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Home My WebLink AboutHEARTSIDE HILL RESIDENTIAL DEVELOPMENT - FDP230007 - DOCUMENT MARKUPS - ROUND 2 - DRAINAGE REPORT FINAL DRAINAGE REPORT FOR Heartside Hill Prepared by: Highland Development Services 6355 Fairgrounds Ave, Suite 100 Windsor, Colorado 80550 Phone: 970.674.7550 Prepared for: CARE Housing, Inc. 1303 W. Swallow Road Fort Collins, CO 80525 Office: 970.282.7522 February 22, 2023 Job Number 21-1045-00 Highland Development Services, Inc. 6355 Fairgrounds Avenue, Suite 100 | Windsor, CO 80550 | 970.674.7550 February 22, 2023 Mr. Matt Simpson, P.E. Fort Collins Utilities – Stormwater Department 700 Wood Street Fort Collins, CO 80522 RE: Final Drainage Report for Heartside Hill Fort Collins Stormwater Department, We are pleased to submit for your review, the Final Drainage Report for the Heartside Hill affordable residential housing project. This report describes the drainage design in accordance with the City of Fort Collins Stormwater Criteria Manual. We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Sincerely, Highland Development Services Jason T. Claeys, P.E., LEED AP Page i TABLE OF CONTENTS Table of Contents ............................................................................................................................. i Engineer Certification ......................................................................................................................ii General Description and Location .................................................................................................. 1 Site Description and Location ...................................................................................................... 1 Site Soils ....................................................................................................................................... 2 Storm Drainage Criteria .................................................................................................................. 3 Hydrologic Criteria ....................................................................................................................... 3 Hydraulic Criteria ......................................................................................................................... 3 Drainage Basins ............................................................................................................................... 4 Drainage Facility Design .................................................................................................................. 5 Drainage Conveyance Design ...................................................................................................... 5 Detention/Water Quality Pond Design ....................................................................................... 5 Low Impact Development ............................................................................................................... 6 Stormwater Pollution Prevention ................................................................................................... 8 Conclusions ..................................................................................................................................... 9 References .................................................................................................................................... 10 Appendix ....................................................................................................................................... 11 Appendix A – Site Descriptions, Characteristics, & References .................................................. A Appendix B – Rational Calculations ............................................................................................. B Appendix C – Pond Calculations .................................................................................................. C Appendix D – Low Impact Development Calculations ................................................................ D Appendix E – Inlet, Pipe, & Swale Capacity Calculations ............................................................ E Page ii ENGINEER CERTIFICATION I hereby certify that this report (plan) for the final drainage design of Heartside Hill was prepared by me (or under my direct supervision) in accordance with the provisions of the City of Fort Collins Stormwater Criteria Manual and Construction of Public and Private Improvements for the Responsible Parties thereof. I understand that the City of Fort Collins does not and shall not assume liability for drainage facilities designed by others. ________________________________________ Jason T. Claeys, PE Registered Professional Engineer State of Colorado No. 42122 Page 1 GENERAL DESCRIPTION AND LOCATION SITE DESCRIPTION AND LOCATION The project site is situated in the southeast quarter of Section 12, Township 6 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, in the State of Colorado. The property consists of Lots 1 and 2, Block 1 of the Heart of the Rockies Second Subdivision, dated June 9, 1999. Heartside Hill is located within Lot 2, at the northwest corner of the intersection of S. Lemay Ave. and E. Trilby Rd. Lot 1 contains the existing Heart of the Rockies Christian Church. It is bounded by private residential lots to the north and west, E. Trilby Rd. to the south, and S Lemay Ave to the east. The existing church facilities are anticipated to remain. The site area is currently undeveloped and is approximately 8.84 acres. The development would consist of up to 72 CARE Housing for rent apartment units ([6] 12-unit buildings), 9 Habitat for Humanity (H4H) single-family detached lots, 2 L’arche group homes, and a planned shared community center to be designed and constructed at a future date. The project is anticipated to be completed in a single phase. The project site generally slopes from the southwest to the northeast at approximately 4% toward an existing pond at the northeast of the property. Storm runoff is currently conveyed from a grate inlet in the pond to a ditch along the east side of the property and into the existing storm