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HomeMy WebLinkAboutDrainage Reports - 03/11/2014A 1 UNITED CIVIL ' \ Design Group City of Ft. Collins pWovl Plans Approved By r Final Drainage & Erosion Control Study r The Square Fort Collins, CO r i Prepared for: Square Shopping Center LLC P.O. Box 1001 Tustin, CA 92781 March 11, 2014 1 2501 Academy Ct. Ste. 203 Fort Collins, Colorado 80524 (970) 530-4044 I I ' UNITED CIVIL Design Group .� 1 Drainage & Erosion Control Report The square Fort Collins, CO TABLE OF CONTENTS 1. GENERAL PROJECT LOCATION AND DESCRIPTION ..................... A. Location........................................................................... B. Description of Property .................................................. 11. DRAINAGE BASINS AND SUB -BASINS .......................................... A. Major Basin Description ................................................. B. Sub -Basin Description..................................................... III. DRAINAGE DESIGN CRITERIA...................................................... A. Regulations..................................................................... B. Hydrological Criteria....................................................... C. Hydraulic Criteria............................................................ D. Variance Request............................................................ IV. DRAINAGE FACILITY DESIGN ....................................................... A. General Concept............................................................. B. Specific Details................................................................ V. CONCLUSIONS ............................................................................. A. Compliance with Standards ............................................ B. Drainage Concept........................................................... C. Water Quality.................................................................. VI. EROSION AND SEDIMENT CONTROL .......................................... A. Site Description............................................................... B. Stormwater Management Controls ................................ C. Erosion Control Sequencing ............................................ D. Final Stabilization and Long Term Stormwater Quality.. E. Inspection and Maintenance Procedures ....................... F. Erosion Control Surety Calculations ............................... VII. REFERENCES ............................................................................. APPENDICES APPENDIX A - Runoff Calculations APPENDIX B - Detention Pond Analysis APPENDIX C - Hydraulic Analyses APPENDIX D - City of Fort Collins Forms APPENDIX E - References APPENDIX F - Plans and Maps PAGE 1 2 2 2 2 2 2 3 4 4 4 6 7 7 7 7 8 8 .... 30 .... 15 .... 16 .... 16 .... 17 .... 18 I U13011-DrainageReWn-Finall.doc I UNITED CIVIL Z4\ Design Group . General Location and Description A. Location Drainage & Erosion Control Report The Square Fort Collins, CO The Square site is located in the Southwest Quarter of Section 25, Township 7 North, Range 69 West of the 6th Principal Meridian to the City of Fort Collins, Larimer County, Colorado. The site is located immediately east of South College Avenue, north of Horsetooth Road, west John F. Kennedy Parkway, and south of East Monroe Drive. There are no major drainage ways, facilities, or easements within the existing site. B. Description of Property The Square site (referred herein as "the site", "this site") is approximately 8.5 acres in size and was previously developed into a shopping center complex (The Square Mall) in 1978. There are five outlying parcels with separate buildings surrounding The Square Mall that share the same parking lot. The approximate area of the Square Mall plus these five parcels is 13.8 acres. The following is a summary of the existing conditions: Ground Cover- The site currently contains one building and the utilities to serve that building. The existing ground cover consists mostly of pavement, building, and minimal landscaping. Grades - In general, the majority of the site slopes southeasterly at a slope of ' approximately 1-2%. The existing landscaping slopes range from approximately 1%to 30%. The existing parking lot slopes range from approximately 1%to 7%. Soil Type - According to the NRCS Web Soil Survey, the majority of the site consists of Nunn Clay loam, 1 to 3 percent slope (Soil Type C). There are also some Heldt clay loams, Fort Collins loam, Renohill clay loam, and Thedalund loam ranging from 0 to 5 percent slopes. Utilities —There are service lines to the buildings and mains in the adjacent streets and easements. Detention Ponds and Storm Sewer —There are no detention ponds currently on the site. There is a storm sewer that runs along the west and south side of the building and collects storm water in inlets. The storm sewer exits the site to the east under 1FK Parkway. I U33011-DralnageReport-Flnall.doc 1 UNITED CIVIL Drainage &Erosion Control Report The Square Design Group .� Fort Collins, Co ' II. Drainage Basins and Sub -Basins A. Major Basin Description ' The site is in the Foothills Basin where any increase over the existing imperviousness is required to be detained and released at the 2-year historic ' rate and to provide water quality for the entire site. B. Sub -Basin Description tHistorically, the runoff from this developed site flows off the site to the east undetained and untreated. The runoff exits the site via a storm sewer under JFK ' Parkway that eventually outfalls into Warren Lake. The proposed site will direct the majority of runoff towards a porous landscape ' detention pond located on the east side of the site. The PLD will provide water quality and detention and release the flows to the existing storm sewer system. ' This final drainage study includes the calculations from the off -site basins for the outlying parcels owned by the separate property owners. These flows combine with the flows from the Square Mall as they exit the site to the east across JFK ' Parkway. III. Drainage Design Criteria ' A. Regulations The design criteria for this study are directly from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual and the Urban Storm Drainage Criteria Manuals Volumes 2, and 3 (referred to herein as USDCM). B. Hydrological Criteria In accordance with the Fort Collins policy, a minor and major storm for the Fort Collins area is identified as the 2-year and 100-year storms, respectively. A major ' storm for the Fort Collins area has a recurrence interval of 100 years has a peak intensity of 9.95 in/hr. ' These storms have been used as a basis for planning and system design. The peak flow rates for design points have been calculated based on the Rational Method as described in the USDCM with storm duration set equal to the time of ' concentration for each sub -basin. This method was used to analyze the developed runoff from the 2-year (minor) and the 100-year (major) storm events. The Rational Method is widely accepted for drainage design involving 2 U13011-DrainageReport-Flnall.doc [] UNITED CIVIL Drainage &Erosion Control Report The square Design Group . Fort Collins, Co small drainage areas (less than 160 acres) and short time of concentrations. The Rational Method is ideal for storm sewer