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Drainage Reports - 05/18/2022
May 10, 2022 FINAL DRAINAGE REPORT Bucking Horse Park Fort Collins, Colorado Prepared for: City of Fort Collins Attn: Matt Schaefer PO Box 580 Fort Collins, Colorado 80522 Prepared by: 200 South College Avenue, Suite 10 Fort Collins, Colorado 80524 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 1748-002 This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is necessary, we recommend double-sided printing. May 10, 2022 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage Report for Bucking Horse Park Dear Staff: Northern Engineering is pleased to submit this Drainage and Erosion Control Report for your review. This report accompanies the Basic Development Review (BDR) submittal for the proposed Bucking Horse Park development. This report was prepared in accordance with Fort Collins Stormwater Criteria Manual (FCSCM) and serves to document the stormwater impacts associated with the proposed project. We understand that review by the city is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, Northern Engineering Services, Inc. Blaine Mathisen, PE Project Engineer Bucking Horse Park Final Drainage Report TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ............................................................... 1 A. Location ............................................................................................................................................. 1 B. Description of Property ..................................................................................................................... 2 C. Floodplain.......................................................................................................................................... 3 II. DRAINAGE BASIN AND SUB-BASIN ........................................................................ 5 A. Major Basin Description .................................................................................................................... 5 B. Sub-Basin Description ....................................................................................................................... 5 III. DRAINAGE DESIGN CRITERIA ................................................................................. 5 A. Regulations........................................................................................................................................ 5 B. Original provisions and previous studies .......................................................................................... 5 C. Updated SWMM Model .................................................................................................................... 6 D. Update To Existing Drainage Channel ............................................................................................... 6 E. Hydrological Criteria ......................................................................................................................... 6 F. Hydraulic Criteria .............................................................................................................................. 7 G. Modifications of Criteria ................................................................................................................... 7 H. Storm Management Strategy ............................................................................................................ 7 IV. DRAINAGE FACILITY DESIGN ................................................................................. 8 A. General Concept ............................................................................................................................... 8 B. Specific Details .................................................................................................................................. 8 C. LID Summary ................................................................................................................................... 10 V. CONCLUSIONS ..................................................................................................... 11 A. Compliance with Standards ............................................................................................................ 11 VI. REFERENCES ........................................................................................................ 12 VII. EROSION CONTROL REPORT ................................................................................ 20 APPENDICES APPENDIX A – Hydrologic Computations APPENDIX B– Updated SWMM Model for Bucking Horse Second Filing APPENDIX C– Hydraulic Computations APPENDIX D– LID Calculations and Variance Request APPENDIX E– Erosion Control Report and USDA Soils Report APPENDIX F– Standard Operating Procedures (SOP) LIST OF FIGURES Figure 1 – Aerial Photograph ................................................................................................ 2 Figure 2 – Proposed Site Plan ............................................................................................... 3 Figure 3 – Existing Floodplain Mapping .................................................................................. 4 MAP POCKET Bucking Horse Filing 2 Drainage Exhibit w/ Associated Rational Calcs Proposed Drainage Exhibit Bucking Horse Park Bucking Horse Park Drainage Report 1 I. GENERAL LOCATION AND DESCRIPTION Vicinity Map A. LOCATION 1. Bucking Horse Park is located in the Southeast ¼ of Section 20, Township 7 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. It is generally bound to the northwest by single family homes, the east\northeast by the Great Western Railroad, the southwest by Miles Horse Avenue, and the southeast by a daycare facility and Detention Pond 215. 2. An existing channel runs along the northeast boundary of the site parallel to the railroad right-of-way, conveying stormwater from the surrounding area to Detention Pond 215. Additional information regarding this drainage channel can be found in subsequent sections. 3. Aside from the large channel that borders the site, offsite flows through the project area are minimal. Refer to the Drainage Exhibit for offsite basin locations. Bucking Horse Park Bucking Horse Park Drainage Report 2 B. DESCRIPTION OF PROPERTY 1. The project area is roughly 7.54± acres. Figure 1 – Aerial Photograph 2. The subject property is an undeveloped parcel with native ground cover. The existing ground generally slopes at moderate grades (1%–3%) from the southwest to the northeast, towards the channel that borders the east side of the site. There is a soil stockpile located on the southeast corner of the site. 3. A soils report (Project No. FC09343-125) was completed by CTL Thompson, Inc. on May 8, 2020. The report contains the results of a complete geotechnical subsurface exploration as well as pertinent geotechnical recommendations. 4. The proposed project site plan is composed of one small restroom building, numerous park amenities, and open spaces. Please see Figure 2, on the following page, showing the proposed site plan. 5. This project does not include the future trail project that is proposed to run along the north side of the drainage channel. Additionally, this project is proposing to remove a constricting 36” culvert and berm along this drainage channel to alleviate backwater issues caused by this undersized infrastructure. If the future trail project proposes any alterations to this drainage channel, including any abutments, new berm with culverts, or erosion control associated with the installation of a pedestrian bridge, shall need to meet the FCSCM. Bucking Horse Park Bucking Horse Park Drainage Report 3 Figure 2 – Proposed Site Plan C. FLOODPLAIN 1. The Bucking Horse Park is currently located within a FEMA Moderate Risk Flood Hazard Area for the Cache la Poudre River. This area is designated as Zone X on Firm Panel 0992G, Revised May 2, 2012. Therefore, it falls outside of the regulated 100-year floodway and floodplain fringe. (Figure 3 – Area Floodplain Mapping) Bucking Horse Park Bucking Horse Park Drainage Report 4 Figure 3 – Existing Floodplain Mapping It should be noted an updated floodplain map is being prepared by consultants for the Colorado Water Conservation Board (CWCB) in coordination with the Federal Emergency Management Agency (FEMA). This remapping is called RiskMAP. The updated mapping will entirely remove the project site from any floodplain designations. Therefore, the project site is not required to conform with the provisions of Chapter 10. Figure 4 – Updated RiskMAP Floodplain Mapping Bucking Horse Park Bucking Horse Park Drainage Report 5 II. DRAINAGE BASIN AND SUB-BASIN A. MAJOR BASIN DESCRIPTION The Bucking Horse Park is a part of the Foothills Drainage Basin. The Foothills Basin is centrally located in Fort Collins and covers about 3,750 acres generally between Taft Hill and Ziegler Road and Horsetooth Road and Drake Road. The basin is mostly developed with commercial development and mixed-use. The basin drains from west to east through open channels or storm sewer systems to the Fossil Creek Reservoir Inlet Ditch (FCRID). B. SUB-BASIN DESCRIPTION The subject property is located within the Bucking Horse Filing Two development and has historically drained overland from southwest to northeast where runoff is detained and treated in Detention Pond 215. Bucking Horse Park drains to Detention Pond 215. This pond currently provides approximately 32.4 ac-ft of storage volume. The pond also provides water quality as a 40- hour dry extended detention basin (EDB). The projects area was most previously modeled as part of the SWMM model for Bucking Horse Filing Two. This model has been updated to reflect the constructed conditions within the study area and to document the final required detention volume for Pond 215 and the peak flow for the channel running along the east boundary of the site. (See Appendix B). A description of the project drainage patterns follows in Section IV.B. below. III. DRAINAGE DESIGN CRITERIA A. REGULATIONS Bucking Horse Park does not need to provide detention or water quality on site because that is being taken care at the regional Pond 215 near the northeast corner of the site. However, Bucking Horse Park is responsible for meeting LID requirements. Bucking Horse Park has an impervious value of 13% and the previous Bucking Horse Filing 2 assumed the park to have an impervious value of 8.4%. The park is associated with basin F1 in Bucking Horse Filing 2’s drainage report. This minor or nominal increase has inconsequential impacts to downstream infrastructure including Pond 215. Refer to Map Pocket at the end of this report for additional information. Bucking Horse Park submitted a variance request asking for alternative compliance to meet LID requirements using the MHFD standards for vegetative buffers instead of FCSCM standards. Specifically, the percent slopes of the grass buffers as well as the type of native soil being utilized. Please refer to variance request and subsequent LID section for additional information. B. ORIGINAL PROVISIONS AND PREVIOUS STUDIES Large portions of the Bucking Horse neighborhood, including