drain sewer. The existing project site is approximately 0.0% impervious. No wetlands are located within the area of proposed development. The project site is not located within the FEMA floodway or floodplain and is within the non- printed FEMA FIRM panel 08069C1200F, effective 12/19/2006. The site is also not located within the City of Fort Collins floodplain. The proposed development includes six multi-family buildings with a clubhouse along with eleven low-income housing lots. The required parking areas, driveways, sidewalks, and open space are also included in the development. A rain garden is proposed to provide the stormwater quality enhancement requirement as a low impact development technique. The site was previously analyzed within the “Drainage Investigation for Heart of the Rockies Christian Church,” prepared by Messner Engineering, Inc., dated June 29, 1999. Page 2 SITE SOILS The Heatside Hill project site consists primarily of Renohill clay loam and a small portion of Longmont clay and are both classified as Type D hydrologic group. According to USDA/Natural Resource Conservation Group, Type D soils a have very slow infiltration rate when thoroughly wet. These soils consist chiefly of clays that have a high shrink-swell potential, soils that have a high-water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils also have a very slow rate of water transmission. Per the “Preliminary Geotechnical Subsurface Exploration Report, Proposed Residential Development Lots 1 and 2, Heart of the Rockies Second Subdivision”, prepared by Soilogic, Inc. dated August 13, 2021: “The subsurface materials encountered in the completed site borings were quite variable across the site, but generally consisted of a thin mantle of vegetation and topsoil underlain by brown/beige/rust lean clay with varying amounts of sand. A portion of the near-surface lean clay encountered at the location of boring B-2 extending to a depth of about 3 to 4 feet below ground surface was somewhat mottled in color, appeared to contain bedrock fragments and was identified as possible existing fill material which may have been placed to develop present site grade. In general, the lean clay varied from medium stiff to very stiff in terms of consistency, exhibited variable swell potential (ranging from none to very high) at current moisture and density conditions and extended to depths between 2½ to 18 feet below present site grade, where it was underlain by brown/olive/beige/gray/rust interbedded claystone/siltstone/ sandstone bedrock of varying composition. The bedrock varied from weathered to very hard in terms of hardness, also exhibited variable swell potential (ranging from low to high) at in-situ moisture and density conditions and extended to the bottom of each boring at depths ranging from approximately 15 to 30 feet below present site grades. In general, we judge the bedrock unit underlying the site to possess moderate to high swell potential overall.” Groundwater was also observed during the subsurface soil exploration: “Groundwater was measured in borings B-1, B-2, B-3 and B-6 at depths between about 13 and 27 feet below ground surface, but was not encountered in any of the remaining site borings to the depths explored when checked immediately after completion of drilling. When checked seven (7) days after drilling, groundwater was measured in all borings with the exception of boring B-3 at depths between about 5 and 15 feet below ground surface. The ground surface in the area of boring B-3 had been disturbed, such that subsequent groundwater level measurements could not be completed.” Page 3 STORM DRAINAGE CRITERIA This drainage report was prepared to meet or exceed the City of Fort Collins Stormwater Criteria Manual. The Criteria Manual and amendments to the Urban Drainage Flood Control District’s (UDFCD) Drainage Criteria Manual (USDCM) Volumes 1, 2 and 3 were referenced as guidelines for this design. HYDROLOGIC CRITERIA The rational method was performed to calculate the peak runoff rates for each basin. Percent imperviousness and runoff coefficients were calculated for each basin using the surface characteristics of each basin. The time of concentration was calculated using City of Fort Collins initial time of concentration and the intensity was calculated using the corresponding storm rainfall depth and the City of Fort Collins’ Intensity-Duration-Frequency Curve. The City of Fort Collins area has a 2-yr, 1-hr rainfall depth of 0.82 inches and a 100-yr, 1-hr rainfall depth of 2.86 inches. These depths do account for the 1999 adjusted rainfall depths. HYDRAULIC CRITERIA The Heartside Hill storm drainage system will been designed to convey the minor and major storm events through the combination of private drives, storm sewer pipes and swales. Runoff flows determined with the rational method will be attenuated through the site. Inlet capacities will be calculated using UDFCD’s spreadsheet UD-Inlet_v4.05.xlsm. The Autodesk Hydraflow Express program will be used to compute the open channel hydraulics and check the capacities of the drainage swales throughout the site. Flow velocities within these swales will be reviewed and where flows are found to be supercritical, the swales will be lined with turf reinforcement mat. All swale and pipe outlets will be protected with riprap or suitable erosion protection methods. Storm sewer pipe outlets will be protected using the requirements set by the USDCM for the protection downstream of culverts. All supporting calculations are located in the Appendix. Page 4 DRAINAGE BASINS The Heartside Hill developed drainage basins are delineated by areas draining through the site. The drainage basins are placed to limit the runoff flowing from the site into Brittany Street. The site is broken into 3 main drainage systems: Drainage Basin D1: Drainage Basin D1 has an approximate area of 3.74 acres and is approximately 39.8% impervious. This basin consists of a portion of the existing church property and building, the future community center, the H4H single-family lots, and the park and open space. Runoff is conveyed via swales to a curb cut and is conveyed through Rain Garden