sizing and small detention pond sizing (for tributary areas no larger than 90 to 160 acres). Runoff coefficients were assumed based on impervious area and soil type and are given in Appendices. C. Hydraulic Criteria The developed site will convey runoff similar to the existing site with addition of some onsite detention and water quality. The runoff will be directed offsite to IN Parkway or to the Porous Landscape Detention Pond in a safe and effective manner via storm sewer, grass lined swales and concrete pans. The proposed site will likely be redeveloped in at least two phases. It is the intent of the property owner to provide adequate detention and water quality in the first phase to satisfy the requirements for the ultimate build out of the site. The assumptions made in this drainage report will need to be verified with the development of subsequent phases. Detention Areas A portion of the runoff produced by the site will be conveyed to the proposed detention area within the development. The detention area was sized utilizing the Rational Formula -Based Modified FAA Procedure (assuming the required pond volume is maximized at 120 minutes or less). The detention area was sized based only on the increased imperviousness of the new development. The proposed detention area will include a porous landscape detention area with 1' of storage above the surface and storage throughout the gravel and sand area below. The detention will release through the underdrain connected to the bottom of the outlet structure or spill into the opening at the top of the outlet structure. An orifice plate limiting the flows has not been included as the inlet capacity and the capacity of the 30" pipe restricts the flows below the allowable release rate already. Refer to Appendix B for detention pond calculations. Water Quality Water quality is provided by the same porous landscape detention area utilized for detention storage. A portion of the site runoff will not be directed through the PLD, but an offsite area will be directed through it so that the net treated area is greater than the proposed site. The porous landscape detention pond will include an underdrain and is designed based on the entire 8.5 acre site with a 12 hour drain time according to UDFCD standards for Bioretention Facilities. In addition, there is some additional uncalculated water quality provided on site via disconnected impervious 3 U13011-DrainageReport-Flnall.doc UNITED CIVIL Drainage &Erosion Control Report 'A\The square Design Group . Fort Collins, Co surfaces and a grass buffer swale provided in the large landscaped area west of the building. t Open Channels Sidewalk chases and curb cuts are typically designed for the minor storm with overtopping of the curbs/sidewalks in larger storm events. In all cases ' on this project, the minimum 12" wide curb channel and sidewalk chase is adequate to convey the minor storm event. ' Storm Sewer The existing storm sewer main is made up of 8" PVC pipes, which is clearly inadequate to handle the major storm event on the site. The storm sewer system was not analyzed for capacity as there is adequate overland flow paths to convey the major storm event. ' D. Variance Request The site is not able to provide the required detention storage volume plus the ' water quality capture volume. The site is limited in space due to the fact that it is entirely developed already. This project is providing adequate storage for ' both detention and water quality individually, but it is not adequate for both items added together. IV. Drainage Facility Design A. General Concept ' The site will ultimately consist of ground covered by pavement, rooftop, and landscape. All referenced tables, charts, formulas, etc. are included in the Appendix. The area, time of concentration, and runoff of each proposed sub -basin is summarized in Appendix A. The project site was divided into several different ' developed sub -basins as explained further below: Basin A ' Basin A consists of rooftop, sidewalk, parking lot, and landscaped area on the northern portion of the site. Sub -basin Al is the portion that is associated with this site and Sub -basin A2 is the portion associated with the northwest parcel. These flows combine and run along the drive on the north side of the building until they outfall directly into the western curb & gutter on JFK ' Parkway. These flows are undetained and are not treated for water quality. A larger area from offsite Sub -basins 82, B3, and B4 will be routed through the PLD to make up for the undetained and untreated Sub -basin Al. 4 U13011-DralnageKepwrt-nnall.dm I A UNITED CIVIL Design Group uc Basin B Drainage & Erosion Control Report The Square Fort Collins, CO Basin B consists of rooftop, sidewalk, parking lot, and landscaped area on the southern portion of the site. Sub -basin Bl is the portion that is associated with this site and Sub -basin B2, B3, and B4 is the portion associated with the outlying parcels. These flows combine and run along the drive on the south side of the building. The minor storm flows will be captured by the area ' inlets and conveyed by the storm sewer to the east. The major storm flows will be conveyed via the curb & gutter and pans to the east. All of these flows will be directed to the PLD on the east side of the site. As mentioned ' above, a larger area from offsite Sub -basins B2, B3, and B4 will be routed through the PLD to make up for the undetained and untreated Sub -basin Al. The flows exiting the PLD will be conveyed easterly via a storm sewer across 1FK Parkway. 1 1 11 Basin OS1 Basin OSl consists of rooftop, sidewalk, and landscaped area on the northeastern portion of the northeast outlying parcel. This offsite runoff was calculated separately from Basin A2 as this runoff is directed towards East Monroe Drive. Basin OS2 Basin OS2 consists of rooftop, sidewalk, and landscaped area on the southeastern portion of the southeast outlying parcel. This offsite runoff is calculated separately from Basin B2 as this runoff is directed towards JFK Parkway and East Horsetooth Road and will not pass through the PLD. Existing Basins The existing onsite basins were also calculated to quantify the existing flows that are coming from the site. These basin areas are the same areas that are shown for the proposed basins. 