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Home My WebLink AboutPROSPECT SPORTS CLUB - PDP230009 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPRELIMINARY DRAINAGE REPORT 19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com P ROSPECT S PORTS Lot 5 Prospect Park East P.U.D Fort Collins, CO Prepared for: RB+B Architects, Inc. 315 E. Mountain Ave, Suite 100 Fort Collins, CO 80524 Date: May 30 th , 2023 P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO i U22014_Drainage Report City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Prospect Sports Fort Collins, Colorado Project Number: U22014 Dear Staff: United Civil Design Group, LLC. is pleased to submit this Preliminary Drainage Report for the Prospect Sports site in Fort Collins, Colorado. In general, this report serves to document the stormwater impacts associated with the proposed improvements related to the existing site. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in the Fort Collins Stormwater Criteria Manual (FCSCM). This report was prepared in compliance with technical criteria set forth in the Fort Collins Stormwater Criteria Manual. If you should have any questions or comments as you review this report, please feel free to contact us at your convenience. Sincerely, United Civil Design Group Nate Stroud, PE, LSIT Project Manager P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO ii U22014_Drainage Report TABLE OF CONTENTS I. General Location and Description ...................................................................................................................................... 1 A. General Location & Existing Site Information ............................................................................................. 1 B. Description of Property ............................................................................................................................... 1 C. Project Description ..................................................................................................................................... 2 D. Floodplains .................................................................................................................................................. 2 II. Drainage Basins and Sub-Basins ......................................................................................................................................... 3 A. Major Basin Description .............................................................................................................................. 3 B. Sub-Basin Description ................................................................................................................................. 3 III. Drainage Design Criteria ..................................................................................................................................................... 3 A. Regulations ................................................................................................................................................. 3 B. Directly Connected Impervious Area (DCIA) ............................................................................................... 3 C. Hydrological Criteria ................................................................................................................................... 4 D. Hydraulic Criteria ........................................................................................................................................ 4 E. Modifications of Criteria ............................................................................................................................. 4 IV. Drainage Facility Design ..................................................................................................................................................... 5 A. General Concept ......................................................................................................................................... 5 B. Specific Details ............................................................................................................................................ 5 V. Erosion Control ................................................................................................................................................................... 8 VI. Conclusions ........................................................................................................................................................................ 9 A. Compliance with Standards ........................................................................................................................ 9 B. Drainage Concept........................................................................................................................................ 9 C. Stormwater Quality..................................................................................................................................... 9 VII. References ...................................................................................................................................................................... 9 APPENDICES APPENDIX A – Hydrology Calculations APPENDIX B – Hydraulic Calculations B.1 – Low Impact Development Calculations B.2 – Water Quality Calculations B.3 – Inlet Sizing Calculations (Reserved for Final Submittal) B.4 – Storm Pipe Calculations (Reserved for Final Submittal) B.5 – Channel Capacity Calculations (Reserved for Final Submittal) B.6 – Riprap Calculations (Reserved for Final Submittal) APPENDIX C – Referenced Materials C.1 – Variance Request APPENDIX D – Drainage Exhibits P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 1 U22014_Drainage Report I.GENERAL LOCATION AND DESCRIPTION A.GENERAL LOCATION &EXISTING SITE INFORMATION The Prospect Sports site (referred herein as “the site”) is located within the Prospect Park East P.U.D, situated in the northwest quarter of Section 20, T7N, R68W of the 6th P.M., City of Fort Collins, Larimer County, Colorado. The property, consisting of approximately 2.46 acres, is located immediately south of East Prospect Road. The property is bounded by Sharp Point Drive to the east, and Prospect Park East P.U.D lots to the west and south. On-site stormwater drains off-site to an existing detention pond within Tract A of the Prospect Park East P.U.D. FIGURE 1:SITE VICINITY MAP B.DESCRIPTION OF PROPERTY The property currently exists largely as grass/weed landscape with sidewalk adjacent to East Prospect Road and Sharp Point Drive. Immediately south of the property are existing parking and drive lanes associated with the Prospect East P.U.D. – it is intended that the proposed surface improvements tie-in to these existing features. In its existing condition, the site primarily sheet flows to a low point at the south side of the site and ultimately drain to the existing pond located south of the site. Below are summaries of key components of the site in its existing conditions. Land Use - The site’s current land use is commercial. Ground Cover - The site exists largely as grass/weed landscape. The weed/grass cover is good (ie., heavy or dense cover with nearly all ground surfaces protected by vegetation). The southern portion of the site is fully developed as consists largely of impervious hardscaping. Existing Topography and Grades – In general the site slopes from north to south at approximately 0.5% to 25%. The center of the site has been built up with fill material and ties to the existing commercial lot south of the project at approximately 4:1 slopes. A majority of the site slopes from top back of curb along public roadways down into the site. Sharp Point DriveProspect Park WaySite P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 2 U22014_Drainage Report Soil Type – The USDA’s Web Soil Survey shows that the site consists of “Type C” and “Type D” soils. The Web Soil Survey indicates