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HomeMy WebLinkAboutKYLE AVENUE SOLAR ARRAY - PDP / FDP - FDP180026 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTDRAINAGE AND EROSION CONTROL REPORT FOR 6422 KYLE AVENUE SOLAR AT 6422 KYLE AVENUE FORT COLLINS, CO 80525 PREPARED FOR NSE KYLE AVE SOLAR, LLC Boulder, CO 80304 NOVEMBER 6, 2018 Namaste Solar – 6422 Kyle Avenue Solar ENGINEER’S STATEMENT: “I hereby certify that this report (plan) for the Preliminary Drainage Design for the 6422 Kyle Avenue Solar project was prepared by me (or under my direct supervision) in accordance with the provisions of the City of Fort Collins Standards for the Responsible Parties thereof. I understand that the City of Fort Collins does not and shall not assume liability for drainage facilities designed by others.” ______________________________ Charles R. Hager, IV, P.E. Registered Professional Engineer State of Colorado No. 37146 Namaste Solar – 6422 Kyle Avenue Solar DRAINAGE AND EROSION CONTROL REPORT FOR 6422 KYLE AVENUE SOLAR JVA, Inc. 213 Linden Street, Suite 200 Fort Collins, CO 80524 phone: 970-225-9099 JVA Project No. 3004c NOVEMBER 6, 2018 Namaste Solar – 6422 Kyle Avenue Solar Page 3 of 12 TABLE OF CONTENTS SITE LOCATION AND DESCRIPTION ......................................................................................... 4 DRAINAGE BASINS AND HISTORIC RUNOFF ............................................................................. 4 HISTORIC DRAINAGE ......................................................................................................... 4 DRAINAGE DESIGN CRITERIA ................................................................................................ 5 HYDROLOGIC METHOD AND DESIGN STORM FREQUENCIES ................................................... 5 HYDRAULIC CRITERIA ........................................................................................................ 5 DRAINAGE FACILITY DESIGN ................................................................................................. 5 GENERAL CONCEPT ......................................................................................................... 5 PROPOSED DETENTION POND AND LID .............................................................................. 6 STORMWATER POLLUTION PREVENTION/EROSION CONTROL .................................................... 6 TEMPORARY EROSION CONTROL ....................................................................................... 6 PERMANENT EROSION CONTROL ....................................................................................... 7 STORMWATER MANAGEMENT CONTROLS .............................................................................. 7 SEQUENCE OF CONSTRUCTION ACTIVITIES ............................................................................ 10 CONCLUSIONS .................................................................................................................. 11 REFERENCES ...................................................................................................................... 12 APPENDICES Appendix A – Figures Appendix B – Hydraulic/Hydrologic Computations Appendix C – Referenced Documents Appendix D – Erosion Control Escrow Namaste Solar – 6422 Kyle Avenue Solar Page 4 of 12 SITE LOCATION AND DESCRIPTION The 6422 Kyle Avenue Solar project is being developed by NSE Kyle Ave Solar LLC and is located in the Southwest Quarter of Section 12, Township 6 North, Range 69 West of the 6 th Principal Meridian, in Larimer County, Fort Collins, Colorado. Refer to Appendix A, Figure 1, for the site vicinity map. The site is bounded by Kyle Avenue to the west, private residential property to the south, and City of Fort Collins open space to the north and east (known as Prairie Dog Meadows Natural Area). The site is located in the Fossil Creek Stormwater Basin. The Fossil Creek basin drains west to east through open channels and storm sewer which discharges into the Fossil Creek Reservoir Inlet Ditch. The subject property totals 8.72 acres of partially developed land with an existing residence at the southern end. The proposed project will occupy a fenced 5.90 acres of the northern end of the property, which is currently undeveloped farmland, approximately 80% vegetative coverage. The site historically generally drains to the northeast towards and into the natural area via overland flow with slopes ranging from 4.0% to 8.0%. A soil map created using the USDA Natural Resources Conservation Service Web Soil Survey identifies the site’s soil as primarily Renohill Clay Loam with some Cushman Sandy Loam, which are in the hydrologic soil groups D & C, respectively. Group D & C soils have slow infiltration rates and high runoff potential. The web soil survey results are provided in Appendix C. According to the FEMA Flood Insurance Rate Map Panel Number 08069C1200F, the site is located outside of the 100-year floodplain area. A FEMA FIRMette is included in Appendix C. The proposed site improvements include construction of new solar PV array network with electrical equipment pad, gravel emergency access loop, detention pond with outlet structure, natural landscaping and swales, and perimeter fencing. The site development will increase the overall percent impervious from 0% to 2.2%. Runoff will sheet flow across the site, and swales located along the perimeter will convey stormwater to the detention pond. The main purpose of this study is to analyze the existing and developed drainage patterns in order to convey stormwater to its historic path without causing adverse effects to the site and the surrounding and downstream properties. An outlet structure and pipe with a restrictor plate will be installed in the pond to control the 100-year storm outflow rate to the 2-year historical runoff rate for Fossil Creek Basin. WQCV will be included in the detention pond. An emergency spillway