5 U13011-DrainageRepon-Flnall.doc I ' A UNITED CIVIL Design Group u, ' B. Specific Details The following is a basin summary table: 1 1 Drainage & Erosion Control Report The Square Fort Collins, CO Basin Design Point Area_ (acre) %I CI Clop Q: -(cjs) - QM _ (CIS) - Proposed Basins Al Al 3.58 86% 0.89 1.00 7.34 28.79 A2 A2 0.89 85% 0.86 1.00 2.18 8.90 B1 81 4.97 85% 0.88 1.00 9.33 36.91 B2 82 0.78 82% 0.83 1.00 1.64 6.87 B3 B3 2.49 75% 0.78 0.98 4.68 20.43 B4 B4 0.62 78% 0.80 1.00 1.43 6.20 OSl OSl 0.18 52% 0.65 0.81 0.33 1.45 OS2 OS2 0.25 44% 0.58 0.73 0.41 1.80 Toile Total 13.77 82% 0.85 1.00 27.35 111.34 Existing Basins Al Al 3.58 0.80 0.84 1.00 6.64 27.67 A2 A2 0.89 0.87 0.87 1.00 2.22 8.90 B1 Bl 4.97 0.76 0.81 1.00 8.21 35.61 B2 B2 0.78 0.80 0.82 1.00 1.60 6.87 83 B3 2.49 0.75 0.78 0.98 4.66 20.33 94 B4 0.62 0.74 0.78 0.98 1.39 6.06 OS1 OSi 0.18 0.52 0.65 0.81 0.33 1.45 052 OS2 0.25 0.44 0.58 0.73 0.41 1.80 Onsite Total 13.77 7796 0.81 1.00 25.47 108.69 The following is a summary of the detention pond volumes: Water Detention Total Top Outfall Quality Storage Volume Elevation Elevation Storage Total Provided 9,770 9,770 9,770 5012.30 5004.40 Total Required 9,119 9,466 9,466 6 U13011-DrainageReport-Finall.doc r UNITED CIVIL Drainage Erosion Control Report The Square Design Group ,c Fort Collins, CO ' The spillway for the Porous Landscape Detention Pond will be on the west side of the PLD into the parking lot. The water will spill to the west and then drain back towards JFK through the driveway south of the PLD. The spillway is at an elevation of 5012.63, which is 0.33' higher than the water surface elevation at the rim of the area inlet used as the outlet structure. This effectively creates additional detention storage of approximately 864 cf that could be taken into ' consideration if needed in future phases of this development. The lowest finished floor elevation is the building immediately south which is at an elevation of 5015.65. ' Water quality is provided for the entire 8.5 acre site by treating Basins Bl, B2, ' B3, & B4 in the porous landscape detention pond. The porous landscape detention pond is limited to a ponding depth of 1'. There is additional water quality treatment that takes places through the PLD material and the calculated ' void space in the material. A 4" underdrain is connected to the outlet structure to effectively drain the PLD slowly. V. Conclusions ' A. Compliance with Standards Storm drainage calculations have typically followed the guidelines provided by the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual and/or the Urban Storm Drainage Criteria Manuals Volumes 2, and 3. There is a variance that has been requested for combining detention and water quality volumes. B. Drainage Concept ' The general drainage system and patterns has not been changed from the previously designed site. As proposed, the site has a detention pond volume ' (9,770 cf) in excess of that required (9,466 cf). Since the new impervious area is required to be released at the 2-year storm level, the post detention 100-year storm runoff is less than the existing 300-year storm runoff. ' C. Water Quality Water quality has been provided by porous landscape detention. There is 9,770 cf of porous landscape detention volume provided for the entire 8.5 acre site. This is greater than the 9,119 cf of porous landscape detention that is required for the entire site. The actual treated area comes from Basin B3 and offsite ' basins B2, B3, and B4 which contributes a larger area (8.9 acres) than the entire 8.5 acre site. 1 7 U13011-DralnageRepon-Flnall dtl UNITED CIVIL Drainage Erosion Control Report ,, A\ The Square Design Group Fort Collins, Co LL, VI. Erosion and Sediment Control A. Site Description ' 1. Construction Activity Description ' The proposed redevelopment project includes the construction of additional building space at The Square Mall including supplementary site improvements. It is expected that the building and site will be redeveloped in phases. The landscape and hardscape areas currently around the existing The Square Mall will be removed for this additional space. In addition, existing site features at various surrounding parcels, such as landscaping, parking area and sidewalk will be removed and replaced with new landscaping, parking area, and sidewalk. A porous landscape detention pond southeast of the Square Mall will be constructed for water quality and detention storage improvements. The site improvements will require ' mostly minor changes in grade on the order plus or minus one foot. 2. Proposed Sequence for Major Activities The project is expected to be constructed in two phases. The western half of the building and site along with the porous landscape detention will be constructed with the initial phase. The second phase will include the expansion of the eastern portion of the building and site. Both phases will include the anticipated sequence for major construction activities: ' • Installation of erosion control • Removal and demolition of building, pavement, utilities, landscaping, etc. ' • Installation of utilities • Installation of building foundation ' • Site grading and paving • Construction of buildings • Final landscaping. ' The first phase of construction is estimated to begin in the early part of 2014 and be fully tcompleted by the fall of 2014. The timing for the second phase is still unknown. 3. Area Estimates ' The Square shopping center area as defined by the property boundaries is 372,819 square - feet. The five additional parcels adjacent to the Square total 272,038 square -feet. The total area is approximately 600,000 sf or 13.77 acres. A large portion of the existing building and ' parking lot will remain in place. The total area to be reconstructed or overlaid with additional asphalt is approximately 375,000 sf or 8.6 acres. The total area to be 8 U13011-DrainageNepon-Finall.dw UNITED CIVIL Drainage &Erosion Control Report The Square Design Group uc Fort Collins, CO ' reconstructed in the first phase is approximately 205,000 sf. The total area to be reconstructed in the second phase is approximately 170,000 sf.' The site areas do not include any additional offsite areas (for staging, material storage, ' overburden stockpiles of dirt, borrow areas, etc) other than that mentioned above. It is expected that this activity would take place on site in the areas to be reconstructed. ' 4. Soil Description Earth Engineering Consultants completed the soils investigations for the project site and ' presented the results in the Subsurface Exploration Report Proposed Building Additions and Pavement Improvements, The Square Retail Center, 3500 South College Avenue, Fort Collins, Colorado. According to this report, the existing topsoil and pavement areas are underlain ' by lean clay soils to a depth of 2 to 14 feet. S. Existing Vegetation ' The existing site is developed with paving, buildings and vegetative cover that is 100% established. The vegetative cover consists of well established lawn, trees and bushes and ' covers approximately 20% of the site. 6. Location and Description of Other Potential Pollution Sources ' Potential pollutant sources include sediment, uncovered soil, construction machinery, building materials, paints, and fertilizers. It is anticipated that any storage of materials or ' machinery will be on site and surrounded by silt fence or straw wattles. 7. Non-Stormwater Components of Discharge ' According to the Geotechnical Subsurface Exploration Report Proposed Building Additions and Pavement Improvements, The Square Retail Center, 3500 South College Avenue, Fort Collins, Colorado by Earth Engineering Consultants: Groundwater was encountered at approximate depths of S X to 21 feet below site grade during the drilling operations. At these depths, it is expected that groundwater will not likely be encountered during the construction of utilities. If groundwater is encountered, a temporary sediment/retention basin should be constructed to store pumped dewatering flows. The other non -storm water components of discharge include water line flushing, irrigation to establish seeding, washing out concrete trucks, and watering for dust mitigation and compaction. It is important for the contractor to manage the runoff from these items utilizing the BMP's mentioned in this report (i.e. silt fence, straw waddles, rock socks or inlet protection) 0 U13011-DrainageRepon-Finall.doc I 1 1 L C 1 1 AUNITED CIVIL Design Group . 