D1 to detention Pond D. Drainage Basin D2: Drainage Basin D2 has an approximate area of 4.65 acres and is approximately 37.9% impervious. This basin consists of six low-income housing lots, private drives, parking areas, and detention Pond D. Runoff is conveyed to Pond D via swales, culverts and curb & gutter. Sub- Basins D2a, D2b, D2c, and D2d divide the overall Basin D2 for conveyance element sizing and capacity confirmation. Drainage Basin OS1: Drainage Basin OS1 pertains to the drainage from the existing improvements in Lot 1. This basin has an approximate area of 2.03 acres and is approximately 65.4% impervious. This basin consists of half of the existing church building, private drives, parking areas, and open space. Runoff is conveyed via roadways to a swale and to Rain Garden OS1 and ultimately to detention Pond D. Page 5 DRAINAGE FACILITY DESIGN DRAINAGE CONVEYANCE DESIGN Storm infrastructure to convey runoff will include swales, inlets, and storm sewer pipes. Stormwater detention and water quality enhancement are achieved through the use of detention Pond D and Rain Garden D1. DETENTION/WATER QUALITY POND DESIGN An extended detention basin, Detention Pond D, will be utilized as the detention and water quality facility for Heartside Hill. For the preliminary drainage study, the FAA method was used to determine the detention volume needed. UDFCD is referenced for the standard water quality capture volume (WQCV) with a 40-hr drain time. Below is a brief summary of the proposed design for the pond: Pond D: Extended detention basin for both Lots 1 and 2 with standard water quality treatment. A 100-yr orifice plate maximizes volume in the pond and restricts release rate into the existing stormwater system. The existing 100-yr release rate into the existing stormwater system is 13.2 cfs according to the Drainage Investigation for Heart of the Rockies Christian Church, prepared by Messner Engineering, Inc (Revised June 29, 1999). The 100-yr water surface elevation is 4911.03 feet, with a maximum depth in the pond of 3.28 feet. During an event that exceeds the 100-yr storm, or the pond outlet should be obstructed, overtopping will occur along on the east side of the pond into Lemay Ave. Pond Summary Table Pond 100- yr Peak Inflow (cfs) 100-yr Peak Release (cfs) WQCV (ac-ft) Detention Volume (ac-ft) Combined Volume (ac-ft) Total Volume Provided (ac-ft) Pond Bottom (ft) WQCV WSE (ft) 100-yr WSE (ft) Max Depth (ft) Pond D 44.16 13.20 0.08 0.82 0.90 1.46 4907.75 4908.86 4911.03 3.28 Page 6 LOW IMPACT DEVELOPMENT The City of Fort Collins updated the Low Impact Development ordinance in 2016 (Ordinance No. 007, 2016) to require: · Treat at least 75% of any newly developed or redeveloped impervious area using one or a combination of LID techniques, or · Treat at least 50% of any newly developed or redeveloped impervious area using one or a combination of LID techniques when 25% of private driveable surfaces are permeable. To satisfy the required implementation of Low Impact Development (LID) techniques, Heartside Hill utilizes two (2) a bioretention ponds, Rain Garden D1 and Rain Garden OS1. Due to site constraints and the inability to treat the required amount of newly developed impervious area, the Rain Garden D1 is designed to treat a portion of the newly developed impervious area able to be directed to the bioretention pond, and Rain Garden OS1 is designed to treat the existing church impervious area. The rain gardens are designed to treat the total drainage area being directed to the rain garden. The result is that with the combination of both rain gardens, an equivalent of 83% of the total onsite impervious area is treated by a LID feature. The water quality capture volume provided within the LID features is: Rain Garden D1 is 2,914 cu-ft, and within Rain Garden OS1 is 1,845 cu-ft. Standard water quality capture volume is 0.08 ac-ft, treating the remaining area that is directed to Pond D. Both the LID and standard WQCVs provide an additional 20% volume to account for potential loss of volume due to the accumulation of sediment. Below is a description of the 4-step process for selecting structural BMPs: Urban Drainage and Flood Control District (UDFCD) recommends a Four Step Process for receiving water protection that focuses on reducing runoff volumes, treating the water quality capture volume (WQCV), stabilizing drainageways and implementing long-term source controls. The Four Step Process applies to the management of smaller, frequently occurring events. Step 1: Employ Runoff Reduction Practices To reduce runoff peaks, volumes, and pollutant loads from urbanizing areas, implement Low Impact Development (LID) strategies, including Minimizing Directly Connected Impervious Areas (MDCIA). Page 7 Captured runoff from strategic areas are routed through bioretention pond/rain gardens. Rain gardens will slow runoff, promote infiltration, and filter runoff prior to being released into the adjacent storm drain system. Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow Release The bioretention pond/rain gardens are designed to provide water quality capture volume per Urban Drainage’s recommendations and calculations. The captured runoff is designed for a 12- hr drain time. Step 3: Stabilize Drainageways Natural Drainageways are subject to bed and bank erosion due to increases in frequency, duration, rate and volume of runoff during and following development. Because the site will drain to an existing storm system, bank stabilization is unnecessary with this project. Step 4: Implement Site Specific and Other Source Control BMPs The proposed project will improve upon site specific source controls compared to historic conditions by providing localized trash enclosures within the development for disposal of solid waste; a rain garden for water treatment prior to flows entering storm systems; and additional water quality measures to protect and prolong the design life of BMPS delineated in Step 1. All calculations are attached for reference. Page 8 STORMWATER POLLUTION PREVENTION Erosion and sedimentation will be controlled on-site by use of sediment control logs, inlet protection, and