is located at the north end of the pond to direct flow into the natural area if the outlet structure is ever clogged or not performing correctly. DRAINAGE BASINS AND HISTORIC RUNOFF HISTORIC DRAINAGE The site historically drains to the northeast towards and into the Prairie Dog Meadows Natural Area via overland flow with slopes ranging from 4.0% to 8.0%. The site consists of undeveloped farmland with a percent imperviousness of 0%. The peak 2-year and 100-year runoff rates are 2.81 cfs and 12.27 cfs, respectively. Namaste Solar – 6422 Kyle Avenue Solar Page 5 of 12 The historic drainage is outlined below. Design flow calculations and the historical drainage map are provided in Appendix A. Table 1. Historic Basin Properties and Flows Drainage Basin Design Point Area (acre) % Impervious Q-2 (cfs) Q-10 (cfs) Q-100 (cfs) Runoff Coefficient H1 1 5.90 0.0% 2.81 4.81 12.27 0.31 Total 5.90 0.0% 2.81 4.81 12.27 0.31 DRAINAGE DESIGN CRITERIA HYDROLOGIC METHOD AND DESIGN STORM FREQUENCIES The drainage for the site was designed to meet or exceed the City of Fort Collin’s Standards and Specifications, including the Stormwater Criterial Manual which incorporates most of the Urban Drainage and Flood Control District Criteria Manual (USDCM). The site’s percent impervious values were calculated using impervious values from Table 6-3 in the USDCM. For the Modified FAA calculations, the values for the 10-year and 100-year event rainfall intensity duration for 0 to 60 minutes were taken from Table RA-7 in the City of Fort Collins’ Stormwater Criteria Manual. Equation 5.30 from the USDCM was used to calculate intensities for the 60 to 180 minute time steps. The runoff coefficients were calculated using USDCM’s Table 6-4 equations. HYDRAULIC CRITERIA The proposed drainage facility has been designed to comply with the City of Fort Collins Stormwater Criteria Manual, the Fossil Creek Basin Master Plan design, and UDFCD’s Drainage Criteria Manual. The Fossil Creek Basin Master Plan requires best management practices to have both flood control and water quality. UD-Inlet Version 3.14, Manning’s Equation, Hydraflow, and/or Flowmaster will be utilized as needed for the outlet structure and pipe sizing calculations. Final drainage plans are included in the construction documents. As required by the City’s stormwater criteria manual, the pond volume was calculated using the modified FAA method and includes the required 100-year runoff volume. Pond volume, WQCV, and runoff calculations are attached in Appendix B. DRAINAGE FACILITY DESIGN GENERAL CONCEPT As per the Fossil Creek Basin Master Plan design, the site was graded in an attempt to mimic historic drainage patterns and capture all site runoff to be treated and detained in the extended detention basin located in the northeast corner of the site. The detention pond has an outlet structure that discharges at grade into the natural area at the 2-year release rate of 0.2 cfs/acre, per the Fossil Creek Basin Master Plan requirements. Namaste Solar – 6422 Kyle Avenue Solar Page 6 of 12 Table 2. Developed Basin Properties and Flows Coefficients Drainage Basin Design Point Area (acre) % Impervious Q-2 (cfs) Q-100 (cfs) Runoff Coeff's C100 D1 1 5.90 2.2% 2.83 12.31 0.33 Total to Pond 5.90 2.2% 2.83 12.31 0.33 PROPOSED DETENTION POND AND LID As per the City’s requirement, the 100-year runoff volume is captured in the detention pond and has an outflow rate equal to the 2-year release rate of 1.18 cfs. This is accomplished through the installation of a restrictor plate on the 12 inch RCP outlet pipe. The bottom of the detention pond is at an elevation of 4936.2 feet, with a 100-year water surface elevation of 4940.7 feet, 4.5 feet of depth and a total volume of 0.367 acre-ft. The detention pond’s emergency overflow spillway is located on the north edge of the pond with a top of berm elevation at 4941.7 ft and will safely discharge flows to the natural area if the outlet structure of the pond is ever clogged or malfunctioning. The spillway was designed to discharge the peak 100-year runoff rate of 12.3 cfs with 4 inches of head. Chapter 2 of the Urban Drainage and Flood Control District’s Urban Storm Drainage Criteria Manual Volume 3 (USDCM) provides guidelines for the selection of appropriate structural BMPs for a site that is to be developed or redeveloped. 6422 Kyle Avenue is best characterized as a “conventional development” with less than 1/3 acre of impervious area on the project site. The BMP decision tree for such sites is provided in Figure 2-2 of the USDCM. The site and surrounding vicinity is comprised of hydrologic soil group Type C & D soils, per the NRCS soil survey, with a depth to bedrock of greater than 5 feet. Permeable pavement (with partial or no infiltration) and/or the use of a “green roof” or grass swale/buffer are the recommended runoff reduction practices (also known as Low Impact Development techniques, or LID) for this scenario. The gravel emergency access road is the only source of added impervious area to this site, and already acts as a surface that promotes infiltration of runoff vs. a paved surface. The site layout acts essentially as one large grass buffer that sheet flows across the site and into 1,440 linear feet of vegetated swales to convey runoff to the detention pond. The LID requirement is to treat a minimum of 75% of added impervious area, the proposed improvements will reduce runoff, treat, and slow down the release of the majority of all runoff generated on the site. Since these features facilitate sedimentation and filtering while limiting erosion, and since the limited redevelopment of the site and construction of a new 100-year storm detention pond will not subject natural drainageways to increased frequency, rate, duration, or volume of runoff, the proposed measures to reduce water quality and quantity impacts are sufficient for this site and no additional structural BMPs are proposed. STORMWATER