portions of Sidehill Filings 1 & 2 as well as Bucking Horse Filings 1, 2, 3 and 5 drain to Pond 215. Pond 215 is found near the northeast corner of the Bucking Horse Park project site. Due to the size of the drainage basin, a SWMM model was developed with the original filings to document the overall drainage patterns in the study area. The original SWMM model was developed by JR Engineering as part of the Sidehill development utilizing the outdated software of MODSWMM. The SWMM model was subsequently updated with Bucking Horse First and Second Filings also using MODSWMM. Bucking Horse Park Bucking Horse Park Drainage Report 6 C. UPDATED SWMM MODEL Due to the number of discrepancies between the original SWMM, the subsequent Bucking Horse Filing SWMM models, and the Bucking Horse Park SWMM model Northern Engineering will be revamping the entire SWMM model to be consistent with current FCSCM standards. Northern Engineering will be issuing this updated SWMM model with the Bucking Horse Trail project and the update will be apart of “Bucking Horse Trail Drainage Memorandum”. D. UPDATE TO EXISTING DRAINAGE CHANNEL The existing drainage channel that runs adjacent to the park has an existing 36” culvert and associated berm at the downstream end right next to Pond 215. This existing 36” culvert is severely undersized to handle the 341 cfs flowing in the drainage channel which causes the drainage channel to act as an attenuation pond. In the existing condition during the 100- year event the tailwater backs up to an elevation of 4889.96, as shown in the HY-8 analysis in Appendix C. However, the top of the drainage channel is 4890.00 which means that this drainage channel does not meet the criteria set forth in the FCSCM Chapter 9 Section 5.1 which states that drainage channels with a flow greater than 100 cfs must have a minimum of 1’ of freeboard. To bring this drainage channel into compliance with current FCSCM standards the Bucking Horse Park will be removing this existing 36” culvert and associated berm to alleviate this choke point. By removing this constriction point the drainage channel will now be an extension of Pond 215 while still safely conveying the 341 cfs downstream. During the 100-year event the WSEL is 4887.30, see updated stage storage in Appendix B for calculation. Elevation 4887.30 is shown on the grading plan of the Utility Plans to show where the transition of detention to normal flow depth within the channel occurs. Lastly, the drainage channel was modeled at section A-A, see grading and drainage sheets for further clarification on location, for normal depth flow at 341 cfs. Modeling the channel at normal depth flow shows a depth of 2.83’. The total depth within the drainage channel is roughly 4.30’ feet. Therefore, this channel does meet FCSCM Chapter 9 Section 5.1 criteria if the constrictive 36” culvert and berm are removed. There is an anticipated future trails project that may look to put this berm back and it is up to that project to adequately size proper infrastructure at their crossing to handle 341 cfs that will not cause tailwater to backup into the channel and recreate this existing issue. The future trail project must meet all FCSCM requirements. As mentioned in Section III.C an updated SWMM model, which will impact swale calculations, is going to be issued with “Bucking Horse Trail Drainage Memorandum”. E. HYDROLOGICAL CRITERIA 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure 3.4-1 of the FCSCM, serve as the source for all hydrologic computations associated with the proposed development. Tabulated data contained in Table 3.4-1 was utilized for Rational Method runoff calculations. 2. The Rational Method was employed to compute localized stormwater runoff utilizing coefficients contained in Tables 3.2-1 and 3.2-2 of the FCSCM. 3. The previously approved SWMM model that was approved with Bucking Horse Filing Two was updated to analyze the adjacent drainage channel that runs parallel to the Bucking Horse Park Bucking Horse Park Drainage Report 7 project site. 4. Two separate design storms were utilized to address distinct drainage scenarios. The first event analyzed is the “Minor” or “Initial” Storm, which has a two-year recurrence interval. The second event considered is the “Major” Storm, which has a 100-year recurrence interval. 5. No other assumptions or calculation methods were used with this development that are not referenced by the current City of Fort Collins Stormwater Criteria Man. F. HYDRAULIC CRITERIA 1. As previously noted, the subject property maintains historical drainage patterns. 2. All drainage facilities proposed with the project are designed in accordance with the criteria outlined in the FCSCM and/or Mile High Flood District (UDFCD) Urban Storm Drainage Criteria Manual. 3. As previously mentioned, this project is not subject to any floodplain regulations. G. MODIFICATIONS OF CRITERIA A variance request has been submitted with Bucking Horse Park. The variance is requesting that LID credits be given for the informal grass buffers that meet MHFD standards but not FCSCM standards for LID credits. Please refer to the subsequent LID section for additional information as well as Appendix D. H. STORM MANAGEMENT STRATEGY The overall stormwater management strategy employed with the Bucking Horse Park development utilizes the "Four Step Process" to minimize adverse impacts of urbanization on receiving waters. The following describes how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices. Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the current use to a park. · Providing large swaths of vegetated land to promote natural infiltration and filtration. · Routing runoff generated from the basketball court, ping-pong court, and some sidewalk through a rain garden in the northeast corner of the site. · No parking lot or vehicular access paths have been proposed to help minimize the amount of impervious area. Step 2 – Implement Best Management Practices (BMPs) that provide a Water Quality Capture Volume (WQCV) with slow release. The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring storm events; however, development still generates additional stormwater runoff beyond historical conditions. The primary water quality treatment and volume control will occur in a detention pond previously calculated in the Bucking Horse Second Filing by Northern Engineering, dated July 2012. However, the Bucking Horse Park is also proposing to install a rain garden at the northeast corner of the project site. Additionally, Bucking Horse Park Bucking Horse Park Bucking Horse Park Drainage Report 8 has a calculated impervious area of 13% with most of the impervious area being conveyed via overland flow over wide areas of vegetated land. This low percent impervious along with the large amount of open space will promote natural infiltration and filtration. Step 3 – Stabilize Drainageways. As stated in Section III.B there is a drainage channel that runs along the northeast project boundary. This drainage channel is being modified to adequately and safely convey the 341 cfs to Pond 215 by removing an existing constriction point caused by the existing 36” culvert and associated berm. The drainageway will be stabilized using erosion control blankets to get vegetation stabilized along the 4:1 slopes. Additionally, there is a 2’ concrete pan at the bottom of the drainage channel to convey nuisance flows to help prevent wetland development. Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments. However, localized trash bins with lids have been placed around the site to decrease the potential impacts of garbage making its way downstream. IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 1. The main objectives of the project drainage design is to maintain existing drainage patterns and improve an overtopping and tailwater condition within the existing drainage channel to ensure no adverse impacts to any adjacent properties and downstream infrastructure occurs. 2. Detention and traditional water quality for Bucking Horse Park are provided in Detention Pond 215. 3. The site was broken into twelve (12) onsite basins and one (1) offsite basin for design purposes. Anticipated drainage patterns for proposed drainage basins are described below. B. SPECIFIC DETAILS Basin 1 Basin 1 is consisting of sidewalks, gravel, and open areas. This basin will convey flows via overland flow to a drainage channel that will route the runoff to a proposed 12” HDPE culvert. From the culvert the runoff will be conveyed to the existing drainage channel which will route the runoff to Detention Pond 215. Basin 2 Basin 2 conveys runoff from the crusher fines path and open field via overland flow. Runoff is then collected in a Nyloplast inlet and then conveyed via a storm drain to the existing drainage channel that runs along the northeast of the project site. Runoff from Basin 2 eventually makes it to Detention Pond 215. Basin 3 Basins 3 is associated with a planter bed, a small amount of concrete, and the bathrooms. Bucking Horse Park Bucking Horse Park Drainage Report 9 Runoff from Basin 3 is conveyed via overland flow, collected in a storm drain, and routed to the existing drainage channel that borders the project site along the northeast boundary. Runoff generated from Basin 3 eventually makes it to Detention Pond 215. Basin 4 Basin 4 consists of a large amount of vegetation (sod), crusher fine path, and concrete sidewalks. Just like Basins 2 & 3 runoff is collected in a storm drain and eventually makes its way to the existing drainage channel. Basin 4 eventually makes it to Detention Pond 215. Basin 5 Basin 5 consists of a large amount of vegetation (sod), crusher fine path, and concrete sidewalks. Just like Basins 2, 3, and 4 runoff is collected in a storm drain and eventually makes its way to the existing drainage channel. Basin 5 eventually makes it to Detention Pond 215. Basin 6 Basin 6 consists of a large amount of vegetation (sod), crusher fine path, and concrete sidewalks. Just like Basins 2, 3, 4, and 5 runoff is collected in a storm drain and eventually makes its way to the existing drainage channel. Basin 6 eventually makes it to Detention Pond 215. Basin 7 Basin 7 encompasses the playground area and some concrete sidewalks. Runoff from Basin 7 is conveyed to the existing drainage channel that runs parallel to the project site via overland flow. Basin 7 eventually makes it to Detention Pond 215. Basin 8 Basin 8 encompasses the hammock garden and some concrete sidewalks. Runoff from Basin 8 is conveyed to the existing drainage channel that runs parallel to the project site via overland flow. Basin 8 eventually makes it to Detention Pond 215. Basin 9 Basin 9 encompasses some landscaping and concrete sidewalks. Runoff from Basin 9 is conveyed to an existing Type R inlet in Mile House Avenue. From there the runoff enters an existing 36” RCP that conveys the runoff to the existing drainage channel that runs parallel to the project site. Basin 9 eventually makes it to Detention Pond 215. Basin 10 Basin 10 encompasses some landscaping and concrete sidewalks. Runoff from Basin 10 is conveyed to an existing Type R inlet in Mile House Avenue. From there the runoff enters an existing 36” RCP that conveys the runoff directly to Detention Pond 215. Basin 11 Basin 11 encompasses the basketball court, ping-pong court, concrete sidewalk, and some crusher fines path. Runoff from Basin 11 is conveyed via overland flow and concentrated flow (storm drain) to a rain garden near the northeast corner of the project site. The rain garden will promote infiltration and filtration for the water quality storm event. From the rain garden the runoff will be conveyed directly to Detention Pond 215 via HDPE piping. Bucking Horse Park Bucking Horse Park Drainage Report 10 Basin 12 Basin 12 consists of sidewalk and vegetated open space. Runoff is conveyed via a swlae to an open field where it then sheet flows to the northeast and enters Detention Pond 215. Basin OS1 Basin OS1 is the only offsite basin that gets routed through the project site. Basin OS1 is associated with the back of lots that are adjacent to the northwest project boundary. Runoff is routed to Basin 1 via overland flow. From there the runoff is conveyed just like Basin 1 and it eventually makes its way to Detention Pond 215. C. LID SUMMARY 1. Bucking Horse Park is submitting a variance request to ask for LID credits informal grass buffers. The criteria in question are the requirements set forth Chapter 7 Section 6.7 of the FCSCM. Per Section 6.7 “Vegetated Buffers” need to have a max cross slope no greater than 5% and have soil types A or B for vegetated buffers to count as LID credit. 