the site is comprised of Aquepts, Loveland Clay Loam (0% to 1% slopes), and Riverwash material. The on-site soils provide moderate infiltration and are suitable for development. Utilities – The following utilities exist adjacent to the site in Prospect Road, Sharp Point Road, or in easement on the west side of the site: potable water, sanitary sewer, natural gas, electric and telecommunications. Drainage Features and Storm Sewer – Storm sewer infrastructure does not currently exist adjacent to the site. There is an existing detention pond for the proposed subdivision that is located to the south of the site within Tract A of the Prospect Park East P.U.D, but this facility is inaccessible to the proposed site due to lack of drainage easements. There is also an existing lake/pond across Sharp Point Drive to the east of the site that will be utilized by the proposed project and improvements and is owned by the same owner that is developing the Prospect Sports facility. C.PROJECT DESCRIPTION The proposed Prospect Sports site improvements are limited to approximately 2.5 acres of disturbance. The proposed site improvements consist of the construction of a new 3-court basketball venue with associated site improvements including proposed drive lanes, parking, utilities, and storm and water quality infrastructure. On-site stormwater is designed to be conveyed to the proposed storm sewer and conveyed to the existing lake/wet pond east of the proposed site and across Sharp Point Drive. D.FLOODPLAINS AND FLOODPLAIN INFORMATION The proposed development is within the Poudre River designated floodplain. According to the FEMA Flood Insurance Rate Map (08069C0984H), the site is zoned in a “High Risk – Floodway” boundary area. The Floodway boundary is provided on the Drainage Plan (see Appendix D) and FEMA FIRMette map is included in Appendix C. A Floodplain Use Permit will be required for all work within the floodplain and all improvements will be required to be in compliance with Chapter 10 of the City Municipal Code. Note that this development is considered a non-residential and non-critical use structure. Note that the existing Poudre River Floodplain is currently being revised by the City of Fort Collins. Currently, it is anticipated that the proposed development will be removed from the 100-year floodplain. To comply with Chapter 10 of the City Code, the finished floor of the proposed building is proposed to be elevated 2.5 feet above the 100-year Poudre River base flood elevation. However, due to the basketball courts sitting 4.5’ lower than the finished floor in the rest of the building, the walls, and doors adjacent to the basketball courts (largely on the south side of the building) sitting at this lower finished floor are proposed to be floodproofed. Floodproofing information shall be submitted at the time of the building permit application and a FEMA Elevation or floodproofing certificate will be completed prior to the certificate of occupancy being issued. The building is proposing to use slab on-grade foundations with all elevations being tied to the NAVD 1988 Datum. A table summarizing elevations of critical items is shown on this sheet. FIGURE 2:FLOODPLAIN MAP FLOODPLAIN AND STRUCTURE ELEVATIONS SUMMARY DESCRIPTION ELEVATION FEMA BFE at Upstream End of Structure 4,901.00 Regulatory Flood Protection / Floodproofing Elevation 4,903.00 Upper Finished Floor Elevation 4,903.50 Lower Finished Floor Elevation 4,899.00 HVAC Elevation *4,919.50 *HVAC equipment to be located on top of lower roof on north end of building. Site P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 3 U22014_Drainage Report II.DRAINAGE BASINS AND SUB-BASINS A.MAJOR BASIN DESCRIPTION The proposed development is located within the Cache La Poudre Basin and will adhere to the Cache La Poudre Master Drainage Plan. B.SUB-BASIN DESCRIPTION Historically the site drains off-site to an existing detention pond within Tract A of the Prospect Park East P.U.D. As drainage easements were never recorded south of the site to the pond and the southern property owner has denied any new easements on the property, from communications with City personnel, the proposed site will not be able to drain developed stormwater flows through the existing property to the south and to the pond. In the proposed conditions, stormwater will be collected via storm sewer, inlets, swales, and curb and gutter and conveyed to the east beyond Sharp Point Drive to an existing lake/pond and lot under the same ownership as this site. In its improved condition, on-site runoff is intended to drain to multiple water quality facilities by way of sheet flow, swales, curb and gutter, inlets, and storm sewer. The Prospect Sports site was previously discussed in the “Final Drainage Report and Erosion Control Plan” for the Advanced Energy Buildings 7 and 8 project. This report shows Lot 5, the project area of the subdivision being included in the calculations as part of Basin J10 which is designed with a 100-year C value of 1.00. This basin was designed to drain to the south via overland flow to the existing detention pond within Tract A and ultimately discharge into culverts across Sharp Point to an existing lake/pond east of the site. III.DRAINAGE DESIGN CRITERIA A.REGULATIONS The design criteria for this study are directly from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual and the Urban Storm Drainage Criteria Manual’s (referred to herein as USDCM) Volumes 2, and 3, used for supplement only. B.DIRECTLY CONNECTED IMPERVIOUS AREA (DCIA) The City drainage criteria has also adopted the “Four Step Process” that is recommended in Volume 3 of the USDCM in selecting structural BMPs for the redeveloping urban areas. The following portions of this summary describe each step and how it has been utilized for this project: Step 1 – Employ Runoff Reduction Practices The objective of this step is to reduce runoff peaks and volumes and to employ the technique of “minimizing directly connected impervious areas” (MDCIA). This project accomplishes this by: Routing the roof and pavement flows through water quality treatment/infiltration facilities and vegetated swales to increase time of concentration, promote infiltration and provide water quality. Step 2 – Provide Water Quality Capture Volume (WQCV) The objective of providing WQCV is to reduce the sediment load and other pollutants that exit the site. For this project WQCV is provided within the permeable paver system in the western parking lot. Step 3 – Stabilize Drainageways Although the site is not adjacent to the Cache La Poudre River, it does exist within its floodplain. The project will not be directly connecting or stabilizing this drainageway but will improve the existing drainageway by providing water quality for the proposed site and reducing peak flows via the existing lake/pond prior to draining to the river. P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 4 U22014_Drainage Report Step 4 – Consider Need for Site Specific and Source Control BMPs Site specific and source control BMPs are generally considered for large industrial and commercial sites. The redevelopment of the existing site will include multiple site specific and source controls, including: Dedicated maintenance personnel providing landscape maintenance and snow and ice management. Pervious pavers being utilized in the parking area to collect and treat proposed pavement. C.HYDROLOGICAL CRITERIA City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, provided by Table 3.4-1 of the Fort Collins Stormwater Criteria Manual, are utilized for all hydrologic computations related to the site in its existing/historic and proposed conditions. Since this site is relatively small and does not have complex drainage basins, the peak flow rates for design points have been calculated based on the Rational Method as described in the USDCM and the City of Fort Collins Stormwater Criteria Manual (FCSCM) with storm duration set equal