POLLUTION PREVENTION/EROSION CONTROL TEMPORARY EROSION CONTROL A temporary erosion control plan is to be implemented for the site during construction of the proposed solar array development. Temporary erosion control measures include, but are not limited to, slope and swale protection provided by the use of erosion control wattles/sediment Namaste Solar – 6422 Kyle Avenue Solar Page 7 of 12 control logs, inlet protection at the detention pond outlet structure, vehicle tracking control at access points to the site, and erosion control blankets on the detention pond slopes. All temporary erosion control measures are to be removed after they are deemed unnecessary. Refer to the Erosion Control Plan and Details for the Kyle Avenue Solar project for additional detailed information. PERMANENT EROSION CONTROL The rainfall erodibility factor, K, is 0.20 to 0.24 for the Type C & D soils that exist on site and will cause rilling and gulling over longer distances and steeper slopes. Perimeter control will be the primary means of minimizing the extent of gulling, with swales graded around the downstream sides of the property to direct runoff toward the detention pond before discharging off site. There are no irrigation canals passing through the site. Permanent erosion control measures include, but are not limited to, the constructed detention pond, riprap pad placed flared end section outlet protection, seeding and mulch placed to enable and established vegetative growth, etc. Long-term maintenance of these erosion control measures shall be the responsibility of the owner of the property. A general erosion control plan has been provided in the utility plans on sheet C1.0. An erosion control escrow calculation is provided in Appendix D. STORMWATER MANAGEMENT CONTROLS The Stormwater Management Plan (SWMP) administrator is to be determined. According to the CDPHE Stormwater Fact Sheet – Construction, construction activities produce many different kinds of pollutants which may cause stormwater contamination problems. The main pollutant of concern at construction sites is sediment. Grading activities remove grass, rocks, pavement, and other protective ground covers, resulting in the exposure of underlying soil to the elements. The soil is then easily picked up by wind and/or washed away by rain or snowmelt. In addition, construction activities often require the use of toxic or hazardous materials such as fuel, fertilizers, pesticides, and herbicides, and building materials such as asphalt, sealants, and concrete, which may also pollute stormwater. These materials can be harmful to humans, plants, and aquatic life. Other pollution sources that could be present include: runoff from vehicle washing, vehicle maintenance and/or fueling, There are no known existing non-stormwater components of discharge (i.e., springs, landscape irrigation return flow, etc.), or any anticipated during construction. 1. All Disturbed and Stored Soil: The total disturbed area will be approximately 6.0 acres. Soil stockpiles should be kept below the locally mandated maximum height of 10 feet and surrounded with sediment control devices. If the storage of these soils occurs over a period greater than 30 days, then consider temporarily seeding the soil to minimize soil loss to wind and water erosion. No phasing of grading activities is proposed. Sediment control logs along the downstream sides of the property will prevent sediment and disturbed soils from being Namaste Solar – 6422 Kyle Avenue Solar Page 8 of 12 carried offsite. Rock socks will be placed on the inlet side of the detention pond outlet structure as well as around the flared end section outfall to prevent sediment and debris from leaving the site. 2. Vehicle Tracking of Sediments: The existing site is undeveloped farmland. A temporary stabilized stone pad (Vehicle Tracking Control pad, VTC) will be provided at the point of ingress and egress onto the unpaved area from Kyle Avenue. The VTC is designed to reduce the amount of mud transported onto the roads by construction traffic. If the site is extraordinarily muddy, then consider designating an area to wash construction vehicles before they leave the site and enter the public right-of-way. A BMP such as this is a good way to avoid the costs associated with street cleaning or accidentally discharging large amounts of sediment into other storm drain systems. Street sweeping will be conducted as necessary to remove sediment tracked on to pavement and adjacent streets. When in doubt, choose methods that prevent pollution rather than ones that force clean-up at the downstream end just before the stormwater enters the receiving waters. In other words, the most efficient construction site BMPs are those that prevent erosion from happening. 3. Management of Contaminated Soils: There are no known contaminated soils on site. If contaminated soils are found, the contractor shall report to the SWMP administrator and engineer to determine appropriate removal and/or mitigation measures. 4. Loading and Unloading Operations: Loading/unloading activities that may result in sediment tracking or spills will occur within the paved area of the site or a temporary gravel staging area will be provided in the area shown on the plans. 5. Outdoor Storage Activities: Materials storage and waste disposal will occur within a contained and secure area with the use of berms or silt fence around the storage areas and dumpsters for waste disposal. Coordinate location with SWMP administrator. 