8. Receiving Waters Drainage & Erosion Control Report The Square Fort Collins, CO This site is located in the Foothills Basin of Fort Collins, Colorado. Runoff from the majority of the site will drain directly to the detention pond located on the southeast portion of The Square Mall. The northern portion of the site and small area on the southeast corner of the site will drain directly to JFK Parkway, where it will enter storm drain inlets that are tied to the same storm sewer system that the onsite detention pond drains to. This storm sewer system continues through the properties to the east of JFK Parkway and eventually outfalls at Warren Lake, which is approximately Ya mile east of this property on the south side of Horsetooth Road. The ultimate receiving water is the Cache La Poudre River which is approximately 4 miles east of the property. B. Stormwater Management Controls 1. SWMP Administrator The SWMP Administrator is currently: Mr. Darrell Knudson Square Shopping Center LLC P.O. Box 1001 Tustin, CA 92781 2. Identification of Potential Pollutant Sources This section focuses on the identification of the potential pollutant sources and briefly ' discusses the Best Management Practices (BMPs) that will be used. More information on the BMP's utilized on this site is included in the next section "3. Best Management ' Practices". A. All disturbed and stored soils; It is expected that there will be stockpiles of dirt on the site from the utility installations ' and the foundation excavation. Where possible, stockpiles should be located in areas where Silt Fence or Straw wattles may be placed around the individual stockpiles to contain the runoff (i.e. landscaped or disturbed earth areas). Should the stockpile area ' be located within a paved area rock socks shall be installed around the perimeter of the stockpile. ' B. Vehicle tracking of sediments It is anticipated that the contractor will access the property from the existing paved access points adjacent to the site on JFK Parkway and East Monroe Drive. A vehicle ' tracking control pad may be required onsite during construction to reduce tracking 1 sediment onto the adjacent streets. 1 10 U33011-DrainageReport-Flnall.dm I UNITED CIVIL Drainage &Erosion Control Report ' The Square Design Group . Fort Collins, CO ' At the end of each workday, the Contractor shall sweep or scrape East Monroe Drive, JFK Parkway, and internal site driveways of sediment that may have accumulated during the workday. ' C. Management of contaminated soils There are not any known contaminated soils on the site. However, if the contractor ' encounters contaminated soils during the construction process they should stop construction immediately and notify the appropriate government authorities in accordance with good construction safety and practice. ' D. Loading and Unloading operations Loading and unloading will take place on the site. Truck access should be limited to the extent possible to locations within the disturbed limits of the project. BMP's such as ' rock socks should be placed to keep sediment from exiting the disturbed area limits and entering the adjacent streets, primarily JFK Parkway as this is the low side of the site. I E. Outdoor storage activities (building materials, fertilizers, chemicals, etc.) Storage of onsite materials including building materials, fertilizers, waterline, and sanitary sewer will be covered and placed on pallets to prevent direct contact with the ground and potential surface runoff. F. Vehicle and equipment maintenance Vehicle and equipment maintenance should be performed offsite or onsite within an area surrounded by silt fence or straw wattles. Vehicle and equipment maintenance shall not happen along the adjacent public streets. At a minimum all vehicle and equipment maintenance shall be performed on the hard surface or gravel areas at least 50' from any stormwater feature (i.e. inlet, storm sewer, concentrated runoff, Swale, etc.) G. Significant dust or particulate generating processes The Contractor shall comply with applicable air pollution control requirements of the City. The Contractor shall take appropriate actions to minimize atmospheric pollution and take reasonable precautions which shall include, but not be limited to: 1. The use of water for control of dusts for construction processes such as demolition, grading, or the clearing of land. 2. Covering, at all times when in motion, open -bodied trucks transporting materials likely to give rise to airborne dusts. 3. Require lower speeds for vehicles entering, exiting, and driving within the project limits to minimize the amount of dust disturbed by moving vehicles. H. Routine maintenance activities Involving fertilizers, pesticides, detergents, fuels, solvents, oils, etc; Chemicals, fuels, lubricants, and paints typical with building construction stored on -site will be in water tight containers and covered as necessary and stored in a bermed area, a storage building, or within a vehicle to act as secondary containment. i j U13011-DrainageRepon-FlnallAm UNITED CIVIL Drainage &Erosion Control Report A , The Square Design Group . Fort Collins, CO ' I. On -site waste management practices (waste piles, liquid wastes, dumpsters, etc.); 1. Waste piles should be covered or surrounded by silt fence or straw wattles. Liquid wastes should be collected and stored in covered containers and ' disposed of properly. 2. Solid waste materials, including disposable materials incidental to the major construction activities, will be collected in on site dumpsters. The containers will be emptied periodically and trucked away from the site. Dumpsters should ' have covers. J. Concrete truck / equipment washing, including the concrete truck chute and ' associated fixtures and equipment; A dedicated concrete washout area is necessary for this project. The contractor shall clean out equipment within the washout area so that runoff is not allowed to leave site ' and enter the public streets or neighboring properties. K. Dedicated asphalt and concrete batch plants; ' There will not be dedicated asphalt or concrete batch plants on this site. L. Non -industrial waste sources such as worker trash and portable toilets ' Worker's trash shall be disposed of in an onsite dumpster. The site should be free of trash at the end of each working day. Portable toilets shall be utilized by construction personnel and serviced regularly by a ' commercial operator. They shall be located a minimum of 5 feet from the curb or 50 feet from inlets. If sanitary facilities are located on a paved surface, toilets shall be equipped with a containment pan or a secondary containment BMP. Regardless of ' location all portable toilets shall be anchored per manufacturer recommendations. ' M. Other areas or procedures where potential spills can occur. BMP's such as tarps and drip pans should be used for painting, stucco, dry -wall etc. operations ' 3. Best Management Practices (BMP's) Once construction activity begins, Best Management Practices (BMP's) intended to contain sediment onsite must be constructed, inspected and repaired as necessary. Such controls must be functional before upslope land disturbance takes place. The BMP's will be installed as shown on the Grading and Erosion Control plan shown in Appendix D. They must be supplemented as on -site experience proves necessary in order to control sediment, pollutant discharge, and insure public safety. The following temporary and permanent BMP's will be installed and maintained to control on -site erosion and prevent sediment from traveling off -site during construction. The descriptions below provide some information about each BMP, but further information can be found in Urban Storm Drainage Criteria Manual, Volume 3 — Best Management Practices by Urban Drainage and Flood Control District. 