to the time of concentration for each sub-basin. This method was used to analyze the developed runoff from the 2-year (minor) and the 100-year (major) storm events. The Rational Method is widely accepted for drainage design involving small drainage areas (less than 160 acres) and short time of concentrations. Runoff coefficients are assumed based on impervious area and are given in the Appendices. D.HYDRAULIC CRITERIA The developed site will convey runoff to the proposed pond or underground treatment facility via swales, concrete channels, and pipes. The City of Fort Collins Stormwater Criteria Manual (FCSCM) and USDCM are referenced for all hydraulic calculations. In addition, the following computer programs are utilized: Storm Sewer Extension for AutoCAD Civil3D Hydraflow Express Extension for AutoCAD Civil3D UD-Inlet by UDFCD Drainage conveyance facility capacities proposed with the development project, including storm sewer, swales, and inlet capacities, are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District’s Urban Storm Drainage Criteria Manual (UDFCD) used for supplement purposes only. E.MODIFICATIONS OF CRITERIA The original subdivision development planned for drainage to be conveyed via overland flow to the drainage facility located south of the site; therefore, no storm sewer currently exists on the site. Additionally, the development team has worked with the property owner south of the site to determine if improvements and/or easements/agreements could be made to allow stormwater to continue being conveyed through this adjacent property and to the existing detention pond within Tract A of the Prospect Park East P.U.D. After discussion with the south property owner and their attorney, the southern property owner has denied any new easements for drainage and stormwater conveyance. These storm sewer difficulties generated by the design of the existing subdivision, the inability to modify the southern property easements/agreements and the resulting site plan configuration culminate into hardships with providing standard water quality and LID treatment techniques that are approved by the City. A Stormwater Variance Request has been submitted to the City requesting that the development, due to the hardships documented, is allowed to meet reduced or modified water quality and LID treatment requirements and allowed to provide treatment techniques that differ from those typically allowed in the Fort Collins Stormwater Criteria Manual. In addition to a more limited LID requirement for this project, providing detention through conveying stormwater to the existing pond within Tract A of the Prospect Park East P.U.D. will not be feasible. In addition to this, the storm outfall was not able to achieve enough depth for underground detention to be a viable option on site and there is not adequate space to provide a formal detention pond onsite. It was noted through discussions with the City that detention would not be required for this project. It was also noted through these discussions that the existing detention pond in Tract A currently overtops Sharp Point during the 100-year event and drains to the same lake/pond that the Prospect Sports site will outfall to. Due to these conditions, the City waived detention requirements for this project. P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 5 U22014_Drainage Report IV.DRAINAGE FACILITY DESIGN A.GENERAL CONCEPT Developed runoff is designed to be conveyed in a safe and effective manner via swales, curb and gutter, and storm sewer systems/inlets. Stormwater is designed to be released to an existing lake/pond east of the site and across Sharp Point Drive and ultimately to the Cache La Poudre River. Runoff that drains off-site to the south was minimized with the proposed site and is greatly reduced from existing flows heading to the same area. Runoff from the proposed site is primarily conveyed to pervious pavers and grass swales for water quality treatment and then collected via storm sewer and discharged offsite to the existing pond east of the site. Although most of the site runoff is treated through the pervious pavers or grass swales, due to grading, site, and legal constraints discussed above, the remainder of the site is treated for water quality using alternative measures discussed in water quality section of this report and in the stormwater variance submitted with the project. B.SPECIFIC DETAILS Hydrology As previously stated, hydrology from the developed site is designed to comply with criteria set forth in the City of Fort Collins Stormwater Criteria Manual. Referenced tables, charts, formulas, etc. are included in the appendices. The area, time of concentration, and runoff of each proposed sub-basin is summarized in Appendix A. The following information outlines the basin characteristics and drainage patterns for each basin. Existing Basins The following basins provide proposed drainage delineations for the site in its existing condition. Refer to Appendix A for hydrology computations. Basin EX1 Basin EX1 represents on-site runoff that drains to the existing property to the south and ultimately to the detention pond within Tract A of the Prospect Park East P.U.D. There is a very small portion of this basin that has existing public concrete sidewalk, but the majority of the existing site is undeveloped. Proposed Basins The following basins provide proposed drainage delineations for the site in its improved condition. Refer to Appendix A for hydrology computations and Appendix B for calculations related to Water Quality, Low Impact Development, and other hydraulic features. Basin A Sub-basins A1-A5 (see Drainage Plans attached) include the area of the site being collected by the proposed storm sewer infrastructure and are a majority of the site. These basins consist of roofs, asphalt and concrete paving, and landscaping. Runoff within these basins is conveyed to permeable pavers, grass swales, and a water quality manhole via sheet flow, curb, inlets, and storm sewer. Runoff from these basins is conveyed through the proposed storm sewer to the existing lake/pond across Sharp Point and ultimately released to the Cache La Poudre River. Basin OS1 Basin OS1 represents the portion of the proposed site draining offsite to the south undetained. This basin consists of concrete sidewalk, asphalt pavement, and landscaping. In its improved condition, this basin will continue to function as most of the existing site did with conveying flows offsite to the south property and ultimately to the detention pond within Tract A of the Prospect Park East P.U.D. Detention and Water Quality No formal detention is being provided for the site due to previously discussed site constraints. Although no extended detention is being provided for water quality on the site, water quality is provided and will be achieved largely through the use of permeable pavers (and LID technique) and other treatment techniques that differ from those typically allowed in the P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 6 U22014_Drainage Report Fort Collins Stormwater Criteria Manual. These techniques include grass swales, a water quality manhole, and the use of an existing wet pond (the lake/pond east of the site). As shown in the stormwater variance request submitted with this project, the use of these techniques does meet the requirements set forth in the State MS4 permit. Low Impact Development (LID) In December of 2015, Fort Collins City Council adopted the revised Low Impact Development (LID) policy and criteria which requires developments within City limits to meet certain enhanced stormwater treatment requirements in addition to more standard treatment techniques. The proposed development will be required to meet the newly adopted LID criteria which requires the following: -Treat no less than 75% of any newly added impervious area using one or a combination of LID techniques. -Treat no less than 50% of any newly added