6. Vehicle and Equipment Maintenance and Fueling: Materials should be stored and handled in covered areas to prevent contact with stormwater, and chemicals should be stored within berms or secondary containment devices to prevent leaks and spills from entering stormwater runoff. Spill Management In general, the spill prevention and response plan must be kept on site at all times during construction and should include the following: Namaste Solar – 6422 Kyle Avenue Solar Page 9 of 12 a) Notification procedures to be used in the event of an accident. At the very least, the SWMP Administrator should be notified. Depending on the nature of the spill and the material involved, the Colorado Department of Health, downstream water users, or other agencies may also need to be notified. b) Instructions for clean-up procedures. c) Provisions for absorbents are to be made available for use in fuel areas, and for containers to be available for used absorbents. d) Procedures for properly washing out concrete trucks and other equipment in a manner and location so that the materials and wash water cannot discharge from the site and never into a storm drain system or stream. 7. Significant Dust or Particulate Generating Processes: Disturbed areas not yet ready to be seeded, landscaped, paved, or otherwise stabilized shall be watered, or ripped as necessary to preclude visible dust emissions. Contractor shall make every effort to minimize particulate emissions and dust generation from vehicles performing the work (including but not limited to regular maintenance of construction equipment). Contractor to follow local and state dust ordinances at all times. 8. Routine Maintenance Activates Involving Fertilizer, Pesticides, Detergents, Fuels, Solvents, Oils, Etc: Materials should be stored and handled in covered areas to prevent contact with stormwater, and chemicals should be stored within berms or secondary containment devices to prevent leaks and spills from entering stormwater runoff. 9. On-site Waste Management Practices (Waste Piles, Liquid Wastes, Dumpsters, etc): Materials storage, waste disposal, and vehicle maintenance and fueling can occur within an enclosed and secure area. The area can be enclosed with temporary fencing and accessed through a gate with a lock. 10. Concrete Truck/Equipment Washing: A mobile concrete washout facility will be provided onsite. Properly wash out concrete trucks and other equipment in a manner and location (a minimum of 50 feet away from any inlet structures) so that the materials and wash water cannot discharge from the site, and never into a storm drain system or stream. 11. Dedicated Asphalt and Concrete Batch Plants: There will be no dedicated batch plant on site. 12. Non-Industrial Waste Source Such as Workers Trash And Portable Toilets: Garbage cans shall be located at break areas and portable toilets shall be provided if onsite bathroom facilities cannot be used. Locate dumpsters and portable toilets away from drainage courses (minimum 50 feet from any inlet structure) and stake down toilets to prevent tipping. Namaste Solar – 6422 Kyle Avenue Solar Page 10 of 12 13. Other Areas or Procedures where Potential Spills can Occur: Records of spills, leaks, or overflows that result in the discharge of pollutants must be documented and maintained. Record all spills that are responded to, even if they do not result in a discharge of pollutants. 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 immediately. Specifically, a release of any chemical, oil, petroleum product, sewage, etc., which may 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. More guidance is available on the web at www.colorado.gov. The Division’s toll-free 24-hour number for environmental hazards and chemical spills and releases is 1-877-518-5608. SEQUENCE OF CONSTRUCTION ACTIVITIES Construction Start Date (This is the day you expect to begin disturbing soils, including grubbing, stockpiling, excavating, demolition, and grading activities): June 2019 Final Stabilization Date (this is when the site is finally stabilized. This means that all disturbed areas have been either built on, paved, or a uniform vegetative cover reaching over 70% vegetative density has been established.) Even if you are doing one part of the project, the estimated completion date must be for the overall project: October 2020 Construction Sequencing: (Detailed construction sequencing to be determined by the contractor) 1. Installation of temporary erosion and sediment control measures. This includes all sediment control logs, vehicle tracking pad, and inlet protection where land disturbing activities will occur. Implementations of individual BMPs is to coincide with construction to minimize the exposure of unprotected areas. Inlet protection will be installed as the storm sewers are constructed. Structural BMPs that do not become part of the permanent stormwater management plan are to be removed as the paving, landscaping, and other permanent groundcover installations are completed. 2. Sequence of all land disturbing activity. Overlot grading in preparation for installation of the solar arrays will occur early in the construction schedule. Additional land disturbance will occur around the site for utility installation and the construction of the new gravel access road. 3. Drainage facility construction. Construction of the detention pond, outlet structure and piping will occur early in the schedule. 4. Sediment basins, temporary channel stabilization. Sediment control logs or erosion control blankets will be installed on the banks of the detention pond and swales. Namaste Solar – 6422 Kyle Avenue Solar Page 11 of 12 5. Seeding All disturbed areas will be seeded upon completing of finish grading. Refer to the landscape plans for detailed planting and seeding schedule. Temporary seed mix to be as follows: SPECIES COMMON NAME VARIETY LBS/ACRE AGROPYRON SMITHI WESTERN WHEATGRASS ARRIBA 8.0 ARRHENATHERUM ELATES TALL OATGRASS 3.0 LOLIUM PERENNE PERENNIAL RYEGRASS PENNFINE 2.0 6. Mulching Refer to landscape plans for mulching procedures. 