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HomeMy WebLinkAbout2022-09-29 Stevens Engineers - Stormwater Management Plan Storm Water Management Plan St. Croix Car Wash Oak Park Heights, Minnesota August 16, 2022 Revised September 29, 2022 Prepared by: 642 Brakke Drive Suite 202, Hudson, WI 54016 Phone (715) 386-5819 Storm Water Narrative St. Croix Car Wash August 16, 2022 Revised 9.29.2022 Page 2 of 6 Storm Water Calculations for St. Croix Car Wash Oak Park Heights, Minnesota August 16, 2022 Revised September 29, 2022 Table of Contents SUMMARY Site Overview SITE ANALYSIS & SCREENING Soils Review Topographic Analysis Endangered Resources Nearby Waterbodies and Wetlands STORMWATER MANAGEMENT TECHNICAL BASIS Required Standards Rate Control Summary Water Quality Summary Maintenance Agreement Appendix Appendix A – Location Map Appendix B – Endangered Resources Review Appendix C – Waterbodies and Wetlands Appendix D – MIDS Flowchart Appendix E – Pre and Post Development Drainage Map Appendix F – Site Modeling (Hydrocad) Appendix G – P8 Modeling Output Appendix H – Phosphorus Calculation Storm Water Narrative St. Croix Car Wash August 16, 2022 Revised 9.29.2022 Page 3 of 6 SUMMARY Site Overview The purpose of this report is to provide an analysis of the stormwater management plan for the St. Croix Car Wash redevelopment site in Oak Park Heights, Minnesota. The property consists of a paved parking lot used for overflow parking from the adjacent Tire Pros Building. Proposed improvements include connections to adjacent streets, construction of a car wash and storage building, and improvements to the parking areas through the installation of curb and gutter, bituminous pavement and storm water management. SITE ANALYSIS & SCREENING Soils Review USDA soils map shows Urban land-Chetek complex and does not provide a HSG rating for the soils. For this analysis, we have assumed no infiltration below the underdrain. Soil borings were not completed since the City of Oak Park Heights prohibits infiltration, and our design is based on engineered filtration media with underdrains. Topographic Analysis The existing property survey along with Washington County Lidar was utilized to determine overall drainage areas. The property generally drains from the south to the northeast with a small strip of land along the west property line that drains west. The proposed improvements retain the original drainage patterns but capture the runoff from the proposed impervious into 2 filtration basins. The west portion will continue to drain to the west. Endangered Resources The Washington County Biological Survey Native Plan Community and Rare Species Map was utilized as a preliminary assessment and concluded that there are no endangered resources in this area. Storm Water Narrative St. Croix Car Wash August 16, 2022 Revised 9.29.2022 Page 4 of 6 Nearby Waterbodies and Wetlands MnDNR MWI Wetland Finder was utilized to determine wetlands in the areas. There are no wetland indicators near this property. MPCA Construction Stormwater Special Waters search was utilized to check for outstanding or impaired waters within 1 mile of the site. The only water body within 1 mile of the site is Lily Lake, which has a Mercury impairment and no impact to stormwater runoff. STORMWATER MANAGEMENT TECHNICAL BASIS Required Standards • MSCWMO Requirements for sites disturbing greater than 10,000 SF of land: o Rate control of 2, 10, and 100-year o Volume Control – capture/retain 1.1” of runoff from new and/or fully reconstructed surfaces ▪ Alternative compliance sequencing applies since Oak Park Heights requires filtration rain gardens*** • Oak Park Heights Requirements – provide a filtration rain garden, NO infiltration allowed Rate Control Summary The pre-development and post-development hydrology were modeled in HydroCAD software using MSE 3 Rainfall Distribution, 24-hour duration storm and MSCWMO recommended rainfall depths. A summary of the outflows is below and the full HydroCAD output is attached to this report as Appendix F. Outflow – Storm Event and Location Existing (cfs) Proposed (cfs) 2-Year Storm Event Offsite to West 0.10 0.10 0.09 Offsite to North 1.79 1.47 1.11 10-Year Storm Event Offsite to West 0.22 0.22 0.20 Offsite to North 3.11 2.81 2.98 100-Year Storm Event Offsite to West 0.51 0.52 0.46 Offsite to North 6.07 5.72 5.69 Storm Water Narrative St. Croix Car Wash August 16, 2022 Revised 9.29.2022 Page 5 of 6 Water Quality Summary Water quality is calculated for the new and reconstructed impervious surfaces. Total new and reconstructed impervious areas = 17,242 SF. At 1.1 inches over this entire area, the site water quality volume is 2,581 CF. The water quality volume is the volume required to infiltrate onsite. Since the City of Oak Park Heights disallows infiltration, the site is subject to alternative compliance sequencing per the MIDS Calculator. Appendix D shows the marked- up MIDS flowchart. Since infiltration is completely disallowed, the site is subject to FTO #2 – volume reduction to the maximum extent practicable AND Remove 60% of annual TP load. Total annual phosphorus removal is calculated using the Mn Stormwater Manual guidelines for particulate phosphorus and dissolved phosphorus. P8 is not accurate in calculating phosphorus removal with a filtration basin, so manual calculation is required. P8 was used to determine volume of runoff treated for a year vs volume of runoff leaving the site untreated. Total phosphorus removal was calculated at 59% 58%. While the requirement is 60%, we have modified the site and re-graded to catch the maximum volume of runoff for the site as possible and are requesting lenience for the 1% 2% calculated shortfall of this site stormwater design. With infiltration disallowed by the City, few options considered on this small site were feasible while still allowing a functional site. A wet pond would help with phosphorus removal, but there physically isn’t enough space on the site to provide adequate pretreatment and wet pond volume. The runoff to the west is on a slope and is impossible to capture before traveling to the adjacent parcel. Rain gardens were considered, but do not adequately treat the dissolved portion of the phosphorus loading. Therefore, iron enhanced media will be used to enhance phosphorus removal and meet FTO #2 requirements. Offsite mitigation was not considered, as it should be a last resort when all other options fail. Both filtration basins will be iron-enhanced, with 5-8% iron filings included per the MPCA stormwater manual guidelines. Bottom of the basin will be bare to allow the iron filings to operate properly, with plantings on the sides of the basin for aesthetics. Storm Water Narrative St. Croix Car Wash August 16, 2022 Revised 9.29.2022 Page 6 of 6 Monitoring and Inspection Monitoring and inspection of the site will occur on a quarterly basis on the first 5 years to observe that the facilities continue to function as they are intended to. After the first 5 years, monitoring can occur annually. This monitoring will consist of checking for erosion and ensuring no garbage or debris are located within the filtration basin and raking the bottom media as well as inspecting and cleaning Rain Guardian structures. Appendix A Location Map APPENDIX A – LOCATION MAP Appendix B Endangered Resources Appendix C Waterbodies and Wetlands PFO1A PFO1A PFO1A PEM1A Date Printed: 08/16/2022 This map is for general reference only. Neither the state of Minnesota nor the Minnesota Department of Natural Resources make any representations or warranties with respect to the use of or reliance on the data. There are no guarantees as to the accuracy, currency, completeness, suitability or reliability of this data for any purpose. 