12 U13011-DrainageReport-Flnall.doc t 1 1 [1 A,� UNITED CIVIL Design Group u, Temporary BMP's Drainage & Erosion Control Report The Square Fort Collins, CO • Construction Fence is a temporary BMP. The contractor is to place construction fencing around development as needed to limit access by construction equipment and personal vehicles to designated areas of ingress and egress. Since the majority of site will soon be surrounded by a permanent fence, there will be limited construction fence needed on this project. Inlet Protection is a temporary BMP that helps prevent soil and debris from the site from entering the storm drain inlets and usually consists of a sediment filter around, upstream, or inside the storm drain inlet. Inlet protection allows storm water to flow into the drain but only after excess sediment has been filtered out. Inlet protection will be used on existing and proposed storm inlets and will be installed at such time as construction of the storm sewer system occurs. Onsite inlet protection for this site will consist of the dandy sack that sits inside the inlet. The offsite inlets on 1FK Parkway will consist of wattles, which are meshed netting "tubes" filled with straw, excelsior, or coconut fiber placed around grated inlets and curb inlets. Wattles require proper installation and maintenance to ensure their performance. Sizing shall be per manufacturer's recommendation. • Regular Meetings is a temporary and non-structural BMP. Regular meetings with on -site workers including builders, suppliers, landscape personnel, etc. should be conducted so that they are kept up to date with site standard operating procedures. • Silt Fence is a woven synthetic permeable fabric that filters runoff. Silt fence is a ' temporary barrier that is installed prior to earthmoving activities and is placed downstream of areas where runoff from construction activities is expected to occur, especially along the site perimeter to allow sediment to settle from runoff ' before water leaves the construction site. Silt fences will be installed per manufacturer's recommendations. Silt fence encourages sheet flow and is not intended to be used in areas of concentrated flow. If concentrated flow is encountered during the placement of the fence, an alternative BMP shall be used ' and the SWMP should be updated to reflect this change. • Straw Wattles are a temporary BMP that are used for a variety of purposes. They ' are used for inlet protection, curbside check dams, swale protection, at the bottom of slopes, or at the limits of property boundaries. Straw wattles are meshed netting ' "tubes" filled with straw, excelsior, or coconut fiber. Wattles for swale protection should be installed following rough grading of channel areas. Wattles require proper installation and maintenance to ensure their performance. ' • Rock Socks are a temporary BMP that are used for a variety of purposes. They are used for inlet protection, curbside check dams, or at the limits of property ' boundaries. Rock socks are wire meshed "tubes" filled with rocks. Rock Socks require installation and maintenance to ensure their performance. proper ' 13 U13011-DrainageRepon-FlnallAx 1 UNITED CIVIL Drainage &Erosion Control Report ' The Square Design Group . Fort Collins, Co ' • Street Sweeping and Vacuuming removes sediment that has been tracked onto roadways to reduce sediment transport into storm drain systems or a surface waterway. This practice should be used on the adjacent paved road to the ' construction site. Paved roads should be inspected on a daily basis and more frequently as needed. • Saw Cutting Pollution Prevention prevents 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 surface operations and shall not be allowed to remain on pavement surface overnight. Collected slurry and ' cuttings shall be disposed of in a manner that does not violate groundwater or surface water standards. ' • Temporary Seeding is the establishment of a temporary vegetative cover on a graded area that will be exposed for longer 30 days. Temporary seeding can be used on areas requiring temporary protection that will eventually need permanent ' vegetation at the completion of the construction or it can be used for areas that will be re -disturbed after a period of inactivity. The seed mix 100% smooth brome at a minimum application rate of 30 pls/lbs/acre. Fertilizer and Mulch shall be included ' as specified on the plans. • Vehicle Tracking Control is a stabilized stone pad located at points of ingress and ' egress on a construction site and acts as a temporary BMP. The stone pad is designed to reduce the amount of mud transported onto public roads by construction traffic by removing mud and sediment from the vehicle's wheels when ' it drives over the gravel pad. These areas are limited to the minimum number necessary to provide functional construction access and installed prior to overlot grading activities. Whenever the construction entrance exists onto a public road, ' the road shall be cleaned at the end of each day. Vehicle Tracking Control will also be use on this site at the stockpile area exit(s). • Wind Borne Sediment and Dust Control measures will be provided during the construction process to control wind borne sediment. During grading activities, water will be applied to the disturbed soils for the purpose of maintaining cohesion ' with clay type soils and also to meet moisture requirements for compaction of disturbed soils. Other measures of mitigation for wind erosion may include the timely installation of seed and mulch following the establishment of final grade, and ' the timely installation of pavement following completion of utility trenching operations and curb construction. Open areas should be kept in a roughened condition. ' Permanent BMP's ' • Permanent Seeding and Planting is the establishment of a permanent perennial vegetation such as trees, shrubs, vines, grasses/sod, or legumes on exposed areas for final permanent stabilization in order to provide stabilization of the soil by 14 U13031-Dra'mageRepon-Finan.dm UNITED CIVIL Drainage &Erosion Control Report ' The Square Design Group � Fort Collins, co holding soil particles in place. These items should be installed as per the approved Landscape Plan. Soil Amendments shall be incorporated in all landscape areas to a depth of 6" at a rate of 3 cubic yards per 1000 square feet of area unless 4" of loose ' topsoil have been imported onto the site over 4" of loosened subgrade soils. Permanent Landscaping reduces storm water runoff velocity, maintains sheet flow, protects the soil surface from erosion, promotes infiltration of runoff, and improves wildlife habitat. • Preservation of Existing Vegetation should occur where no