7. Required maintenance activities (e.g. after-storm checks of all BMPs, etc.). All temporary sediment control BMPs shall be inspected after each rain event to ensure proper protection and to determine if cleaning is necessary. Final cleaning of all storm facilities shall be provided upon final stabilization of site. CONCLUSIONS The goal of the Drainage and Erosion Control Report for the 6422 Kyle Avenue Solar project is to describe appropriate controls and measures to improve water quality by reducing pollutants in stormwater discharges and ensure compliance with the requirements of the City of Fort Collins Erosion Control and Stormwater Standards and the UDFCD. The proposed drainage system presented in this report is designed to convey the 100-year peak stormwater runoff through the site to the proposed detention pond. This report also proposes best management practices for erosion control, permanent landscaping, riprap, and on-site construction facilities. The proposed permanent structural BMP’s on site, including the vegetated buffer and swales, detention basin, capture the majority of the runoff discharged from the site and improve storm water quality by facilitating sedimentation and filtering while limiting erosion through slowed-release of runoff. Temporary BMP’s to be employed during the construction of the proposed improvements include sediment control logs at the downstream limits of disturbance, slope protection on the vegetated swales and detention basin, a concrete washout facility on site, street sweeping practices to eliminate tracked sediment, and construction of a temporary sedimentation basin in the proposed detention basin. These measures, along with the other standard Best Management Practices described in this report, will serve to reduce pollutants in the storm water runoff and satisfy the requirements of the City of Fort Collins Erosion Control Standards. It can therefore be concluded that development of the detention pond complies with all of the stormwater jurisdictional criteria and will not adversely affect the existing streets, storm drain system and/or detention/water quality facilities. Namaste Solar – 6422 Kyle Avenue Solar Page 12 of 12 REFERENCES 1. Urban Storm Drainage Criteria Manual (Volumes 1, 2, and 3), Urban Drainage and Flood Control District, June 2001, January 2016. 2. City of Fort Collins Stormwater Criteria Manual, City of Fort Collins, December 2013. 3. City of Fort Collins Fossil Creek Basin Master Plan, Retrieved from http://www.fcgov.com/ utilities/what-we-do/stormwater/drainage-basins/fossil-creek- basin on October 8, 2018. APPENDIX A – FIGURES FIGURE 1 - VICINITY MAP 6422 KYLE AVENUE SOLAR OCTOBER 9, 2018 213 Linden Street, Suite 200 Fort Collins, CO 80524 970.225.9099 www.jvajva.com JVA, Inc. Boulder ● Fort Collins ● Winter Park Glenwood Springs ● Denver PROJECT T CHERYLEN STREET (60' Right-of-Way) Lot 3, Block 3 Lynn Acres Lot 6, Block 2 Lynn Acres Lot 5, Block 5 Lynn Acres Lot 6, Block 5 Lynn Acres Lot 1, Amended Plat of Lot 4 & 7, Block 5, Lynn Acres & a Portion of Kyle Avenue KYLE AVENUE (60' Right-of-Way) Lot 8, Block 5 Lynn Acres Lot 9, Block 5 Lynn Acres Lot 10, Block 5 Lynn Acres Lot 7, Block 7 Lynn Acres Hansen MRD Unplatted Unplatted Unplatted Tract B, South Side Service Center PUD Phase 2 KYLE AVENUE (60' Right-of-Way) EXISTING DRAINAGE PLAN FIG 2 NO. DATE DES'D D'WN REVISION DESCRIPTION DESIGNED BY: DRAWN BY: CHECKED BY: JOB #: DATE: © JVA, INC. 6422 KYLE AVENUE SOLAR FINAL DEVELOPMENT PLAN SHEET NO. 3004c OCT 2018 BJC KRB KRB JVA, Inc. 213 Linden Street, Suite 200 www.jvajva.com Fort Collins, CO 80524 970.225.9099 Boulder ● Fort Collins ● Winter Park Glenwood Springs ● Denver T CHERYLEN STREET (60' Right-of-Way) Lot 3, Block 3 Lynn Acres Lot 6, Block 2 Lynn Acres Lot 5, Block 5 Lynn Acres Lot 6, Block 5 Lynn Acres Lot 1, Amended Plat of Lot 4 & 7, Block 5, Lynn Acres & a Portion of Kyle Avenue KYLE AVENUE (60' Right-of-Way) Lot 8, Block 5 Lynn Acres Lot 9, Block 5 Lynn Acres Lot 10, Block 5 Lynn Acres Lot 7, Block 7 Lynn Acres Hansen MRD Unplatted Unplatted Unplatted Tract B, South Side Service Center PUD Phase 2 KYLE AVENUE (60' Right-of-Way) PROPOSED DRAINAGE PLAN FIG 3 NO. DATE DES'D D'WN REVISION DESCRIPTION DESIGNED BY: DRAWN BY: CHECKED BY: JOB #: DATE: © JVA, INC. 6422 KYLE AVENUE SOLAR FINAL DEVELOPMENT PLAN SHEET NO. 3004c OCT 2018 BJC KRB KRB JVA, Inc. 213 Linden Street, Suite 200 www.jvajva.com Fort Collins, CO 80524 970.225.9099 Boulder ● Fort Collins ● Winter Park Glenwood Springs ● Denver APPENDIX B – HYDRAULIC/HYDROLOGIC COMPUTATIONS JVA Incorporated Job Name: Kyle Ave Solar I% C2 C5 C10 C100 213 Linden Street, Suite 200 Job Number: 3004c Streets Paved 100% 0.95 0.00 0.95 1.00 Fort Collins, CO 80524 Date: 10/9/18 Concrete Drives/Walks 90% 0.95 0.00 0.95 1.00 Ph: (970) 225 9099 By: KRB Roof 90% 0.95 0.00 0.95 1.00 Gravel 40% 0.50 0.00 0.50 0.63 Landscaping (B soil) 0% 0.15 0.00 0.15 0.19 Kyle Ave Solar Landscaping (C/D soil) 0% 0.25 0.00 0.25 0.31 Historic Runoff Coefficient & Time of Concentration Calculations Playground 10% 0.11 0.00 0.11 0.14 Location: Fort_Collins Artificial Turf 25% 0.20 0.00 0.20 0.25 Minor Design Storm: 2 Major Design Storm: 100 Soil Type: C/D Basin Design Data I (%) = 100% 90% 90% 40% 10% 25% 0% 0% I (%) tc Comp tc Final Basin Name Design Point Apaved streets (sf) Adrives/co nc (sf) Aroof (sf) Agravel (sf) Aplygnd (sf) Aart. turf (sf) Alscape (B soil) (sf) Alscape (C/D soil) (sf) ATotal (sf) ATotal (ac) Imp (%) C2 C5 C10 C100 Upper most Length (ft) Slope (%) ti (min) Length (ft) Slope (%) Type of Land Surface K Velocity JVA Incorporated Job Name: Kyle Ave Solar I% C2 C5 C10 C100 213 Linden Street, Suite 200 Job Number: 3004c Streets Paved 100% 0.95 0.00 0.95 1.00 Fort Collins, CO 80524 Date: 10/9/18 Concrete Drives/Walks 90% 0.95 0.00 0.95 1.00 Ph: (970) 225 9099 By: KRB Roof 90% 0.95 0.00 0.95 1.00 Gravel 40% 0.50 0.00 0.50 0.63 Landscaping (B soil) 0% 0.15 0.00 0.15 0.19 Kyle Ave Solar Landscaping (C/D soil) 0% 0.25 0.00 0.25 0.31 Composite Runoff Coefficient Calculations Playground 10% 0.11 0.00 0.11 0.14 Location: Fort_Collins Artificial Turf 25% 0.20 0.00 0.20 0.25 Minor Design Storm: 2 Major Design Storm: 100 