0 0.1 0.20.05 mi National Wetland Inventory MPCA's Construction Stormwater Special Waters Search Washington County, MN, Esri Canada, Esri, HERE, Garmin, GeoTechnologies, Inc., USGS, METI/NASA, EPA, USDA Waterbody Units - Lakes (1) Waterbody Units - Streams (1) Impaired Lakes without additional construction requirements Impaired Lakes with additional construction requirements Scenic and Recreational River Segments 8/16/2022, 9:34:22 AM 0 0.2 0.40.1 mi 0 0.35 0.70.17 km 1:18,056 Minnesota Pollution Control Agency Washington County, MN, Esri Canada, Esri, HERE, Garmin, GeoTechnologies, Inc., USGS, METI/NASA, EPA, USDA | Minnesota Pollution Control Agency | Appendix D MIDS Flowchart Conduct Site Review: · Aerial Photos and Topographic Maps · County Soil Surveys and other Soil Information as Available · County Geologic Atlas · Local Groundwater Levels · DWSMA and Wellhead Protection Maps · FEMA and Local Floodplain Maps · Soil Borings and Site Survey · MPCA Listing of Potentially Contaminated Sites · Phase 1 and 2 Environmental Site Assessments · TMDLs and Local Water Quality Standards · Wetland Delineations, MNRAM Assessments, and Wetland Classifications · Proposed Conditions, Conceptual/Preliminary Site Design · Local zoning and land use requirements/ordinances, including stormwater rate control requirements · Communication with Local Landowners, LGU, or Others Knowledgeable about the Site · Site Inspection Is shallow groundwater or shallow bedrock present on site? Are there very low infiltrating soils (<0.2 inches per hour)? Is BMP relocation onsite to avoid shallow groundwater and bedrock feasible? Conduct detailed site investigation (i.e., borings, excavations, consultation with a professional geologist). Is there >3 feet of soil depth (> 10 feet is preferred) from bottom of BMP to bedrock and groundwater? Can BMP be raised? Can BMP be sized to drain dry within 48 hours (24 hours in locations that are tributary to trout streams)? Define Performance Goal New and redevelopment projects: Retain on site a volume of 1.1" from impervious surfaces Linear projects: Retain on site the larger of 1.1" from all new, or .55" from all new and fully reconstructed (D) impervious surfaces. Is the site located in a DWSMA, wellhead protection area, or within 200 feet of a drinking well? Yes Are there existing or proposed structures or infrastructure (e.g., rate control BMPs, utilities, buildings, roadway, easements) that make the Performance Goal not feasible? (G) No Is BMP relocation feasable?Yes No Is FTO Alternative No. 1 feasible?No No No Raise BMP enough to ensure 3 feet (preferably 10 feet) of soil between bottom of BMP and top of bedrock and groundwater. Yes Is there presence of contaminated soils and/ or groundwater, or hotspot runoff? (H) No Can hotspot or contamination be isolated or remediated to mitigate risk of increased contamination? Yes No Yes Is BMP relocation onsite to a higher-infiltrating location feasible? Yes No Provide soil boring or infiltration test results documenting low-infiltrating soils. Is FTO Alternative No. 1 (lower volume control standard) feasible, allowing the BMP to drain within 48 hours (24 hours in locations that are tributary to trout streams)? No No Are there very high infiltrating soils (>8 inches per hour)? (E) No Yes Yes Yes Is BMP relocation onsite to a lower-infiltrating location feasible? Can subgrade be modified to slow the rate of infiltration to less than 8 inches per hour? Yes No No Yes Yes MIDS DESIGN SEQUENCE FLOW CHART version 6.18.13 · Select FTO Alternative No. 1 · Provide soil boring or infiltration test results documenting high-infiltrating soils. Is the project linear? Are there zoning and land use requirements (density, parking, setbacks, etc.) that make the Performance Goal not feasible? (G) No Is BMP relocation feasible? Is FTO Alternative No. 1 feasible? Select FTO #3. Provide site survey, maps, regulations, and/or cost estimates documenting that meeting the original performance goal or FTO alternatives is not feasible in addition to other documentation as required by LGU. NoYesNo Is FTO Alternative No. 2 feasible? Can a local unit of government provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater? Is FTO Alternative No. 2 feasible? Are active karst areas within 1000 feet up- gradiant or 100 feet downgradiant of the BMP location? No Yes No Are there adverse surface water hydrologic impacts from infiltration practices (e.g., impacting perched wetland)? Can the BMP be relocated onsite to avoid adverse hydrologic impacts? Yes Is BMP relocation onsite to a location without karst feasible? Yes No Would BMPs accommodating FTO Alternative #1 avoid adverse hydrologic impacts?Yes No MIDS performance goal does not apply Does the project create one acre or more of new and/or fully reconstructed (D) impervious surfaces? No Is FTO Alternative No. 2 feasible? Yes Yes No No No Complete Design Using Performance Goal (As modified by FTO Alternatives, if applicable) No Yes Yes No No · Select FTO Alternative No. 2 · No infiltration practices allowed · Explore non-infiltration volume reduction practices · Provide soil boring or infiltration test results documenting low infiltration rates. · Select FTO Alternative No. 2 · No infiltration practices allowed · Explore non-infiltration volume reduction practices · Provide soil boring or infiltration test results documenting high-infiltrating soils. · Select FTO Alternative No. 2 · Maximize infiltration BMPs to treat up to the 0.55 inch goal, if possible. · Explore non-infiltration volume reduction practices · Provide report documenting potential hydrologic impacts from infiltration on the site, prepared by registered engineer, hydrologist, or wetlands specialist. · Select FTO Alternative No. 1 · Maximize infiltration BMPs to treat more than 0.55 inch goal, if possible. · Provide report documenting potential hydrologic impacts from infiltration on the site, prepared by registered engineer, hydrologist, or wetlands specialist. · Select Flexible Treatment Option (FTO) Alternative No. 2 · No infiltration practices allowed · Explore non-infiltration volume reduction practices · Provide Phase I or II ESAs, or other documentation of potential contamination or hotspot runoff · Provide documentation of extent of contamination and remediation alternatives considered · Select Flexible Treatment Option (FTO) Alternative No. 2 · No infiltration practices allowed · Explore non-infiltration volume reduction practices · Provide soil borings or report from a professional geologist or geotechnical engineer. · Select Flexible Treatment Option (FTO) Alternative No. 2 · No infiltration practices allowed · Explore non-infiltration volume reduction practices · Provide soil borings or report from a professional geologist or geotechnical engineer. · Select Flexible Treatment Option (FTO) Alternative No. 2 · Provide regulations, and/or cost estimates documenting infeasibility of meeting the original Performance Goal · Select Flexible Treatment Option (FTO) Alternative No. 1 · Provide regulations, and/or cost estimates documenting infeasibility of meeting the original Performance Goal · Select Flexible Treatment Option (FTO) Alternative No. 2 · No infiltration practices allowed · Explore non-infiltration volume reduction practices · Provide DWSMA or well location map · Select Flexible Treatment Option (FTO) Alternative No. 1 · Provide regulations, and/or cost estimates documenting infeasibility of meeting the original Performance Goal · Select Flexible Treatment Option (FTO) Alternative No. 2 · Provide regulations, and/or cost estimates documenting infeasibility of meeting the original Performance Goal. · Select Flexible Treatment Option (FTO) Alternative No. 2 · Provide documentation of offsite run on to project area · Provide documentation of lack of right-of-way. Yes No Are there restraints due to lack of available ROW, off site drainage and/or rate control requirements? (F) Yes Yes No NoNo Yes Select FTO #3. Provide site survey, maps, regulations, and/or cost estimates documenting that meeting the original performance goal or FTO alternatives is not feasible in addition to other documentation as required by LGU.No Yes Yes Yes No Yes MIDS Project Flexible Treatment Options (FTO) The Flexible Treatment Options (FTO) alternatives presented here should be employed when the Performance Goal is not feasible and/or allowed. The designer should document the reasons why the Performance Goal and rejected FTO Alternatives are not feasible and/ or allowed. FTO 1 Applicant attempts to comply with the following conditions: 1.a. Achieve at least 0.55” volume reduction goal, and 1.b.Remove 75% of the annual TP load, and 1.c. Options considered and presented shall examine the merits of relocating project elements to