construction activity is expected to occur. Preservation of natural vegetation is generally a permanent EMIR ' and is applicable to construction sites with pre-existing vegetation. Only land needed for building activities and vehicle traffic needs to be cleared. ' C. Erosion Control Sequencing The erosion control sequencing for construction is as follows: tPrior to Construction Preserve Existing Vegetation — Before construction commencement, areas that are not disturbed by construction activity should be preserved as needed with construction ' fencing, silt fencing, or other means to keep vehicular traffic out of the area to be left undisturbed. ' Silt Fence or Straw Wattles — Before construction commencement, silt fence will be placed as needed to control sediment transport. ' Inlet Protection — Inlet protection should be in place in the existing onsite inlets and the inlets within JFK Parkway. ' These erosion control devices shall be in place, functional, and maintained during and ' following the construction operations. During Construction Street Sweeping and Cleaning —The adjacent streets and parking lots shall be swept and ' cleaned on a daily basis to ensure sediment is not being tracked away from the construction site. ' Concrete Washout area — An area to washout concrete trucks shall be established and maintained through the completion of the concrete work. ' 15 U13011.DrainageReport-Finall.doc r7 L UNITED CIVIL Drainage Erosion Control Report ' The Square AN Design Group u. Fort Collins, co ' Wind Borne Sediment and Dust Control — Wind borne sediment and dust control measures should be implemented during grading activities. ' Permanent Seeding —Permanent seeding or landscaping shall be placed immediately in areas that are final graded and where little future disturbance is expected. In particular, ' permanent seeding should be included on the side slopes of the detention pond. Temporary Seeding —The majority of the landscaped areas will be permanently seeded/planted. However, if any of the areas are left disturbed without permanent ' stabilization 30 days after grading, temporary seeding will be required. Post Construction BMP's shall be maintained until final site stabilization. ' D. Final Stabilization and Long-term Stormwater Quality ' Final stabilization is reached when all soil disturbing activities at the site have been completed and vegetative cover has been established with a density of at least 70 percent of pre -disturbance levels or when equivalent permanent erosion reduction methods have been utilized. Upon final stabilization, temporary BMP's may be removed. ' Water quality will be provided through established landscaping and pervious areas on the site. 1 E. Inspection and Maintenance Procedures Appropriate measures shall be taken to inspect and maintain existing erosion control features, as described herein or per manufacturers specifications (whichever is more stringent) and install new erosion control elements as needed. LJ 1 t t I The temporary BMP's will be inspected and documented at a minimum of once every 14 days and after each precipitation or snowmelt event. Records should include complete inspection reports for each inspection, maintenance and/or repair. A record -keeping system is recommended in managing inspection and maintenance reports and should include all maintenance records, spill response, weather conditions, training, correspondence, etc. Preventative maintenance also involves the regular inspection and testing of equipment, timely maintenance of the equipment, and complete records of the maintenance and inspections of the equipment. The maintenance and inspection records should be kept on site and made available upon request. 16 U13011-DralnageReport-Finall.doc 11 I ' J(_ UNITED CIVIL Drainage &Erosion Control Report The Square Design Group . Fort Collins, CO ' Inspections must include the observation of the construction site perimeter, runoff discharge points, disturbed areas, staging areas (including concrete washout areas and fueling areas), erosion and sediment control measures identified, and any other structural ' BMP's that may require maintenance. The inspection must determine if there is evidence of or potential for pollutants to enter the drainage system and if they should be modified, replaced, or added to. ' The following list includes some recommended maintenance procedures: • Erosion and sediment control measures determined, upon inspection, to be in need of repair shall be maintained before the next anticipated storm event or as necessary to maintain continued effectiveness of erosion and sediment control measures. If it is impractical to maintain erosion and sediment control measures before the next storm event, maintenance should be accomplished as soon as practical. • Locations where vehicles enter or exit the site shall be inspected for evidence of sediment being tracked off -site by construction traffic. Such sediment shall be removed before it can be conveyed to the receiving storm drains or creeks. • Seeded areas will be checked to see that grass coverage is maintained. Areas will be watered, fertilized and reseeded as needed. • It is the responsibility of the Operator to maintain effective pollutant discharge controls. Actual physical site conditions or contractor practices could make it necessary to install more control than are shown on the Erosion Control Plan. For example, localized concentrations of surface runoff or unusually steep areas could require additional erosion control devices. Assessing the need for, and implementing additional controls will be a continuing aspect of the SWMP until final stabilization. This plan intends to control water -borne and liquid pollutant discharges by some combination of interception, filtration, and containment. Parties implementing this plan must remain alert to the need to periodically refine and update the plan in order to accomplish the intended goals. • Sediment that has escaped the construction site must be removed at a frequency sufficient to minimize off -site impacts. F. Erosion Control Surety Calculations An Engineer's opinion of probable cost for the erosion/sediment control is included in Appendix D. 17 U13011-DrainageRepan-Finall.doc 1 UNITED CIVIL Drainage Control Report The Square Design Group . Fort Collins, CO ' VII. References 1. Subsurface Exploration Report Proposed Building Additions and Pavement ' Improvements, The Square Retail Center, 3500 South College Avenue, Fort Collins, Colorado, EEC Project No. 1132087, Earth Engineering Consultants, November 22, 2013 ' 2. Natural Resources Conservation Service Web Soil Survey at websoilsurvey.nrcs.usda.gov/app ' 3. Urban Storm Drainage Criteria Manual Volume 1 and 2, Urban Drainage and Flood Control District, Denver, Colorado, June 2001, Revised April 2008 ' 4. Urban Storm Drainage Criteria Manual Volume 3 — Best Magament Practices, Urban Drainage and Flood Control District, Denver, Colorado, November 201 1 18 U13011-0nlnageRepon-Finall.dac l Runoff Calculations The Square St _ UNITED CIVIL Port Collins, CO Runoff Summary 7`' Design Group ' Area Ct2 Q1aa Basin Design Point %I C2 C1� ' (acre! (chl (clsl Proposed Basins 1 1 1 1 1 [1 r Al Al 3.58 86% 0.89 1.00 7.34 28.79 A2 A2 0.89 85% 0.86 1.00 2.18 8.90 Bl B1 4.97 85% 0.88 1.00 9.33 36.91 B2 B2 0.78 82% 0.83 1.00 1.64 6.87 B3 B3 1 2.49 75% 0.78 1 0.98 4.68 20.43 B4 B4 0.62 78% 0.80 1.00 1.43 6.20 O51 OSl 0.18 52% 0.65 0.81 0.33 1.45 052 052 0.25 44% 0.58 0.73 0.41 1.80 Onsite Total 13.77 82% 0.85 1.00 27.35 111.34 Existing Basins Al Al 3.58 0.80 0.84 1.00 6.64 27.67 A2 A2 0.89 0.87 0.87 1.00 2.22 8.90 Bl 81 4.97 0.76 0.81 1.00 8.21 35.61 B2 B2 0.78 0.80 0.82 1.00 1.60 6.87 B3 B3 2.49 0.75 0.78 0.98 4.66 20.33 B4 84 0.62 0.74 0.78 0.98 1.39 6.06 OSl OSl 0.18 0.52 0.65 0.81 0.33 1.45 OS2 OS2 US 0.44 0.58 0.73 0.41 1.80 Onsite Total 13.77 77% 0.81 1.00 25.47 108.69 Calculations by: KR8 Date: 211012014 C:IUnited0vill0ropboxiProjects1U13011-SquorelDrainagelHydrologylU13008-Runoff Final.xlsx 800 a_ C _ V m C d d O 6 d 0 0 N d d « c a E w m n o d a, a E II N 00 II `I n OJ b A d N O H rn m rn m N N N N A N n n 0 rl -1 a � C d C G q m O x d w O U J >_ a V 'o o w' c I— ea Z.