Soil Type: C/D Basin Design Data I (%) = 100% 90% 90% 40% 10% 25% 0% 0% I (%) Basin Name Design Point Apaved streets (sf) Adrives/c onc (sf) Aroof (sf) Agravel (sf) Aplygnd (sf) Aart. turf (sf) Alscape (B soil) (sf) Alscape (C/D soil) (sf) ATotal (sf) ATotal (ac) Imp (%) C2 C5 C10 C100 D 1 14,374 242,684 257,058 5.90 2.2% 0.26 0.00 0.26 0.33 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 JVA Incorporated Job Name: Kyle Ave Solar I% C2 C5 C10 C100 213 Linden Street, Suite 200 Job Number: 3004c Streets Paved 100% 0.95 0.00 0.95 1.00 Fort Collins, CO 80524 Date: 10/9/18 Concrete Drives/Walks 90% 0.95 0.00 0.95 1.00 Ph: (970) 225 9099 By: KRB Roof 90% 0.95 0.00 0.95 1.00 Gravel 40% 0.50 0.00 0.50 0.63 Landscaping (B soil) 0% 0.15 0.00 0.15 0.19 Kyle Ave Solar Landscaping (C/D soil) 0% 0.25 0.00 0.25 0.31 Composite Runoff Coefficient Calculations Playground 10% 0.11 0.00 0.11 0.14 Location: Fort_Collins Artificial Turf 25% 0.20 0.00 0.20 0.25 Minor Design Storm: 2 Major Design Storm: 100 Soil Type: C/D Basin Design Data I (%) = 100% 90% 90% 40% 10% 25% 0% 0% I (%) Basin Name Design Point Apaved streets (sf) Adrives/c onc (sf) Aroof (sf) Agravel (sf) Aplygnd (sf) Aart. turf (sf) Alscape (B soil) (sf) Alscape (C/D soil) (sf) ATotal (sf) ATotal (ac) Imp (%) C2 C5 C10 C100 Runoff Coeff's 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB Kyle Ave Solar Time of Concentration Calculations Location: Fort_Collins Minor Design Storm: 2 Major Design Storm: 100 Soil Type: C/D Sub-Basin Data tc Comp tc Final Basin Name Design Point ATotal (ac) C5 Upper most Length (ft) Slope (%) ti (min) Length (ft) Slope (%) Type of Land Surface Cv Velocity (fps) tt (min) Time of Conc ti + tt = tc Total Length (ft) tc =(L/180)+ 10 (min) Min tc D 1 5.90 0.00 41 3.5% 8.5 1049 2.5% Grassed waterway 15 2.4 7.4 15.9 1090 16.1 15.9 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB Kyle Ave Solar Time of Concentration Calculations Location: Fort_Collins Minor Design Storm: 2 Major Design Storm: 100 Soil Type: C/D Sub-Basin Data tc Comp tc Final Basin Name Design Point ATotal (ac) C5 Upper most Length (ft) Slope (%) ti (min) Length (ft) Slope (%) Type of Land Surface Cv Velocity (fps) tt (min) Time of Conc ti + tt = tc Total Length (ft) tc =(L/180)+ 10 (min) Min tc Initial Overland Time (ti ) Travel Time (tt ) tt =Length/(Velocity x 60) tc Urbanized Check ON 0 0 0.00 Paved areas & shallow paved swales JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB Kyle Ave Solar Developed Storm Runoff Calculations Design Storm : 100 Year Point Hour Rainfall (P1) : 2.86 Basin Name Design Point Area (ac) Runoff Coeff tc (min) C*A (ac) I (in/hr) Q (cfs) Total tc (min) ΣC*A (ac) I (in/hr) Q (cfs) Inlet Type Q intercepted Q carryover Q bypass Pipe Size (in) or equivalent Pipe Material Slope (%) Pipe Flow (cfs) Max Pipe Capacity (cfs) Length (ft) Velocity (fps) tt (min) Total Time (min) Notes D 1 5.90 0.33 15.90 1.95 6.32 12.31 15.90 1.95 6.32 12.31 Direct Runoff Total Runoff Inlets Pipe Pipe/Swale Travel Time 3004c - Rational Calculations.xlsx Q100 Page 6 of 12 JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/4/18 Ph: (970) 225 9099 By: KRB Kyle Ave Solar Water Quality Capture Volume (WQCV) Calculations (UDFCD Volume 3 Chapter 3) WQCV=a((0.91I3)-(1.19I2)+(0.78I)) Where: WQCV = Water Quality Capture Volume (watershed inches) a = Drain Time Coefficient (see table below ) I = Imperviousness (%/100) Drainage Time (Coefficient, hrs) a 12 0.8 24 0.9 40 1.00 a= 1.00 40 hour drawdown time I= 0.022 %/100 WQCV= 0.017 watershed inches V=(WQCV/12)*A*43560 WQCV= 0.017 watershed inches A = 5.90 acre V = 356 cf V = 0.008 acre-ft JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB Kyle Ave Solar Detention Pond Volume Calculations: FAA Procedure Based on FAA Procedure, per Federal Aviation Agency "Airport Drainage" Manual Drainage Basin A Design Storm 100 year Composite "C" Factor 0.33 Basin Size 5.90 Release Rate Calculations Allowable Release Rate for Site 1.18 cfs Less Undetained Offsite Flows - 0.00 cfs Allowable Release Rate for Pond 1.18 cfs Rainfall Intensity Calculations Point Hour Rainfall (P1) : 2.86 Rainfall Intensity: FortCollinsIDF Volume Calculations Inflow Volume = C * I * A * time (sec) Outflow Volume = Alowable Release Rate * time (sec) Storage Volume = Invflow Volume - Outflow Volume Time t (min) Time t (sec) Intensity I (in/hr) Inflow Vin (ft3) Outflow Vout (ft3) Storage Vstor (ft3) 5.0 300 9.95 5,812 354 5,458 10.0 600 7.72 9,019 708 8,311 15.0 900 6.52 11,425 1,062 10,363 20.0 1,200 5.60 13,084 1,416 11,668 25.0 1,500 4.98 14,544 1,770 12,774 30.0 1,800 4.52 15,841 2,124 13,717 35.0 2,100 4.09 16,715 2,478 14,237 40.0 2,400 3.75 17,504 2,832 14,672 45.0 2,700 3.47 18,215 3,186 15,029 50.0 3,000 3.23 18,890 3,540 15,350 55.0 3,300 3.03 19,494 3,894 15,600 60.0 3,600 2.86 20,046 4,248 15,798 Maximum Volume (ft3) 15,798 50% WQCV 175 ft3 Required 100-yr Volume + 50% WQCV 15,973 ft3 Detention Storage Calculations 3004c - Rational Calculations.xlsx FAA-100-yr Page 9 of 12 JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB Kyle Ave Solar Emergency Overflow Spillway Calculations Broad-Crested Weir Equation-Trapezoidal Shape where: Q = Discharge (cfs) C = Weir Coeffecient L = Weir Length (ft) H = Average Weir Head (ft) H:V =Side Slope Calculations Knowns: 4.00 0.35 ft 3.087 4940.70 ft 12.7 cfs 18.44 ft 20.00 ft 1.00 ft 4941.7 ft 28.00 ft Berm Width 4.0 ft Side Slopes (H:V) Desired Spillway Weir Coefficient Spillway Elevation 100-yr Pond Inflow Calculated Spillway Use Spillway Length Spillway Depth Top of Berm Top of Berm Length 2 5 2 3 H V H QCLH C       = + JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB POND VOLUME CALCULATIONS - STAGE / STORAGE Pond Volume = Prismoidal Formula Volume Equation = (A1+A2+SQRT(A1*A2)*D/3 WEIGHTED INCREMENTAL CUMMULATIVE ELEVATION DEPTH (D) AREA (A1) AVG AREA (A2) VOLUME VOLUME ft ft ft2 ft2 ft3 ft3 4936.2 0 0 4937.0 0.8 710 355 189 189 4938.0 