gravel construction entrances. The measures are designed to limit the overall sediment yield increase due to construction as required by the City of Fort Collins. During overlot and final grading the soil will be roughened and furrowed perpendicular to the prevailing winds. During the performance of the work required by these specifications or any operations appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the contractor shall furnish all labor, equipment, materials, and means required. The Contractor shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance, and to prevent dust nuisance that has originated from his operations from damaging crops, orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor will be held liable for any damage resulting from dust originating from his operations under these specifications on right-of-way or elsewhere. It is unlawful to track or cause to be tracked mud or other debris onto public streets or rights- of-way. Wherever construction vehicles access routes or intersect paved public roads, previsions must be made to minimize the transport of sediment by runoff or vehicles tracking onto the paved surface. Stabilized construction entrances are required with base material consisting of 6” coarse aggregate. The contractor will be responsible for clearing mud tracked onto public streets on a daily basis. All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Maintenance is the responsibility of the contractor. All disturbed areas must be seeded and mulched within 30 days of project start. Vegetation shall not be considered established until a ground cover is achieved which is demonstrated to be mature enough to control soil erosion to the satisfaction of the City Inspector and to survive severe weather conditions. Page 9 CONCLUSIONS This Final Drainage Report for Heartside Hill has been prepared to comply with the stormwater criteria set by the City of Fort Collins. The proposed drainage system will be designed to convey the developed peak 100-yr storm water runoff through the site to the proposed detention pond, and ultimately to the existing storm system. Drainage conveyance systems is designed to convey drainage to the proposed roadways and collect onsite drainage and treat it in accordance with LID requirements before discharging it into the proposed detention pond. This drainage report anticipates the implementation of best management practices for erosion control, temporary and permanent, and on-site construction facilities. It can therefore be concluded that development of Heartside Hill complies with the storm water jurisdictional criteria and the approved City of Fort Collins Stormwater Criteria Manual and will not adversely affect the adjacent properties, streets, storm drain system and/or detention/water quality facilities. Page 10 REFERENCES 1. Urban Storm Drainage Criteria Manual (Volumes 1, 2, and 3), Urban Drainage and Flood Control District, June 2001, Revised January 2016. 2. Fort Collins Stormwater Criteria Manual, Fort Collins Utilities, City of Fort Collins, Colorado, Dated December 2018, Adopted January 2019. 3. “Hydrologic Group Rating for Larimer County Area, Colorado”, USDA-Natural Resources Conservation Service, National Cooperative Soil Survey. Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov. [11/15/2021] 4. “Preliminary Geotechnical Subsurface Exploration Report, Proposed Residential Development Lots 1 and 2, Heart of the Rockies Second Subdivision”, prepared by Soilogic, LLC, Dated August 13, 2021. 5. “Drainage Investigation for Heart of the Rockies Christian Church”, prepared by Messner Engineering, Inc., Dated June 29, 1999. Page 11 APPENDIX Appendix A – Site Descriptions, Characteristics, & References Appendix B – Rational Calculations Appendix C – Pond Calculations Appendix D – Low Impact Development Calculations Appendix E – Inlet, Pipe, & Swale Capacity Calculations Appendix A APPENDIX A – SITE DESCRIPTIONS, CHARACTERISTICS, & REFERENCES SITE Vicinity Map Scale: 1" = 1000' PROJECT DATUM: NAVD88 CITY OF FORT COLLINS BENCHMARK #24-94 ON THE NORTHEAST CORNER OF THE INTERSECTION OF EAST TRILBY ROAD AND PORTNER DRIVE, ON TOP OF THE WEST END OF A CONCRETE HEADWALL ELEV= 4960.69 CITY OF FORT COLLINS BENCHMARK #25-94 ON THE NORTHWEST CORNER OF THE INTERSECTION OF EAST TRILBY ROAD AND SOUTH LEMAY AVENUE, ON TOP OF THE SOUTHEAST EDGE OF THE CONCRETE RING TO AN ELECTRIC MANHOLE ELEV= 4913.16 PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM. SURROUNDING DEVELOPMENTS HAVE USED NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) FOR THEIR VERTICAL DATUMS. IF NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) IS REQUIRED FOR ANY PURPOSE, THE FOLLOWING EQUATIONS SHOULD BE USED: NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = 4960.69 (NAVD88 DATUM) - 3.19' NGVD29 UNADJUSTED DATUM (PRIOR CITY OF FORT COLLINS DATUM) = 4913.16 (NAVD88 DATUM) - 3.19' E TRILBY RDS LEMAY AVEBRIT T A N Y S T AUTUMN RIDGE DRBRITTANY DRHEARTSIDE HILL Hydrologic Soil Group—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/21/2021 Page 1 of 444826504482690448273044827704482810448285044828904482650448269044827304482770448281044828504482890494720494760494800494840494880494920494960495000495040495080495120 494720 494760 494800 494840 494880 494920 494960 495000 495040 495080 495120 40° 29' 48'' N 105° 3' 44'' W40° 29' 48'' N105° 3' 27'' W40° 29' 39'' N 105° 3' 44'' W40° 29' 39'' N 105° 3' 27'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 25 50 100 150 Meters Map Scale: 1:1,880 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 Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 16, Sep 2, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/21/2021 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 63 Longmont clay, 0 to 3 percent slopes D 0.8 6.2% 90 Renohill clay loam, 3 to 9 percent slopes D 12.8 93.8% Totals for Area of Interest 13.6 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Hydrologic Soil Group—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/21/2021 Page 3 of 4 Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/21/2021 Page 4 of 4 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 