� a a o E � V U V N y a « c O a u E IA _ 7 c mm u 'O emu, O m 10 a n n Y trz 25 m m N A II II p M 3 u d yyu�� �F Q Crz o m = 7 O N OL 1 ¢ X V N O M H � y F y O C 00 N a Q O c U 'v, N � n m C C Q V m o � O LL H o 000c�o Wn o O1 t0 W M W O N W N W W m W^ W m N 00 0 0 0 0 0 0 0 0 O 00 0 2° 1D N N N N W N d' N W W W W n n N V W W m°°mW o N m^ CmC, W m w W N M N m m n m Q N W O O N a m CO m^ o w M W �o V N C l0 N N n N m v W O Q1 N O N lD n O W ID N o N n o tD m Of Q m MMM W n W e+ N V C •-I N m 0 m N ^ W m n W W N m Q PI Q < Q m m m m 00 N N rl N m Q 0 0 ~ a < Q Q m m m m 0 0 c O O O O O M M W n O W W CO W n n iD N W O O C1 C) I o I o 0 0 1 O W W n W n n N R ^ In ry v d. io N io m N N .-I W N Q1 N N O1 � WarvoN.�oo ^' W �D N Q1 N lD "1 N N� N C N n N n M lOD m m O n W W N W N � e4 01 "I W m Qv W .-I ^ W m n m W N m a .-I a < Q m m m m co A < N Q m N Cm M CO o r o O C O m In ti r W In u1 vi m N Q N Q ti O ti 'i H ti ti ti ti r1 ti ai vi ti r; r; v o v a ov�0000.-� ry .�QNQ-+oo .-1 N Q M l0 W M Q1 N M N N N M tJ tJ 0 0 0 0 0 0 0 0 N N N N N N N N .y IA N N O O O� p lD lD M r N N ti M m N l0 N �O N ip m i0 ui M m m Q N N N N N N hl N MMMMMIM m r M1 r n h n M1 n O O O O O O G O O O O y 0 0 0 0 ll1 m Ql m O Q O N o o 0 4 Q m m m m 0 0 a a m m m$ 00 � vi ti r oo In In In O In O O In In p O ti Q m ID In n O �D M 01 M l0 N "I O7 N ti r h Q Q Q NQm0000.i v-i rev v-+oo N M N N N M lD lD 0 0 0 0 0 0 0 0 N N N N N N N N .-I v1 In O O O O� p N lO n h N N 'y M Vl N OJ N tD N vi m Q In m m m m Q N N N N N N N N ti O O � v1 vt In O m m m m m m m m h n n r n h n h 0 0 0 0 0 0 0 0 O O O Y 10 0 0 0 0 mo mo mo 0 0 0 0 mn Vl W 01 Q l0 � N m O Q O N 0 0 0 ti N rl N M V' e-I N Q m m m m 0 0 ti N rl N m Q� N Q Q m m m m 00 1 E 0 3 0 � O _ a > O O � al a � O U iiQ ro C 9 = O �p v c' u c in a e 0U a U n m � c u s o N �� E LL N Q N C W 6 � O c - u C m ` a tJ m n w o � � t O a H LL .r eY T T T 00 O n T N m N M IA N O Ci N 4!1 V1 oma OpT v+mm I of I r-I col 00 of s m O �n m N O v+ in vi N N N N N N N N 0 0 0 0 o m 0 0 0 o m M o 0o w n 0 0 1616161616161 O1 N � n ap V1 N V1 vwi W .�i Q O r r 0 Obi N rl N m Q N N N < d d m m m m m ¢¢ m m m Q m N O ~ 0 0 a C O H M Ol O u'1 00 00 M N r lD N N �O t0 T m Q 7 N N V1 ip O 00 VI V1 V1 n m�aommmm r � n ao ao ai ai Oi ti V1 VI N O VI N V1 N m O V1 Q m m m N N N N N N N N 0 0 0 o m m m n 0 0 0 0 0 0 0 0 � ✓1 � r m ✓1 vt N W nC P �-1 N rl Yf ti N e-1 N m Q� N d¢ m m m m 0 0 O 1- ¢ c O Ii f I I 1 i I I I I I I I APPENDIX B Detention Pond Analysis I I ' � The Square �2 _ UNITED CIVIL Fort Collins, CO Pond Summary '�\ Design Group C 1 I Water Detention Total Top Outfall Quality Storage (tp Volume (cJ) Elevation Elevation Storage Total Provided 9,770 9,770 9,770 5012.30 5004.40 Total Required 1 9,119 1 9,466 1 9,466 Calculations by: KRB ' Date: 211012014 C.lUnited CiviADropboxlProjectsIU13011-SquarelDroinagelHydrologylU13008-Runoff Final.xlsx The Square Detention Volume UNITED CIVIL Fort Collins, CID Design Group 100 vear storm into detention facility Al Area (sf) Area (acres)l QIN Cry Area %I I Comments 3653G 0.839 1 7.381 0.84 88% 1 Based only on additional im ervious area. Release rate out of detention system based on Q., (cfs) ifs/acre T, (min) I Comments 0.415 0.50 7 1 Based on 2 yr historic release rate of new impervious area. Required Detention Volume Rainfall Duration (T) Rainfall Intensity 2C,,,*Area'I Inflow Volume Adjustment Factor Average Outflow Rate Outflow Volume Required StorageVolume Vi=(Q.,'T'60) m= 0.5(1 + Tc/T) 0.v= m*Q.ut V.=Qe *T *60 V,=V,-Vo min in/hr Cfs t3 C s ft 3 ft 3 5 9.95 8.35 2,504 1.00 0.42 125 2,379 10 7.72 6.48 3,885 _ 0.86 _ 1 0.36 215 3,670 15 6.52 5.47 4,922 0.74 0.31 277 4,645 20 5.60 4.70 5,636 0.68 0.28 339 5,297 25 4.98 4.18 6,265 0.64 0.27 402 5,864 30 4.52 3.79 6,824 0.62 0.26 464 6,360 35 4.08 3.42 7,186 0.60 0.25 526 6,660 40 3.74 3.14 7,529 0.59 0.25 589 6,940 45 3.46 2.90 7,836 0.58 0.24 651 7,185 50 3.23 1 2.71 8,127 0.57 0.24 713 7,414 55 3.03 2.54 8,387 0.57 0.23 775 7,611 60 2.86 2.40 8,636 0.56 0.23 838 7,798 70 2.59 2.17 9,124 0.55 0.23 962 8,162 80 2.39 2.00 9,622 0.55 0.23 1,087 8,535 90 2.23 1.87 10,100 0.54 0.22 1,211 8,889 100 2.08 1.74 10,468 0.54 0.22 1,336 9,132 110 1.96 1.64 10,850 0.53 0.22 1,460 9,390 _ 120 1 1.83 1 1.53 11,051 0.53 1 0.22 1 1,585 9,466 Max Volume, ft' = 9,466 > a x V o o � 4 ` C L � r O Zw � � 2 M 01 O O U x N Q. O C 6 Oo w `o c h m N j a — .-_ to u 13 C a C CO N y x Y f/1 If1 Ol O dN_ 3 0 0 O g N V 3 C CO CY � c j y CJ w � a � i .i v � c 3 o 00W o u v LKr-� rev m Q1 0 w � � w c � w o N N C C N u M M x N CD � 'OC ry Ol 7 O ro ro c a u a o C N Y p m la vt C� C Y O C ° 3 ¢ m° C N N Q O U L •y LE W Nin m M -+ ry `aCT co m M c 3 o I 1 1 1 1 1 7 1 APPENDIX C 1 Hydraulic Analyses 1 1 1 1 1 1 1 1 ' The Square Weir Capacity St _ UNITED CIVIL Fort Collins. CO ��\ Design Group 1 Outlet Structure ID: Existing Inlet at Basin 81 Governing Equation: The trapezoidal weir is a broad -crested weir governed by the follaMng equation: Q = C. I L + 0.8 H tan ( 0 I H 1 where 0 = discharge (cfs) L l )] where C„ - weir coefficient where L = crest length (it) where H = head on weir (A) where b = 1.5 For 4:1 side slopes, 6 - 151.9276" so that tan (e/2) - 4 Parameters: i op or weir rieva ion tn) = ouiz.ai Crest Elevation (ft) = 5012.63 Length of Weir (ft) = 10 Weir Coefficient = 2.60 ' Depth vs. Flow: Depth Above Crest (ft) Elevation (ft) Outlet Structure Weir Discharge (cfs) 0.00 5012.31 0 ' 0.10 5012.41 1 0.20 5012.51 2 0.30 5012.61 5 ' 0.32 5012.63 5.19 E- Flowrate at Existing 0.40 5012.71 7 Overflow Elevation 0.50 5012.81 11 ' 0.65 5012.96 16 0.75 5013.06 21 0.85 5013.16 26 0.95 5013.26 31 ' 1.05 5013.36 37 1.09 5013.40 40 Calculations by: KRB ' Date: 121612013 C:IUnited CivillDropboxlProjectslU13011-SquorelOrainogelHydroulicslTropezoidal-Weir(outlet sizing).xls 11 CJ C The Square Weir Capacity UNITED CIVIL Fort Collins, CO f'�\ Design Group Outlet Structure ID: Ultimate Pond Outlet B1 Governing Equation: The trapezoidal weir is a broad -crested weir governed by the following equation: Q = C. L + 0.8 H tan I 0 IH 6 • where 0 = discharge (ats) L ` J • where C„ = wea coel6cient 'where L - crest length (re) where H = head on weir (ft) where b = 1.5 For 4:1 side slopes, 6 = 151.92761 so that tan (0/2) = 4 Parameters: 1 op or weir elevauon trr) = outz.au Crest Elevation (ft) = 5012.63 Length of Weir (ft) = 17.17 Weir Coefficient = 2.60 L �I_JH -�8 ' Depth vs. Flow: Depth Above Crest (ft) Elevation (ft) Outlet Structure Weir