address, varying soil conditions and other constraints across the site FTO #2 Applicant attempts to comply with the following conditions: 2.a. Achieve volume reduction to the maximum extent practicable (as determined by the Local Authority), and 2.b.Remove 60% of the annual TP load, and 2.c. Options considered and presented shall examine the merits of relocating project elements to address, varying soil conditions and other constraints across the site. FTO #3 Off-site mitigation (including banking or cash or treatment on another project, as determined by the local authority) equivalent to the volume reduction performance goal can be used in areas selected in the following order of preference: 1. Locations that yield benefits to the same receiving water that receives runoff from the original construction activity 2) Locations within the same Department of Natural Resource (DNR) catchment area as the original construction activity 3) Locations in the next adjacent DNR catchment area up-stream 4) Locations anywhere within the local authorities jurisdiction Notes: A. Volume reduction techniques considered shall include infiltration, rainwater harvesting & reuse, bioretention, permeable pavement, tree boxes, grass swales and/or additional techniques included in the MIDS calculator or the Minnesota Stormwater Manual. B. Applicant shall document the flexible treatment options decision sequence, following the order of alternatives presented here. C. For Alternative #2, the applicant is encouraged to use BMPs that reduce volume. Secondary preference is to employ filtration techniques, followed by rate control BMPs. D. Fully reconstructed impervious surfaces: Areas where impervious surfaces have been removed down to the underlying soils. Activities such as structure renovation, mill and overlay projects and other pavement rehabilitation projects that do not alter the underlying soil material beneath the structure, pavement or activity are not considered full reconstruction. In addition, other maintenance activities such as catch basin and pipe repair/ replacement, lighting, and pedestrian ramp improvements shall not be considered fully reconstructed impervious surfaces. Reusing an existing building foundation and re-roofing of an existing building are not considered fully reconstructed. E. Soils that infiltrate too quickly may not provide sufficient pollutant removal before the infiltrated runoff enters groundwater. F. A reasonable attempt must be made to obtain right-of-way during the project planning process G. Other, this is not an exhaustive list Is FTO Alternative No. 2 feasible? Select FTO #3. Provide site survey, maps, regulations, and/or cost estimates documenting that meeting the original performance goal or FTO alternatives is not feasible in addition to other documentation as required by LGU. NO YES Is FTO Alternative No. 2 feasible? Select FTO #3. Provide site survey, maps, regulations, and/or cost estimates documenting that meeting the original performance goal or FTO alternatives is not feasible in addition to other documentation as required by LGU. H. Hotspots includes any portion of a facility where infiltration is prohibited under an NPDES/SDS industrial stormwater permit issued by the MPCA Can a local unit of government provide a higher level of engineering review to ensure a functioning system that prevents adverse impacts to groundwater? YES YESYES YES NO Appendix E Pre and Post Development Drainage Map APPENDIX C - PRE-DEVELOPMENT DRAINAGE MAP APPENDIX C - POST-DEVELOPMENT DRAINAGE MAP Appendix F Site Modeling (Hydrocad) Exisitng conditions 2S Area 1 3S Area 2 4S Area 3 1P Offsite to Gas Station 5P Offsite to Frontage 6P Offsite to West 9P Offsite to North Routing Diagram for Tire Pros Rev 9.29 Prepared by Stevens Engineers, Printed 9/29/2022 HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Subcat Reach Pond Link Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 2HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 0.363 74 >75% Grass cover, Good, HSG C (2S, 3S, 4S) 0.075 96 Gravel surface, HSG C (2S) 0.355 98 Paved parking, HSG C (3S, 4S) 0.793 87 TOTAL AREA Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 3HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 0.000 HSG B 0.793 HSG C 2S, 3S, 4S 0.000 HSG D 0.000 Other 0.793 TOTAL AREA Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 4HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Ground Covers (selected nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 0.000 0.363 0.000 0.000 0.363 >75% Grass cover, Good 2S, 3S, 4S 0.000 0.000 0.075 0.000 0.000 0.075 Gravel surface 2S 0.000 0.000 0.355 0.000 0.000 0.355 Paved parking 3S, 4S 0.000 0.000 0.793 0.000 0.000 0.793 TOTAL AREA MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 5HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Time span=4.00-20.00 hrs, dt=0.05 hrs, 321 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=10,849 sf 0.00% Impervious Runoff Depth>1.10"Subcatchment 2S: Area 1 Tc=10.0 min CN=81 Runoff=0.44 cfs 0.023 af Runoff Area=20,973 sf 72.65% Impervious Runoff Depth>1.81"Subcatchment 3S: Area 2 Tc=10.0 min CN=91 Runoff=1.35 cfs 0.073 af Runoff Area=2,724 sf 8.99% Impervious Runoff Depth>0.83"Subcatchment 4S: Area 3 Tc=5.0 min CN=76 Runoff=0.10 cfs 0.004 af Inflow=0.44 cfs 0.023 afPond 1P: Offsite to Gas Station Primary=0.44 cfs 0.023 af Inflow=1.35 cfs 0.073 afPond 5P: Offsite to Frontage Primary=1.35 cfs 0.073 af Inflow=0.10 cfs 0.004 afPond 6P: Offsite to West Primary=0.10 cfs 0.004 af Inflow=1.79 cfs 0.096 afPond 9P: Offsite to North Primary=1.79 cfs 0.096 af Total Runoff Area = 0.793 ac Runoff Volume = 0.100 af Average Runoff Depth = 1.51" 55.19% Pervious = 0.438 ac 44.81% Impervious = 0.355 ac MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 6HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Area 1 Runoff = 0.44 cfs @ 12.18 hrs, Volume= 0.023 af, Depth> 1.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 3,266 96 Gravel surface, HSG C 7,583 74 >75% Grass cover, Good, HSG C 10,849 81 Weighted Average 10,849 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 2S: Area 1 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.48 0.46 0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=10,849 sf Runoff Volume=0.023 af Runoff Depth>1.10" Tc=10.0 min CN=81 0.44 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 7HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Area 2 Runoff = 1.35 cfs @ 12.17 hrs, Volume= 0.073 af, Depth> 1.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 15,236 98 Paved parking, HSG C 5,737 74 >75% Grass cover, Good, HSG C 20,973 91 Weighted Average 5,737 27.35% Pervious Area 15,236 72.65% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 3S: Area 2 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=20,973 sf Runoff Volume=0.073 af Runoff Depth>1.81" Tc=10.0 min CN=91 1.35 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 8HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Area 3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.10 cfs @ 12.13 hrs, Volume= 0.004 af, Depth> 0.