1.0 1,960 1,335 1,283 1,473 4939.0 1.0 3,990 2,975 2,915 4,388 4940.0 1.0 6,775 5,383 5,321 9,709 4940.5 0.5 8,995 7,885 3,929 13,639 4941.0 0.5 10,395 9,695 4,843 18,482 4941.7 0.7 0 5,198 2,425 20,908 Top of Pond 4941.7 5.5 20,908 cf 0.480 ac-ft Required Volume (ft3) Required Volume (ac-ft) Water Surface Elevation Water Depth WQCV 349 cf 0.008 ac-ft 4937.12 ft 0.92 ft V2 + 50% WQCV 2,561 cf 0.059 ac-ft 4938.37 ft 2.17 ft V100 + 50% WQCV 15,973 cf 0.367 ac-ft 4940.74 ft 4.54 ft V2 + 50% WQCV V100 + 50% WQCV Vol Elev Vol Elev Vol Elev 189.33 4937.00 1472.55 4938.00 13638.88 4940.50 349.00 4937.12 2561.14 4938.37 15972.81 4940.74 1472.55 4938.00 4388.05 4939.00 18482.17 4941.00 Stage / Storage Input Table TOTAL VOLUME Volume Summary Table Volume Interpolation Calculations WQCV 3004c - Rational Calculations.xlsx Vol Pond Page 11 of 12 JVA Incorporated Job Name: Kyle Ave Solar 213 Linden Street, Suite 200 Job Number: 3004c Fort Collins, CO 80524 Date: 10/9/18 Ph: (970) 225 9099 By: KRB Top of Pond 20,908 cf 4941.7 WQCV 349 cf 4937.12 ft V2 + 50% WQCV 2,561 cf 4938.37 ft V100 + 50% WQCV 15,973 cf 4940.74 ft 4935.0 4936.0 4937.0 4938.0 4939.0 4940.0 4941.0 4942.0 0 5,000 10,000 15,000 20,000 25,000 WATER SURFACE ELEVATION (FEET ABOVE MSL) POND VOLUME (CF) STAGE VS. STORAGE Water Quality Detention Pond 3004c - Rational Calculations.xlsx Vol Pond Page 12 of 12 Sheet 1 of 1 Designer: Company: Date: Project: Location: 1. Design Discharge A) 2-Year Peak Flow Rate of the Area Draining to the Grass Buffer Q2 = 2.8 cfs 2. Minimum Width of Grass Buffer WG = 56 ft 3. Length of Grass Buffer (14' or greater recommended) LG = 750 ft 4. Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft) SG = 0.050 ft / ft 5. Flow Characteristics (sheet or concentrated) A) Does runoff flow into the grass buffer across the entire width of the buffer? B) Watershed Flow Length FL = 750 ft C) Interface Slope (normal to flow) SI = 0.001 ft / ft D) Type of Flow SHEET FLOW Sheet Flow: FL * SI < 1 Concentrated Flow: FL * SI > 1 6. Flow Distribution for Concentrated Flows 7 Soil Preparation (Describe soil amendment) 8 Vegetation (Check the type used or describe "Other") 9. Irrigation (*Select None if existing buffer area has 80% vegetation AND will not be disturbed during construction.) 10. Outflow Collection (Check the type used or describe "Other") Notes: Native seed mix Onsite topsoil to be stripped, stockpiled, and reused Design Procedure Form: Grass Buffer (GB) Karen Brigman JVA, Inc. Kyle Ave Solar November 6, 2018 6422 Kyle ave, Fort Collins 80525 Existing Xeric Turf Grass Irrigated Turf Grass Other (Explain): Choose One Choose One Grass Swale Street Gutter Storm Sewer Inlet Other (Explain): None (sheet flow) Slotted Curbing Level Spreader Choose One Other (Explain): APPENDIX C – REFERENCED DOCUMENTS USGS The National Map: Orthoimagery. Data refreshed October 2017. National Flood Hazard Layer FIRMette 0 250 500 1,000 1,500 2,000 Feet Ü 105°4'25.14"W 40°29'42.91"N 105°3'47.69"W 40°29'15.54"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT HAZARD SPECIAL AREAS FLOOD Without Zone A, V, Base A99 Flood Elevation (BFE) With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 0.of 2% 1% Annual annual Chance chance Flood flood with Hazard, average Areas depth areasdrainage of less less than than one one foot square or with mile Zone X Future ChanceAnnual Conditions Flood Hazard 1% Zone X Area Levee.to with See Reduced Notes. Flood Risk due Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This digital map flood complies maps if with it is FEMA's not void standards as described for the below. use of The accuracy basemap standards shown complies with FEMA's basemap The authoritative flood hazard NFHL information web services is derived provided directly by FEMA. from This the map was reflectnot exported changes on or 10/amendments 9/2018 at 4:subsequent 50:22 PM to and this does date and time. becomeor The superseded NFHL and effective by new data information over time. may change This elementsmap map image do not is appear: void if basemap the one or imagery, more of flood the following zone labels, legend, FIRM panel scale number, bar, map and creation FIRM effective date, community date. Map identifiers,images for unmapped regulatoryfor purposes. and unmodernized areas cannot be used Legend OTHER FLOOD AREAS HAZARD OF OTHER AREAS STRGUECNTUERREASL FEATURES OTHER MAP PANELS 8 1:6,000 B 20.2 The point pin selected displayed by the on the user map and is does an approximate not represent an authoritative property location. Hydrologic Soil Group—Larimer County Area, Colorado (6422 Kyle Ave SOlar) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 1 of 4 4482910 4482950 4482990 4483030 4483070 4483110 4483150 4483190 4483230 4482910 4482950 4482990 4483030 4483070 4483110 4483150 4483190 4483230 494080 494120 494160 494200 494240 494280 494320 494080 494120 494160 494200 494240 494280 494320 40° 29' 59'' N 105° 4' 11'' W 40° 29' 59'' N 105° 4' 1'' W 40° 29' 48'' N 105° 4' 11'' W 40° 29' 48'' N 105° 4' 1'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,630 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 27 Cushman fine sandy loam, 3 to 9 percent slopes C 0.8 12.2% 48 Heldt clay loam, 0 to 3 percent slopes C 0.2 3.7% 63 Longmont clay, 0 to 3 percent slopes D 0.3 4.3% 65 Midway clay loam, 5 to 25 percent slopes D 0.8 12.0% 90 Renohill clay loam, 3 to 9 percent slopes D 4.3 67.8% Totals for Area of Interest 6.3 100.0% Hydrologic Soil Group—Larimer County Area, Colorado 6422 Kyle Ave SOlar Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 3 of 4 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Larimer County Area, Colorado 6422 Kyle Ave SOlar Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 4 of 4 K Factor, Whole Soil—Larimer County Area, Colorado (6422 Kyle Ave SOlar) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 1 of 3 4482910 4482950 4482990 4483030 4483070 