2. Bucking Horse Park is providing a rain garden to treat an area of the park that will see the highest runoff rate and that is the area associated with the basketball court, ping- pong court, and associated sidewalks (Basin 12). 3. Bucking Horse Park is not providing on-site parking and is considered a “Low Intense Use” which drastically reduces the migration of pollutants such as oil, magnesium chloride, gas, etc. 4. Bucking Horse Park is utilizing the same procedure that Trail Head Park utilized to get LID credits for informal grass buffers. Basin ID LID Treatment Impervious Area (i%>=90%)(sq. ft.) Impervious Area Treated By LID (sq. ft.) Percent of Impervious Treated by LID 1 Grass Buffer 2957 2586 87% 4 Grass Buffer 3688 3688 100% 5 Grass Buffer 583 583 100% 6 Grass Buffer 1923 866 45% 11 Rain Garden 6781 6781 100% 12 Grass Buffer 3127 3127 100% Total Site 25492 17631 69% Table 1 LID SUMMARY 5. Please refer to the formal variance request within Appendix D for additional information. 6. An LID Exhibit can be found in Appendix D. 7. The rain garden was sized using Mile High Flood Control District criteria and sizing spreadsheets. These calculations can be found in Appendix D. 8. The grass buffers were sized using Mile High Flood District criteria and sizing spreadsheets. These calculations can be found in Appendix D. Bucking Horse Park Bucking Horse Park Drainage Report 11 V. CONCLUSIONS A. COMPLIANCE WITH STANDARDS 1. The drainage design proposed with the proposed project complies with the City of Fort Collins Stormwater Criteria Manual, as well as previous drainage studies from which downstream stormwater infrastructure was constructed. 2. The drainage design proposed with this project complies with requirements for the Foothills Basin. 3. The drainage plan and stormwater management measures proposed with the proposed development are compliant with all applicable State and Federal regulations governing stormwater discharge. 4. Bucking Horse Park is utilizing an alternative method to meet LID requirements. Bucking Horse Park Bucking Horse Park Drainage Report 12 VI. REFERENCES 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007. 4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Mile High Flood Control District, Denver, Colorado, Updated January 2016. 6. Geotechnical Investigation Proposed Improvements Bucking Horse Park, Fort Collins, Colorado, May 8, 2020, CLT Thompson. (Project No. FC09343-125) 7. Final Drainage Report Bucking Horse Filing One, Dated September 19, 2012, by Northern Engineering. 8. Final Drainage Report Bucking Horse Filing Two, Dated December 17, 2012, by Northern Engineering APPENDIX A Hydrologic Computations Runoff Coefficient1 Percent Impervious1 Project: Location: 0.95 100%Calc. By: 0.95 90%Date: 0.50 40% 0.55 50% 0.20 2% 0.20 2% Basin ID Basin Area (sq.ft.) Basin Area (acres) Asphalt, Concrete (acres)Rooftop (acres) Gravel (acres) Residential: Low Density (acres) Undeveloped: Greenbelts, Agriculture (acres) Lawns, Clayey Soil, Flat Slope < 2% (acres) Percent Impervious C2*Cf Cf = 1.00 C5*Cf Cf = 1.00 C10*Cf Cf = 1.00 C100*Cf Cf = 1.25 1 25,068 0.58 0.07 0.00 0.01 0.00 0.00 0.50 14% 0.29 0.29 0.29 0.37 2 16,494 0.38 0.01 0.00 0.04 0.00 0.00 0.33 9% 0.26 0.26 0.26 0.32 3 7,129 0.16 0.01 0.01 0.00 0.00 0.00 0.14 15% 0.31 0.31 0.31 0.38 4 34,412 0.79 0.08 0.00 0.05 0.00 0.00 0.66 15% 0.30 0.30 0.30 0.37 5 17,315 0.40 0.01 0.00 0.02 0.00 0.00 0.36 8% 0.24 0.24 0.24 0.30 6 41,579 0.95 0.04 0.00 0.04 0.00 0.00 0.87 8% 0.25 0.25 0.25 0.31 7 18,789 0.43 0.04 0.00 0.00 0.00 0.00 0.38 13% 0.28 0.28 0.28 0.35 8 24,295 0.56 0.04 0.00 0.11 0.00 0.00 0.41 16% 0.31 0.31 0.31 0.39 9 5,918 0.14 0.02 0.00 0.00 0.00 0.00 0.12 16% 0.31 0.31 0.31 0.38 10 16,797 0.39 0.01 0.00 0.00 0.00 0.00 0.38 4% 0.21 0.21 0.21 0.27 11 16,201 0.37 0.16 0.00 0.02 0.00 0.00 0.20 45% 0.53 0.53 0.53 0.66 12 43,157 0.99 0.07 0.00 0.00 0.00 0.00 0.92 9% 0.25 0.25 0.25 0.32 OS1 28,326 0.65 0.00 0.07 0.00 0.00 0.00 0.58 12% 0.29 0.29 0.29 0.36 1 to 12 (Onsite) 267,154 6.13 0.57 0.01 0.29 0.00 0.00 4.34 13% 0.26 0.26 0.26 0.32 2 to 6 (Storm A) 116,929 2.68 0.16 0.01 0.15 0.00 0.00 2.36 11% 0.27 0.27 0.27 0.33 1 + OS1 53,394 1.23 0.07 0.07 0.01 0.00 0.00 1.08 13% 0.29 0.29 0.29 0.36 DEVELOPED RUNOFF COEFFICIENT CALCULATIONS Asphalt, Concrete Rooftop Gravel Residential: Low Density Streets, Parking Lots, Roofs, Alleys, and Drives: Character of Surface:Bucking Horse Park Fort Collins B. Mathisen March 9, 2022 Lawns and Landscaping: Combined Basins: 2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins Stormwater Manual (FCSM). Lawns, Clayey Soil, Flat Slope < 2% USDA SOIL TYPE: D Undeveloped: Greenbelts, Agriculture Composite Runoff Coefficient2 1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM. Developed Basins: Notes: Page 1 of 16 Where: Length (ft) Elev Up Elev Down Slope (%) Ti 2-Yr (min) Ti 10-Yr (min) Ti 100-Yr (min) Length (ft) Elev Up Elev Down Slope (%)Surface n Flow Area3 (sq.ft.) WP3 (ft)R (ft)V (ft/s) Tt (min) Tc 2-Yr (min) Tc 100-Yr (min) 1 1 50 100.00 95.00 10.00%4.96 4.96 4.51 200 100.00 98.00 1.00% Swale (8:1)0.04 8.00 16.12 0.50 2.67 1.25 6.2 5.8 2 2 70 100.00 96.50 5.00%7.72 7.72 7.13 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 7.7 7.1 3 3 20 100.00 98.00 10.00%3.08 3.08 2.78 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 5.0 5.0 4 4 180 100.00 94.00 3.33%13.48 13.48 12.23 40 100.00 99.20 2.00% Swale (8:1)0.04 8.00 16.12 0.50 3.77 0.18 11.2 11.2 5 5 180 100.00 94.00 3.33%14.39 14.39 13.37 40 100.00 99.20 2.00% Swale (8:1)0.04 8.00 16.12 0.50 3.77 0.18 11.2 11.2 6 6 190 100.00 93.70 3.32%14.75 14.75 13.68 40 100.00 99.20 2.00% Swale (8:1)0.04 8.00 16.12 0.50 3.77 0.18 11.3 11.3 7 7 100 94.00 92.00 2.00%12.16 12.16 11.12 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 10.6 10.6 8 8 100 94.00 92.00 2.00%11.70 11.70 10.54 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 10.6 10.5 9 9 50 100.00 95.00 10.00%4.86 4.86 4.39 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 5.0 5.0 10 10 50 100.00 95.00 10.00%5.43 5.43 5.11 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 5.4 5.1 11 11 60 100.00 94.00 10.00%3.84 3.84 2.96 120 100.00 99.40 0.50% Swale (8:1)0.04 8.00 16.12 0.50 1.89 1.06 5.0 5.0 12 12 180 100.00 88.00 6.67%11.27 11.27 10.43 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 11.0 10.4 os1 OS1 90 100.00 94.00 6.67%7.68 7.68 7.01 0 N/A N/A N/A Swale (8:1)0.04 8.00 16.12 N/A N/A 0.00 7.7 7.0 1 to 12 (Onsite)60 100.00 94.00 10.00%5.68 5.68 5.25 40 100.00 99.20 2.00% Swale (8:1)0.04 8.00 16.12 0.50 3.77 0.18 5.9 5.4 Storm A 2 to 6 (Storm A)60 100.00 94.00 10.00%5.61 5.61 5.16 40 100.00 99.20 2.00% Swale (8:1)0.04 8.00 16.12 0.50 3.77 0.18 5.8 5.3 1 + os1 1 + OS1 50 100.00 95.00 10.00%4.98 4.98 4.54 200 100.00 98.00 1.00% Swale (8:1)0.04 8.00 16.12 0.50 2.67 1.25 6.2 5.8 Notes S = Longitudinal Slope, feet/feet R = Hydraulic Radius (feet) n = Roughness Coefficient V = Velocity (ft/sec)WP = Wetted Perimeter (ft) DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Maximum Tc:Overland Flow, Time of Concentration: Channelized Flow, Velocity:Channelized Flow, Time of Concentration: Bucking Horse Park Fort Collins B. Mathisen March 9, 2022 COMBINED BASINS Design Point Basin ID Overland Flow Channelized Flow Time of Developed Basins: (Equation 3.3-2 per Fort Collins Stormwater Manual)𝑇 =1.87 1.1 − 𝐶 ∗ 𝐶𝑓𝐿 𝑆ଵ ଷൗ 𝑉 = 1.49 𝑛∗ 𝑅 ଶ/ଷ ∗𝑆(Equation 5-4 per Fort Collins Stormwater Manual) 𝑇𝑐 =𝐿 180 + 10 (Equation 3.3-5 per Fort Collins Stormwater Manual) 𝑇𝑡 =𝐿 𝑉 ∗ 60 (Equation 5-5 per Fort Collins 1) Add 4900 to all elevations. 2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min. 3) Assume a water depth of 6" and a typical curb and gutter per Larimer County Urban Street Standard Detail 701 for curb and gutter channelized flow. Assume a water depth of 1', fixed side Page 2 of 16 Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100 1 1 0.58 6.2 6.2 5.8 0.3 0.3 0.4 2.7 4.6 9.6 0.45 0.77 2.03 2 2 0.38 7.7 7.7 7.1 0.3 0.3 0.3 2.5 4.2 8.8 0.24 0.41 1.07 3 3 0.16 5.0 5.0 5.0 0.3 0.3 0.4 2.9 4.9 10.0 0.14 0.24 0.63 4 4 0.79 11.2 11.2 11.2 0.3 0.3 0.4 2.1 3.6 7.4 0.50 0.85 2.18 5 5 0.40 11.2 11.2 11.2 0.2 0.2 0.3 2.1 3.6 7.4 0.21 0.35 0.90 6 6 0.95 11.3 11.3 11.3 0.2 0.2 0.3 2.1 3.6 7.4 0.50 0.86 2.19 7 7 0.43 10.6 10.6 10.6 0.3 0.3 0.4 2.2 3.7 7.6 0.26 0.45 1.15 8 8 0.56 10.6 10.6 10.5 0.3 0.3 0.4 2.2 3.7 7.6 0.38 0.64 1.65 9 9 0.14 5.0 5.0 5.0 0.3 0.3 0.4 2.9 4.9 10.0 0.12 0.20 0.52 10 10 0.39 5.4 5.4 5.1 0.2 0.2 0.3 2.9 4.9 10.0 0.24 0.40 1.03 11 11 0.37 5.0 5.0 5.0 0.5 0.5 0.7 2.9 4.9 10.0 0.56 0.96 2.44 12 12 0.99 11.0 11.0 10.4 0.3 0.3 0.3 2.1 3.6 7.7 0.54 0.91 2.43 os1 OS1 0.65 7.7 7.7 7.0 0.3 0.3 0.4 2.5 4.2 8.8 0.46 0.78 2.04 1 to 12 (Onsite) 6.13 5.9 5.9 5.4 0.3 0.3 0.3 2.8 4.7 10.0 4.33 7.39 19.49 2 to 6 (Storm A) 2.68 5.8 5.8 5.3 0.3 0.3 0.3 2.8 4.7 10.0 1.97 3.37 8.89 1 + os1 1 + OS1 1.23 6.2 6.2 5.8 0.3 0.3 0.4 2.7 4.6 9.6 0.94 1.61 4.26 COMBINED BASINS DEVELOPED DIRECT RUNOFF COMPUTATIONS Intensity (in/hr)Flow (cfs) Bucking Horse Park B. Mathisen March 9, 2022 Design Point Basin Intensity, I, from Fig. 3.4.1 Fort Collins Stormwater Manual. Rational Equation: Q = CiA (Equation 6-1 per MHFD) Area (acres) Runoff CTc (Min) Date: Fort Collins Project: Location: Calc. By: Page 3 of 16 APPENDIX B Updated SWMM Model for Bucking Horse Second Filing Computation W D D X X X X D X D E D E D D D DDD D D D D D D LP D D D D R.T.U. R.T.U. R.T.U. UP MI L E S H O U S E A V E N U E NANCY G R A Y A V E N U E PALO M I N O D R I V E PALO M I N O C O U R T W A L K A L O O S A W A Y PALOMINO DRI V E WAL K A L O O S A W A Y M I L E S H O U S E A V E N U E DRAKE ROAD GR E A T W E S T E R N R A