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 245 98 Paved parking, HSG C 2,479 74 >75% Grass cover, Good, HSG C 2,724 76 Weighted Average 2,479 91.01% Pervious Area 245 8.99% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Area 3 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.11 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=2,724 sf Runoff Volume=0.004 af Runoff Depth>0.83" Tc=5.0 min CN=76 0.10 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 9HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 1P: Offsite to Gas Station [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.249 ac, 0.00% Impervious, Inflow Depth > 1.10" for 2-year event Inflow = 0.44 cfs @ 12.18 hrs, Volume= 0.023 af Primary = 0.44 cfs @ 12.18 hrs, Volume= 0.023 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 1P: Offsite to Gas Station Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.48 0.46 0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.249 ac 0.44 cfs 0.44 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 10HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 5P: Offsite to Frontage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.481 ac, 72.65% Impervious, Inflow Depth > 1.81" for 2-year event Inflow = 1.35 cfs @ 12.17 hrs, Volume= 0.073 af Primary = 1.35 cfs @ 12.17 hrs, Volume= 0.073 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 5P: Offsite to Frontage Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 Inflow Area=0.481 ac 1.35 cfs 1.35 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 11HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 6P: Offsite to West [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.063 ac, 8.99% Impervious, Inflow Depth > 0.83" for 2-year event Inflow = 0.10 cfs @ 12.13 hrs, Volume= 0.004 af Primary = 0.10 cfs @ 12.13 hrs, Volume= 0.004 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 6P: Offsite to West Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.11 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.063 ac 0.10 cfs 0.10 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 12HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 9P: Offsite to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.731 ac, 47.88% Impervious, Inflow Depth > 1.57" for 2-year event Inflow = 1.79 cfs @ 12.18 hrs, Volume= 0.096 af Primary = 1.79 cfs @ 12.18 hrs, Volume= 0.096 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 9P: Offsite to North Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 Inflow Area=0.731 ac 1.79 cfs 1.79 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 13HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Time span=4.00-20.00 hrs, dt=0.05 hrs, 321 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=10,849 sf 0.00% Impervious Runoff Depth>2.19"Subcatchment 2S: Area 1 Tc=10.0 min CN=81 Runoff=0.86 cfs 0.046 af Runoff Area=20,973 sf 72.65% Impervious Runoff Depth>3.10"Subcatchment 3S: Area 2 Tc=10.0 min CN=91 Runoff=2.24 cfs 0.124 af Runoff Area=2,724 sf 8.99% Impervious Runoff Depth>1.81"Subcatchment 4S: Area 3 Tc=5.0 min CN=76 Runoff=0.22 cfs 0.009 af Inflow=0.86 cfs 0.046 afPond 1P: Offsite to Gas Station Primary=0.86 cfs 0.046 af Inflow=2.24 cfs 0.124 afPond 5P: Offsite to Frontage Primary=2.24 cfs 0.124 af Inflow=0.22 cfs 0.009 afPond 6P: Offsite to West Primary=0.22 cfs 0.009 af Inflow=3.11 cfs 0.170 afPond 9P: Offsite to North Primary=3.11 cfs 0.170 af Total Runoff Area = 0.793 ac Runoff Volume = 0.179 af Average Runoff Depth = 2.71" 55.19% Pervious = 0.438 ac 44.81% Impervious = 0.355 ac MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 14HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Area 1 Runoff = 0.86 cfs @ 12.18 hrs, Volume= 0.046 af, Depth> 2.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 3,266 96 Gravel surface, HSG C 7,583 74 >75% Grass cover, Good, HSG C 10,849 81 Weighted Average 10,849 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 2S: Area 1 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=10,849 sf Runoff Volume=0.046 af Runoff Depth>2.19" Tc=10.0 min CN=81 0.86 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 15HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Area 2 Runoff = 2.24 cfs @ 12.17 hrs, Volume= 0.124 af, Depth> 3.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 15,236 98 Paved parking, HSG C 5,737 74 >75% Grass cover, Good, HSG C 20,973 91 Weighted Average 5,737 27.35% Pervious Area 15,236 72.65% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 3S: Area 2 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=20,973 sf Runoff Volume=0.124 af Runoff Depth>3.10" Tc=10.0 min CN=91 2.24 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 16HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Area 3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.22 cfs @ 12.12 hrs, Volume= 0.009 af, Depth> 1.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 245 98 Paved parking, HSG C 2,479 74 >75% Grass cover, Good, HSG C 2,724 76 Weighted Average 2,479 91.01% Pervious Area 245 8.99% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Area 3 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.24 0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=2,724 sf Runoff Volume=0.009 af Runoff Depth>1.81" Tc=5.0 min CN=76 0.22 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 17HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 1P: Offsite to Gas Station [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.249 ac, 0.00% Impervious, Inflow Depth > 2.19" for 10-year event Inflow = 0.86 cfs @ 12.18 hrs, Volume= 0.046 af Primary = 0.86 cfs @ 12.18 hrs, Volume= 0.046 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 1P: Offsite to Gas Station Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.249 ac 0.86 cfs 0.86 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 18HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 5P: Offsite to Frontage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.481 ac, 72.65% Impervious, Inflow Depth > 3.10" for 10-year event Inflow = 2.24 cfs @ 12.17 hrs, Volume= 0.124 af Primary = 2.24 cfs @ 12.17 hrs, Volume= 0.124 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 5P: Offsite to Frontage Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 Inflow Area=0.481 ac 2.24 cfs 2.24 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 19HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 6P: Offsite to West [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.063 ac, 8.99% Impervious, Inflow Depth > 1.81" for 10-year event Inflow = 0.22 cfs @ 12.12 hrs, Volume= 0.009 af Primary = 0.22 cfs @ 12.12 hrs, Volume= 0.009 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 6P: Offsite to West Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.24 0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.063 ac 0.22 cfs 0.22 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 20HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 9P: Offsite to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.731 ac, 47.88% Impervious, Inflow Depth > 2.79" for 10-year event Inflow = 3.11 cfs @ 12.17 hrs, Volume= 0.170 af Primary = 3.11 cfs @ 12.17 hrs, Volume= 0.170 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 9P: Offsite to North Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)3 2 1 0 Inflow Area=0.731 ac 3.11 cfs 3.11 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 21HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Time span=4.00-20.00 hrs, dt=0.05 hrs, 321 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=10,849 sf 0.00% Impervious Runoff Depth>4.90"Subcatchment 2S: Area 1 Tc=10.0 min CN=81 Runoff=1.88 cfs 0.102 af Runoff Area=20,973 sf 72.65% Impervious Runoff Depth>6.04"Subcatchment 3S: Area 2 Tc=10.0 min CN=91 Runoff=4.19 cfs 0.242 af Runoff Area=2,724 sf 8.99% Impervious Runoff Depth>4.35"Subcatchment 4S: Area 3 Tc=5.0 min CN=76 Runoff=0.51 cfs 0.023 af Inflow=1.88 cfs 0.102 afPond 1P: Offsite to Gas Station Primary=1.88 cfs 0.102 af Inflow=4.19 cfs 0.242 afPond 5P: Offsite to Frontage Primary=4.19 cfs 0.242 af Inflow=0.51 cfs 0.023 afPond 6P: Offsite to West Primary=0.51 cfs 0.023 af Inflow=6.07 cfs 0.344 afPond 9P: Offsite to North Primary=6.07 cfs 0.344 af Total Runoff Area = 0.793 ac Runoff Volume = 0.367 af Average Runoff Depth = 5.55" 55.19% Pervious = 0.438 ac 44.81% Impervious = 0.355 ac MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 22HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Area 1 Runoff = 1.88 cfs @ 12.17 hrs, Volume= 0.102 af, Depth> 4.90" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 3,266 96 Gravel surface, HSG C 7,583 74 >75% Grass cover, Good, HSG C 10,849 81 Weighted Average 10,849 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 2S: Area 1 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=10,849 sf Runoff Volume=0.102 af Runoff Depth>4.90" Tc=10.0 min CN=81 1.88 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 23HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Area 2 Runoff = 4.19 cfs @ 12.17 hrs, Volume= 0.242 af, Depth> 6.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 15,236 98 Paved parking, HSG C 5,737 74 >75% Grass cover, Good, HSG C 20,973 91 Weighted Average 5,737 27.35% Pervious Area 15,236 72.65% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 3S: Area 2 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)4 3 2 1 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=20,973 sf Runoff Volume=0.242 af Runoff Depth>6.04" Tc=10.0 min CN=91 4.19 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 24HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Area 3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.51 cfs @ 12.12 hrs, Volume= 0.023 af, Depth> 4.