12/7/2021 at 10:59 AM 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°3'53"W 40°29'57"N 105°3'16"W 40°29'30"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 8 Table 3.4-1. IDF Table for Rational Method Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 9 Figure 3.4-1. Rainfall IDF Curve – Fort Collins Appendix B APPENDIX B – RATIONAL CALCULATIONS Design Engineer: Design Firm: Project Number: Date: % Impervious Runoff Coefficient C Return Period Frequency Adjustment Factor (Cf) 100% 0.95 2-year to 10-year 1.00 90% 0.95 100-year 1.25 90% 0.95 45% 0.55 70% 0.65 0% 0.25 C2 to C10 C100 OS1 88,538 2.03 48,364 3,889 6,687 0 0 29,598 65.4% 0.72 0.89 D1 163,080 3.74 24,710 3,742 5,916 33,798 23,353 71,561 39.8% 0.52 0.65 D2a 48,086 1.10 0 12,931 1,430 0 0 33,725 26.9% 0.46 0.57 D2b 42,280 0.97 231 12,931 1,857 0 0 27,262 32.0% 0.50 0.62 D2a+D2b 90,366 2.07 231 25,861 3,287 0 0 60,987 29.3% 0.48 0.60 D2c 67,394 1.55 44,316 0 4,531 0 0 18,546 71.8% 0.76 0.95 D2d 44,606 1.02 0 0 2,055 0 0 42,551 4.1% 0.28 0.35 D2 202,366 4.65 44,547 25,861 9,874 0 0 122,084 37.9% 0.53 0.66 Total 453,984 10.42 117,621 33,492 22,476 33,798 23,353 223,244 44.0% 0.56 0.70 COMPOSITEApaved (sq feet) Aroof (sq feet) Awalk (sq feet) Alawn (sq feet) ASF Lot (sq feet) ACC Lot (sq feet) Lawns (Heavy, 2-7% Slope) Sub-basin Designation Atotal (sq feet) Atotal (acres) Weighted % Impervious Single-Family (SF) Lots Community Center (CC) Lot Paved Roof Walks Land Use Heartside Hill DEVELOPED IMPERVIOUS AREA CALCULATION DESIGN CRITERIA: Fort Collins Stormwater Criteria Manual BASINS: Highland Development Services Runoff Coefficients and Frequency Adjustment Factors for City of Fort Collins - Storm Water Criteria Manual % Impervious values from Table 3.2.2 in the Fort Collins Stormwater Criteria Manual J.Claeys 20-1045-00 February 22, 2023 21-1045-00 Rational Calcs.xlsx Page 1 of 5 Highland Development Services Design Engineer:Design Firm:Project Number:Date:EQUATIONS:-Equation 5-3-Equation 5-4-Urbanized Check Equation 3.3-5- CoFC Overland FlowCONSTRAINTS:300ft - Overland flow shall not exceed for developed condition500ft - Overland flow shall not exceed for undeveloped conditionFinal tc = minimum of ti + tt and urbanized basin checkrecommended minimum tc = 5 min for urbanized basinsTime of Concentration (2-yr to 10-yr)OS1 OS1 65.4% 0.72 2.03 240 0.0381 7.12 457 0.0165 0.10 0.016 2.57 2.96 10.08 697 13.8710.08D1 D1 39.8% 0.52 3.74 300 0.0282 13.36 468 0.0433 0.10 0.016 4.17 1.87 15.23 768 14.2714.27D2a D2a 26.9% 0.46 1.10 75 0.0760 5.29 371 0.0392 0.14 0.030 2.65 2.33 7.62 446 12.487.62D2b D2b 32.0% 0.50 0.97 18 0.1470 1.96 391 0.0343 0.14 0.030 2.48 2.63 5.00 409 12.275.00D2c D2c 71.8% 0.76 1.55 109 0.0504 3.89 521 0.0389 0.10 0.016 3.96 2.19 6.09 630 13.506.09D2d D2d 4.1% 0.28 1.02 93 0.0492 8.65 233 0.0050 0.14 0.030 0.94 4.11 12.76 326 11.8111.81Total Total 44.0% 0.56 10.42 240 0.0381 10.00 1048 0.0272 0.10 0.030 1.77 9.89 19.89 - -19.89OVERALL LENGTH(ft/ft)tc(min)SLOPE(ft/ft)ti(min)LENGTH(ft)SLOPE(ft/ft)VELOCITY(ft/s)ROUGHNESS COEFFICIENTHYDRAULIC RADIUS(ft)LENGTH(ft)DESIGN CRITERIA:City of Fort Collins Stormwater Criteria ManualOverland Flow Equations for City of Fort Collins Stormwater Criteria ManualSUB-BASIN DATAINITIAL/OVERLAND TIME (ti)TRAVEL TIME (tt)tc=ti+tt(min)Urban CheckFinaltc(min)DESIGN POINTSub-basin%ImperviousC2-10AREA (acres)tt(min)February 22, 2023Heartside HillDEVELOPED TIME OF CONCENTRATIONJ.Claeys21-1045-00Highland Development Servicesticttt+=VLtt60=1.871.1 10180+=LtcV.R2/3S 1/221-1045-00 Rational Calcs.xlsxPage 2 of 5Highland Development Services Design Engineer:Design Firm:Project Number:Date:EQUATIONS:-Equation 5-3-Equation 5-4-Urbanized Check Equation 3.3-5- CoFC Overland FlowCONSTRAINTS:300ft - Overland flow shall not exceed for developed condition500ft - Overland flow shall not exceed for undeveloped conditionFinal tc = minimum of ti + tt and urbanized basin checkrecommended minimum tc = 5 min for urbanized basinsTime of Concentration (100-yr)OS1 OS1 65.4% 0.89 2.03 240 0.0381 3.80 457 0.0165 0.10 0.016 2.57 2.96 6.76 697 13.876.76D1 D1 39.8% 0.65 3.74 300 0.0282 10.40 468 0.0433 0.10 0.016 4.17 1.87 12.27 768 14.2712.27D2a D2a 26.9% 0.57 1.10 75 0.0760 4.34 371 0.0392 0.14 0.030 2.65 2.33 6.67 446 12.486.67D2b D2b 32.0% 0.62 0.97 18 0.1470 1.56 391 0.0343 0.14 0.030 2.48 2.63 5.00 409 12.275.00D2c D2c 71.8% 0.95 1.55 109 0.0504 1.74 521 0.0389 0.10 0.016 3.96 2.19 5.00 630 13.505.00D2d D2d 4.1% 0.35 1.02 93 0.0492 7.90 233 0.0050 0.14 0.030 0.94 4.11 12.02 326 11.8111.81Total Total 44.0% 0.70 10.42 240 0.0381 7.40 1048 0.0272 0.100.030 1.77 9.89 17.29 - -17.29OVERALL LENGTH(ft/ft)tc(min)SLOPE(ft/ft)ti(min)LENGTH(ft)SLOPE(ft/ft)VELOCITY(ft/s)HYDRAULIC RADIUS(ft)ROUGHNESS COEFFICIENTLENGTH(ft)DESIGN CRITERIA:City of Fort Collins Stormwater Criteria ManualOverland Flow Equations for City of Fort Collins Stormwater Criteria ManualSUB-BASIN DATAINITIAL/OVERLAND TIME (ti)TRAVEL TIME (tt)tc=ti+tt(min)Urban CheckFinaltc(min)DESIGN POINTSub-basin%ImperviousC100AREA (acres)tt(min)February 22, 2023Heartside HillDEVELOPED TIME OF CONCENTRATIONJ.Claeys21-1045-00Highland Development Servicesticttt+=VLtt60=1.871.1 10180+=LtcV.R2/3S 1/221-1045-00 Rational Calcs.xlsxPage 3 of 5Highland Development Services Design Engineer:Design Firm:Project Number:Date:EQUATIONS:P1-2yr =0.82inP1-10yr =1.40inP1-100yr =2.86inBASIN SUMMARY:tc(min)Runoff Coeff(C2-10)C(A) (acres)Intensity (in/hr)Q2 (ft3/s)tc(min)Runoff Coeff(C2-10)C(A) (acres)Intensity (in/hr)Q10 (ft3/s)tc(min)Runoff Coeff. (C100)C(A) (acres)Intensity (in/hr)Q100 (ft3/s)OS1 OS1 2.033 65.4% 10.08 0.72 1.46 2.213.2110.08 0.72 1.46 3.775.486.76 0.89 1.82 8.8716.14D1 D1 3.744 39.8% 14.27 0.52 1.94 1.903.6814.27 0.52 1.94 3.256.2812.27 0.65 2.42 7.1017.17D2a D2a 1.104 26.9% 7.62 0.46 0.51 2.451.247.62 0.46 0.51 4.182.126.67 0.57 0.63 8.915.64D2b D2b 0.971 32.0% 5.00 0.50 0.48 2.851.385.00 0.50 0.48 4.872.365.00 0.62 0.60 9.956.02D2c D2c 1.547 71.8% 6.09 0.76 1.17 2.633.086.09 0.76 1.17 4.495.265.00 0.95 1.46 9.9514.57D2d D2d 1.024 4.1% 11.81 0.28 0.29 2.070.6011.81 0.28 0.29 3.531.0211.81 0.35 0.36 7.212.61Total Total 10.422 44.0% 19.89 0.56 5.84 