I L R O A D TRACT BFUTURE CITY PARK TRACT E HORSEAREA NANCY GRAY WETLAND TRACT ICOMMUNITYSUPPORTED AGRICULTURE X X X X X 420 SFCLASSROOM9 HALL11 1149 SFBARN12 6" 114 SFOFFICE15 115 SFOFFICE16 WOMENS17 MENS18 371 SFTRACTOR / E Q U I P . STORAGE19 COW MILKI N G 20 MILKING PR E P 21 JAN.22 MECH.23 OFFICEBUILDING 1 OFFICEBLDG 2 OFFICEBLDG 3 TR A C T A TRACT F TRAC T G T R A C T H TRACT D OUTLOT A OUTLOT D OUTLOT F OUTLOT EOUTLOT G OUTLOT H OFFICECOMPLEX NATIVE UPLANDHABITAT AREA/DETENTION POND TRACT CWORKINGFARM 101 102 103 105 108 109 100 107a 107b 104 DRAWN BY: ATC SCALE: 1" = 500' ISSUED: 10/19/2021 SWMM BASIN UPDATE SHEET NO: 1 BUCKING HORSE SECOND FILING 109 108 100 102 101 104 105 106 107a 107b 202 201 203 204 205 206 IN_215a IN_215b out002 out001 out4 5 out215 302 mh002 mh001 303 304 305 306 307 OUTFALL 001 002 4 18 215 FtCollins-100yr SWMM 5 Page 1 Elapsed Time (hours) 6543210 Vo l u m e ( f t 3 ) 900000.0 800000.0 700000.0 600000.0 500000.0 400000.0 300000.0 200000.0 100000.0 0.0 Node 215 Volume (ft3) SWMM 5 Page 1 Project Title Date: Project Number Calcs By: Client Pond Designation Invert Elevation Water Quality Volume 100-yr Detention Volume D = Depth between contours (ft.) A1 = Surface Area lower contour (ft2) A2 = Surface Area upper contour (ft2) 4882.00 272.65 0.27 24.54 24.54 0.0006 WQCV 0 4883.00 6507.32 1.00 2703.99 2728.53 0.0626 0.20 4884.00 37152.29 1.00 19736.10 22464.63 0.5157 0.40 4885.00 154446.09 1.00 89116.05 111580.68 2.5615 0.60 4886.00 314859.76 1.00 229941.79 341522.47 7.8403 0.80 4887.00 457175.34 1.00 383812.47 725334.94 16.6514 1.00 4888.00 495167.86 1.00 476045.24 1201380.18 27.5799 Total Vol 1.20 4889.00 195384.02 1.00 333865.03 1535245.22 35.2444 1.40 Elevation Depth Volume WQCV N/A N/A N/A 100-yr Detention 5.57 19.9800 Overall Detention 4887.30 5.57 19.9800 City of Fort Collins Bucking Horse Park March 27, 2022 1748-002 B. Mathisen Pond 215 4881.73 ft N/A 19.9800 ac-ft 19.9800 ac-ftTotal Pond Volume Pond 215 Volume Elevation (ft) Surface Area (ft2) Incremental Depth (ft) Incremental Vol. (ft3)Total Vol. (ft3)Total Vol. (ac-ft) Calc. Depths () 3 **2121AAAADV++= Elapsed Time (hours) 6543210 Fl o w ( C F S ) 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 Link out215 Flow (CFS) SWMM 5 Page 1 Elapsed Time (hours) 6543210 Fl o w ( C F S ) 350.0 300.0 250.0 200.0 150.0 100.0 50.0 0.0 Link IN_215a Flow (CFS) SWMM 5 Page 1 EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.014) -------------------------------------------------------------- WARNING 02: maximum depth increased for Node 302 WARNING 02: maximum depth increased for Node 303 WARNING 02: maximum depth increased for Node 304 WARNING 02: maximum depth increased for Node 305 WARNING 02: maximum depth increased for Node 306 WARNING 02: maximum depth increased for Node 307 ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. ********************************************************* **************** Analysis Options **************** Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES RDII ................... NO Snowmelt ............... NO Groundwater ............ NO Flow Routing ........... YES Ponding Allowed ........ NO Water Quality .......... NO Infiltration Method ...... HORTON Flow Routing Method ...... KINWAVE Starting Date ............ 11/21/2012 00:00:00 Ending Date .............. 11/21/2012 06:00:00 Antecedent Dry Days ...... 0.0 Report Time Step ......... 00:01:00 Wet Time Step ............ 00:05:00 Dry Time Step ............ 01:00:00 Routing Time Step ........ 30.00 sec ************************** Volume Depth SWMM 5 Page 1 Runoff Quantity Continuity acre-feet inches ************************** --------- ------- Total Precipitation ...... 62.620 3.669 Evaporation Loss ......... 0.000 0.000 Infiltration Loss ........ 18.769 1.100 Surface Runoff ........... 43.386 2.542 Final Storage ............ 0.753 0.044 Continuity Error (%) ..... -0.458 ************************** Volume Volume Flow Routing Continuity acre-feet 10^6 gal ************************** --------- --------- Dry Weather Inflow ....... 0.000 0.000 Wet Weather Inflow ....... 43.385 14.138 Groundwater Inflow ....... 0.000 0.000 RDII Inflow .............. 0.000 0.000 External Inflow .......... 0.000 0.000 External Outflow ......... 34.675 11.299 Flooding Loss ............ 1.442 0.470 Evaporation Loss ......... 0.000 0.000 Exfiltration Loss ........ 0.000 0.000 Initial Stored Volume .... 0.000 0.000 Final Stored Volume ...... 7.247 2.361 Continuity Error (%) ..... 0.050 ******************************** Highest Flow Instability Indexes ******************************** Link out002 (36) Link 202 (27) Link 5 (23) Link 204 (3) Link 203 (2) ************************* Routing Time Step Summary ************************* Minimum Time Step : 30.00 sec SWMM 5 Page 2 Average Time Step : 30.00 sec Maximum Time Step : 30.00 sec Percent in Steady State : 0.00 Average Iterations per Step : 1.27 Percent Not Converging : 0.00 *************************** Subcatchment Runoff Summary *************************** ------------------------------------------------------------------------------------------------------------------------------ Total Total Total Total Imperv Perv Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Runoff Runoff Coeff Subcatchment in in in in in in in 10^6 gal CFS ------------------------------------------------------------------------------------------------------------------------------ 109 3.67 0.00 0.00 0.68 1.98 0.97 2.95 1.15 101.36 0.805 108 3.67 0.00 0.00 0.68 1.98 0.97 2.95 1.74 153.81 0.805 100 3.67 0.00 0.00 0.42 2.52 0.69 3.20 1.04 105.75 0.873 102 3.67 0.00 0.00 0.68 1.94 1.03 2.96 2.61 245.74 0.808 101 3.67 0.00 0.00 1.33 1.76 0.51 2.28 0.97 39.41 0.621 104 3.67 0.00 0.00 0.65 1.99 1.00 2.99 0.78 75.55 0.816 105 3.67 0.00 0.00 0.64 2.01 0.98 2.99 1.71 161.94 0.816 106 3.67 0.00 0.00 2.68 0.04 0.95 0.99 0.00 0.04 0.270 107a 3.67 0.00 0.00 1.76 0.62 1.28 1.90 1.63 73.64 0.519 107b 3.67 0.00 0.00 1.66 0.83 1.16 1.99 2.52 127.09 0.542 ****************** Node Depth Summary ****************** --------------------------------------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- 302 JUNCTION 1.84 4.00 101.90 0 00:56 4.00 mh002 JUNCTION 0.51 2.29 102.59 0 00:49 2.29 mh001 JUNCTION 2.78 10.00 109.00 0 00:52 10.00 303 JUNCTION 1.05 1.84 97.74 0 00:40 1.83 SWMM 5 Page 3 304 JUNCTION 1.14 2.79 96.69 0 00:40 2.77 305 JUNCTION 1.23 3.03 95.93 0 00:41 3.03 306 JUNCTION 1.23 3.03 95.53 0 00:41 3.03 307 JUNCTION 0.59 1.49 93.49 0 00:41 1.49 OUTFALL OUTFALL 0.00 0.00 90.00 0 00:00 0.00 001 STORAGE 2.36 6.15 106.15 0 01:14 6.15 002 STORAGE 0.84 7.43 109.43 0 00:49 7.43 4 STORAGE 2.77 3.64 105.64 0 02:07 3.64 18 STORAGE 0.74 2.84 104.84 0 00:55 2.84 215 STORAGE 3.08 4.17 95.17 0 02:25 4.17 ******************* Node Inflow Summary ******************* ------------------------------------------------------------------------------------------------- Maximum Maximum Lateral Total Flow Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent ------------------------------------------------------------------------------------------------- 302 JUNCTION 0.00 98.62 0 01:42 0 6.3 0.000 mh002 JUNCTION 0.00 109.39 0 00:49 0 2.61 0.000 mh001 JUNCTION 0.00 122.79 0 01:14 0 6.77 -0.000 303 JUNCTION 75.55 120.51 0 00:40 0.78 7.07 -0.000 304 JUNCTION 161.94 274.44 0 00:40 1.71 8.77 0.000 305 JUNCTION 0.04 270.30 0 00:41 0.00269 8.76 0.000 306 JUNCTION 73.64 340.99 0 00:41 1.63 10.4 0.000 307 JUNCTION 127.09 464.21 0 00:41 2.52 12.9 -0.000 OUTFALL OUTFALL 0.00 82.00 0 01:55 0 11.3 0.000 001 STORAGE 39.41 183.67 0 00:47 0.965 6.79 0.031 002 STORAGE 245.74 245.74 0 00:40 2.61 2.61 0.033 4 STORAGE 255.17 255.17 0 00:40 2.89 2.89 0.016 18 STORAGE 105.75 105.75 0 00:40 1.04 1.04 0.043 215 STORAGE 0.00 464.29 0 00:41 0 12.9 -0.000 ********************* Node Flooding Summary ********************* SWMM 5 Page 4 Flooding refers to all water that overflows a node, whether it ponds or not. -------------------------------------------------------------------------- Total Maximum Maximum Time of Max Flood Ponded Hours Rate Occurrence Volume Volume Node Flooded CFS days hr:min 10^6 gal 1000 ft3 -------------------------------------------------------------------------- mh001 0.93 30.42 0 01:14 0.470 0.000 ********************** Storage Volume Summary ********************** -------------------------------------------------------------------------------------------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------------- 001 49.352 12 0 0 184.148 46 0 01:13 122.79 002 6.389 5 0 0 78.352 60 0 00:49 109.39 4 184.780 8 0 0 289.040 13 0 02:07 16.00 18 11.650 2 0 0 60.646 8 0 00:54 23.90 215 536.149 11 0 0 870.255 17 0 02:25 82.00 *********************** Outfall Loading Summary *********************** ----------------------------------------------------------- Flow Avg Max Total Freq Flow Flow Volume Outfall Node Pcnt CFS CFS 10^6 gal ----------------------------------------------------------- OUTFALL 97.08 72.08 82.00 11.298 ----------------------------------------------------------- System 97.08 72.08 82.00 11.298 SWMM 5 Page 5 ******************** Link Flow Summary ******************** ----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/ |Flow| Occurrence |Veloc| Full Full Link Type CFS days hr:min ft/sec Flow Depth ----------------------------------------------------------------------------- 202 CONDUIT 109.39 0 00:49 9.98 0.23 0.33 201 CONDUIT 98.62 0 01:42 8.55 1.07 1.00 203 CONDUIT 97.93 0 00:56 7.71 0.01 0.08 204 CONDUIT 117.67 0 00:41 8.27 0.02 0.09 205 CONDUIT 270.26 0 00:41 10.26 0.04 0.14 206 CONDUIT 269.50 0 00:41 11.02 0.10 0.22 IN_215a CONDUIT 341.10 0 00:41 32.19 0.01 0.07 IN_215b CONDUIT 464.29 0 00:41 45.01 0.01 0.07 out002 DUMMY 109.39 0 00:49 out001 DUMMY 122.79 0 01:14 out4 DUMMY 16.00 0 00:50 5 DUMMY 23.90 0 00:55 out215 DUMMY 82.00 0 01:55 ************************* Conduit Surcharge Summary ************************* ---------------------------------------------------------------------------- Hours Hours --------- Hours Full -------- Above Full Capacity Conduit Both Ends Upstream Dnstream Normal Flow Limited ---------------------------------------------------------------------------- 201 0.92 0.92 0.92 0.93 0.92 Analysis begun on: Wed Oct 20 08:52:10 2021 Analysis ended on: Wed Oct 20 08:52:10 2021 Total elapsed time: < 1 sec SWMM 5 Page 6 109 108 100 102 101 104 105 106 107 202 201 203 204 205 206 IN_215 out002 out001 out4 5 out215 302 mh002 mh001 303 304 305 306 OUTFALL 001 002 4 18 215 FtCollins-100yr 11/21/2012 00:15:00 SWMM 5 Page 1 109 108 100 102 101 104 105 106 107a 107b 202 201 203 204 205 206 IN_215a IN_215b out002 out001 out4 5 out215 302 mh002 mh001 303 304 305 306 307 OUTFALL 001 002 4 18 215 FtCollins-100yr SWMM 5 Page 1 APPENDIX C Hydraulic Computations FES ID W (FT)L (FT)QUANTITY OF MATS Velocity (ft/s) 18" HDPE FES-A1 4 12 3 5.12 10" HDPE FES-B1 4 4 1 3.37 12" HDPE FES-C1 4 4 1 5.56 12" HDPE FES-P1 4 12 3 8.26 *Refer to Scourstop design brochure for sizing requirments Scourstop Summary ScourStop® DESIGN GUIDE Circular Culvert Outlet Protection scourstop.com PERFORMANCE AESTHETICS NPDES-COMPLIANT COST-EFFECTIVE the green solution to riprap ® ScourStop transition mats protect against erosion and scour at culvert outlets with a vegetated solution in areas traditionally protected with rock or other hard armor. ScourStop is part of a system that includes semi-rigid transition mats installed over sod or turf reinforcement mats. Each 4’ x 4’ x 1/2” mat is made of high-density polyethylene and secured tightly to the ground with anchors. why use the SCOURSTOP SYSTEM? - If velocity is greater than 16 fps, contact manufacturer for design assistance. - ScourStop mats have been shown to at least double the effectiveness of turf reinforcement mats. - ScourStop fully vegetated channel (2:1 slope): velocity = 31 fps, shear stress = 16 psf. PIPE DIAMETER VELOCITY < 10 FT/SEC 10 < VELOCITY < 16 FT/SEC TRANSITION MAT W x L QUANTITY OF MATS TRANSITION MAT W x L QUANTITY OF MATS 12”4’ x 4’1 4’ x 8’2 24”8’ x 8’4 8’ x 12’6 36” 8’ x 12’6 12’ x 20’ 15 48” 12’ x 16’ 12 12’ x 24’ 18 60” 12’ x 20’ 15 16’ x 32’ 32 72” 16’ x 24’ 24 20’ x 36’ 45 Circular Culvert Outlet Protection These are minimum recommendations. More ScourStop protection may be needed depending upon site and soil conditions, per project engineer. 