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 245 98 Paved parking, HSG C 2,479 74 >75% Grass cover, Good, HSG C 2,724 76 Weighted Average 2,479 91.01% Pervious Area 245 8.99% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Area 3 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=2,724 sf Runoff Volume=0.023 af Runoff Depth>4.35" Tc=5.0 min CN=76 0.51 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 25HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 1P: Offsite to Gas Station [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.249 ac, 0.00% Impervious, Inflow Depth > 4.90" for 100-year event Inflow = 1.88 cfs @ 12.17 hrs, Volume= 0.102 af Primary = 1.88 cfs @ 12.17 hrs, Volume= 0.102 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 1P: Offsite to Gas Station Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 Inflow Area=0.249 ac 1.88 cfs 1.88 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 26HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 5P: Offsite to Frontage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.481 ac, 72.65% Impervious, Inflow Depth > 6.04" for 100-year event Inflow = 4.19 cfs @ 12.17 hrs, Volume= 0.242 af Primary = 4.19 cfs @ 12.17 hrs, Volume= 0.242 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 5P: Offsite to Frontage Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)4 3 2 1 0 Inflow Area=0.481 ac 4.19 cfs 4.19 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 27HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 6P: Offsite to West [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.063 ac, 8.99% Impervious, Inflow Depth > 4.35" for 100-year event Inflow = 0.51 cfs @ 12.12 hrs, Volume= 0.023 af Primary = 0.51 cfs @ 12.12 hrs, Volume= 0.023 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 6P: Offsite to West Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.063 ac 0.51 cfs 0.51 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 28HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 9P: Offsite to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.731 ac, 47.88% Impervious, Inflow Depth > 5.65" for 100-year event Inflow = 6.07 cfs @ 12.17 hrs, Volume= 0.344 af Primary = 6.07 cfs @ 12.17 hrs, Volume= 0.344 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 9P: Offsite to North Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)6 5 4 3 2 1 0 Inflow Area=0.731 ac 6.07 cfs 6.07 cfs Proposed conditions 9S Area 1 10S Area 2 11S Area 3 12S Area 4 - rooftop 10P Offsite to North 11P Raingarden B2 12P Raingarden B1 13P Offsite to Frontage 14P Offsite to West Routing Diagram for Tire Pros Rev 9.29 Prepared by Stevens Engineers, Printed 9/29/2022 HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Subcat Reach Pond Link Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 2HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 0.230 74 >75% Grass cover, Good, HSG C (9S, 10S, 11S) 0.562 98 Paved parking, HSG C (9S, 10S, 11S, 12S) 0.792 91 TOTAL AREA Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 3HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 0.000 HSG B 0.792 HSG C 9S, 10S, 11S, 12S 0.000 HSG D 0.000 Other 0.792 TOTAL AREA Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 4HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Ground Covers (selected nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 0.000 0.230 0.000 0.000 0.230 >75% Grass cover, Good 9S, 10S, 11S 0.000 0.000 0.562 0.000 0.000 0.562 Paved parking 9S, 10S, 11S, 12S 0.000 0.000 0.792 0.000 0.000 0.792 TOTAL AREA Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 5HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pipe Listing (selected nodes) Line# Node Number In-Invert (feet) Out-Invert (feet) Length (feet) Slope (ft/ft) n Diam/Width (inches) Height (inches) Inside-Fill (inches) 1 11P 904.50 904.40 10.0 0.0100 0.012 12.0 0.0 0.0 2 12P 904.50 904.40 15.0 0.0067 0.012 12.0 0.0 0.0 MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 6HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Time span=4.00-20.00 hrs, dt=0.05 hrs, 321 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=17,178 sf 72.10% Impervious Runoff Depth>1.81"Subcatchment 9S: Area 1 Tc=10.0 min CN=91 Runoff=1.11 cfs 0.060 af Runoff Area=10,644 sf 71.50% Impervious Runoff Depth>1.81"Subcatchment 10S: Area 2 Tc=10.0 min CN=91 Runoff=0.69 cfs 0.037 af Runoff Area=2,451 sf 10.36% Impervious Runoff Depth>0.83"Subcatchment 11S: Area 3 Tc=5.0 min CN=76 Runoff=0.09 cfs 0.004 af Runoff Area=4,221 sf 100.00% Impervious Runoff Depth>2.49"Subcatchment 12S: Area 4 - rooftop Tc=10.0 min CN=98 Runoff=0.33 cfs 0.020 af Inflow=1.11 cfs 0.115 afPond 10P: Offsite to North Primary=1.11 cfs 0.115 af Peak Elev=907.16' Storage=222 cf Inflow=0.69 cfs 0.037 afPond 11P: Raingarden B2 Outflow=0.68 cfs 0.035 af Peak Elev=909.50' Storage=1,012 cf Inflow=1.11 cfs 0.060 afPond 12P: Raingarden B1 Primary=0.45 cfs 0.060 af Secondary=0.00 cfs 0.000 af Outflow=0.45 cfs 0.060 af Inflow=1.11 cfs 0.115 afPond 13P: Offsite to Frontage Primary=1.11 cfs 0.115 af Inflow=0.09 cfs 0.004 afPond 14P: Offsite to West Primary=0.09 cfs 0.004 af Total Runoff Area = 0.792 ac Runoff Volume = 0.121 af Average Runoff Depth = 1.83" 29.06% Pervious = 0.230 ac 70.94% Impervious = 0.562 ac MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 7HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 9S: Area 1 Runoff = 1.11 cfs @ 12.17 hrs, Volume= 0.060 af, Depth> 1.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 12,386 98 Paved parking, HSG C 4,792 74 >75% Grass cover, Good, HSG C 17,178 91 Weighted Average 4,792 27.90% Pervious Area 12,386 72.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 9S: Area 1 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=17,178 sf Runoff Volume=0.060 af Runoff Depth>1.81" Tc=10.0 min CN=91 1.11 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 8HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 10S: Area 2 Runoff = 0.69 cfs @ 12.17 hrs, Volume= 0.037 af, Depth> 1.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 7,610 98 Paved parking, HSG C 3,034 74 >75% Grass cover, Good, HSG C 10,644 91 Weighted Average 3,034 28.50% Pervious Area 7,610 71.50% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 10S: Area 2 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=10,644 sf Runoff Volume=0.037 af Runoff Depth>1.81" Tc=10.0 min CN=91 0.69 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 9HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 11S: Area 3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.09 cfs @ 12.13 hrs, Volume= 0.004 af, Depth> 0.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 254 98 Paved parking, HSG C 2,197 74 >75% Grass cover, Good, HSG C 2,451 76 Weighted Average 2,197 89.64% Pervious Area 254 10.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 11S: Area 3 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=2,451 sf Runoff Volume=0.004 af Runoff Depth>0.83" Tc=5.0 min CN=76 0.09 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 10HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 12S: Area 4 - rooftop Runoff = 0.33 cfs @ 12.17 hrs, Volume= 0.020 af, Depth> 2.