Discharge (cfs) 0.00 5012.30 0 ' 0.10 5012.40 1 0.20 5012.50 4 0.33 5012.63 8.98 E- Flowrate at ' 0.40 5012.70 12 Proposed Overflow 0.50 5012.80 17 Elevation 0.60 5012.90 23 ' 0.70 5013.00 30 0.80 5013.10 37 0.90 5013.20 45 1.00 5013.30 53 ' 1.10 5013.40 62 1.20 5013.50 72 1 Calculations by: KRB ' Date:121612013"United OvillDropboxtProjectstU13011-SquarelDrainagelHydroulicslTrapezoidal-Weir(outlet sizing).xls APPENDIX D City of Fort Collins Forms 1 1 1 1 1 1 I 1 I [1 The Square - Phase 1 Erosion Control Surety Cost Estimate Project Number: U13012 Location: Fort Collins, CO Date: February 5, 2014 Total Acres: 4.65 Estimated Unit Total EROSION CONTROL MEASURE Units Quantity Price Price Inlet Protection each 5 $100.00 $500.00 Silt Fencing L.F. 135 $1.25 $168.75 Rock Socks L.F. 20 $1.75 $35.00 Concrete Washout Area each 1 $200.00 $200.00 Vegetate Landscaped Areas acre 2.00 $1,000.00 $2,000.00 TOTAL = $2,903.75 AMOUNT OF SECURITY = 1.5 x $2,903.75 = TOTAL = $4,355.63 -OR- COST TO VEGETATE: TOTAL ACRES x ($1000/acre) x 1.5 = TOTAL = $6,975.00 (WHICHEVER IS GREATER) REQUIRED AMOUNT OF SECURITY NOTE: Total Acres' represents total dis area 1 QLLhtltee Cv1N)mpbekPmie XU13e11Square0Mhle9e\U1301I—E=ia Es-Estlmate.As 1 1 [1 STANDARD OPERATING PROCEDURES (SOPS) A. Purpose In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential. Maintenance includes both routinely scheduled activities, as well as non -routine repairs that may be required after large storms, or as a result of other unforeseen problems. Standard Operating Procedures should clearly identify BMP maintenance responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP. Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either publicly or privately. For this project, the privately owned BMPs shown in Section B below are to be maintained by the property owner or property manager. B. Site -Specific SOPS The following stormwater facilities contained within The Square are subject to SOP requirements: - Bioretention Pond The location of said facilities can be found on the Utility Plans for The Square. Inspection and maintenance procedure and frequencies, specific maintenance requirements and activities, as well as BMP-specific constraints and considerations shall follow the guidelines outlined in Volume 3 of the Urban Drainage and Flood Control District ' (UDFCD) Urban Storm Drainage Criteria Manual for the Bioretention. In addition, the pea gravel forebay will need to be cleaned and replaced with clean pea gravel when sediment accumulates in this area. It is anticipated that this may need to be done every one to two ' years to function properly as the primary interceptor of sediment entering the pond. SOP Maintenance Summary Table Stormwater Facility / Ownership / BMP Responsibility Maintenance Reference Follow applicable guidelines for Bioretention Pond Private Bioretention within UDFCD. ' The complete UDFCD BMP maintenance references listed above can be found in Chapter ' 6 of Volume 3. Applicable excerpts for 'Routine' maintenance requirements for the BMP can be found on the following page. Additionally, it is strongly recommended that the Guidelines for Use of Pesticides, Herbicides and Fertilizers (UDFCD Fact Sheet S-8), and 1 the Landscape Maintenance procedures (UDFCD Fact Sheet S-9) be followed, not just within the drainage facilities themselves, but for the entire development. ' Bioretention Pond Routine Maintenance Table (Summary from Chapter 6 of UDFCD) 1 r Required Action Maintenance Objective Frequency of Action Occasional mowing of grasses and weed Lawn mowing and remoxal to limit unwanted vegetation. Routine —Depending on aesthetic vegetative care Maintain irrigated turf grass as 2 to 4 inches requirements. tall and nonirrigated native turf grasses at 4 to 6 inches. Remove debris and litter from detention area to minimize clogging of the sand media. Routine — Including just before annual Debris and Litter Remove debris and litter from the pond area storm seasons (that is, April and May), remo�l and outlet orifice plate to minimize clogging. end of storm season after leaves have Remove debris and litter from curb channel fallen, and following significant rainfall and sidewalk chase outlets adjacent to pond events. if applicable to minimize clogging. The bioretention sand media and landscaping Every 5 to 10 years, depending on Sand Media and layer will clog with time. This layer will need infiltration rates needed to drain the Landscaping to be removed and replaced, along with all WOCV in 12-hours or less. May need to removal and turf and other vegetation growing on the be performed more frequently if replacement surface, to rehabilitate infiltration rates. exfiltration rates are too low to achieve this goal. Inspect detention area to determine if the sand media is allowing acceptable Infiltration. Routine — Bi-annual inspection of Inspections If standing water persists for more than 24 hydraulic performance. hours after storm runoff has ceased, clogging should be further investigated and remedied. r APPENDIX E ' References r I j d 5 A 6 A ■ `�•¢ A �� A d Y pT J O m � u E E 'd0 Y N N Y N p C b C C m ym C 'N N y Y •C C N$ T G 'a s Na 2d U U Pt g88 � c s� a e�� u 9�tt e p 6 6 4 Q 6 0� g 6 6 6 Ul Uf VI 3 3 Q O C LL e VI (� N li li I I I a o a e Q �o a n m N ZZ O e f L O q L OC ; o e 3 p > m L S N 9 O O� N m N Q O M N 3 Y V q i Q Cl G yY y Y 3 : ,� O✓ r� .n F pW cc F `o L' rg o d y q yid yu d V N e9 09I G N N q tlI U V V I..I U U a q> JY N pOp L C L N ; C .G o TO a u'Q 9 Y � e c a SP °u Jos O t Q V 3e .2 a s =�d EjT Q• R N R Y C O Y Q Q aq Qq � 9 F C S q q a i N Vu Yli $L ON.P 90 F C O 1.1 9 9 e 9 e L e g a �u E�� way' N v S y v 33 E' YLL O g✓ Y r G G9 uV $$y L L"Y C �p'p� n �p q y tJ q .s UI P N O m g e N n e n n m pvp ,Me 8%3 e> n F �' l7g U N a e E. APPENDIX F Plans and Maps C a I nuKoc I w I n nvnv SCALE: 1'=500' A 0 0 NOTES SMlea]uazweu5n unouruoAaucuo wan We3rrA meaxAzuneunreoemwoem Meer IIORW.IYnI.V4LVl[m M[WCQA. MOp,ml WLL Maauucaewlxanxsnon ezuren YIIYtt 4Vf N489M1%!1 WY,OrKeTWOIISnIFd wIA BEpUMH]0. MCM'IR.SCIIM,6WLLBF aawxnarouuruvmm mrumlti<lun Aa+.m ww m enr ranrAe]w m,xlm aa]er W eIn uunoru > MmrAsmurnae zesnouminrnrlolnw5mur WveuwaroAzaeasDD»rEPrar. MwAoSr cxuA,lore.rD so,ula uroeaue ouDPw ae taro ou5ua alo zanxmx e,a eum w M urewre elre MM901R`MGMnlM W011NLR OVMI w Awuz. Meewaumaxu,ammeevosmer M tea e W ze z n cuwD ua muoeP LEGEND X eua aaD,wrax MKYC a]n ,� NMmeii. aeeaozw. xSwuGNup ■EMNON eraAeaebwr Aoeewxroxr � rlm owed e.e� W4 ue, az alm eW ♦1 4 1L e61 L.A '35 el el esx aa3 az P]e ea cm u u zn rsx Pn PSe Mn o.6E ]als on am On SM OAS aI3 ]AS a ai] 035 554 0.55 613 0.ai ]lp re0e p pE lm D.35 IYJS u 3L mo 04 Im u az m m on Im eeo u n u] Pax an ,m Ssu u u an 1m eaz el itl 0.]S r au Pn Pre Pae OSI O.le 0.5] 011 a33 !AS OS3 0.15 PN Sp °im raex u.A nx ou Im Iwae City of Port Collins, Colorado UTHXrY PLAN APPROVAL APPROVED: O4 bdmer ate CHECKED BY: Teter t Pr4nlu UUtlry a4 ',, CHECKED BY: suu w Utwp De4 CHECKEDBY: Pub 1 PeunBm Vela CHECKED BY: ife.t PodCNr BetO CHECKED BY: Bib 74S�N UNITED CIVIL Design Croup Q a Lu CQ z H LOTC C6.00 10 s 15 s m acne TmC K D z D a sa ,m L� au�: r-an GRADING NOTES . Emnro LR9vEDnaw w9wE9woruucAw rMrAreun]nEeMOX�.avux PRIEY WYO AM6ER+9Ed WYE9i0E 0]PVGMIlNE60RA6 MFAROCN 11E0E tlUYN84. 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