1.619.4319.89 0.56 5.84 2.7616.1017.29 0.70 7.30 6.0544.16Cn = n-yr runoff coefficientIn = n-yr rainfall intensity (in/hr) An = Basin drainage area (ac)I = rainfall intensity (in/hr)P1 = one-hour point rainfall depth (in)tc = time of concentration (min)10-yr Peak Runoff100-yr Peak RunoffHeartside HillDEVELOPED PEAK RUNOFFDESIGN CRITERIA:Design PointSub-basinArea(acres)J.ClaeysHighland Development Services21-1045-00December 21, 20212-yr Peak RunoffCity of Fort Collins Stormwater Criteria Manual%ImperviousQn = n-yr peak discharge (cfs)nnnnAICQ=(0.786651)1)10(5.28ctPI+=21-1045-00 Rational Calcs.xlsxPage 4 of 5Highland Development Services Heartside Hill Attenuated Flows Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: EQUATIONS: -Equation 5-3 -Equation 5-4 -CoFC Overland Flow CONSTRAINTS: 300 ft - Overland flow shall not exceed for developed condition Final t c = minimum of t i + t t and urbanized basin check 500 ft - Overland flow shall not exceed for undeveloped condition recommended minimum t c = 5 min for urbanized basins Qn = n -yr peak discharge (cfs)I = rainfall intensity (in/hr) Cn = n -yr runoff coefficient P1 = one-hour point rainfall depth (in) In = n -yr rainfall intensity (in/hr) tc = time of concentration (min) A = drainage area (ac)P1-2yr =0.82 in. P1-10yr =1.40 in. P1-100yr =2.86 in. BASINS: DP/Manhole D2b Contributing Basins D2a+D2b Contributing Area (acres)2.07 C2-10 C100 Runoff Coefficients 0.48 0.60 Overland Flow Time Length (ft) 75 Slope (%) 7.60 2-yr to 10-yr 100-yr ti (min)5.14 4.15 Travel Time Length (ft) Slope (%) Hydraulic Radius (ft) Roughness Coefficient Velocity (ft/s)tt (min) 371 3.92%0.10 0.016 3.97 1.56 84 2.74%0.10 0.016 3.32 0.42 pipe conveyance 320 4.03%0.10 0.016 4.03 1.32 Total Time 3.30 Final Time of Concentration - tc (min) 2-yr to 10-yr 100-yr 8.44 7.45 Intensities (in/hr) 2-yr 10-yr 100-yr 2.36 4.03 8.60 Discharge (cfs) 2-yr 10-yr 100-yr 2.34 3.99 10.65 J.Claeys Highland Development Services 21-1045-00 February 22, 2023 Fort Collins Stormwater Criteria Manual 1.87 1.1 . V .R2/3 S 1/2 28.5 10 + . !"# + $ $60& Appendix C APPENDIX C – POND CALCULATIONS Design Engineer: Design Firm: Project Number: Date: Pond 100-yr Peak Inflow (cfs) 100-yr Peak Release (cfs) WQCV (ac-ft) Detention Volume (ac-ft) Combined Volume (ac-ft) Total Volume Provided (ac-ft) Pond Bottom (ft) WQCV WSE (ft) 100-yr WSE (ft) Max Depth (ft) Pond D 44.16 13.20 0.08 0.82 0.90 1.46 4907.75 4908.86 4911.03 3.28 Pond Summary Heartside Hill Pond Summary Table J.Claeys Highland Development Services 21-1045-00 February 21, 2023 21-1045-00 PondCalcs.xlsx Page 1 of 6 Highland Development Services Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA 0.56 1.25 0.70 ft3 acre-ft 10.42 acres 35,584 0.82 13.20 cfs Time (min) 100-yr Intensity (I , in/hr) Q100 (cfs) Accumulative Runoff Volume (ft3) Accumulative Release Volume (ft3) Detained Volume (ft3) Detained Volume (acre-ft) 0 0.00 0.00 0 0 0 0.00 5 9.95 72.58 21,773 3,960 17,813 0.41 10 7.72 56.31 33,786 7,920 25,866 0.59 15 6.52 47.56 42,801 11,880 30,921 0.71 20 5.60 40.85 49,016 15,840 33,176 0.76 25 4.98 36.32 54,486 19,800 34,686 0.80 30 4.52 32.97 59,344 23,760 35,584 0.82 35 4.08 29.76 62,495 27,720 34,775 0.80 40 3.74 27.28 65,471 31,680 33,791 0.78 45 3.46 25.24 68,141 35,640 32,501 0.75 50 3.23 23.56 70,679 39,600 31,079 0.71 55 3.03 22.10 72,933 43,560 29,373 0.67 60 2.86 20.86 75,099 47,520 27,579 0.63 65 2.72 19.84 77,375 51,480 25,895 0.59 70 2.59 18.89 79,344 55,440 23,904 0.55 75 2.48 18.09 81,401 59,400 22,001 0.51 80 2.38 17.36 83,327 63,360 19,967 0.46 85 2.29 16.70 85,187 67,320 17,867 0.41 90 2.21 16.12 87,047 71,280 15,767 0.36 95 2.13 15.54 88,556 75,240 13,316 0.31 100 2.06 15.03 90,154 79,200 10,954 0.25 105 2.00 14.59 91,904 83,160 8,744 0.20 110 1.94 14.15 93,392 87,120 6,272 0.14 115 1.89 13.79 95,121 91,080 4,041 0.09 120 1.84 13.42 96,631 95,040 1,591 0.04 Adjusted Runoff Coefficient (CC f ) Area (A ) Allowed Release Rate Fort Collins Amendments to the Urban Drainage and Flood Control District Criteria Manual City of Fort Collins - Storm Water Criteria Manual Detention Volume Calculation - Pond D Runoff Coefficient (C ) Frequency Factor (C f )Required Detention February 21, 2023 Heartside Hill 100-yr Detention Volume - FAA Method J.Claeys Highland Development Services 21-1045-00 21-1045-00 PondCalcs.xlsx Page 2 of 6 Highland Development Services Heartside Hill Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA: REQUIRED WATER QUALITY CAPTURE VOLUME (WQCV): Tributary Area, A 4.65 acres Basin D2 (not treated by LID) Composite. Imperviousness, I 37.9% WQCV (watershed inches)0.174 inches 40-Hour Drain Time (Fig SQ-2) Required WQCV 0.081 acre-feet Including 20% for Sedimentation WATER QUALITY OUTLET SIZING (Per USDCM, Volume 3): Design Water Quality Depth, DWQ 1.11 ft Determine K40 K40 = 0.013DWQ 2 + 0.22DWQ - 0.10 0.160 Maximum Area per Row, a a = WQCV / K40 0.505 square inches Number of Rows, nr 3 rows Number of Columns, nc (See Table 6a-1 for Max.)1 columns Choose Hole Diameter 3/4 inches Use USDCM Volume 3, Figure 5 0.750 inches Total Area per Row, Ao 0.44 square inches Total Outlet Area, Aot 1.33 square inches Does design work?Yes Minimum Steel Plate Thickness 1/4 inch (Not Used) Number of Rows, nr 2 rows Choose Rectangular Hole Width (w/ 2" Height)0 inches Use USDCM Volume 3, Figure 5 0.000 inches Total Outlet Area, Aot 0.00 square inches Does design work?Yes Minimum Steel Plate Thickness 1/4 inch Urban Storm Drainage Criteria Manual (USDCM) Volume III, Urban Drainage and Flood Control District, June 2001 (Updated November 2010) Circular Perforation Sizing Rectangular Perforation Sizing J.Claeys Highland Development Services 21-1045-00 February 21, 2023 Water Quality Pond and Outlet Sizing - Pond D 12 **1.2 21-1045-00 PondCalcs.xlsx Page 3 of 6 Highland Development Services Heartside Hill Design Engineer: Design Firm: Project Number: Date: J.Claeys Highland Development Services 21-1045-00 February 21, 2023 Water Quality Pond and Outlet Sizing - Pond D WATER QUALITY TRASH RACK SIZING (Per USDCM, Volume 3) Required Open Area, At At=0.5*[77(e-0.124D)]*Aot 46 square inches Min. Distance between Columns, Sc 3 