impervious area using one or a combination of LID techniques when at least 25% of any newly added pavement is provided with permeable pavement. It should be noted that this project is requesting a variance for lower LID standards due to site constraints and hardships. The following measures are implemented with this proposed development: I.Permeable Paver Water Quality Basins A4 and A5, combined for 23,684-sf of proposed composite impervious area, are designed to be routed through permeable pavers located in the perimeter of the proposed parking area. The proposed impervious area treated through permeable pavers includes proposed parking, driveway, roof areas, and landscaping. Approximately 6,616 sf of impervious area in Basin A4 is proposed to drain to 1,865 sf of permeable pavers. For Basin A5 approximately 11,980 sf of impervious area is proposed to drain to 7,867 sf of permeable pavers. The amount of impervious area “running onto” the paver area within both basins is within the maximum 3:1 ratio as described in City of Fort Collins LID criteria. Additionally, considering all the proposed pavement for the project totals 31,346 sf and permeable paver area totals 9,732 sf, the site proposes to treat approximately 31% of the newly added impervious area with permeable pavers. All permeable paver areas will be designed with underdrains which will be conveyed to the proposed storm sewer onsite. II.Water Quality Manhole Basin A2, accounting for 31,916-sf of proposed composite impervious area (entire roof area), is designed to be conveyed to proposed storm sewer system. The manhole at the downstream end of this basin shall be installed with a stormwater management device attached to the inside of the manhole such as a SAFL Baffle, Snout, or Envirohood. This feature is designed to trap pollutants from stormwater runoff in a manhole and promote the water quality of stormwater being discharged. Although this feature is not a traditional LID or water quality treatment technique approved by the City, it has been shown to improve overall water quality and meet TSS removal thresholds per MS4 requirements. III.Grass Swales Basins A1 and A3, accounting for 3,154-sf of proposed composite impervious area, are designed to be conveyed to grass swales and ultimately to the proposed storm sewer system. The grass swales are proposed to serve as water quality features to disconnect impervious areas and remove pollutants prior to being collected by the storm sewer system and discharging offsite. Although grass swales are not a traditional LID and water quality treatment technique approved by the City, it has been shown to improve overall water quality and meet TSS removal thresholds per MS4 requirements. It should be noted that the grass swales in Basin A3 will be conveyed through the water quality manhole and will be treated further through that water quality feature. Provided the LID measures in the permeable pavers, approximately 37.7% of the site is treated in its improved condition. The 50% requirement for LID treatment will not be met for the site and a separate variance for this has been submitted for this project. Although the grass swales and water quality manhole will provide some water quality treatment, these measures P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 7 U22014_Drainage Report 100-year Event: Proposed Runoff to South Basin Designation Flowrate (cfs) Basin OS1 1.17 are not formally accepted as LID treatment techniques. Refer to Appendix B for LID calculations and Appendix D for a LID Treatment Map. Below is a summary LID treatment table for reference. 75% On-Site Treatment by LID Requirement New or Modified Impervious Area (Total) 1.42 acre Required Minimum Impervious Area to be Treated 0.71 acre Impervious Area Treated by Permeable Pavers 0.54 acre Total Impervious Area Treated 0.54 acre Percent of Impervious Areas Treated by LID 37.7 % Drainage Summary A basin summary table is included below: Existing/Historic Basins Basin Area %I C2 C10 C100 Q2 Q10 Q100 (acre) (cfs) (cfs) (cfs) EX1 2.65 3.8% 0.26 0.26 0.33 1.48 2.53 6.46 Proposed Basins Basin Area %I C2 C10 C100 Q2 Q10 Q100 (acre) (cfs) (cfs) (cfs) A1 0.10 15% 0.34 0.34 0.42 0.08 0.13 0.36 A2 0.81 90% 0.95 0.95 1.00 2.20 3.77 8.10 A3 0.48 12% 0.32 0.32 0.40 0.34 0.59 1.50 A4 0.46 42% 0.53 0.53 0.67 0.52 0.89 2.38 A5 0.58 60% 0.66 0.66 0.83 0.78 1.34 4.45 Total 2.44 52% 0.63 0.63 0.79 2.95 5.05 15.41 OS1 0.22 43% 0.54 0.54 0.68 0.26 0.44 1.17 It should be noted from the proposed basins table that the overall site 100-year C value is 0.79 which is less than the previously planned 100-year C value of 1.00 for Basin J10 in the Advanced Energy buildings 7 and 8 drainage report. Refer to Appendix D for an Existing Drainage Map that provides a visual representation of the proposed drainage basins. In the existing conditions, the site drains undetained to the south and is conveyed to the existing detention pond in Tract A of the Prospect Park East P.U.D. The improved site is designed to convey the 100-yr storm to the east to an existing pond / lake. The tables below summarize the impacts of the proposed improvements vs. existing conditions to property to the south. 100-year Event: Existing Runoff to South In relation to the property to the south, the majority of the site is designed to outfall to the east via proposed storm sewer due to previously discussed site and easement constraints. The tables above show that the proposed site is significantly reducing the amount of stormwater being conveyed to the south from existing conditions and no negatives impacts to the south are anticipated from the proposed improvements. Ultimately all stormwater runoff from this site and surrounding sites will be conveyed to the Cache La Poudre River Basin Designation Flowrate (cfs) Basin EX1 6.46 P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 8 U22014_Drainage Report Standard Operating Procedures (SOPs) In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential. Maintenance includes both routinely scheduled activities, as well as non-routine repairs that may be required after large storms, or as a result of other unforeseen problems. Standard Operating Procedures should clearly identify BMP maintenance responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP. Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either publicly or privately. For this project, the privately owned BMPs including grass swales, permeable pavers, and a water quality manhole are to be maintained by the property owner. Storm Sewers There are multiple storm sewer networks proposed with the site improvements. Several networks including roof drains, storm drains, and underdrain lines for permeable pavers are proposed ultimately with outfalls to the existing pond east of the site. Proposed storm sewer systems are designed to accommodate the flows from the 100-year storm event. Hydraulic computations of these systems are provided in Appendix B. Inlets There are multiple inlets proposed with site improvements, including Nyloplast drain basins and Type R inlets. Type R Inlets are designed in sump to capture developed runoff. On-site drain basins are designed in a sump condition and are designed to convey runoff produced within smaller interior basins to proposed storm sewer and ultimately to the existing lake/pond east of the site. All inlets on the site are sized to provide adequate capacity and convey the 100-year storm event. Hydraulic computations of these systems are provided in Appendix B. V.EROSION CONTROL A separate Erosion Control Report / Storm Water Management Plan (SWMP) will be prepared for the site in accordance with the Stormwater Discharge Permit for Colorado Department of Public Health and Environment as the site will disturb an area greater than 1-acre. The Erosion Control Report will be completed during the Final Compliance phase of the project and will include more detailed information on the sediment and erosion control items