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2-year Rainfall=2.80" Area (sf) CN Description 4,221 98 Paved parking, HSG C 4,221 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 12S: Area 4 - rooftop Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 MSE 24-hr 3 2-year Rainfall=2.80" Runoff Area=4,221 sf Runoff Volume=0.020 af Runoff Depth>2.49" Tc=10.0 min CN=98 0.33 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 11HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 10P: Offsite to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.736 ac, 75.58% Impervious, Inflow Depth > 1.87" for 2-year event Inflow = 1.11 cfs @ 12.19 hrs, Volume= 0.115 af Primary = 1.11 cfs @ 12.19 hrs, Volume= 0.115 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 10P: Offsite to North Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 Inflow Area=0.736 ac 1.11 cfs 1.11 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 12HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 11P: Raingarden B2 Inflow Area = 0.244 ac, 71.50% Impervious, Inflow Depth > 1.81" for 2-year event Inflow = 0.69 cfs @ 12.17 hrs, Volume= 0.037 af Outflow = 0.68 cfs @ 12.19 hrs, Volume= 0.035 af, Atten= 0%, Lag= 0.9 min Primary = 0.68 cfs @ 12.19 hrs, Volume= 0.035 af Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 907.16' @ 12.19 hrs Surf.Area= 248 sf Storage= 222 cf Plug-Flow detention time= 48.6 min calculated for 0.035 af (95% of inflow) Center-of-Mass det. time= 29.5 min ( 802.9 - 773.4 ) Volume Invert Avail.Storage Storage Description #1 905.50' 514 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 905.50 41 0 0 906.00 87 32 32 907.00 218 153 185 907.70 349 198 383 908.00 525 131 514 Device Routing Invert Outlet Devices #1 Primary 904.50'12.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 904.50' / 904.40' S= 0.0100 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 905.50'3.600 in/hr Exfiltration over Surface area #3 Device 1 907.00'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.67 cfs @ 12.19 hrs HW=907.16' (Free Discharge) 1=Culvert (Passes 0.67 cfs of 4.39 cfs potential flow) 2=Exfiltration (Exfiltration Controls 0.02 cfs) 3=Orifice/Grate (Weir Controls 0.65 cfs @ 1.30 fps) MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 13HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pond 11P: Raingarden B2 Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.244 ac Peak Elev=907.16' Storage=222 cf 0.69 cfs 0.68 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 14HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 12P: Raingarden B1 Inflow Area = 0.394 ac, 72.10% Impervious, Inflow Depth > 1.81" for 2-year event Inflow = 1.11 cfs @ 12.17 hrs, Volume= 0.060 af Outflow = 0.45 cfs @ 12.37 hrs, Volume= 0.060 af, Atten= 59%, Lag= 11.8 min Primary = 0.45 cfs @ 12.37 hrs, Volume= 0.060 af Secondary = 0.00 cfs @ 4.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 909.50' @ 12.37 hrs Surf.Area= 1,454 sf Storage= 1,012 cf Plug-Flow detention time= 66.8 min calculated for 0.060 af (100% of inflow) Center-of-Mass det. time= 66.4 min ( 839.8 - 773.4 ) Volume Invert Avail.Storage Storage Description #1 908.50' 3,526 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 908.50 540 0 0 909.00 1,026 392 392 909.50 1,453 620 1,011 910.00 1,935 847 1,858 910.20 2,719 465 2,324 910.50 5,298 1,203 3,526 Device Routing Invert Outlet Devices #1 Primary 904.50'12.0" Round Culvert L= 15.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 904.50' / 904.40' S= 0.0067 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 908.50'3.600 in/hr Exfiltration over Surface area #3 Secondary 910.20'2.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #4 Device 1 909.40'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.44 cfs @ 12.37 hrs HW=909.50' (Free Discharge) 1=Culvert (Passes 0.44 cfs of 6.33 cfs potential flow) 2=Exfiltration (Exfiltration Controls 0.12 cfs) 4=Orifice/Grate (Weir Controls 0.32 cfs @ 1.03 fps) Secondary OutFlow Max=0.00 cfs @ 4.00 hrs HW=908.50' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 15HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pond 12P: Raingarden B1 Inflow Outflow Primary Secondary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 Inflow Area=0.394 ac Peak Elev=909.50' Storage=1,012 cf 1.11 cfs 0.45 cfs 0.45 cfs 0.00 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 16HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 13P: Offsite to Frontage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.736 ac, 75.58% Impervious, Inflow Depth > 1.87" for 2-year event Inflow = 1.11 cfs @ 12.19 hrs, Volume= 0.115 af Primary = 1.11 cfs @ 12.19 hrs, Volume= 0.115 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 13P: Offsite to Frontage Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 Inflow Area=0.736 ac 1.11 cfs 1.11 cfs MSE 24-hr 3 2-year Rainfall=2.80"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 17HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 14P: Offsite to West [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.056 ac, 10.36% Impervious, Inflow Depth > 0.83" for 2-year event Inflow = 0.09 cfs @ 12.13 hrs, Volume= 0.004 af Primary = 0.09 cfs @ 12.13 hrs, Volume= 0.004 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 14P: Offsite to West Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.056 ac 0.09 cfs 0.09 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 18HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Time span=4.00-20.00 hrs, dt=0.05 hrs, 321 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=17,178 sf 72.10% Impervious Runoff Depth>3.10"Subcatchment 9S: Area 1 Tc=10.0 min CN=91 Runoff=1.84 cfs 0.102 af Runoff Area=10,644 sf 71.50% Impervious Runoff Depth>3.10"Subcatchment 10S: Area 2 Tc=10.0 min CN=91 Runoff=1.14 cfs 0.063 af Runoff Area=2,451 sf 10.36% Impervious Runoff Depth>1.81"Subcatchment 11S: Area 3 Tc=5.0 min CN=76 Runoff=0.20 cfs 0.008 af Runoff Area=4,221 sf 100.00% Impervious Runoff Depth>3.84"Subcatchment 12S: Area 4 - rooftop Tc=10.0 min CN=98 Runoff=0.51 cfs 0.031 af Inflow=2.98 cfs 0.193 afPond 10P: Offsite to North Primary=2.98 cfs 0.193 af Peak Elev=907.23' Storage=239 cf Inflow=1.14 cfs 0.063 afPond 11P: Raingarden B2 Outflow=1.13 cfs 0.060 af Peak Elev=909.66' Storage=1,254 cf Inflow=1.84 cfs 0.102 afPond 12P: Raingarden B1 Primary=1.48 cfs 0.102 af Secondary=0.00 cfs 0.000 af Outflow=1.48 cfs 0.102 af Inflow=2.98 cfs 0.193 afPond 13P: Offsite to Frontage Primary=2.98 cfs 0.193 af Inflow=0.20 cfs 0.008 afPond 14P: Offsite to West Primary=0.20 cfs 0.008 af Total Runoff Area = 0.792 ac Runoff Volume = 0.204 af Average Runoff Depth = 3.10" 29.06% Pervious = 0.230 ac 70.94% Impervious = 0.562 ac MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 19HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 9S: Area 1 Runoff = 1.84 cfs @ 12.17 hrs, Volume= 0.102 af, Depth> 3.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 12,386 98 Paved parking, HSG C 4,792 74 >75% Grass cover, Good, HSG C 17,178 91 Weighted Average 4,792 27.90% Pervious Area 12,386 72.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 9S: Area 1 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=17,178 sf Runoff Volume=0.102 af Runoff Depth>3.10" Tc=10.0 min CN=91 1.84 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 20HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 10S: Area 2 Runoff = 1.14 cfs @ 12.17 hrs, Volume= 0.063 af, Depth> 3.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 7,610 98 Paved parking, HSG C 3,034 74 >75% Grass cover, Good, HSG C 10,644 91 Weighted Average 3,034 28.50% Pervious Area 7,610 71.50% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 10S: Area 2 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=10,644 sf Runoff Volume=0.063 af Runoff Depth>3.10" Tc=10.0 min CN=91 1.14 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 21HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 11S: Area 3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.20 cfs @ 12.12 hrs, Volume= 0.008 af, Depth> 1.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 254 98 Paved parking, HSG C 2,197 74 >75% Grass cover, Good, HSG C 2,451 76 Weighted Average 2,197 89.64% Pervious Area 254 10.