clean up: use wet wiping, wet sweeping, or vacuuming with HEPA filtration for equipment and work area clean up and do not cause dust to become airborne during clean up. (iv) Slurry clean up: prevent water used for dust control or clean up from entering any public right-of-way, storm drainage facility, or watercourse by using containment, vacuuming, absorption, or other method to remove the slurry, and dispose of slurry and containment materials properly. Follow additional procedures prescribed in the Fort Collins Stormwater Criteria Manual or contract documents and specifications. Dust Prevention and Control Manual Page 23 (b) Additional Best Management Practices: In the event 3.10(a)(i)-(iv) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) On-tool local exhaust ventilation: use a tool-mounted dust capture and collection system. (ii) On-tool wet suppression: use a tool-mounted water application system. (iii) Vacuuming: use a vacuum equipped with a HEPA filter simultaneously with cutting or grinding operations. (iv) Wet suppression: use a water sprayer or hose simultaneously with cutting or grinding operations. (v) Enclosure: conduct cutting or grinding within an enclosure with a dust collection system or temporary tenting over the work area. Above: These photos illustrate how dust generated from cutting can be minimized by applying on-tool wet suppression, an additional best management practice associated with saw cutting and grinding. Dust Prevention and Control Manual Page 24 3.11 Abrasive Blasting Above: This photo illustrates abrasive blasting without dust mitigation in place. Abrasive blasting is used to smooth rough surfaces; roughen smooth surfaces; and remove paint, dirt, grease, and other coatings from surfaces. Abrasive blasting media may consist of sand; glass, plastic or metal beads; aluminum oxide; corn cobs; or other materials. Abrasive blasting typically generates a significant amount of fugitive dust if not controlled. The material removed during abrasive blasting can become airborne and may contain silica, lead, cadmium or other byproducts removed from the surface being blasted.* Best Management Practices to Control Dust (a) Required Best Management Practices: Any person, owner, or operator who conducts outdoor abrasive blasting or indoor abrasive blasting with uncontrolled emissions vented to the outside and whose operations are a dust generating activity or source shall implement the following best management practices to prevent off-property transport of fugitive dust emissions: (i) Restrict access: prevent the public from entering the area where dust emissions occur. (ii) High winds restriction: temporarily halt work activities during high wind events greater than 30 mph if operations would result in off-property transport. (iii) Equipment and work area clean up: use wet wiping, wet sweeping, or vacuuming with HEPA filtration for equipment and work area clean up and do not cause dust to become airborne during clean up. (iv) Slurry clean up: prevent water used for dust control or clean up from entering any public right-of-way, storm drainage facility, or watercourse by using containment, vacuuming, absorption, or other method to remove the slurry, and dispose of slurry and containment materials properly. (b) Additional Best Management Practices: In the event 3.11(a)(i)-(iv) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Enclosure: conduct abrasive blasting within an enclosure with a dust collection system or temporary tenting over the work area. Dust Prevention and Control Manual Page 25 (ii) Wet suppression blasting: use one of several available methods that mix water with the abrasive media or air during blasting operations. (iii) Vacuum blasting: conduct air-based blasting that uses a nozzle attachment with negative air pressure to capture dust. (iv) Abrasive media: select less toxic, lower dust-generating blasting media. * Blasting on surfaces that contain lead paint or wastes from sand blasting that contain hazardous materials may be subject to additional state and federal requirements. Above: This photo illustrates wet suppression blasting, an additional best management practice. Dust Prevention and Control Manual Page 26 3.12 Mechanical Blowing Above: This photo illustrates mechanical blowing without dust mitigation in place. Mechanical blowers are commonly used to move dirt, sand, leaves, grass clippings and other landscaping debris to a central location for easier pick-up and removal. Mechanical blowing with a leaf blower can be a significant source of fugitive dust in some situations and can create nuisance conditions and cause health effects for sensitive individuals. Mechanical blowing can re-suspend dust particles that contain allergens, pollens, and molds, as well as pesticides, fecal contaminants, and toxic metals causing allergic reactions, asthma attacks and exacerbating other respiratory illnesses. Best Management Practices to Control Dust (a) Required Best Management Practices: Any person, owner, or operator who operates a mechanical leaf blower (gas, electric, or battery-powered) in a manner that is a dust generating activity or source shall use the following best management practices as necessary to prevent off-property transport of fugitive dust emissions (i) Low speed: use the lowest speed appropriate for the task and equipment. (ii) Operation: use the full length of the blow tube and place the nozzle as close to the ground as possible. (iii) High winds restriction: temporarily halt work activities during high wind events greater than 30 mph if operations would result in off-property transport. (b) Additional Best Management Practices: In the event 3.11(a)(i)-(iii) are ineffective to prevent off- property transport, the person, owner, or operator shall use at least one of the following best management practices: (i) Alternative method: use an alternative such as a rake, broom, shovel, manually push sweeper or a vacuum machine equipped with a filtration system. (ii) Prevent impact: do not blow dust and debris off-property or in close proximity to people, animals, open windows, air intakes, or onto adjacent property, public right-of-way, storm drainage facility, or watercourse. Dust Prevention and Control Manual Page 27 (iii) Minimize use on dirt: minimize the use of mechanical blower on unpaved surfaces, road shoulders, or loose dirt. (iv) Wet suppression: use a light spray of water, as necessary and appropriate considering current weather conditions, to dampen dusty work areas. Prevent water, dirt, and debris from entering any storm drainage facility, or watercourse. (v) Remove debris: remove and properly dispose of blown material immediately. Above: These photos illustrate alternative methods to mechanical blowing that can minimize dust generation. Dust Prevention and Control Manual Page 28 4.0 Dust Control Plan for Land Development Greater Than Five Acres A dust control plan is required for all development projects or construction sites with greater than five (5) acres in size. If the project is required to obtain a development construction permit, then the dust control plan shall be submitted with the development review application or the development construction permit application. A copy of the dust control plan shall be available onsite at all times for compliance and inspection purposes. For dust control plans associated with a Development Construction Permit (DCP) issued by the City, applications for the DCP are available online at www.fcgov.com/developmentreview/applications.php. The dust control plan may be submitted on the Dust Control Plan Form included in Chapter 4 of this Manual or other equivalent format and shall include the following information:  Project name and location.  