for this project. It is intended that the proposed improvements will comply with Erosion Control Criteria per the FCSCM, and all Erosion Control Materials will be provided with the Final Drainage Report. At a minimum, the following temporary BMP’s will be installed and maintained to control on-site erosion and prevent sediment from traveling off-site during construction: Silt Fence – a woven synthetic fabric that filters runoff. The silt fence is a temporary barrier that is placed at the base of a disturbed area. Vehicle Tracking Control – a stabilized stone pad located at points of ingress and egress on a construction site. The stone pad is designed to reduce the amount of mud transported onto public roads by construction traffic. Riprap – Riprap will be used downstream of all storm sewer outfalls to control erosion of the receiving channels. Inlet Protection – acts as a sediment filter. It is a temporary BMP and requires proper installation and maintenance to ensure their performance. Straw Wattles – wattles act as a sediment filter in swales around inlets. They are a temporary BMP and require proper installation and maintenance to ensure their performance. Slope Protection – Slopes should be terraced using a “tracked” vehicle, run perpendicular to slope to inhibit rill/gulley erosion. The contractor shall store all construction materials and equipment and shall provide maintenance and fueling of equipment in confined areas on-site from which runoff will be contained and filtered. Temporary Best Management Practices (BMP’s) will be inspected by the contractor at a minimum of once every two weeks and after each significant storm event. P RELIMINARY D RAINAGE R EPORT P ROSPECT S PORTS F ORT C OLLINS ,CO 9 U22014_Drainage Report VI.CONCLUSIONS A.COMPLIANCE WITH STANDARDS Storm drainage calculations have followed the guidelines provided by the Urban Storm Drainage Criteria Manuals Volumes 1, 2 and 3 and the City of Fort Collins Stormwater Criteria Manual. Moreover, Chapter 10 of the City Code has been adhered to. Detention Pond A1 also adheres to State Senate Bill 15-212 drain time requirements (refer to Appendix C for calculations). B.DRAINAGE CONCEPT The drainage system has been designed to convey the runoff to the designated design points and the existing public infrastructure in an effective, safe manner. No negative impacts are anticipated to the City of Fort Collins Master Drainage Plan or to downstream properties or infrastructure due to the proposed improvements. C.STORMWATER QUALITY Multiple long-term stormwater quality measures have been selected for the site that will provide treatment of stormwater prior to it to being discharged from the site. For this site this includes grass swales, permeable pavers, and a water quality manhole. VII.REFERENCES 1.City of Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, December 2018. 2.Urban Storm Drainage Criteria Manual Volume 1 and 2, Urban Drainage and Flood Control District, Denver, Colorado, June 2001, Revised April 2008. 3.Natural Resources Conservation Service Web Soil Survey at: websoilsurvey.nrcs.usda.gov/app 4.Preliminary Flood Insurance Rate Map, FEMA, Panel 2079E, https://hazards.fema.gov/femaportal/ 5.Stormwater Discharges Associated with Construction Activity, Stormwater Management Plan Preparation Guides, State of Colorado, www.colorado.com 6.Low Impact Development Stormwater Management Planning and Design Guide, Sustainable Technologies Evaluation Program, June 2022. 7.Final Drainage Report and Erosion Control Plan for Advanced Energy Buildings 7 & 8, Park Engineering Consultants, April 1999. A PPENDIX A H YDROLOGY C ALCULATIONS RUNOFF COEFFICIENTS AND % IMPERVIOUS Prospect Sports, Fort Collins, CO Basin Design Pt.Composite Total Total Roof (1)Asphalt Concrete(1)Gravel(1)Lawns(1)Imperviousness C2 C10 C100 acres %I = 90%%I = 100%%I = 100%%I =40%%I=2%(%I) C=0.95 C=0.95 C=0.95 C=0.50 C=0.25 sf sf sf sf sf sf EX1 EX1 2.65 115,512 2,110 113,402 3.8%0.26 0.26 0.33 -0.00 ----- -0.00 ----- -0.00 ----- Basin Design Pt.Composite Total Total Roof (1)Asphalt Concrete(1)Pavers(1)Lawns(1)Imperviousness C2 C10 C100 acres sf %I = 90%%I = 100%%I = 100%%I =40%%I=2%(%I) C=0.95 C=0.95 C=0.95 C=0.50 C=0.25 sf sf sf sf sf A1 A1 0.10 4,361 557 3,804 14.5%0.34 0.34 0.42 A2 A2 0.81 35,462 35,462 -90.0%0.95 0.95 1.00 A3 A3 0.48 21,021 2,144 18,877 12.0%0.32 0.32 0.40 A4 A4 0.46 20,050 3,470 4,020 1,865 10,695 42.1%0.53 0.53 0.67 A5 A5 0.58 25,236 9,859 2,121 7,867 5,390 60.4%0.66 0.66 0.83 -0.00 ----- TOTAL TOTAL 2.44 106,130 35,462 13,329 8,841 48,498 51.9%0.63 0.63 0.79 -0.00 ----- OS1 OS1 0.22 9,382 862 3,059 5,461 43.0%0.54 0.54 0.68 -0.00 ----- -0.00 ----- -0.00 ----- -0.00 ----- -0.00 ----- -0.00 ----- -0.00 ----- Notes: (1) Recommended % Imperviousness Values per Table 4.1-3 Surface Type - Percent Impervious in Fort Collins Stormwater Criteria Manual (2) Runoff C is based Table 3.2-2. Surface Type - Runoff Coefficients and Table 3.2-3. Frequency Adjustment Factors in Fort Collins Stormwater Manual (3) the "Total" basin is an analysis of the routed onsite flows. Areas Composite Runoff Coefficients (2) Composite Runoff Coefficients (2)Areas Existing Basins Proposed Basins (3) Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs TIME OF CONCENTRATION (2-YR) Prospect Sports, Fort Collins, CO Basin Design Pt.Area CXCF(1)Length Slope Ti (2)Slope Length n R Velocity (3)Tt (4)Tc max (5) acres ft %min %ft fps min min min min EX1 EX1 2.65 0.26 200 2.0%80.5 1.0%180 0.035 0.2 1.5 2.1 82.6 11.0 11.0 Basin Design Pt.Area CXCF(1)Length Slope Ti (2)Slope Length n R Velocity (3)Tt (4)Tc max (5) acres ft %min %ft fps min min min min A1 A1 0.10 0.34 19 25.0%9.8 1.5%110 0.016 0.2 3.9 0.5 10.3 10.6 10.3 A2 A2 0.81 0.95 25 12.5%2.8 12.5%140 0.016 0.2 11.3 0.2 3.0 10.8 5.0 A3 A3 0.48 0.32 78 2.5%43.4 2.0%42 0.016 0.2 4.5 0.2 43.6 10.2 10.2 A4 A4 0.46 0.53 25 2.0%19.2 2.0%165 0.016 0.2 4.5 0.6 19.8 10.9 10.9 A5 A5 0.58 0.66 54 2.5%20.4 0.5%284 0.013 0.2 2.8 1.7 22.1 11.6 11.6 TOTAL TOTAL 2.44 0.63 54 2.5%21.8 0.5%634 0.013 0.2 2.8 3.8 25.6 13.5 13.5 OS1 OS1 0.00 0.54 42 4.5%18.8 5.0%51 0.016 0.2 7.1 0.1 18.9 10.3 10.3 Notes: (1) C=CX*CF is less than or equal to 1.0 (Cf = 1.0) (2) ti = [1.87(1.1-CXCF)L1/2]/S1/3, S= slope in %, L=length of overland flow (200' max urban, 500' max rural) (3) V=(1.49/n)R2/3S1/2, S = slope in ft/ft, FCSCM Equation 5-4 (4) tt=L/(V*60 sec/min) (5) Maximum tc = total length/180 + 10 (6) Minimum tc = 5 min Travel/Channelized Time of Flow (Tt) Existing Basins Proposed Basins Overland Flow (Ti)Travel/Channelized Time of Flow (Tt) Ti+Tt Final Tc (6) Ti+Tt Final Tc (6) Overland Flow (Ti) Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs TIME OF CONCENTRATION (10-YR) Prospect Sports, Fort Collins, CO Basin Design Pt.Area CXCF(1)Length Slope Ti (2)Slope Length n R Velocity (3)Tt (4)Tc max (5) acres ft %min %ft fps min min min min EX1 EX1 2.65 0.26 200 2.0%80.5 1.0%180 0.035 0.2 1.5 2.1 82.6 11.0 11.0 Basin Design Pt.Area CXCF(1)Length Slope Ti (2)Slope Length n R Velocity (3)Tt (4)Tc max (5) acres ft %min %ft fps min min min min A1 A1 0.10 0.34 19 25.0%9.8 1.5%110 0.016 0.2 3.9 0.5 10.3 10.6 10.3 A2 A2 0.81 0.95 25 12.5%2.8 12.5%140 0.016 0.2 11.3 0.2 3.0 10.8 5.0 A3 A3 0.48 0.32 78 2.5%43.4 2.0%42 0.016 0.2 4.5 0.2 43.6 10.2 10.2 A4 A4 0.46 0.53 25 2.0%19.2 2.0%165 0.016 0.2 4.5 0.6 19.8 10.9 10.9 A5 A5 0.58 0.66 54 2.5%20.4 0.5%284 0.013 0.2 2.8 1.7 22.1 11.6 11.6 TOTAL TOTAL 2.44 0.63 54 2.5%21.8 0.5%634 0.013 0.2 2.8 3.8 25.6 13.5 13.5 OS1 OS1 0.22 0.54 42 4.5%18.8 5.0%51 0.016 0.2 7.1 0.1 18.9 10.3 10.3 Notes: (1) C=CX*CF is less than or equal to 1.0 (Cf = 1.0) (2) ti = [1.87(1.1-CXCF)L1/2]/S1/3, S= slope in %, L=length of overland flow (200' max urban, 500' max rural) (3) V=(1.49/n)R2/3S1/2, S = slope in ft/ft, FCSCM Equation 5-4 (4) tt=L/(V*60 sec/min) (5) Maximum tc = total length/180 + 10 (6) Minimum tc = 5 min Existing Basins Overland Flow (Ti)Travel/Channelized Time of Flow (Tt) Ti+Tt Final Tc (6) Proposed