4483110 4483150 4483190 4483230 4482910 4482950 4482990 4483030 4483070 4483110 4483150 4483190 4483230 494080 494120 494160 494200 494240 494280 494320 494080 494120 494160 494200 494240 494280 494320 40° 29' 59'' N 105° 4' 11'' W 40° 29' 59'' N 105° 4' 1'' W 40° 29' 48'' N 105° 4' 11'' W 40° 29' 48'' N 105° 4' 1'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,630 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons .02 .05 .10 .15 .17 .20 .24 .28 .32 .37 .43 .49 .55 .64 Not rated or not available Soil Rating Lines .02 .05 .10 .15 .17 .20 .24 .28 .32 .37 .43 .49 .55 .64 Not rated or not available Soil Rating Points .02 .05 .10 .15 .17 .20 .24 .28 .32 .37 .43 .49 .55 .64 Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads K Factor, Whole Soil Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 27 Cushman fine sandy loam, 3 to 9 percent slopes .20 0.8 12.2% 48 Heldt clay loam, 0 to 3 percent slopes .28 0.2 3.7% 63 Longmont clay, 0 to 3 percent slopes .24 0.3 4.3% 65 Midway clay loam, 5 to 25 percent slopes .32 0.8 12.0% 90 Renohill clay loam, 3 to 9 percent slopes .24 4.3 67.8% Totals for Area of Interest 6.3 100.0% Description Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by water. Factor K is one of six factors used in the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict the average annual rate of soil loss by sheet and rill erosion in tons per acre per year. The estimates are based primarily on percentage of silt, sand, and organic matter and on soil structure and saturated hydraulic conductivity (Ksat). Values of K range from 0.02 to 0.69. Other factors being equal, the higher the value, the more susceptible the soil is to sheet and rill erosion by water. "Erosion factor Kw (whole soil)" indicates the erodibility of the whole soil. The estimates are modified by the presence of rock fragments. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Layer Options (Horizon Aggregation Method): Surface Layer (Not applicable) K Factor, Whole Soil—Larimer County Area, Colorado 6422 Kyle Ave SOlar Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 3 of 3 APPENDIX D – EROSION CONTROL ESCROW 11/6/2018 Project: Disturbed Acres: 6.00 EROSION CONTROL BMPs Units Estimated Quantity Unit Price Total Price each 1 $750.00 $750.00 LF 1450 $2.00 $2,900.00 each 1 $1,200.00 $1,200.00 each 1 $250.00 $250.00 LS 1 $2,000.00 $2,000.00 LS 1 $1,000.00 $1,000.00 SF 6000 $2.00 $12,000.00 Sub-Total: $20,100.00 1.5 x Sub-Total: $30,150.00 Amount of security: $30,150.00 AC 6 $2,000.00 $12,000.00 Sub-Total: $12,000.00 1.5 x Sub-Total: $18,000.00 Amount to Re-seed: $18,000.00 Minimum escrow amount: $3,000.00 Erosion Control Escrow: $30,150.00 6422 Kyle Ave Solar Detention Pond Outlet Structure Protection Miniumum Escrow Amount Seeding Riprap Outlet Protection Reseeding Amount Sediment Control Log Erosion and Sediment Control Escrow/Security Calculation for The City of Fort Collins BMP Amount Vehicle Tracking Control Pad Concrete Washout Street Sweeping and Cleaning “The amount of the security must be based on one and one-half times the estimate of the cost to install the approved measures, or one and one-half times the cost to re-vegetate the disturbed land to dry land grasses based upon unit cost determined by the City's Annual Revegetation and Stabilization Bid, whichever is greater. In no instance, will the amount of security be less than one thousand five hundred dollars ($1,500) for residential development or three thousand dollars ($3,000) for commercial development” NAG250 Erosion Control Blankets Final Escrow Amount (Maximum between BMP, Reseeding and Minimum Escrow) 11/6/2018 3:47 PM V:\3004c NME Kyle Road Solar\Reports\Attachments\3004c Kyle Ave Solar Erosion Control Escrow.xls Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 13, Sep 10, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 20, 2015—Oct 15, 2016 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. K Factor, Whole Soil—Larimer County Area, Colorado (6422 Kyle Ave SOlar) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 2 of 3 of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 13, Sep 10, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 20, 2015—Oct 15, 2016 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—Larimer County Area, Colorado (6422 Kyle Ave SOlar) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/4/2018 Page 2 of 4 Choose One Yes No Choose One Permanent None* Temporary 3004c UD-BMP_v3_01.xls, GB 11/6/2018, 11:21 AM 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 3004c - Rational Calculations.xlsx Developed Tc Page 5 of 12 paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 Initial Overland Time (ti ) Travel Time (tt ) tt =Length/(Velocity x 60) tc Urbanized Check ON 3004c - Rational Calculations.xlsx Developed Tc Page 4 of 12 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 3004c - Rational Calculations.xlsx Developed C Page 3 of 12 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 Runoff Coeff's 3004c - Rational Calculations.xlsx Developed C Page 2 of 12 (fps) tt (min) Time of Conc ti + tt = tc Total Length (ft) tc=(L/180)+ 10 (min.) Min tc H 1 257,058 257,058 5.90 0.0% 0.25 0.00 0.25 0.31 150 5.5% 14.0 630 5.5% Tillage/field 5 1.2 9.0 22.9 780 14.3 14.3 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 0 0.00 Paved areas & shallow paved swales 20 0 10.0 TOTAL SITE 0 0 0 0 0 0 0 257,058 257,058 5.90 0.0% 0.25 0.00 0.25 0.31 Basin Name Design Point Time of Conc (tc) C2 C5 C10 C100 2 5 10 100 ATotal (sf) ATotal (ac) Q2 Q5 Q10 Q100 H 1 14.3 0.25 0.00 0.25 0.31 1.91 0.00 3.26 6.65 257,058 5.90 2.81 0.00 4.81 12.27 0 0 0 0.00 0 0 0 0.00 0 0 0 0.00 0 0 0 0.00 TOTAL SITE 257,058 5.90 2.81 0.00 4.81 12.27 Initial Overland Time (ti) Travel Time (tt) tt=Length/(Velocity x 60) tc Urbanized Check ON Runoff Coeff's Rainfall Intensities (in/hr) Area Flow Rates (cfs) Runoff Coeff's 3004c - Rational Calculations.xlsx Historic Page 1 of 12