inches Width of Trash Rack and Concrete Opening per Column 4 inches Use USDCM Volume 3, Table 6a-1 Total Width, Wconc 4 inches Height of Trash Rack Screen, Htr 13 5/16 inches Check - Larger than Required Type of Screen S.S. #93 VEE Wire (US Filter) Screen Opening Slot Dimension 0.139" (US Filter) Support Rod Type (See Table 6a-2) Spacing of Support Rod (O.C.)3/4 inches O.C. Total Screen Thickness (See Table 6a-2)0.31 inches Carbon Steel Frame Type (See Table 6a-2) (Not Used) Required Open Area, At (including 50% clogging) At=0.5*[77(e-0.124D)]*Aot 0 square inches Width of Trash Rack Opening, Wopening 1 inches Use USDCM Volume 3, Table 6b-1 Width of Concrete Opening, W conc 12 inches Min Height of Trash Rack Screen, Htr (including 2' 4" below lowest openings)28.00 inches Type of Screen Kelmp KRP Series Aluminum Bar Gate (or Equal) Screen Opening Slot Dimension 3/16" Bars on 1-3/16" Centers Minimum Bearing Bar Size (See Table 6b-2) 1 in x 3/16 in #156 VEE 3/8in x 1.0in flat bar Circular Perforation Trash Rack Sizing Rectangular Perforation Trash Rack Sizing 21-1045-00 PondCalcs.xlsx Page 4 of 6 Highland Development Services Heartside Hill Critical Pond Elevations Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, June 2001 (Revised January 2016) Water Quality Capture Volume (WQCV): Tributary Area, A 4.65 acres Basin D2 (not treated by LID) Composite. Imperviousness, I 37.9% WQCV (watershed inches)0.174 inches 40-Hour Drain Time (Fig SQ-2) Required WQCV 0.081 acre-feet Including 20% for Sedimentation Stage Storage Volume (pond volume calculated using the prismoidal formula): CONTOUR (FT)AREA (FT2)AREA (ACRE)VOLUME (ACRE-FT)DEPTH (FT)CUMULATIVE VOLUME (ACRE-FT) 4907.75 0 0.000 0.000 0.00 0.000 4908.0 333 0.008 0.001 0.25 0.001 4908.5 4052 0.093 0.021 0.75 0.022 4909.0 10788 0.248 0.082 1.25 0.104 4909.5 15630 0.359 0.151 1.75 0.255 4910.0 17272 0.397 0.189 2.25 0.443 4910.5 18975 0.436 0.208 2.75 0.651 4911.0 21476 0.493 0.232 3.25 0.883 4911.5 24750 0.568 0.265 3.75 1.149 4912.0 29037 0.667 0.308 4.25 1.457 0.08 4908.86 ft 0.90 4911.03 ft 1.32 4911.78 ft Provided Freeboard (33% Additional Volume) = Acre-Ft Interpolates to an Elev. of J.Claeys Highland Development 21-1045-00 Acre-Ft Interpolates to an Elev. of Required 100-yr Detention Volume (including WQCV) = February 21, 2023 Required Water Quality Capture Volume (WQCV) = Acre-Ft Interpolates to an Elev. of () 3 2121 DepthAAAAV++= 12 ∗ ∗ 1.2 21-1045-00 PondCalcs.xlsx Page 5 of 6 Highland Development Services Heartside Hill Circular Orifice Plate Sizing - Pond D Design Engineer: Design Firm: Project Number: Date: Orifice Equation where:C = Orifice Discharge Coefficient A o = Orifice Area (ft2) g = Gravity (32.2 ft/s2) Dh = Difference in Elevation Head (ft) D o = Orifice Diameter (in) Calculations 100-yr Orifice Sizing 100-yr Orifice Rating Table Knowns: 100-yr Release Rate 13.20 cfs 100-yr WSEL 4911.03 ft 4907.75 0.00 0.000 4908.00 0.00 0.001 Pond Outlet Invert 4907.75 ft 4908.50 1.67 0.022 4909.00 6.06 0.104 Discharge Coefficient 0.65 4909.50 8.40 0.255 4910.00 10.22 0.443 Tailwater Elevation 4907.75 ft 4910.50 11.77 0.651 4911.00 13.13 0.883 Orifice Diameter 17 in 4911.50 14.36 1.149 4912.00 15.50 1.457 Orifice Area 1.579 ft2 Centroid Elevation 4908.46 ft Actual Release Rate 13.20 cfs Pond Volume (ac-ft) J.Claeys Highland Development Services 21-1045-00 February 21, 2023 Elevation (ft) Discharge (cfs) hgC QAhgCAQoo D =D= 2 2 p o o AD576= 21-1045-00 PondCalcs.xlsx Page 6 of 6 Highland Development Services Appendix D APPENDIX D – LOW IMPACT DEVELOPMENT CALCULATIONS TRILBY ROAD BR I T T A N Y S T R E E T LEMAY AVENUEBRITTANY STREETPOND D RAIN GARDEN RAIN GARDEN HIGHLANDDEVELOPMENT SERVICES6355 FAIRGROUNDS AVENUE, SUITE 100 | WINDSOR, CO 80550PHONE: 970.674.7550 | EMAIL: Info@Highland-DS.com | www.Highland-DS.comOFSHEET DRAWN BY CHECKED BY DATE SCALE (H) HDS PROJ # SCALE (V)HEARTSIDE HILLLID & WQ TREATMENT AREAS EXHIBIT2/22/23 1" = 80' N/A JTC JTC 21-1045-00 LID 1 1 AREA CONTRIBUTING TO LID TREATMENT AREA CONTRIBUTING TO EXTENDED DETENTION BASIN WATER QUALITY TREATMENT LEGEND UNTREATED AREAS N W E S0 SCALE: 1" = 80' 8040 Design Engineer: Design Firm: Project Number: Date: Sq-Ft Acres Impervious Area (sq-ft) % of Impervious Area Requiring Treatment Impervious Area Requiring Treatment 105,661 2.43 62,922 0% 0 363,964 8.36 155,022 75% 116,266 443,462 10.78 217,943 - 116,266 LID Facility Contributing Basins Area Drainage to LID (sq-ft) % Impervious Impervious Area Treated (sq-ft) WQCV12-hr (watershed inches) WQCV12-hr (cu-ft) (includes 20% for sedimention) Treatment Method OS1 OS1 88,538 65.4% 58,940 0.20 1,811 Rain Garden D1 D1 163,080 39.8% 69,430 0.14 2,339 Rain Garden EDB Pond Contributing Basins Drainage Area (sq-ft) Drainage Area (acre)% Impervious WQCV40-hr (watershed inches) WQCV40-hr (ac-ft) (includes 20% for sedimention) Pond D D2 202,366 4.65 37.9% 0.17 0.081 155,022 128,370 83% Area (sq-ft) Area (acres)Treatment Ratio 251,618 5.78 53.6% 202,366 4.65 43.1% 15,641 0.36 3.3% 469,625 10.78 100.0% Development Area Breakdown City of Fort Collins - Ordinance No. 007, 2016 - Treat at least 75% of any newly developed or redeveloped impervious area using one or a combination of LID techniques, or - Treat at least 50% of any newly developed or redeveloped impervious area using one or a combination of LID techniques when 25% of private driveable surfaces are permeable. Total Impervious Area LID Treated (sq-ft) LID Treatment Summary LID Treatment Areas Totals Standard Water Quality Areas Description Existing Church Site Proposed Site Total Proposed Impervious Area Total % Impervious Area LID Treated Low Impact Development Summary Total Improvement Area Water Quality Area Treatment Summary Description Total Area Treated by LID Total Area Treated by EDB Total Area Not Treated February 21, 2023 Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016) Heartside Hill Low Impact Development J.Claeys Highland Development Services 21-1045-00 DESIGN CRITERIA Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =39.8 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.398 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.14 