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 11S: Area 3 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=2,451 sf Runoff Volume=0.008 af Runoff Depth>1.81" Tc=5.0 min CN=76 0.20 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 22HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 12S: Area 4 - rooftop Runoff = 0.51 cfs @ 12.17 hrs, Volume= 0.031 af, Depth> 3.84" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10-year Rainfall=4.20" Area (sf) CN Description 4,221 98 Paved parking, HSG C 4,221 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 12S: Area 4 - rooftop Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 MSE 24-hr 3 10-year Rainfall=4.20" Runoff Area=4,221 sf Runoff Volume=0.031 af Runoff Depth>3.84" Tc=10.0 min CN=98 0.51 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 23HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 10P: Offsite to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.736 ac, 75.58% Impervious, Inflow Depth > 3.14" for 10-year event Inflow = 2.98 cfs @ 12.21 hrs, Volume= 0.193 af Primary = 2.98 cfs @ 12.21 hrs, Volume= 0.193 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 10P: Offsite to North Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)3 2 1 0 Inflow Area=0.736 ac 2.98 cfs 2.98 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 24HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 11P: Raingarden B2 Inflow Area = 0.244 ac, 71.50% Impervious, Inflow Depth > 3.10" for 10-year event Inflow = 1.14 cfs @ 12.17 hrs, Volume= 0.063 af Outflow = 1.13 cfs @ 12.19 hrs, Volume= 0.060 af, Atten= 0%, Lag= 0.8 min Primary = 1.13 cfs @ 12.19 hrs, Volume= 0.060 af Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 907.23' @ 12.19 hrs Surf.Area= 261 sf Storage= 239 cf Plug-Flow detention time= 34.0 min calculated for 0.060 af (95% of inflow) Center-of-Mass det. time= 15.2 min ( 779.4 - 764.2 ) Volume Invert Avail.Storage Storage Description #1 905.50' 514 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 905.50 41 0 0 906.00 87 32 32 907.00 218 153 185 907.70 349 198 383 908.00 525 131 514 Device Routing Invert Outlet Devices #1 Primary 904.50'12.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 904.50' / 904.40' S= 0.0100 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 905.50'3.600 in/hr Exfiltration over Surface area #3 Device 1 907.00'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.11 cfs @ 12.19 hrs HW=907.22' (Free Discharge) 1=Culvert (Passes 1.11 cfs of 4.45 cfs potential flow) 2=Exfiltration (Exfiltration Controls 0.02 cfs) 3=Orifice/Grate (Weir Controls 1.08 cfs @ 1.55 fps) MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 25HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pond 11P: Raingarden B2 Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)1 0 Inflow Area=0.244 ac Peak Elev=907.23' Storage=239 cf 1.14 cfs 1.13 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 26HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 12P: Raingarden B1 Inflow Area = 0.394 ac, 72.10% Impervious, Inflow Depth > 3.10" for 10-year event Inflow = 1.84 cfs @ 12.17 hrs, Volume= 0.102 af Outflow = 1.48 cfs @ 12.25 hrs, Volume= 0.102 af, Atten= 19%, Lag= 4.5 min Primary = 1.48 cfs @ 12.25 hrs, Volume= 0.102 af Secondary = 0.00 cfs @ 4.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 909.66' @ 12.25 hrs Surf.Area= 1,606 sf Storage= 1,254 cf Plug-Flow detention time= 51.6 min calculated for 0.102 af (100% of inflow) Center-of-Mass det. time= 51.2 min ( 815.4 - 764.2 ) Volume Invert Avail.Storage Storage Description #1 908.50' 3,526 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 908.50 540 0 0 909.00 1,026 392 392 909.50 1,453 620 1,011 910.00 1,935 847 1,858 910.20 2,719 465 2,324 910.50 5,298 1,203 3,526 Device Routing Invert Outlet Devices #1 Primary 904.50'12.0" Round Culvert L= 15.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 904.50' / 904.40' S= 0.0067 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 908.50'3.600 in/hr Exfiltration over Surface area #3 Secondary 910.20'2.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #4 Device 1 909.40'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.48 cfs @ 12.25 hrs HW=909.66' (Free Discharge) 1=Culvert (Passes 1.48 cfs of 6.44 cfs potential flow) 2=Exfiltration (Exfiltration Controls 0.13 cfs) 4=Orifice/Grate (Weir Controls 1.34 cfs @ 1.66 fps) Secondary OutFlow Max=0.00 cfs @ 4.00 hrs HW=908.50' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 27HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pond 12P: Raingarden B1 Inflow Outflow Primary Secondary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 Inflow Area=0.394 ac Peak Elev=909.66' Storage=1,254 cf 1.84 cfs 1.48 cfs 1.48 cfs 0.00 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 28HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 13P: Offsite to Frontage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.736 ac, 75.58% Impervious, Inflow Depth > 3.14" for 10-year event Inflow = 2.98 cfs @ 12.21 hrs, Volume= 0.193 af Primary = 2.98 cfs @ 12.21 hrs, Volume= 0.193 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 13P: Offsite to Frontage Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)3 2 1 0 Inflow Area=0.736 ac 2.98 cfs 2.98 cfs MSE 24-hr 3 10-year Rainfall=4.20"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 29HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 14P: Offsite to West [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.056 ac, 10.36% Impervious, Inflow Depth > 1.81" for 10-year event Inflow = 0.20 cfs @ 12.12 hrs, Volume= 0.008 af Primary = 0.20 cfs @ 12.12 hrs, Volume= 0.008 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 14P: Offsite to West Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.056 ac 0.20 cfs 0.20 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 30HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Time span=4.00-20.00 hrs, dt=0.05 hrs, 321 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=17,178 sf 72.10% Impervious Runoff Depth>6.04"Subcatchment 9S: Area 1 Tc=10.0 min CN=91 Runoff=3.43 cfs 0.198 af Runoff Area=10,644 sf 71.50% Impervious Runoff Depth>6.04"Subcatchment 10S: Area 2 Tc=10.0 min CN=91 Runoff=2.13 cfs 0.123 af Runoff Area=2,451 sf 10.36% Impervious Runoff Depth>4.35"Subcatchment 11S: Area 3 Tc=5.0 min CN=76 Runoff=0.46 cfs 0.020 af Runoff Area=4,221 sf 100.00% Impervious Runoff Depth>6.81"Subcatchment 12S: Area 4 - rooftop Tc=10.0 min CN=98 Runoff=0.88 cfs 0.055 af Inflow=5.69 cfs 0.370 afPond 10P: Offsite to North Primary=5.69 cfs 0.370 af Peak Elev=907.35' Storage=271 cf Inflow=2.13 cfs 0.123 afPond 11P: Raingarden B2 Outflow=2.12 cfs 0.119 af Peak Elev=909.89' Storage=1,645 cf Inflow=3.43 cfs 0.198 afPond 12P: Raingarden B1 Primary=2.79 cfs 0.196 af Secondary=0.00 cfs 0.000 af Outflow=2.79 cfs 0.196 af Inflow=5.69 cfs 0.370 afPond 13P: Offsite to Frontage Primary=5.69 cfs 0.370 af Inflow=0.46 cfs 0.020 afPond 14P: Offsite to West Primary=0.46 cfs 0.020 af Total Runoff Area = 0.792 ac Runoff Volume = 0.397 af Average Runoff Depth = 6.01" 29.06% Pervious = 0.230 ac 70.94% Impervious = 0.562 ac MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 31HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 9S: Area 1 Runoff = 3.43 cfs @ 12.17 hrs, Volume= 0.198 af, Depth> 6.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 12,386 98 Paved parking, HSG C 4,792 74 >75% Grass cover, Good, HSG C 17,178 91 Weighted Average 4,792 27.90% Pervious Area 12,386 72.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 9S: Area 1 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)3 2 1 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=17,178 sf Runoff Volume=0.198 af Runoff Depth>6.04" Tc=10.0 min CN=91 3.43 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 32HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 10S: Area 2 Runoff = 2.13 cfs @ 12.17 hrs, Volume= 0.123 af, Depth> 6.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 7,610 98 Paved parking, HSG C 3,034 74 >75% Grass cover, Good, HSG C 10,644 91 Weighted Average 3,034 28.50% Pervious Area 7,610 71.50% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 10S: Area 2 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=10,644 sf Runoff Volume=0.123 af Runoff Depth>6.04" Tc=10.0 min CN=91 2.13 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 33HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 11S: Area 3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.46 cfs @ 12.12 hrs, Volume= 0.020 af, Depth> 4.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 254 98 Paved parking, HSG C 2,197 74 >75% Grass cover, Good, HSG C 2,451 76 Weighted Average 2,197 89.64% Pervious Area 254 10.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 11S: Area 3 Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.5 0.48 0.46 0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=2,451 sf Runoff Volume=0.020 af Runoff Depth>4.35" Tc=5.0 min CN=76 0.46 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 34HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Subcatchment 12S: Area 4 - rooftop Runoff = 0.88 cfs @ 12.17 hrs, Volume= 0.055 af, Depth> 6.