Basins Overland Flow (Ti)Travel/Channelized Time of Flow (Tt) Ti+Tt Final Tc (6) Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs TIME OF CONCENTRATION (100-YR) Prospect Sports, Fort Collins, CO Basin Design Pt.Area CXCF(1)Length Slope Ti (2)Slope Length n R Velocity (3)Tt (4)Tc max (5) acres ft %min %ft fps min min min min EX1 EX1 2.65 0.41 200 2.0%66.3 1.0%180 0.035 0.2 1.5 2.1 68.4 11.0 11.0 Basin Design Pt.Area CXCF(1)Length Slope Ti (2)Slope Length n R Velocity (3)Tt (4)Tc max (5) acres ft %min %ft fps min min min min A1 A1 0.10 0.53 19 25.0%7.3 1.5%110 0.016 0.2 3.9 0.5 7.8 10.6 7.8 A2 A2 0.81 1.00 25 12.5%1.9 12.5%140 0.016 0.2 11.3 0.2 2.1 10.8 5.0 A3 A3 0.48 0.50 78 2.5%33.4 2.0%42 0.016 0.2 4.5 0.2 33.5 10.2 10.2 A4 A4 0.46 0.84 25 2.0%9.0 2.0%165 0.016 0.2 4.5 0.6 9.6 10.9 9.6 A5 A5 0.58 1.00 54 2.5%4.6 0.5%284 0.013 0.2 2.8 1.7 6.3 11.6 6.3 TOTAL TOTAL 2.44 0.98 54 2.5%5.4 0.5%634 0.013 0.2 2.8 3.8 9.2 13.5 9.2 OS1 OS1 0.22 0.85 42 4.5%8.5 5.0%51 0.016 0.2 7.1 0.1 8.6 10.3 8.6 Notes: (1) C=CX*CF is less than or equal to 1.0 (Cf = 1.25) (2) ti = [1.87(1.1-CXCF)L1/2]/S1/3, S= slope in %, L=length of overland flow (200' max urban, 500' max rural) (3) V=(1.49/n)R2/3S1/2, S = slope in ft/ft, FCSCM Equation 5-4 (4) tt=L/(V*60 sec/min) (5) Maximum tc = total length/180 + 10 (6) Minimum tc = 5 min Existing Basins Overland Flow (Ti)Travel/Channelized Time of Flow (Tt) Ti+Tt Final Tc (6) Proposed Basins Overland Flow (Ti)Travel/Channelized Time of Flow (Tt) Ti+Tt Final Tc (6) Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs RATIONAL METHOD PEAK RUNOFF Prospect Sports, Fort Collins, CO Basin Design Pt.Contributing Area 2-Year 100-Year Basins acre tc tc C2 C10 C100 I2 I10 I100 Q2 Q10 Q100 min min in/hr in/hr in/hr cfs cfs cfs EX1 EX1 EX1 2.65 11 11 0.26 0.26 0.33 2.13 3.63 7.42 1.48 2.53 6.46 Basin Design Pt.Contributing Area 2-Year 100-Year Basins acre tc tc C2 C10 C100 I2 I10 I100 Q2 Q10 Q100 min min in/hr in/hr in/hr cfs cfs cfs A1 A1 A1 0.10 10 8 0.34 0.34 0.42 2.21 3.78 8.38 0.08 0.13 0.36 A2 A2 A2 0.81 5 5 0.95 0.95 1.00 2.85 4.87 9.95 2.20 3.77 8.10 A3 A3 A3 0.48 10 10 0.32 0.32 0.40 2.21 3.78 7.72 0.34 0.59 1.50 A4 A4 A4 0.46 11 10 0.53 0.53 0.67 2.13 3.63 7.72 0.52 0.89 2.38 A5 A5 A5 0.58 12 6 0.66 0.66 0.83 2.05 3.50 9.31 0.78 1.34 4.45 TOTAL TOTAL TOTAL 2.44 14 9 0.63 0.63 0.79 1.92 3.29 8.03 2.95 5.05 15.41 OS1 OS1 OS1 0.22 10 9 0.54 0.54 0.68 2.21 3.78 8.03 0.26 0.44 1.17 (1) the "Total" basin is an analysis of the routed onsite flows. Existing Basins Peak Discharge Proposed Basins Runoff Coefficients Rainfall Intensity Peak Discharge Rainfall IntensityRunoff Coefficients (1) Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs A PPENDIX B H YDRAULIC C ALCULATIONS WATER QUALITY Prospect Sports, Fort Collins, CO Required Water Quality Capture Volume Basin Area Area Imperviousness Watershed WQCV WQ Treatment (sf)(acres)(%)(inches)(cf)Method A1 4,361 0.100 15%0.07 32 Grass Swale A2 35,462 0.814 90%0.32 1,139 Snout Manhole A3 21,021 0.483 12%0.06 131 Grass Swale A4 20,050 0.460 42%0.15 298 Pavers A3 25,236 0.579 60%0.19 479 Pavers TOTAL 106,130 2.436 52%0.17 1,795 OS1 9,382 0.215 43%0.15 141 None Water quality provided based on 12-hour storage Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs LOW IMPACT DEVELOPMENT SUMMARY Prospect Sports, Fort Collins, CO Basin Proposed Impervious Area LID Treatment Area Treated % of Site Treated (sf)(acres)(sf)(%) A1 633 Grass Swale 0 0.0% A2 31,916 Snout Manhole 0 0.0% A3 2,522 Grass Swale 0 0.0% A4 8,450 Pavers 8,450 13.5% A5 15,234 Pavers 15,234 24.3% OS1 4,030 None 0 0.0% Total New/Modified Site 62,785 23,684 37.7% Low Impact Development (LID) Treated Areas Date: 5/23/2023 C:\United Civil Dropbox\Projects\U22014 - Prospect Park East\Reports\Drainage\Calculations\U22014-Drain Calcs A PPENDIX C R EFERENCED M ATERIALS V ARIANCE R EQUEST P ROSPECT P ROPERTIES B ASKETBALL F ACILITY F ORT C OLLINS ,CO 19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com May 30, 2023 DAN MOGEN 700 WOOD STREET FORT COLLINS,CO 80522 RE: STORMWATER VARIANCE REQUEST PROSPECT PROPERTIES BASKETBALL FACILITY –1600 EAST PROSPECT ROAD PROJECT NUMBER:U20017 Dan, This letter is being submitted on behalf of the owners of the Prospect Properties Basketball Facility development. The project is currently in the Preliminary Development Plan process and currently one (1) variance is being requested to modify portions of the Fort Collins Stormwater Criteria Manual as follows: VARIANCE REQUEST –STORMWATER QUALITY AND LOW IMPACT DEVELOPMENT STANDARDS DESIGN CRITERIA OF VARIANCE BEING REQUESTED Section 1.0 within the Fort Collins Stormwater Criteria Manual which states: FCU requires that water quality treatment systems for stormwater are installed for all applicable development sites, including the incorporation of enhanced water quality treatment for stormwater, which has been required since 2013. Section 6.0 within the Fort Collins Stormwater Criteria Manual which states: Integration of LID systems into the drainage design is required for all development projects in order to comply with the City’s policies on LID, the requirements of this Manual, the City Code and the Land Use Code. LID systems provide a higher degree of stormwater quality treatment than that provided with standard water quality design. The implementation of LID systems requires one of the following two options: 1)50% of the newly added or modified impervious area must be treated by LID techniques and 25% of new paved (vehicle use) areas must be pervious. 2)75% of all newly added or modified impervious area must be treated by LID techniques. HARDSHIP REGARDING REQUIREMENT The site is located at 1600 East Prospect Road within Prospect Park East P.U.D and is surrounded by existing fully developed commercial properties to the south (Advanced Energy) and west (Larimer County Coroner) along with Prospect Road and Sharp Point to the north and east respectively. The original subdivision development planned for drainage to be conveyed via overland flow to the drainage facility located south of the site; therefore, no storm sewer currently exists on the site. Additionally, the development team has worked with the property owner south of the site to determine if improvements and/or easements/agreements could be made for the following purposes: Extension of an existing emergency and vehicular access on the Advanced Energy property immediately south of the site to provide access and emergency access to the western third of the site. Shared parking agreement. Drainage easements from the site to the existing detention pond area south of the property. V ARIANCE R EQUEST P ROSPECT P ROPERTIES B ASKETBALL F ACILITY F ORT C OLLINS ,CO 19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com After discussion with the south property owner and their attorney, the southern property owner has denied any new easements on the Advanced Energy property but will honor the existing access easement that allows for access, emergency access and limited work within the easement. Thus, the site plan is arranged with the building to the east and the parking to the west accessed from the existing easement. Additionally, storm sewer for the project will be required to convey both water quality and 100-year developed stormwater flows from the site to the east of Sharp Point to the existing property also owned by the developer of the basketball facility to avoid the need for drainage easements south of the site. These site and storm sewer configurations generated by the design of the existing subdivision and the inability to modify the southern property easements/agreements culminate into hardships with providing standard water quality and LID treatment techniques that are approved by the City: 1.Standard water quality by way of extended detention is not viable due to space and grade limitations on the site. Note that the open landscaped area north of the building is located within an existing pedestrian easement and is also located on the high side of the property. 