Name and contact information of property owner.  Project start and completion dates.  Name and contact information of the developer, general contractor, and each contractor or operator that will be engaged in an earthmoving activity.  Total size of the development project or construction site in acres.  A description of the project phasing or sequencing of the project to minimize the amount of disturbed surface area at any one time during the project.  A list of each dust generating activity or source associated with the project.  A list of each best management practice and engineering control that will be implemented for each dust generating activity or source.  A list of additional best management practices that will be implemented if initial controls are ineffective.  A signed statement from the property owner, developer, general contractor, and each contractor or operator engaged in an earthmoving activity acknowledging receipt of the Dust Control Plan and an understanding of and ability to comply with the best management practices in the plan. Dust Prevention and Control Manual Page 29 DUST CONTROL PLAN PROJECT INFORMATION Project Name Project Location Start and Completion Dates Total Size of Project Site (acres) Maximum disturbed surface area at any one time (acres) Property Owner name, address, phone, e-mail Developer name, address, phone, e-mail General Contractor name, address, phone, e-mail Subcontractor or Operator of a dust generating activity or source name, address, phone, e-mail Subcontractor or Operator of a dust generating activity or source name, address, phone, e-mail Subcontractor or Operator of a dust generating activity or source name, address, phone, e-mail PROJECT PHASING OR SEQUENCING Provide a description of how this project will be phased or sequenced to minimize the disturbed surface area. Attach phasing plan or map if available. Dust Prevention and Control Manual Page 30 DUST CONTROL PLAN CERTIFICATION I certify the information and attachments contained in this Dust Control Plan are true and correct to the best of my knowledge and that I and the project's subcontractors have received a copy of this Dust Control Plan and acknowledge my understanding of and ability to comply with best management practices for controlling fugitive dust emissions. I hereby permit City officials to enter upon the property for the purpose of inspection of any dust generating activity or source for which I am the responsible person, owner, or operator. Name: ________________________________________________________________________________ Title: ___________________________________ Role on project: ________________________________ Address: ________________________________________________ Phone: __________________________ Signature: ___________________________________________________ Date: ____________________ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * List of Subcontractors: Title: ___________________________________ Role on project: ________________________________ Title: ____________________________________ Role on project: ________________________________ Title: ___________________________________ Role on project: ________________________________ Title: ____________________________________Role on project: ________________________________ Title: ____________________________________Role on project: ________________________________ Title: ___________________________________ Role on project: ________________________________ Title: ___________________________________ Role on project: ________________________________ Title: ___________________________________ Role on project: ________________________________ Dust Prevention and Control Manual Page 31 Dust Prevention and Control Checklist Instructions: For projects over 5 acres, in addition to developing a Dust Control Plan (see chapter 4 of the manual), place an X in each box indicating all best management practices (BMPs) that will be implemented for each activity. Fully shaded boxes are required BMPs, hatched boxes are additional BMPs. For projects less than 5 acres, the BMPs for bulk materials transport and saw cutting/grinding are required; other BMPs are listed for use as a guide for preventing and controlling dust. Dust Generating Activity  /Best Management Practice  Earthmoving Demolition/ Renovation Stockpile Street Sweeping Track-out / Carry-out Bulk Materials Transport Unpaved Roads and Haul Roads Unpaved Parking Lot * Paved Parking Lot* Open Area* Saw Cutting or Grinding Abrasive Blasting Mechanical Blowing Abrasive media Asbestos or lead materials Construction sequencing Cover Cover Load Enclosure Equipment & work area clean up Erosion control plan High winds restriction Location Mechanical blowing techniques Minimize disturbed area Minimize drop height On-tool local exhaust ventilation On-tool wet suppression Other method Reduce vehicle speeds Remove deposition Restrict access Slurry clean up Soil retention Stockpile permit Surface improvements Surface roughening Sweeping Track-out prevention system Uncontrolled sweeping prohibited Vacuum Vegetation Wet suppression Wind barrier *Note that in the parking lot and open area standards, only select one of the required BMPs to be in compliance. APPENDIX C LANDSCAPE PLAN APPENDIX D COPIES OF PERMITS/APPLICATIONS APPENDIX E INSPECTION LOGS STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 1 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 2 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 3 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 4 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 5 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 6 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 7 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 8 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 9 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 10 STORM WATER MANAGEMENT PLAN INSPECTION TABLE Engines Energy Conversions Lab BMP Name/ Desc.Date Erosion Control Measures Effective Brief Revision Description ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) ___ Yes ____ No ____ Yes (w/Rev) 11 APPENDIX F CONTRACTOR INSERTS APPENDIX G CONTRACTOR INSERTS