1. ScourStop mats must be installed over a soil cover: sod, seeded turf reinforcement mat (TRM), geotextile, or a combination thereof. 2. For steep slopes (>10%) or higher velocities (>10 ft/sec), sod is the recommended soil cover. 3. Follow manufacturer’s ScourStop Installation Guidelines to ensure proper installation. 4. Install ScourStop mats at maximum 1-2” below flowline of culvert or culvert apron. (No waterfall impacts onto ScourStop mats.) 5. Performance of protected area assumes stable downstream conditions. Transition mat apron protects culvert outlet. *Width of protection: Bottom width of channel and up both side slopes to a depth at least half the culvert diameter. Protect bare/disturbed downstream soils from erosion with appropriate soil cover. Use normal-depth calculator to compute for downstream protection. Install anchors per ScourStop Installation Guidelines. Minimum depth 24” in compacted, cohesive soil. Minimum depth 30” in loose, sandy, or wet soil. Extra anchors as needed to secure mat tightly over soil cover. Abut transition mats to end of culvert or culvert apron. Adjacent mats abut together laterally and longitudinally. Minimum 8 anchors per mat. Extra anchors as needed for loose or wet soils. Extra anchors as needed for uneven soil surface. ScourStop® Installation Recommendations A A MAX. 1"-2" DROP FROM CULVERT FLOWLINE ONTO SCOURSTOP MATSCULVERT FLOWLINE PROFILE VIEW A LEADER in the GEOSYNTHETIC and EROSION CONTROL industries Learn more about our products at: HanesGeo.com | 888.239.4539 the green solution to riprap ©2014 Leggett & Platt, Incorporated | 16959_1114 AA Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Mar 7 2022 Main Channel (341 cfs) User-defined Invert Elev (ft) = 4885.41 Slope (%)= 0.40 N-Value = 0.027 Calculations Compute by:Known Q Known Q (cfs) = 341.00 (Sta, El, n)-(Sta, El, n)... ( 0.00, 4890.43)-(31.00, 4885.82, 0.027)-(44.00, 4885.41, 0.027)-(60.00, 4889.63, 0.027)-(70.00, 4889.84, 0.027) Highlighted Depth (ft)= 2.83 Q (cfs)= 341.00 Area (sqft)= 69.01 Velocity (ft/s)= 4.94 Wetted Perim (ft) = 40.56 Crit Depth, Yc (ft) = 2.33 Top Width (ft)= 40.01 EGL (ft)= 3.21 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Elev (ft)Depth (ft)Section 4884.00 -1.41 4885.00 -0.41 4886.00 0.59 4887.00 1.59 4888.00 2.59 4889.00 3.59 4890.00 4.59 4891.00 5.59 Sta (ft) HY-8 Culvert Analysis Report Crossing Discharge Data Discharge Selection Method: Specify Minimum, Design, and Maximum Flow Minimum Flow: 0 cfs Design Flow: 341 cfs Maximum Flow: 341 cfs Table 1 - Summary of Culvert Flows at Crossing: Ditch Crossing Headwater Elevation (ft) Total Discharge (cfs) 36 Discharge (cfs) Roadway Discharge (cfs) Iterations 4881.05 0.00 0.00 0.00 1 4884.12 34.10 34.10 0.00 1 4886.73 68.20 68.20 0.00 1 4888.84 102.30 85.33 16.86 10 4889.14 136.40 87.48 48.79 7 4889.34 170.50 88.92 81.45 7 4889.50 204.60 90.06 114.40 6 4889.64 238.70 91.01 147.49 5 4889.76 272.80 91.84 180.85 5 4889.87 306.90 92.56 214.18 4 4889.96 341.00 93.16 247.67 3 4888.33 81.56 81.56 0.00 Overtopping Rating Curve Plot for Crossing: Ditch Crossing Table 2 - Culvert Summary Table: 36 ******************************************************************************** Straight Culvert Inlet Elevation (invert): 4881.05 ft, Outlet Elevation (invert): 4880.94 ft Culvert Length: 36.57 ft, Culvert Slope: 0.0030 ******************************************************************************** Total Discharge (cfs) Culvert Discharge (cfs) Headwater Elevation (ft) Inlet Control Depth (ft) Outlet Control Depth (ft) Flow Type Normal Depth (ft) Critical Depth (ft) Outlet Depth (ft) Tailwater Depth (ft) Outlet Velocity (ft/s) Tailwater Velocity (ft/s) 0.00 0.00 4881.05 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000 34.10 34.10 4884.12 2.936 3.073 7-M2c 2.087 1.893 1.893 0.701 7.255 2.132 68.20 68.20 4886.73 5.677 5.223 7-M2c 3.000 2.632 2.632 1.045 10.375 2.698 102.30 85.33 4888.84 7.786 6.718 7-M2c 3.000 2.812 2.812 1.315 12.394 3.079 136.40 87.48 4889.14 8.085 6.925 7-M2c 3.000 2.833 2.833 1.545 12.654 3.373 170.50 88.92 4889.34 8.290 7.069 7-M2c 3.000 2.842 2.842 1.747 12.839 3.616 204.60 90.06 4889.50 8.453 7.184 7-M2c 3.000 2.843 2.843 1.931 13.002 3.823 238.70 91.01 4889.64 8.591 7.274 7-M2c 3.000 2.848 2.848 2.099 13.126 4.005 272.80 91.84 4889.76 8.713 7.356 7-M2c 3.000 2.853 2.853 2.256 13.233 4.167 306.90 92.56 4889.87 8.819 7.431 7-M2c 3.000 2.865 2.865 2.402 13.307 4.315 341.00 93.16 4889.96 8.908 7.489 7-M2c 3.000 2.859 2.859 2.541 13.407 4.450 Culvert Performance Curve Plot: 36 Water Surface Profile Plot for Culvert: 36 Site Data - 36 Site Data Option: Culvert Invert Data Inlet Station: 0.00 ft Inlet Elevation: 4881.05 ft Outlet Station: 36.57 ft Outlet Elevation: 4880.94 ft Number of Barrels: 1 Culvert Data Summary - 36 Barrel Shape: Circular Barrel Diameter: 3.00 ft Barrel Material: Concrete Embedment: 0.00 in Barrel Manning's n: 0.0120 Culvert Type: Straight Inlet Configuration: Square Edge with Headwall Inlet Depression: None Table 3 - Downstream Channel Rating Curve (Crossing: Ditch Crossing) Tailwater Channel Data - Ditch Crossing Tailwater Channel Option: Trapezoidal Channel Bottom Width: 20.00 ft Side Slope (H:V): 4.00 (_:1) Channel Slope: 0.0035 Channel Manning's n: 0.0300 Channel Invert Elevation: 4880.94 ft Roadway Data for Crossing: Ditch Crossing Roadway Profile Shape: Irregular Roadway Shape (coordinates) Irregular Roadway Cross-Section: Coord No. Station (ft) Elevation (ft) 0 0.00 4889.82 1 30.00 4888.64 2 42.50 4888.33 3 55.00 4888.54 4 90.00 4889.89 Roadway Surface: Gravel Roadway Top Width: 10.00 ft Flow (cfs) Water Surface Elev (ft) Depth (ft) Velocity (ft/s) Shear (psf) Froude Number 0.00 4880.94 0.00 0.00 0.00 0.00 34.10 4881.64 0.70 2.13 0.15 0.48 68.20 4881.99 1.05 2.70 0.23 0.50 102.30 4882.26 1.32 3.08 0.29 0.52 136.40 4882.48 1.54 3.37 0.34 0.53 170.50 4882.69 1.75 3.62 0.38 0.54 204.60 4882.87 1.93 3.82 0.42 0.55 238.70 4883.04 2.10 4.00 0.46 0.55 272.80 4883.20 2.26 4.17 0.49 0.56 306.90 4883.34 2.40 4.31 0.52 0.56 341.00 4883.48 2.54 4.45 0.55 0.57 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Ca p a c i t y ( c f s ) Head (ft) Nyloplast 8" Dome Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Ca p a c i t y ( c f s ) Head (ft) Nyloplast 12" Standard Grate Inlet Capacity Chart Basin ID Inlet Size (in.)Nyloplast Grate Type A2 24 Standard A3 18 Standard A3-1 10 Dome A3-2 8 Dome A4 18 Standard A4-1 8 Dome A5 12 Standard A6 8 Dome B2 10 Dome RG OUTFALL-C2 12 Dome Inlet Schedule APPENDIX D LID SIZING 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 =0.5 cfs 2.Minimum Width of Grass Buffer WG =9 ft 3.Length of Grass Buffer (14' or greater recommended)LG =268 ft 4.Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft)SG =0.100 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=35 ft C) Interface Slope (normal to flow)SI=0.013 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: Fort Collins, CO SEE SOIL AMENDMENT NOTES ON LANDSCAPE PLAN Design Procedure Form: Grass Buffer (GB) Basin 1 Northern Engineering Bucking Horse Park March 22, 2022 UD-BMP (Version 3.07, March 2018) 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 =0.5 cfs 2.Minimum Width of Grass Buffer WG =9 ft 3.Length of Grass Buffer (14' or greater recommended)LG =331 ft 4.Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft)SG =0.015 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=65 ft C) Interface Slope (normal to flow)SI=0.015 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: Fort Collins, CO SEE SOIL AMENDMENT NOTES ON LANDSCAPE PLAN Design Procedure Form: Grass Buffer (GB) Basin 4 Northern Engineering Bucking Horse Park March 22, 2022 UD-BMP (Version 3.07, March 2018) 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 =0.2 cfs 2.Minimum Width of Grass Buffer WG =4 ft 3.Length of Grass Buffer (14' or greater recommended)LG =73 ft 4.Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft)SG =0.015 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=65 ft C) Interface Slope (normal to flow)SI=0.015 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: Fort Collins, CO SEE SOIL AMENDMENT NOTES ON LANDSCAPE PLAN Design Procedure Form: Grass Buffer (GB) Basin 5 Northern Engineering Bucking Horse Park March 22, 2022 UD-BMP (Version 3.07, March 2018) 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 =0.5 cfs 2.Minimum Width of Grass Buffer WG =10 ft 3.Length of Grass Buffer (14' or greater recommended)LG =110 ft 4.Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft)SG =0.015 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=65 ft C) Interface Slope (normal to flow)SI=0.015 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: Fort Collins, CO SEE SOIL AMENDMENT NOTES ON LANDSCAPE PLAN Design Procedure Form: Grass Buffer (GB) Basin 6 Northern Engineering Bucking Horse Park March 22, 2022 UD-BMP (Version 3.07, March 2018) Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =45.