2.Underground detention/infiltration is not viable in the parking lot area due to available depths of storm sewer, is not viable on the south or east due to the proximity of the proposed building to the property line and is likely not viable on the north due to lack of access for maintenance. 3.Bioretention for the development is largely not viable due to the lack of space to provide the feature. Although there is potentially room north of the building, the amount of impervious area that would drain to the area is limited to small portions of hardscape due to grade limitations. Additionally, this area is located on the north side of the building, during winter months it is probable that roof drainage if allowed to pond on frozen bioretention areas would not infiltrate causing maintenance and safety concerns. PROPOSED ALTERNATE DESIGN The development team understands that water quality is an important aspect of every new development, not only to simply meet City standards, but to protect downstream infrastructure and environments. Therefore, the design team is requesting that the development, due to the hardships documented, is allowed to meet reduced or modified water quality and LID treatment requirements and allowed to provide treatment techniques that differ from those typically allowed in the Fort Collins Stormwater Criteria Manual. With that basis, the development team proposes to provide the following: 1.Provide grass lined swales and low points along the north side of the building within Basins A1 and A3 to provide, albeit non-standard / non-quantitative, water quality treatment for limited hardscape to be located on the north side of the building. These areas are then collected via storm sewer, conveyed through a water quality manhole containing a Snout® and sump, and discharged to the privately owned wet pond to the east across Sharp Point. These basins, being largely landscaped, will generate minimal pollutants on the site; however, are proposed to be fully treated with multiple stages of treatment. 2.Provide permeable pavers within the parking lot as depicted in the Preliminary Development Plans. Approximately, 9,700 square-feet of permeable pavers are provided which is sufficient to treat the entirety of the parking lot and plaza areas that drain to the pavers within Basins A4 and A5. The parking area will generate the most pollutants from the site and will be fully treated with the paver system. 3.Conserve the existing low point located on the property to the south between the shared property line and the drive lane to the south. This area exists and currently serves as a naturally vegetated area collecting stormwater runoff with a maximum depth of approximately 12-inches. The design team proposes to allow only minor site areas consisting of sidewalks and landscaped areas adjacent to the building and located within Basin OS2 to drain to this existing low area acting as a vegetative buffer and infiltration treatment of runoff prior to allowing larger storm events to overtop and drain via historic patterns to the detention facility south of the property. 4.Collect the proposed building roof drainage within Basin A2, designed to discharge towards the north and directly into a proposed storm sewer system. Flows from this Basin are then conveyed through a water quality manhole containing a Snout® and sump and discharged to the privately owned wet pond to the east across Sharp Point. This basin, containing the entire roof area, will generate less pollutants than those expected in the parking area; however, will be treated with multiple stages of treatment that will provide removal rates satisfying the State’s MS4 permit. See the following section of this variance for additional detail regarding removal rates pertaining to this basin. V ARIANCE R EQUEST P ROSPECT P ROPERTIES B ASKETBALL F ACILITY F ORT C OLLINS ,CO 19 OLD TOWN SQUARE #238 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com Per State of Colorado MS4 Permit requirements related to Basins A2 and A3 improvements, the following “Pollutant Removal Standard” criterion is analyzed with this variance request: The control measure(s) is designed to treat at a minimum the 80th percentile storm event. The control measure(s) shall be designed to treat stormwater runoff in a manner expected to reduce the event mean concentration of total suspended solids (TSS) to a median value of 30 mg/L or less. A Nationwide Urban Runoff Program (US EPA 1983) land use table regarding event mean concentrations is utilized for the purposes of measuring median event mean concentrations of total suspended solids (TSS) assuming the site is included as an urban commercial development. Per Table 4-1 of the EPA report, attached to this variance, a concentration of 69 mg/l is assumed for urban commercial improvements. Basins A2 and A3 are proposed to be treated first with a Snout located on the sports facility property and subsequently with a private wet pond located on the owner’s property located east of Sharp Point. Per 3rd party performance testing, Snouts provide a TSS pollutant removal rate ranging between 53%-85%. Per a National Pollutant Removal Performance Database, a wet pond provides a removal rate for TSS pollutants of 80%. Documents regarding these removal rates can be found in the Appendix of this Variance Request. Using these rates and a starting concentration of 69 mg/l, the Snout lowers TSS concentrations to 32.4 mg/l assuming the most conservative removal rate of 53%. The subsequent treatment within the wet pond provides for a final TSS concentration of 6.5 mg/l prior to allowing runoff being conveyed to the Poudre River. As the vast majority of the proposed site is being treated for water quality and that the treatment techniques proposed are either accepted by the City of Fort Collins or are shown within this variance to remove total suspended solids to levels acceptable to the State of Colorado MS4 permit, the design team anticipates that the alternative compliance proposed with this variance request will not have a negative impact on City infrastructure, downstream properties or the safety of the public. On behalf of the owners of the Prospect Properties Basketball Facility and the design team, we thank you for the consideration of this variance request. If you should have any questions or comments regarding this request, please feel free to contact us at your convenience. Sincerely, United Civil Design Group, LLC Kevin Brazelton, PE Principal APPENDIX A – Referenced Materials 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 Prospect Sports Natural Resources Conservation Service May 10, 2023 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 6—Aquepts, ponded....................................................................................13 64—Loveland clay loam, 0 to 1 percent slopes...........................................14 92—Riverwash............................................................................................15 References............................................................................................................16 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 449062044906404490660449068044907004490720449062044906404490660449068044907004490720497310 497330 497350 497370 497390 497410 497430 497450 497470 497490 497310 497330 497350 497370 497390 497410 497430 497450 497470 497490 40° 34' 2'' N 105° 1' 54'' W40° 34' 2'' N105° 1' 46'' W40° 33' 58'' N 105° 1' 54'' W40° 33' 58'' N 105° 1' 46'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 40 80 160 240 Feet 0 10 20 40 60 Meters Map Scale: 1:863 if printed on A landscape (11" x 8.5") 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 17, Sep 7, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 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 6 Aquepts, ponded 0.6 21.8% 64 Loveland clay loam, 0 to 1 percent slopes 1.1 42.8% 92 Riverwash 0.9 35.4% Totals for Area of Interest 2.7 100.0% 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 Custom Soil Resource Report 11 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. 