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-year Rainfall=7.30" Area (sf) CN Description 4,221 98 Paved parking, HSG C 4,221 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 12S: Area 4 - rooftop Runoff Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 MSE 24-hr 3 100-year Rainfall=7.30" Runoff Area=4,221 sf Runoff Volume=0.055 af Runoff Depth>6.81" Tc=10.0 min CN=98 0.88 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 35HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 10P: Offsite to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.736 ac, 75.58% Impervious, Inflow Depth > 6.03" for 100-year event Inflow = 5.69 cfs @ 12.19 hrs, Volume= 0.370 af Primary = 5.69 cfs @ 12.19 hrs, Volume= 0.370 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 10P: Offsite to North Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)6 5 4 3 2 1 0 Inflow Area=0.736 ac 5.69 cfs 5.69 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 36HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 11P: Raingarden B2 Inflow Area = 0.244 ac, 71.50% Impervious, Inflow Depth > 6.04" for 100-year event Inflow = 2.13 cfs @ 12.17 hrs, Volume= 0.123 af Outflow = 2.12 cfs @ 12.18 hrs, Volume= 0.119 af, Atten= 0%, Lag= 0.7 min Primary = 2.12 cfs @ 12.18 hrs, Volume= 0.119 af Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 907.35' @ 12.18 hrs Surf.Area= 283 sf Storage= 271 cf Plug-Flow detention time= 22.2 min calculated for 0.119 af (97% of inflow) Center-of-Mass det. time= 8.7 min ( 761.3 - 752.5 ) Volume Invert Avail.Storage Storage Description #1 905.50' 514 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 905.50 41 0 0 906.00 87 32 32 907.00 218 153 185 907.70 349 198 383 908.00 525 131 514 Device Routing Invert Outlet Devices #1 Primary 904.50'12.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 904.50' / 904.40' S= 0.0100 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 905.50'3.600 in/hr Exfiltration over Surface area #3 Device 1 907.00'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=2.06 cfs @ 12.18 hrs HW=907.34' (Free Discharge) 1=Culvert (Passes 2.06 cfs of 4.57 cfs potential flow) 2=Exfiltration (Exfiltration Controls 0.02 cfs) 3=Orifice/Grate (Weir Controls 2.04 cfs @ 1.91 fps) MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 37HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pond 11P: Raingarden B2 Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)2 1 0 Inflow Area=0.244 ac Peak Elev=907.35' Storage=271 cf 2.13 cfs 2.12 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 38HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 12P: Raingarden B1 Inflow Area = 0.394 ac, 72.10% Impervious, Inflow Depth > 6.04" for 100-year event Inflow = 3.43 cfs @ 12.17 hrs, Volume= 0.198 af Outflow = 2.79 cfs @ 12.24 hrs, Volume= 0.196 af, Atten= 19%, Lag= 4.0 min Primary = 2.79 cfs @ 12.24 hrs, Volume= 0.196 af Secondary = 0.00 cfs @ 4.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 909.89' @ 12.24 hrs Surf.Area= 1,826 sf Storage= 1,645 cf Plug-Flow detention time= 40.9 min calculated for 0.196 af (99% of inflow) Center-of-Mass det. time= 36.0 min ( 788.6 - 752.5 ) Volume Invert Avail.Storage Storage Description #1 908.50' 3,526 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 908.50 540 0 0 909.00 1,026 392 392 909.50 1,453 620 1,011 910.00 1,935 847 1,858 910.20 2,719 465 2,324 910.50 5,298 1,203 3,526 Device Routing Invert Outlet Devices #1 Primary 904.50'12.0" Round Culvert L= 15.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 904.50' / 904.40' S= 0.0067 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 908.50'3.600 in/hr Exfiltration over Surface area #3 Secondary 910.20'2.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #4 Device 1 909.40'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=2.77 cfs @ 12.24 hrs HW=909.88' (Free Discharge) 1=Culvert (Passes 2.77 cfs of 6.60 cfs potential flow) 2=Exfiltration (Exfiltration Controls 0.15 cfs) 4=Orifice/Grate (Orifice Controls 2.62 cfs @ 3.34 fps) Secondary OutFlow Max=0.00 cfs @ 4.00 hrs HW=908.50' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 39HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Pond 12P: Raingarden B1 Inflow Outflow Primary Secondary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)3 2 1 0 Inflow Area=0.394 ac Peak Elev=909.89' Storage=1,645 cf 3.43 cfs 2.79 cfs 2.79 cfs 0.00 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 40HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 13P: Offsite to Frontage [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.736 ac, 75.58% Impervious, Inflow Depth > 6.03" for 100-year event Inflow = 5.69 cfs @ 12.19 hrs, Volume= 0.370 af Primary = 5.69 cfs @ 12.19 hrs, Volume= 0.370 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 13P: Offsite to Frontage Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)6 5 4 3 2 1 0 Inflow Area=0.736 ac 5.69 cfs 5.69 cfs MSE 24-hr 3 100-year Rainfall=7.30"Tire Pros Rev 9.29 Printed 9/29/2022Prepared by Stevens Engineers Page 41HydroCAD® 10.00-20 s/n 02721 © 2017 HydroCAD Software Solutions LLC Summary for Pond 14P: Offsite to West [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.056 ac, 10.36% Impervious, Inflow Depth > 4.35" for 100-year event Inflow = 0.46 cfs @ 12.12 hrs, Volume= 0.020 af Primary = 0.46 cfs @ 12.12 hrs, Volume= 0.020 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 4.00-20.00 hrs, dt= 0.05 hrs Pond 14P: Offsite to West Inflow Primary Hydrograph Time (hours) 2019181716151413121110987654Flow (cfs)0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.056 ac 0.46 cfs 0.46 cfs Appendix G P8 Modeling P8 Urban Catchment Model, Version 3.5 Run Date 09/29/22 Case p8 Tire Pros try 2.p8c FirstDate 01/01/71 Precip(in) 27.7 Title 2 filtration basins LastDate 12/31/71 Rain(in) 24.42 PrecFile msp_4989.pcp Events 64 Snow(in) 3.32 PartFile nurp50.p8p TotalHrs 7656 TotalYrs 0.87 Case Title 2 filtration basins Case Data File p8 Tire Pros try 2.p8c Path C:\P8_UserFiles\ Case Notes: Storm Data File msp_4989.pcp Particle File nurp50.p8p Air Temp File File msp_4889.tem Time Steps Per Hour 4 Minimum Inter-Event Time (hrs) 10 Maximum Continuity Error % 2 Rainfall Breakpoint (inches) 0.8 Precipitation Scale Factor 1 Air Temp Offset (deg-F) 0 Loops Thru Storm File 1 Simulation Dates Start 1/1/1970 Keep 1/1/1971 Stop 12/31/1971 Max Snowfall Temperature (deg-f) 32.0 SnowMelt Temperature (deg-f) 32.0 Snowmelt Coef (in/degF-Day) 0.06 Soil Freeze Temp (deg-F) 32.0 Snowmelt Abstraction Factor 1.00 Evapo-Trans. Calibration Factor 1.00 Growing Season Start Month 5 Growing Season End Month 10 5-Day Antecedent Rainfall + Runoff (inches) CN Antecedent Moisture Condition AMC-II AMC-III Growing Season 1.40 2.10 NonGrowing Season 0.50 1.10 P8 Urban Catchment Model, Version 3.5 Run Date 09/29/22 Case p8 Tire Pros try 2.p8c FirstDate 01/01/71 Precip(in) 27.7 Title 2 filtration basins LastDate 12/31/71 Rain(in) 24.42 PrecFile msp_4989.pcp Events 64 Snow(in) 3.32 PartFile nurp50.p8p TotalHrs 7656 TotalYrs 0.87 Hydraulics Sedimentation rates assume bulk density of 1 ton per cubic yard of wet sediment. Variable Units Iron Enhanced BasinIron Enhanced Basin 2Treated StormwaterUntreated Stormwater Total Inflow ac-ft 0.65 0.40 0.97 0.11 Total Outflow ac-ft 0.65 0.40 0.97 0.11 Mean Inflow cfs 0.00 0.00 0.00 0.00 Mean Outflow cfs 0.00 0.00 0.00 0.00 Max Inflow cfs 0.39 0.24 0.13 0.42 Max Outflow cfs 0.18 0.22 0.13 0.42 Min Elev ft 908.51 906.01 0.00 0.00 Max Elev ft 909.40 907.16 0.00 0.00 Max Velocity ft/sec 0.00 0.00 0.00 0.00 Wet Period % 0.48 6.79 0.00 0.00 WtrBal Error ac-ft 0.00 0.00 0.00 0.00 WtrBal Error% % 0.00 -0.01 0.00 0.00 Max Area acres 0.03 0.00 0.00 0.00 Mean Hyd Load in/day 0.81 3.73 0.00 0.00 Max Hyd Load in/hr 12.63 58.30 0.00 0.00 Sed Rate Mass tons/ac-yr 3.80 15.83 0.00 0.00 Sed Rate Vol yd3/yr 0.12 0.06 0.00 0.00 Sed Rate Depth in/yr 0.03 0.12 0.00 0.00 Max Volume ac-ft 0.02 0.00 0.00 0.00 Direct Watershed acres 0.39 0.24 0.00 0.06 Unit Runoff inches/yr 23.00 22.72 0.00 5.66 Appendix H Phosphorus Calculation https://stormwater.pca.state.mn.us/index.php?title=Calculating_credits_for_iron_enhanced_sand_filter 0.97 1.07 0.90 0.90 0.58 58% Revised CLH 9.29.22