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i =0.450 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.15 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area)Area = 16,201 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 =0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =250 cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum)DWQCV =12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical)Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin =146 sq ft D) Actual Flat Surface Area AActual =206 sq ft E) Area at Design Depth (Top Surface Area)ATop =583 sq ft F) Rain Garden Total Volume VT=395 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided?1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y =2.2 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =250 cu ft iii) Orifice Diameter, 3/8" Minimum DO =3/8 in Design Procedure Form: Rain Garden (RG) Blaine Mathisen Northern Engineering March 8, 2022 Bucking Horse Park Basin 11 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO Basin 11 - Raingarden.xlsm, RG 3/8/2022, 10:05 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) Blaine Mathisen Northern Engineering March 8, 2022 Bucking Horse Park Basin 11 Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO Basin 11 - Raingarden.xlsm, RG 3/8/2022, 10:05 AM 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 =0.5 cfs 2.Minimum Width of Grass Buffer WG =11 ft 3.Length of Grass Buffer (14' or greater recommended)LG =339 ft 4.Buffer Slope (in the direction of flow, not to exceed 0.1 ft / ft)SG =0.020 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=50 ft C) Interface Slope (normal to flow)SI=0.020 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: Fort Collins, CO SEE SOIL AMENDMENT NOTES ON LANDSCAPE PLAN Design Procedure Form: Grass Buffer (GB) Basin 12 Northern Engineering Bucking Horse Park March 22, 2022 UD-BMP (Version 3.07, March 2018) X M I L E S H O U S E A V E . C.O. STORM DRAIN (TYP.) SWALE (TYP.) RAIN GARDEN 11 FLAT AREA = 206 SQ. FT. MIN. AREA = 146 SQ. FT. LID EXHIBIT RAIN GARDEN AND GRASS BUFFER SUMMARY FORT COLLINS, CO BUCKING HORSE PARK E N G I N E E R N GI EHTRON RN 03.22.2022 P:\1748-002\DWG\DRNG\PARK\1748-002_PARK_LID-V2.DWG NORTH PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED INLET LID SUMMARY: PROPERTY BOUNDARY BASIN 4 GRASS BUFFER NOTES 1. FOR LID, RAIN GARDEN, AND GRASS BUFFER CALCULATIONS PLEASE REFER TO THE FINAL DRAINAGE REPORT BUCKING HORSE PARK DATED MARCH 30, 2022. 2. REFER TO UTILITY PLANS FOR BUCKING HORSE PARK FOR ADDITIONAL GRADING AND UTILITY INFORMATION. 3. REFER TO LANDSCAPE PLANS FOR ADDITIONAL INFORMATION ON HARDSCAPES. 4. REFER TO LANDSCAPING PLANS FOR SOIL AMENDMENT NOTES. ( IN FEET ) 0 1 INCH = 100 FEET 100 100 BASIN 1 GRASS BUFFER Basin ID LID Treatment Impervious Area (i%>=90%)(sq. ft.) Impervious Area Treated By LID (sq. ft.) Percent of Impervious Treated by LID 1 Grass Buffer 2957 2586 87% 4 Grass Buffer 3688 3688 100% 5 Grass Buffer 583 583 100% 6 Grass Buffer 1923 866 45% 11 Rain Garden 6781 6781 100% 12 Grass Buffer 3127 3127 100% Total Site 25492 17631 69% LEGEND: * TOTAL PERCENT IMPERVIOUS FOR ONSITE BASINS ONLY (i) = 13% BASIN 1 IMPERVIOUS (i>=90%) AREA TREATED BY GRASS BUFFER BASIN 4 IMPERVIOUS (i>=90%) AREA TREATED BY GRASS BUFFER BASIN 5 GRASS BUFFERBASIN 5 IMPERVIOUS (i>=90%) AREA TREATED BY GRASS BUFFER BASIN 6 GRASS BUFFERBASIN 6 IMPERVIOUS (i>=90%) AREA TREATED BY GRASS BUFFER BASIN 11 RAIN GARDENBASIN 11 IMPERVIOUS (i>=90%) AREA TREATED BY RAIN GARDEN BASIN 12 GRASS BUFFERBASIN 12 IMPERVIOUS (i>=90%) AREA TREATED BY GRASS BUFFER Basin ID LID Treatment Impervious Area (i%>=90%)(sq. ft.) Impervious Area Treated By LID (sq. ft.) Percent of Impervious Treated by LID 1 Grass Buffer 2957 2586 87% 4 Grass Buffer 3688 3688 100% 5 Grass Buffer 583 583 100% 6 Grass Buffer 1923 866 45% 11 Rain Garden 6,781 6,781 100% 12 Grass Buffer 3,127 3,127 100% Total Site 25,492 17,631 69% LID SUMMARY FORT COLLINS: 301 North Howes Street, Suite 100, 80521 | 970.221.4158 GREELEY: 820 8th Street, 80631 | 970.395.9880 | WEB: www.northernengineering.com ADDRESS: 200 S. College Ave. Suite 10 Fort Collins, CO 80524 PHONE: 970.221.4158 FAX: 970.221.4159 WEBSITE: www.northernengineering.com Administrative Engineering Variance Request Letter Date: April 29, 2022 Project: Bucking Horse Park Project No. 1748-002 Fort Collins, Colorado Attn: Heidi Hansen Stormwater Development Review City of Fort Collins 281 North College Avenue Fort Collins, Colorado 80524 RE: Informal Grass Buffer Dear Staff: This letter is requesting a variance to City LID requirements in the FCSCM. The proposal is to meet LID requirements through an alternative approach that is equal-to or better-than the City’s LID Standards. This approach consists of informal vegetated buffers throughout the park and one formal rain garden. The buffers are designed using the MHFD approach instead of the FCSCM. The rain garden is design to meet the FCSCM standards. Bucking Horse Park will provide LID treatment for 69% of the onsite impervious areas – which is above the base requirement of 50%. Promoting the health, safety, welfare, and property of the City of Fort Collins and citizens through the proper control and treatment of stormwater, whether above or below surface; and, to ensure uniformity in performance with respect to design and construction of all drainage facilities are among the objectives of the Fort Collins Stormwater Criteria Manual (FCSCM) – as adopted by the City Council of the City of Fort Collins, as referenced in Section 26-500 of the Code of the City of Fort Collins December 2018. It is with those considerations in mind that this variance request letter has been prepared. This letter is provided pursuant to Chapter 2 Section 8 of FCSCM to document the site condition proposed to deviate from the current standards. The criteria in question are the requirements set forth in Chapter 7 section 6.7 of the FCSCM for “Vegetated Buffers”. Specifically, the requirements that the soils must be type A or B soils and that no cross slopes can be greater than 5% for vegetated buffers to count as LID credit. Instead, Bucking Horse Park wants to utilize Mile High Flood Control Criteria Manual 3 Chapter 4 Section T-1 Grass Buffer to size proper grass buffers that count towards LID credit. The main differences between MHFD and FCSCM when it comes to grass buffers is the soil types and the buffer slopes. MHFD does not specify that soils need to be Type A or Type B but rather that there be proper soil preparation. MHFD states; “When possible, remove, strip, stockpile, and reuse on-site topsoil.” Per the landscaping plans that is what Bucking Horse Park intends to do. However, MHFD does not specify that only soil Types A & B are suitable for effective infiltration. Bucking Horse Park | Variance Request | 03.23.22 P:\1748-002\Admin\Varriance Request\VarianceRequest - Grass Buffer.docx Page 2 of 2 ADDRESS: 200 S. College Ave. Suite 10 Fort Collins, CO 80524 PHONE: 970.221.4158 FAX: 970.221.4159 WEBSITE: www.northernengineering.com When it comes to vegetation requirements for grass buffers, MHFD states; “[Vegetation] is the most critical component for treatment within a grass buffer. Select durable dense, and drought tolerant grasses to vegetate the buffer. The goal is to provide a dense mat of vegetative cover. Grass buffer performance falls off rapidly as the vegetation coverage declines below 80% (Barret et al.2004). Turf grasses such as Kentucky Bluegrass are often selected due to these qualities. Dense native turf grasses may also be selected where a more natural look is desirable.” Whereas FCSCM doesn’t explicitly describe what type of vegetation is required for LID purposes, but it does state in Appendix C of FCSCM page 3-16; “Select vegetation with uniform cover characteristics. Avoid bunch type vegetation that can result in concreted flow between plants.” Therefore, irrigated sod and native turf, as shown on the landscape plans meets this requirement. Lastly, FCSCM states that for LID credit slopes cannot be greater than 5%. For the most part Bucking Horse Park has cross slopes of 1.5%, specifically, where the soccer field is going, but some locations within the park are closer to 10:1 which is still acceptable per MHFD. To offsite this increase in slope Bucking Horse Park is proposing much wider widths of grass buffers than the minimum requirements. This increase in grass buffer widths along with slopes no greater than 10:1 will offset the FCSCM requirement of a max of 5% cross slope. These increased widths with greatly increase the time that runoff is sheet flowing across these buffers. The proposed alternative design will not reduce the design life of the proposed park and will also reduce the footprint of additional alternative LID systems such as rain gardens, infiltration basins, contrasted wetlands, etc. that take up useable and desirable space within the park for community members to utilize. All the grass buffers greatly exceed the minimum grass buffer widths, see Appendix D of the Final Drainage Report Bucking Horse Park for sizing calculations. These larger widths will bolster the effectiveness of these grass buffers to promote healthy and sustainable infiltration. The landscape plans have also specified a soil amendment that will promote healthy growth for both the native sod and irrigated sod. Lastly, Bucking Horse Park has no vehicular traffic which dramatically reduces the concentrations of pollutants that migrate onto the site. Therefore, the Bucking Horse Park design provides an alternative approach to meeting the City’s LID requirements that is equal-to or better-than the standards in the FCSCM with regards to LID measures. Sincerely, Northern Engineering Blaine Mathisen, PE Project Engineer Attachments: - LID EXHIBIT - DRAINAGE EXHIBIT APPENDIX E Erosion Control Report and USDA Soils Report Bucking Horse Park Final Erosion Control Report VII. EROSION CONTROL REPORT A comprehensive Erosion and Sediment Control Plan (along with associated details) has been included with the construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed, or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways, and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. Grading and Erosion Control Notes can be found on the Utility Plans. The Final Plans will contain a full-size Erosion Control sheet as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in the Development Agreement for the development. Also, the Site Contractor for this project will be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, prior to any earth disturbance activities. Prior to securing the said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Larimer County Area, Colorado Bucking Horse Park Natural Resources Conservation Service November 10, 2021 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Larimer County Area, Colorado......................................................................13 22—Caruso clay loam, 0 to 1 percent slope...............................................13 Soil Information for All Uses...............................................................................15 Soil Properties and Qualities..............................................................................15 Soil Qualities and Features.............................................................................15 Hydrologic Soil Group.................................................................................15 References............................................................................................................20 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 44 8 9 2 7 0 44 8 9 3 1 0 44 8 9 3 5 0 44 8 9 3 9 0 44 8 9 4 3 0 44 8 9 4 7 0 44 8 9 5 1 0 44 8 9 5 5 0 44 8 9 5 9 0 44 8 9 6 3 0 44 8 9 2 7 0 44 8 9 3 1 0 44 8 9 3 5 0 44 8 9 3 9 0 44 8 9 4 3 0 44 8 9 4 7 0 44 8 9 5 1 0 44 8 9 5 5 0 44 8 9 5 9 0 44 8 9 6 3 0 497570 497610 497650 497690 497730 497770 497810 497850 497570 497610 497650 497690 497730 497770 497810 497850 40° 33' 27'' N 10 5 ° 1 ' 4 3 ' ' W 40° 33' 27'' N 10 5 ° 1 ' 3 1 ' ' W 40° 33' 14'' N 10 5 ° 1 ' 4 3 ' ' W 40° 33' 14'' N 10 5 ° 1 ' 3 1 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300Feet 0 25 50 100 150Meters Map Scale: 1:1,890 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 Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features 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 of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 16, Sep 2, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 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. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 22 Caruso clay loam, 0 to 1 percent slope 18.4 100.0% Totals for Area of Interest 18.4 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Larimer County Area, Colorado 22—Caruso clay loam, 0 to 1 percent slope Map Unit Setting National map unit symbol: jpvt Elevation: 4,800 to 5,500 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Caruso and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Caruso Setting Landform:Flood-plain steps, stream terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Mixed alluvium Typical profile H1 - 0 to 35 inches: clay loam H2 - 35 to 44 inches: fine sandy loam H3 - 44 to 60 inches: gravelly sand Properties and qualities Slope:0 to 1 percent Depth to restrictive feature:More than 80 inches Drainage class:Somewhat poorly drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:About 24 to 48 inches Frequency of flooding:NoneOccasional Frequency of ponding:None Calcium carbonate, maximum content:5 percent Maximum salinity:Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: Moderate (about 8.4 inches) Interpretive groups Land capability classification (irrigated): 3w Land capability classification (nonirrigated): 5w Hydrologic Soil Group: D Ecological site: R067BY036CO - Overflow Hydric soil rating: No Minor Components Loveland Percent of map unit:9 percent Custom Soil Resource Report 13 Landform:Terraces Ecological site:R067BY036CO - Overflow Hydric soil rating: Yes Fluvaquents Percent of map unit:6 percent Landform:Terraces Hydric soil rating: Yes Custom Soil Resource Report 14 Soil Information for All Uses Soil Properties and Qualities The Soil Properties and Qualities section includes various soil properties and qualities displayed as thematic maps with a summary table for the soil map units in the selected area of interest. A single value or rating for each map unit is generated by aggregating the interpretive ratings of individual map unit components. This aggregation process is defined for each property or quality. Soil Qualities and Features Soil qualities are behavior and performance attributes that are not directly measured, but are inferred from observations of dynamic conditions and from soil properties. Example soil qualities include natural drainage, and frost action. Soil features are attributes that are not directly part of the soil. Example soil features include slope and depth to restrictive layer. These features can greatly impact the use and management of the soil. Hydrologic Soil Group 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. 15 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. Custom Soil Resource Report 16 17 Custom Soil Resource Report Map—Hydrologic Soil Group 44 8 9 2 7 0 44 8 9 3 1 0 44 8 9 3 5 0 44 8 9 3 9 0 44 8 9 4 3 0 44 8 9 4 7 0 44 8 9 5 1 0 44 8 9 5 5 0 44 8 9 5 9 0 44 8 9 6 3 0 44 8 9 2 7 0 44 8 9 3 1 0 44 8 9 3 5 0 44 8 9 3 9 0 44 8 9 4 3 0 44 8 9 4 7 0 44 8 9 5 1 0 44 8 9 5 5 0 44 8 9 5 9 0 44 8 9 6 3 0 497570 497610 497650 497690 497730 497770 497810 497850 497570 497610 497650 497690 497730 497770 497810 497850 40° 33' 27'' N 10 5 ° 1 ' 4 3 ' ' W 40° 33' 27'' N 10 5 ° 1 ' 3 1 ' ' W 40° 33' 14'' N 10 5 ° 1 ' 4 3 ' ' W 40° 33' 14'' N 10 5 ° 1 ' 3 1 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300Feet 0 25 50 100 150Meters Map Scale: 1:1,890 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 of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 16, Sep 2, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 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. Custom Soil Resource Report 18 Table—Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 22 Caruso clay loam, 0 to 1 percent slope D 18.4 100.0% Totals for Area of Interest 18.4 100.0% Rating Options—Hydrologic Soil Group Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Custom Soil Resource Report 19 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 20 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 21 APPENDIX F Standard Operating Procedures (SOP) 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 (SOPs) clearly identify BMP maintenance responsibility. BMP maintenance is 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. For this project, the privately owned BMPs shown in Section B below are to be maintained by the Developer (or successor in interest which may be a property owner, or Homeowners Association (HOA), or property manager). It is incumbent upon the Developer to keep maintenance records and provide these records to the City upon request. B. Site-Specific SOPs The following stormwater facilities contained within this development are subject to SOP requirements: - Perforated Subdrain - Storm Drain Lines - Bioretention - Vegetated and/or Cobble Swale The location of said facilities can be found on the Bucking Horse Park Utility Plans and Landscape Plans. Required inspection and specific maintenance procedures and frequencies are outlined in the following pages. General 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. SOP Maintenance Summary Table Stormwater Facility / BMP Ownership / Responsibility UDFCD Maintenance Reference Perforated Subdrain Private N/A Storm Drain Lines Private Follow guidelines for Storm Sewer System Cleaning (Chapter 5, Source Control BMP Fact Sheet S-12) Bioretention/Bioswale Private Follow guidelines for Bioretention (Chapter 6, Section 5.0) Vegetated and/or Cobble Swale Private Follow guidelines for Grass Buffers and Swales (Chapter 6, Section 4.0). Take note of native vegetation. Also follow recommendations on Landscape Plans and Specifications. Perforated Subdrain The perforated subdrain system storm drain outfall at the bottom of the Low Impact Development (LID) system is critical to the overall function of the system subbase. As such, special maintenance has been identified to ensure these perforated drain systems perform as they were designed. Perforated subdrains leading away from the LID system is designed to provide faster release of water when accumulation occurs under the LID system. Outflow should be seen into downstream storm boxes. If not seen it is recommended that the system is inspected using a video camera to verify no clogging has occurred. Perforated subdrains leading toward the LID system are designed to provide an opportunity for infiltration. These subdrains may lead to a drywell where additional infiltration capacity is available to reduce runoff per the stated LID goals adopted by the City. Routine Maintenance Table Required Action Maintenance Objective Frequency of Action Inspection Use a video camera to inspect the condition of the perforated drain pipes. Cleanout pipes as needed. If the integrity of the pipe is compromised, then repair the damaged section(s). Every two to five years. Inspection Where accessible, expose inlet and/or outlet of perforated pipe and watch for water inflow and/or outflow. Minimum Annually Storm Drain Lines Maintenance Plan Storm drain lines are subject to sedimentation as well as tree roots clogging the flow path or altering the pipe slope. Maintenance is important to ensure these storm drain systems perform as they were designed. Routine Maintenance Table Required Action Maintenance Objective Frequency of Action Inspection Use a video camera to inspect the condition of the storm drain pipes. Cleanout pipes as needed. If the integrity of the pipe is compromised, then repair the damaged section(s). Every two to five years. Bioretention Routine Maintenance Table (Summary from Chapter 6 of UDFCD) Required Action Maintenance Objective Frequency of Action Lawn mowing and vegetative care Occasional mowing of grasses and weed removal to limit unwanted vegetation. Maintain irrigated turf grass as 2 to 4 inches tall and non-irrigated native turf grasses at 4 to 6 inches. Routine – Depending on aesthetic requirements, planting scheme and cover. Weeds should be removed before they flower. Debris and litter removal and snow stockpiling Remove debris and litter from bioretention area and upstream concrete forebay to minimize clogging of the sand media. Remove debris and litter from the pond area and outlet orifice plate to minimize clogging. Remove debris and litter from curb channel and sidewalk chase outlets adjacent to pond if applicable to minimize clogging. Avoid stockpiling snow in the bioretention area to minimize clogging from sediment accumulation. Routine – Including just before annual storm seasons and after snow season (April or May), end of storm season after leaves have fallen, and following significant rainfall events. Inspections Inspect detention area to determine if the sand media is allowing acceptable infiltration. If standing water persists for more than 24 hours after storm runoff has ceased, clogging should be further investigated and remedied. Routine – Biannual inspection of the hydraulic performance. Growing media replacement Restore infiltration capacity of bioretention facilities. Non-routine – Performed when clogging is due to the migration of sediments deep into the pore spaces of the media. The frequency of replacement will depend on site-specific pollutant loading characteristics. Vegetated and/or Cobble Swales Routine Maintenance Table (Summary from Table GS-1, Chapter 6 of UDFCD) Required Action Maintenance Objective Frequency of Action Lawn mowing and Lawn care Maintain irrigated grass at 2 to 4 inches tall and non-irrigated native grass at 6 to 8 inches tall. Collect cuttings and dispose of them offsite or use a mulching mower. Routine – As needed. Debris and Litter removal Keep the swale area clean for aesthetic reasons, which also reduces the potential for floatables being flushed downstream. Routine – As needed by inspection, but no less than two times per year. Sediment removal Remove accumulated sediment near culverts and in channels to maintain flow capacity. Replace the grass areas damaged in the process. Routine – As needed by inspection. Estimate the need to remove sediment from 3 to 10 percent of total length per year, as determined by annual inspection. Inspections Check the grass for uniformity of cover, sediment accumulation in the swale, and near culverts. Routine – Annual inspection is suggested. MAP POCKET DRAINAGE EXHIBITS X X X X X X X X X X X X X X X X X X X X X X X X X X X X X XX X X X X X X EM EM EM EM X X X X X X X X X X X X X X X D F U D U D U D U D E G R E A T W E S T E R N R A I L R O A D DRAKE ROAD NANCY G R A Y A V E N U E MI L E S H O U S E A V E N U E PAL O M I N O D R I V E PAL O M I N O COU R T P A L O M I N O D R I V E W A L K A L O O S A W A Y A A ENVIRONMENTAL DRIVE FUTURE CITY PARK HORSE AREA OFFICE COMPLEX WORKING FARM EXISTING DETENTION POND 215 BUCKING HORSE FILING ONE PROSPECT INDUSTRIAL PARK WATER / WASTE WATER TREATMENT FACILITY AGGREGATE INDUSTRIES HORSE STABLES & RIDING AREA CARGILL, INC. SI D E H