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 163,080 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 =0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =1,949 cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum)DWQCV =12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin =1298 sq ft D) Actual Flat Surface Area AActual =2373 sq ft E) Area at Design Depth (Top Surface Area)ATop =3454 sq ft F) Rain Garden Total Volume VT=2,914 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided?1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y =ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =cu ft iii) Orifice Diameter, 3/8" Minimum DO = in Design Procedure Form: Rain Garden (RG) J.Claeys Highland Development Services February 21, 2023 Heartside Hill (Basin D1) Fort Collins, CO UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO 21-1045-00 UD-BMP_v3.07 (Basin D1).xlsm, RG 2/21/2023, 10:55 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) J.Claeys Highland Development Services February 21, 2023 Heartside Hill (Basin D1) Fort Collins, CO Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO 21-1045-00 UD-BMP_v3.07 (Basin D1).xlsm, RG 2/21/2023, 10:55 AM Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =65.4 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.654 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.20 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 88,538 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 =0.43 in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =1,509 cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum)DWQCV =12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin =1158 sq ft D) Actual Flat Surface Area AActual =1453 sq ft E) Area at Design Depth (Top Surface Area)ATop =2236 sq ft F) Rain Garden Total Volume VT=1,845 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided?1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y =ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =cu ft iii) Orifice Diameter, 3/8" Minimum DO = in Design Procedure Form: Rain Garden (RG) J.Claeys Highland Development Services February 21, 2023 Heartside Hill (Basin OS1) Fort Collins, CO UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO 21-1045-00 UD-BMP_v3.07 (Basin OS1).xlsm, RG 2/21/2023, 12:21 PM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) J.Claeys Highland Development Services February 21, 2023 Heartside Hill (Basin OS1) Fort Collins, CO Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO 21-1045-00 UD-BMP_v3.07 (Basin OS1).xlsm, RG 2/21/2023, 12:21 PM Appendix E APPENDIX E – INLET, PIPE, & SWALE CAPACITY CALCULATIONS Heartside Hill TYPE C AREA INLET SIZING CALCULATION Design Engineer: Design Firm: Project Number: Date: DESIGN CRITERIA EQUATIONS: Q i = Grate Capacity w/o Reduction Factor (cfs) C = Orifice Discharge Coefficient = 0.67 A = Orifice area (ft2) - Open Area of Grate G = Gravitational Constant (32.2 ft/s2) H = Allowed Head on Grate, Ponding Depth (ft) Grate Dimensions and Information: 3 ft 3 ft 0.65 sqft/sqft 50% 5.85 sqft Allowed Head (ft) Inlet Capacity (Qi, cfs) Inlet Capacity w/ Reduction Factor (Qg, cfs) 0.25 15.73 7.86 0.50 22.24 11.12 1.00 31.45 15.73 1.50 38.52 19.26 2.00 44.48 22.24 INLET SIZING CALCULATIONS Inlet ID: Design Flow Rate (Q 100 , cfs): Allowed Head (H , ft): Inlet Capacity (Qg, cfs) Design Flow Depth (H, ft) Inlet-D2a 5.64 1.5 19.26 0.13 Inlet-D2b 10.65 1.2 17.23 0.46 Outlet-D01 13.20 2.17 23.17 0.70 Outlet-OS1 16.14 0.25 7.86 1.05 Apply Reduction Factor for the Allowable Capacity. J.Claeys Highland Development Services 21-1045-00 February 22, 2023 Width (W ): Assumed Capacity per Head Allowed Inlet Grate Open Area (A ): Reduction Factor (F ): Opening Ratio (R ): Length (L ): 1 CA 2 Page1 Inlet Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Feb 20 2023 Inlet-D2c Capacity Curb Inlet Location = Sag Curb Length (ft) = 10.00 Throat Height (in) = 6.00 Grate Area (sqft) = -0- Grate Width (ft) = -0- Grate Length (ft) = -0- Gutter Slope, Sw (ft/ft) = 0.083 Slope, Sx (ft/ft) = 0.033 Local Depr (in) = 3.00 Gutter Width (ft) = 2.00 Gutter Slope (%) = -0- Gutter n-value = -0- Calculations Compute by: Q vs Depth Max Depth (in) = 8 Highlighted Q Total (cfs) = 5.75 Q Capt (cfs) = 5.75 Q Bypass (cfs) = -0- Depth at Inlet (in) = 8.08 Efficiency (%) = 100 Gutter Spread (ft) = 9.79 Gutter Vel (ft/s) = -0- Bypass Spread (ft) = -0- Bypass Depth (in) = -0- Capacity exceeds 10-yr 100-yr overtops directly into Pond D Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Feb 15 2023 West Culverts Circular Diameter (ft) = 1.25 Invert Elev (ft) = 100.00 Slope (%) = 2.00 N-Value = 0.016 Calculations Compute by: Q vs Depth No. Increments = 10 Highlighted Depth (ft) = 1.13 Q (cfs) = 7.910 Area (sqft) = 1.16 Velocity (ft/s) = 6.80 Wetted Perim (ft) = 3.13 Crit Depth, Yc (ft) = 1.12 Top Width (ft) = 0.75 EGL (ft) = 1.84 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) Exceeds D2a 100-yr Peak of 5.64 cfs Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Feb 20 2023 Circular Diameter (ft) = 1.50 Invert Elev (ft) = 100.00 Slope (%) = 1.50 N-Value = 0.016 Calculations Compute by: Q vs Depth No. Increments = 10 Highlighted Depth (ft) = 1.35 Q (cfs) = 11.14 Area (sqft) = 1.68 Velocity (ft/s) = 6.65 Wetted Perim (ft) = 3.75 Crit Depth, Yc (ft) = 1.28 Top Width (ft) = 0.90 EGL (ft) = 2.04 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) East Culverts Exceeds D2a+D2b Attenuated 100-yr Peak of 10.65 cfs Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Wednesday, Feb 22 2023 Basin D2a & Basin D2b Swale Triangular Side Slopes (z:1) = 4.00, 4.00 Total Depth (ft) = 2.50 Invert Elev (ft) = 100.00 Slope (%) = 1.77 N-Value = 0.030 Calculations Compute by: Q vs Depth No. Increments = 10 Highlighted Depth (ft) = 1.50 Q (cfs) = 47.97 Area (sqft) = 9.00 Velocity (ft/s) = 5.33 Wetted Perim (ft) = 12.37 Crit Depth, Yc (ft) = 1.55 Top Width (ft) = 12.00 EGL (ft) = 1.94 0 2 4 6 8 10 12 14 16 18 20 22 24 Elev (ft)Depth (ft)Section 99.50 -0.50 100.00 0.00 100.50 0.50 101.00 1.00 101.50 1.50 102.00 2.00 102.50 2.50 103.00 3.00 Reach (ft) Minimum Swale Slope Exceeds D2a+D2b Attenuated 100-yr Peak of 10.65 cfs