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 6—Aquepts, ponded Map Unit Setting National map unit symbol: jpx4 Elevation: 4,500 to 6,700 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 39 to 50 degrees F Frost-free period: 80 to 140 days Farmland classification: Not prime farmland Map Unit Composition Aquepts, ponded, and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Aquepts, Ponded Setting Landform:Draws, channels, drainageways Landform position (three-dimensional):Base slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Variable alluvium Typical profile H1 - 0 to 60 inches: variable Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Very poorly drained Runoff class: Negligible Capacity of the most limiting layer to transmit water (Ksat):Moderately high to very high (0.60 to 99.90 in/hr) Depth to water table:About 0 to 18 inches Frequency of flooding:NoneFrequent Frequency of ponding:None Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8w Hydrologic Soil Group: A/D Hydric soil rating: Yes Minor Components Nunn Percent of map unit:10 percent Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 13 64—Loveland clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: jpx9 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 Loveland and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Loveland Setting Landform:Flood plains, stream terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium Typical profile H1 - 0 to 15 inches: clay loam H2 - 15 to 32 inches: loam H3 - 32 to 60 inches: very gravelly sand Properties and qualities Slope:0 to 1 percent Depth to restrictive feature:More than 80 inches Drainage class:Poorly drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately high (0.20 to 0.60 in/hr) Depth to water table:About 18 to 36 inches Frequency of flooding:OccasionalNone Frequency of ponding:None Calcium carbonate, maximum content:15 percent Maximum salinity:Very slightly saline to slightly saline (2.0 to 4.0 mmhos/cm) Available water supply, 0 to 60 inches: Moderate (about 7.5 inches) Interpretive groups Land capability classification (irrigated): 3w Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C Ecological site: R067BY036CO - Overflow Hydric soil rating: No Custom Soil Resource Report 14 Minor Components Aquolls Percent of map unit:5 percent Landform:Swales Hydric soil rating: Yes Poudre Percent of map unit:5 percent Ecological site:R067BY036CO - Overflow Hydric soil rating: No 92—Riverwash Map Unit Composition Riverwash:100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Riverwash Interpretive groups Land capability classification (irrigated): 8 Land capability classification (nonirrigated): 8 Hydric soil rating: No Custom Soil Resource Report 15 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 16 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 17 National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 9/16/2022 at 3:11 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 105°2'10"W 40°34'13"N 105°1'33"W 40°33'46"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020 This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Jul-06-2022 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA A PPENDIX D D RAINAGE E XHIBITS E. PROSPECT R O A D SHARP POINT DR.EXISTING BUILDING LOT 6 PROSPECT PARK EAST P.U.D. LOT 4 PROSPECT PARK EAST P.U.D. TRACT "A" PROSPECT PARK EAST P.U.D. PROPOSED BUILDING FFE = 4903.50 (NORTH) FFE = 4899.00 (GYM / SOUTH) LOT 5 PROSPECT PARK EAST P.U.D. GRASS SWALE GRASS SWALE GRASS SWALE GRASS SWALE EXISTING LAKE/POND STORM SEWER STORM SEWER PAVER SYSTEM DRAIN PERMEABLE PAVERS (TYP.) STORM SEWER 2' CURB CUT PAVER SYSTEM DRAIN PAVER SYSTEM DRAIN AREA INLET AREA INLET AREA INLET CULVERT AREA INLET FLARED END SECTION CURB INLET POUDRE RIVER 100-YR FLOODPLAIN POUDRE RIVER 100-YR FLOODPLAIN POUDRE RIVER 500-YR FLOODPLAIN FLOODPLAIN CR O S S S E C T I O N " B I " 100-YEAR FLOOD E L E V A T I O N - 4900 (NAVD 88) FLOODPLAIN CROSS SECTION 100-YEAR FLOOD ELEVATION - 4904 (NAVD 88) FLOODPLAIN CROSS SEC T I O N 100-YEAR FLOOD ELEVATI O N - 4901 (NAVD 88) LIMITS OF DISTURBANCE LIMITS OF DISTURBANCE ROOF DRAIN (TYP.) DP A5 DP A4 DP A3 DP OS1 DP A1 OS1 0.22 A5 0.58 A4 0.46 A2 0.81 A3 0.48 A1 0.10 STRUCTURAL RETAINING WALL (SEE STRUCTURAL PLANS) 0 30'60' SCALE: 1" = 30' 15'NORTH 5/31/202310:42:34 AMC:\UNITED CIVIL DROPBOX\PROJECTS\U22014 - PROSPECT PARK EAST\CADD\CP\C5.00 - DRAINAGE PLAN.DWGC5.00 - DRAINAGE PLAN--------PROPOSED MAJOR CONTOUR PROPOSED MINOR CONTOUR LEGEND EXISTING MAJOR CONTOUR EXISTING MINOR CONTOUR EXISTING PROPERTY BOUNDARY RIGHT OF WAY XX.X X BASIN DESIGNATION BASIN AREA (ACRE) PROPOSED BASIN PROPOSED BASIN LINE 1.THE TOP OF FOUNDATION ELEVATIONS SHOWN ARE THE MINIMUM ELEVATIONS REQUIRED FOR PROTECTION FROM THE 100-YEAR STORM. MINIMUM FINISHED FLOOR ELEVATIONS ABOVE THE 100-YEAR WATER SURFACE IN STREETS, CHANNELS, DITCHES, SWALES, OR OTHER DRAINAGE FACILITIES, AS ILLUSTRATED BY A MASTER GRADING PLAN ARE TO BE SHOWN. NOTES 1.PORTIONS OF THIS PROJECT ARE LOCATED WITHIN A FEMA-REGULATORY 100-YEAR FLOODPLAIN FOR THE CACHE LA POUDRE RIVER AND IS SUBJECT TO THE REQUIREMENTS OF CHAPTER 10 OF THE CITY CODE. 2.THE FIRST FLOOR OF THE PROPOSED COMMERCIAL BUILDING IS BEING ELEVATED A MINIMUM OF 24-INCHES ABOVE THE BASE FLOOD ELEVATION OR FLOOD PROOFED. REFER TO ARCHITECTURAL PLANS FOR FLOOD PROOFING DETAILS AND SPECIFICATIONS. ALL FLOOD PROOFING MEASURES SHALL ADHERE TO SECTION 10-38 OF CITY CODE AND THE REQUIREMENTS SET FORTH WITHIN THE CITY'S "FLOODPROOFING GUIDELINES". A FLOOD PROOFING CERTIFICATE WILL BE REQUIRED PRIOR TO THE ISSUANCE OF A CERTIFICATE OF OCCUPANCY. 3.THE DEVELOPER SHALL OBTAIN A FLOODPLAIN USE PERMIT FROM THE CITY OF FORT COLLINS AND PAY ALL APPLICABLE FLOODPLAIN USE PERMIT FEES PRIOR TO COMMENCING ANY CONSTRUCTION ACTIVITY (DEMOLITION, EARTHWORK, BUILDING OF STRUCTURES, PARKING LOTS, UTILITIES, LANDSCAPED AREAS, ETC.) WITHIN THE POUDRE RIVER 100-YEAR FLOODPLAIN LIMITS. 4.ALL SPOT ELEVATIONS AND BASE FLOOD ELEVATIONS AS SHOWN ON THIS DRAWING ARE PER VERTICAL CONTROL DATUM NAVD 88. 5.NO STORAGE OF MATERIAL OR EQUIPMENT MAY OCCUR AT ANY TIME IN THE FLOODPLAIN BEFORE, DURING OR AFTER CONSTRUCTION. 6.ANY ITEMS LOCATED IN THE FLOODPLAIN THAT CAN FLOAT (E.G. PICNIC TABLE, BIKE RACKS, ETC.) MUST BE ANCHORED. FLOODPLAIN NOTES DESIGN / CONCENTRATION POINT FLOW DIRECTION DP 1 A A 1 2 3 4 5 1 2 3 4 5 PROJECT INFORMATIONSHEET INFORMATIONPROJECT PHASEARCHITECTSEALISSUE DATE: PROJECT #:CONSULTANTB C D A B C D T - 970.484.0117 F - 970.484.0264 315 East Mountain Ave Suite 100 Fort Collins, CO 80524-2913 © 2015 www.rbbarchitects.com ARCHITECTS REVISIONS: 2204PROSPECT SPORTSCLUBMAX WEST INC.PROJECTDEVELOPMENTPLAN05/31/20231600 EAST PROSPECT ROADFORT COLLINS, CO 80525DESCRIPTION DATE CIVIL ENGINEERING & CONSULTING UNITED CIVIL Design Group 19 OLD TOWN SQUARE #238 FORT COLLINS, CO 80524 (970) 530-4044 www.unitedcivil.com PROJ. MGR:DRAWING NAME:PATH:DESIGNER:DATE:TIME:C5.00 DRAINAGE PLAN NOTE: 1.THE TYPICAL FOUNDATION DETAIL IS SHOWN FOR REFERENCE ONLY AND IS NOT A CONSTRUCTION DETAIL. ADDITIONAL WATERPROOFING MEMBRANE AND DRAINAGE MATERIAL WILL BE REQUIRED BUT NOT SHOWN ON THIS DETAIL. CONTRACTOR SHALL REFER TO APPROVED ARCHITECTURAL AND STRUCTURAL DRAWINGS FOR ALL FOUNDATION AND BUILDING DETAILS. 2.LOCATION OF HVAC EQUIPMENT IS TO BE LOCATED ON THE ROOF OF THE BUILDING. 3.FLOODPROOFING DETAILS WILL BE PROVIDED DURING BUILDING PERMIT REVIEW. CONCRETE SIDEWALK SOUTH WALL TYPICAL FOUNDATION DETAIL NTS CONCRETE SPREAD FOOTING PER STRUCTURAL DRAWINGS LOWER FFE=4899.00 (NAVD-88)FINISHED GRADE VARIES 100-YEAR BFE=4901.00 (NAVD-88) FLOOD PROOFING ELEV.=4903.00 (MIN.) (NAVD-88) PRE-CAST CONCRETE WALL 12" BITUTHENE (WATERPROOFING MEMBRANE) STRIP BITUTHENE (WATERPROOFING MEMBRANE)