I L L - F I L I N G O N E B4 B5 F1 F2 D4 D5 OS3 OS4 OS2 OS1 G B1 B2 A1 B6 C1 C2 C3 D3 D2 E5 D1 E4 E2 E1 acres B5 0.340.82 1.00 acres B4 0.460.83 1.00 acres B6 0.850.45 0.56 acres C3 1.880.70 0.87 acres C1 2.620.65 0.81 acres B3b 2.420.25 0.32 acres B2 3.550.43 0.54 acres B1 1.640.74 0.93 acres A1 2.920.50 0.62 acres OS1 0.840.48 0.60 acres OS2 1.460.64 0.80 acres C2 4.330.64 0.80 acres E1 1.790.65 0.82 acres D4 2.850.60 0.75 acres D2 0.840.69 0.87 acres D3 5.720.39 0.49 acres D1 0.200.48 0.60 acres OS3 1.130.76 0.95 acres E4 2.670.53 0.66 acres OS4 0.050.85 1.00 acres E5 0.500.82 1.00 acres E3 2.350.65 0.81 acres G 20.530.25 0.31 acres B3a 2.640.37 0.47 acres B3c 1.000.36 0.45B3b B3a B3c acres E2 3.410.64 0.79 E3 C C B B D D E E F F G G acres F1 7.520.31 0.39 acres D5 0.590.83 1.00 acres F3 0.540.86 1.00 acres F2 2.070.43 0.53 DR1 DR A I N A G E E X H I B I T OV E R A L L H. F e i s s n e r H. F e i s s n e r 1" = 1 5 0 ' NORTH ( IN FEET ) 1 inch = ft. Feet0150150 150 300 450 Date Date Date Date Date Da t e APPROVED: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: City Engineer Water & Wastewater Utility Stormwater Utility Parks & Recreation Traffic Engineer Environmental Planner City of Fort Collins, Colorado UTILITY PLAN APPROVAL CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what's below. before you dig.Call R FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION LEGEND: 4953 PROPOSED CONTOUR 93 PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTERPROPERTY BOUNDARY PROPOSED INLET ADESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL BASIN DESIGNATION BASIN AREA (AC) DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 11 B2 1.45 ac No . Re v i s i o n s : By : Da t e : RE V I E W E D B Y : N. H a w s DE S I G N E D B Y : DR A W N B Y : SC A L E : DA T E : DE C . 1 4 , 2 0 1 2 PR O J E C T : 68 7 - 0 0 2 Sheet Of 78 Sheets - F i l i n g T w o 20 0 S o u t h C o l l e g e A v e n u e , S u i t e 0 1 0 Fo r t C o l l i n s , C o l o r a d o 8 0 5 2 4 E N G I N E E R N G I E H T R O N R N PH O N E : 9 7 0 . 2 2 1 . 4 1 5 8 F A X : 9 7 0 . 2 2 1 . 4 1 5 9 ww w . n o r t h e r n e n g i n e e r i n g . c o m 12.14.12 DETENTION POND SUMMARY VOLUME REQ'D (ac-ft)WQVOLUMEREQ'D VOLUME PROVIDED (ac-ft)POND INVERT WSEL POND 215 28.80 3.48 32.42 4878.54 4885.25 SWALE SECTIONS MI N . D (F T ) S2:1S1 : 1 MIN. TW (FT) SWALE SUMMARY TABLE SWALE ID MIN D MIN TW MIN BW S1 S2 A 3.00 34.00 20 4 4 B (DP B6)1.69 17.52 4 4 4 C (DP B3c)1.57 16.56 4 4 4 D (DP B3a)1.07 8.56 0 4 4 E (DP D3)1.30 10.40 0 4 4 F (DP D3)0.51 32.64 0 4 60 MIN. BW (FT) EMERGENCY OVERFLOW WEIR SUMMARY TABLE POND NO. 215 4886.25 4886.25 TOP OF WEIR 4885.25 4883.25 300 ELEVATION (FT) TOP OF BANK ELEVATION (FT) NOTCH ELEVATION (FT) BOTTOM ELEVATION (FT) NOTCH WIDTH, W (FT) 3'TOP OF WEIR BOTTOM ELEV. NOTCH ELEV. 3'2'W2'2-#5 BARS 14 (SEE NOTE) 8" MINIMUM THICKNESS 2-#5 BARS 14 3" CLR 3" C L R TOP OF EMBANKMENT NOTE:TRENCH FOR WEIR OUTLET STRUCTURE USING NATIVE GROUND AS FORMWORK. CONSTRUCT WEIR 8" MINIMUM THICKNESS. UPON COMPLETION OFTRENCHING, PLACE TEMPERATURE STEEL AND CONCRETE IMMEDIATELY.FORM TOP 4". POND EMERGENCY OVERFLOW WEIR DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C10 C100 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q10 (cfs) Q100 (cfs) A1 A1 2.92 0.50 0.50 0.62 5.5 5.5 5.0 4.0 6.8 18.0 B1 B1 1.64 0.74 0.74 0.93 10.3 10.3 8.9 2.7 4.6 12.5 B2 B2 3.55 0.43 0.43 0.54 10.2 10.2 9.9 3.4 5.8 15.2 B3a B3a 2.64 0.37 0.37 0.47 11.0 11.0 10.6 2.1 3.7 9.3 B3b B3b 2.42 0.25 0.25 0.32 8.3 8.3 7.7 1.5 2.5 6.6 B3c B3c 1.00 0.36 0.36 0.45 17.5 17.5 16.6 0.6 1.1 2.8 B4 B4 0.46 0.83 0.83 1.00 6.4 6.4 6.1 1.0 1.7 4.2 B5 B5 0.34 0.82 0.82 1.00 5.1 5.1 5.0 0.8 1.4 3.4 B6 B6 0.85 0.45 0.45 0.56 15.1 15.1 14.3 0.7 1.2 3.2 C1 C1 2.62 0.65 0.65 0.81 19.5 19.5 18.6 2.8 4.8 12.4 C2 C2 4.33 0.64 0.64 0.80 27.4 27.4 25.9 3.8 6.5 17.1 C3 C3 1.88 0.70 0.70 0.87 13.3 13.3 12.6 2.6 4.4 11.5 D1 D1 0.20 0.48 0.48 0.60 5.0 5.0 5.0 0.3 0.5 1.2 D2 D2 0.84 0.69 0.69 0.87 5.0 5.0 5.0 1.7 2.8 7.2 D3 D3 5.72 0.39 0.39 0.49 9.6 9.6 9.2 5.0 8.6 22.4 D4 D4 2.85 0.60 0.60 0.75 18.2 18.2 17.2 2.9 4.9 13.0 D5 D5 0.59 0.82 0.82 1.00 6.0 6.0 5.7 1.3 2.3 5.7 E1 E1 1.79 0.65 0.65 0.82 22.8 22.8 21.4 1.8 3.0 8.0 E2 E2 3.41 0.64 0.64 0.79 22.8 22.8 22.0 3.3 5.6 14.4 E3 E3 2.35 0.65 0.65 0.81 19.7 19.7 19.0 2.5 4.3 11.0 E4 E4 3.41 0.64 0.64 0.79 22.8 22.8 22.0 3.3 5.6 14.4 E5 E5 0.50 0.82 0.82 1.00 5.0 5.0 5.0 1.2 2.0 5.0 F1 F1 7.71 0.31 0.31 0.38 28.0 28.0 26.0 3.2 5.4 14.6 F2 F2 2.45 0.50 0.50 0.62 14.8 14.8 10.4 2.3 4.0 11.8 G G 20.53 0.25 0.25 0.31 5.0 5.0 5.0 14.6 25.0 63.8 OS1 OS1 0.84 0.48 0.48 0.60 14.0 14.0 13.0 0.8 1.3 3.5 OS2 OS2 1.46 0.64 0.64 0.80 14.7 14.7 13.8 1.8 3.0 7.9 OS3 OS3 1.13 0.76 0.76 0.95 6.2 6.2 5.9 2.3 3.9 10.3 OS4 OS4 0.05 0.85 0.85 1.00 5.0 5.0 5.0 0.1 0.2 0.5 B1 B1 & OS1 2.48 0.65 0.65 0.8 19.6 19.6 18.6 2.6 4.5 11.8 B2 B2 & OS2 5.01 0.49 0.49 0.6 20.3 20.3 19.3 4.0 6.8 17.7 B3c B1-B3c, OS1 & OS2 13.56 0.45 0.45 0.6 25.2 25.2 24.3 8.7 14.8 38.5 C2 C1 & C2 6.94 0.64 0.64 0.8 27.4 27.4 25.9 6.1 10.5 27.5 E2 E1 & E2 5.20 0.64 0.64 0.8 22.8 22.8 22.0 5.0 8.6 22.2 DEVELOPED RUNOFF SUMMARY Bucking Horse - Filing Two CHARACTER OF SURFACE:Runoff Coefficient Percentage Impervious Project:Bucking Horse - Filing Two Streets, Parking Lots, Roofs, Alleys, and Drives:Calculations By:H. Feissner Asphalt ……....……………...……….....…...……………….…………………………………..0.95 100 Date: Concrete …….......……………….….……….………………..….…………………………………0.95 90 Gravel ……….…………………….….…………………………..………………………………..0.50 40 Roofs …….…….………………..……………….……………………………………………..0.95 90 General Single Family…………………………...………………..……………………………………………..0.60 50 Lawns and Landscaping Sandy Soil ……..……………..……………….……………………………………………..0.15 0 Clayey Soil ….….………….…….…………..……………………………………………….0.25 0 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Single Family (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. A1 127,032 2.92 0.00 0.42 0.00 0.00 1.21 1.29 0.50 0.50 0.62 33.6 B1 71,551 1.64 0.68 0.24 0.00 0.00 0.46 0.26 0.74 0.74 0.93 68.6 B2 154,708 3.55 0.69 0.24 0.00 0.00 0.00 2.62 0.43 0.43 0.54 25.6 B3a 115,058 2.64 0.00 0.00 0.00 0.10 0.86 1.68 0.37 0.37 0.47 17.8 B3b 105,539 2.42 0.00 0.00 0.00 0.04 0.00 2.38 0.25 0.25 0.32 0.7 B3c 43,595 1.00 0.00 0.00 0.00 0.00 0.32 0.68 0.36 0.36 0.45 15.8 B4 19,883 0.46 0.28 0.10 0.00 0.00 0.00 0.08 0.83 0.83 1.00 80.3 B5 14,883 0.34 0.21 0.07 0.00 0.00 0.00 0.06 0.82 0.82 1.00 79.5 B6 36,870 0.85 0.00 0.00 0.00 0.00 0.48 0.36 0.45 0.45 0.56 28.6 C1 114,112 2.62 0.43 0.18 0.00 0.01 1.74 0.25 0.65 0.65 0.81 56.0 C2 188,410 4.33 0.68 0.30 0.00 0.02 2.87 0.46 0.64 0.64 0.80 55.3 C3 82,082 1.88 0.63 0.21 0.00 0.00 0.71 0.33 0.70 0.70 0.87 62.6 D1 8,570 0.20 0.03 0.02 0.01 0.00 0.00 0.13 0.48 0.48 0.60 31.1 D2 36,394 0.84 0.47 0.05 0.01 0.00 0.00 0.31 0.69 0.69 0.87 62.7 D3 249,072 5.72 0.00 0.15 0.12 0.22 1.61 3.63 0.36 0.36 0.45 19.8 D4 124,146 2.85 0.36 0.12 0.00 0.02 1.86 0.49 0.60 0.60 0.75 49.3 D5 25,828 0.59 0.38 0.12 0.00 0.00 0.00 0.10 0.83 0.83 1.00 81.3 E1 78,150 1.79 0.24 0.12 0.00 0.00 1.34 0.09 0.65 0.65 0.82 56.9 E2 148,483 3.41 0.39 0.20 0.00 0.01 2.58 0.23 0.64 0.64 0.79 54.5 E3 102,549 2.35 0.34 0.17 0.00 0.01 1.67 0.17 0.65 0.65 0.81 56.5 E4 116,426 2.67 0.30 0.11 0.00 0.12 1.24 0.92 0.53 0.53 0.66 39.5 E5 21,867 0.50 0.30 0.11 0.00 0.00 0.00 0.10 0.82 0.82 1.00 78.8 F1 327,417 7.52 0.00 0.00 0.00 0.11 1.18 6.23 0.31 0.31 0.39 8.4 F2 89,995 2.07 0.00 0.45 0.07 0.00 0.00 1.55 0.43 0.43 0.53 22.5 F3 23,381 0.54 0.39 0.08 0.00 0.00 0.00 0.07 0.86 0.86 1.00 86.2 G 894,243 20.53 0.00 0.00 0.00 0.00 0.00 20.53 0.25 0.25 0.31 0.0 TOTAL ONSITE 3,320,244 76.222 6.80 3.43 0.21 0.66 20.13 44.99 0.44 0.44 0.55 26.8 OS1 36,563 0.84 0.19 0.09 0.00 0.00 0.00 0.57 0.48 0.48 0.60 31.4 OS2 63,593 1.46 0.26 0.23 0.00 0.00 0.62 0.34 0.64 0.64 0.80 53.6 SWMM 107 3,420,400 78.52 7.24 3.75 0.21 0.66 20.76 45.90 0.35 0.35 0.44 27.3 OS3 49,166 1.13 0.60 0.22 0.00 0.00 0.00 0.30 0.76 0.76 0.95 71.1 OS4 2,091 0.05 0.04 0.00 0.00 0.00 0.00 0.01 0.85 0.85 1.00 84.1 DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. 10-year Cf = 1.00 December 17, 2012 12/17/20122:15 PM D:\Projects\687-002\Drainage\Filing Two\Hydrology\FDP\2012-12-17_FDP\687-002_FT_Rational-Calcs\C-Values S S S S S S S S S S W W W W W CM W W S S S S S S S S S S S S S S S S S S S S S S S S S S E W W W W W X X X X X X X X X X X X X X X X T F EXISTING DETENTION POND 215 C.O. 1 2 4 5 100' ROW GREAT WESTERN RAIL ROAD CO CO CO CO CO S S S S S SS SS SS SS SS SS CO CO CO CO COS S S S S S S S SS SS SS HY D E M I L E S H O U S E A V E N U E PAL O M I N O C O U R T 1 0.58 ac 4 0.79 ac 3 0.16 ac 5 0.40 ac 6 0.95 ac 7 0.43 ac 9 0.14 ac 10 0.39 ac 11 0.37 OS1 0.65 ac 2 0.38 ac PROPERTY BOUNDARY POUDRE RIVER 500-YR FLOODPLAIN (PER RiskMAP) PROPERTY BOUNDARY PROPERTY BOUNDARY PROPERTY BOUNDARY PROPOSED AREA DRAIN PROPOSED AREA DRAIN PROPOSED AREA DRAIN PROPOSED AREA DRAIN PROPOSED AREA DRAIN PROPOSED AREA DRAIN RE-ALIGN EXISTING SWALE 10:1 EDGE OF WETLANDS A A 8 0.56 ac 6 12 0.99 9 10 RAIN GARDEN 11 FLAT AREA = 206 SQ. FT. MIN. AREA = 146 SQ. FT. EXISTING 36" RCP CULVERT SWALE OVERTOPPING LOCATION SWALE M A X Q I N S W A L E = 3 4 1 . 1 C F S 10:1 GRASS BUFFERGRASS BUFFER GRASS BUFFER GRASS BUFFER DR1 DR A I N A G E E X H I B I T 18 NORTH ( IN FEET ) 1 inch = ft. Feet05050 50 100 150 SECTION A-A SWALE SUMMARY (NORMAL DEPTH): 1. REFER TO THE FINAL DRAINAGE REPORT BUCKING HORSE PARK DATED APRIL 10, 2022 FOR ADDITIONAL INFORMATION. 2. THIS PROPERTY IS CURRENTLY LOCATED IN THE FEMA MODERATE RISK FLOOD HAZARD AREA FOR THE CACHE LA POUDRE RIVER. BUT THE PROPOSED REMAPPING FROM RISKMAP WILL REMOVE ALL FLOODPLAIN DESIGNATIONS FROM THE PROJECT AREA. 3. REFER TO THE LANDSCAPE PLANS BY CITY OF FORT COLLINS FOR ADDITIONAL LANDSCAPING INFORMATION. LEGEND: PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET ADESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL GRASS BUFFER PROPOSED SWALE SECTION AA CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow.before you dig.Call R Sheet BU C K I N G H O R S E P A R K of 18 10 0.37 ac BASINDESIGNATION BASINAREA (AC) NOTES: Design Point Basin ID Total Area (acres) C2 C100 2-Yr Tc (min) 100-Yr Tc (min) Q2 (cfs) Q100 (cfs) 1 1 0.58 0.29 0.37 6.21 6.21 0.45 2.03 2 2 0.38 0.26 0.32 7.72 7.72 0.24 1.07 3 3 0.16 0.31 0.38 5.00 5.00 0.14 0.63 4 4 0.79 0.30 0.37 11.22 11.22 0.50 2.18 5 5 0.40 0.24 0.30 11.22 11.22 0.21 0.90 6 6 0.95 0.25 0.31 11.28 11.28 0.50 2.19 7 7 0.43 0.28 0.35 10.56 10.56 0.26 1.15 8 8 0.56 0.31 0.39 10.56 10.56 0.38 1.65 9 9 0.14 0.31 0.38 5.00 5.00 0.12 0.52 10 10 0.39 0.21 0.27 5.43 5.43 0.24 1.03 11 11 0.37 0.53 0.66 5.00 5.00 0.56 2.44 12 12 0.99 0.25 0.32 11.00 11.00 0.54 2.43 os1 OS1 0.65 0.29 0.36 7.68 7.68 0.46 2.04 LID SUMMARY: MIN. TW (FT) MIN. BW (FT) MIN. D (FT) MAX D (FT)S1 S2 40 13 2.83 4.22 4 4 Basin ID LID Treatment Impervious Area (i%>=90%)(sq. ft.) Impervious Area Treated By LID (sq. ft.) Percent of Impervious Treated by LID 1 Grass Buffer 2957 2586 87% 4 Grass Buffer 3688 3688 100% 5 Grass Buffer 583 583 100% 6 Grass Buffer 1923 866 45% 11 Rain Garden 6781 6781 100% 12 Grass Buffer 3127 3127 100% Total Site 25492 17631 69% DRAINAGE SUMMARY: DRAINAGE BASIN BOUNDARY