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HomeMy WebLinkAboutStudies Applicant 12/1/2023STORMWATER ANALYSIS REPORT FOR: Thurston Baptist Church 6364 Main Street Map 17-02-34-42, Tax Lot 4100 Springfield, OR 97478 Prepared by 2350 Oakmont Way, Suite 105 Eugene OR 97401 (541) 485-8383 Contact: Chris Morris, E.I.T Michael A Cox, PE Job #22-7932 November 14, 2023 Based on the City of Springfield Engineering Design Standards and Procedures Manual – 2012 City of Eugene Stormwater Management Manual 2014 Stormwater Analysis Report for Thurston Baptist Church 1 Contents Page No. 1.0 Introduction .......................................................................................................................... 2 2.0 Existing Conditions .............................................................................................................. 2 3.0 Proposed Development ........................................................................................................ 2 4.0 Stormwater Constraints ...................................................................................................... 3 5.0 Proposed Development Stormwater Description ............................................................... 3 6.0 Hydrologic and Hydraulic Analysis .................................................................................... 3 6.1 Computer Model ............................................................................................................................ 3 6.2 Computer Model Data ................................................................................................................... 3 6.3 Infiltration Rates ........................................................................................................................... 4 6.4 Facility Sizing ................................................................................................................................. 5 7.0 Operation and Maintenance ................................................................................................ 5 Appendices Description Appendix A Soil Map and Description Appendix B HydroCAD Report Appendix C Operations and Maintenance Plan Appendix D Well Logs Stormwater Analysis Report for Thurston Baptist Church 2 1.0 Introduction The property is a 1.32-acre parcel of land comprised of Tax Lot 4100 of Lane County Assessor’s Map 17-02-34-42. The subject property is currently under church use and developed with an existing church worship building and a multi-purpose building to remain (6364 Main Street). The subject property is bounded on the North by A Street, South by Main Street and is bounded on the East and west by previously developed residential properties. Said adjacent residential properties are under separate ownership. The subject property is currently designated “Low Density Residential” per the Comprehensive Plan and is currently zoned Commercial Residential. The applicant desires to add an additional 11,424 sf of paved parking and curbs on the northern portion of the parcel which as stated above is currently open grassy area with a stormwater treatment swale on the southernmost portion of the grassy area. The project site lies within the 10–99-year travel time of the Thurston Middle School wellhead (Wellhead Protection Area Map - 2019 City of Springfield and Springfield Utility Board) and is within the Weyerhaeuser Outfall subbasin. The public stormwater follows the drainage system in catchment 6_85. According to the 10-Year Future model (Figure 3-10 of the Stormwater Facility Master Plan – 2008), the nearest major piped system has no excess capacity. Therefore, the proposed new impervious areas need to be treated as well as detained to existing runoff levels through the city’s 25-year storm event. Permits required for the project include stormwater through the City of Springfield. Stormwater discharge is covered under the City of Springfield MS4 NPDES permit. 2.0 Existing Conditions There is minimal grade change across most of the grassy portion of the parcel that is to be developed and paved. The portion to be developed fronts A Street to the north and there is an existing approach and gravel drive that currently connects to the church and parking areas. According to the Soils Survey of Lane County, Oregon, by the Natural Resource Conservation Service, the soils on the site are Salem-Urban land complex (Soil Number 119) and Coburg- Urban land complex (Soil Number 32). Salem-Urban land complex is a well-drained gravelly mixed alluvium of Hydrologic Group B. Coburg-Urban land complex is a well-drained loamy alluvium over clayey alluvium of Hydrologic Group C. A soil map and descriptions are attached as Appendix A. The high groundwater elevation for the site is estimated at greater than 14 feet below ground surface (BGS). Well logs from the immediate vicinity show the groundwater table at 14-18 feet BGS. Copies of the well logs are attached as Appendix E. 3.0 Proposed Development The proposed project includes paving of 11,424 sf of grassy areas, which includes curbs and parking wheel stops. 3.1 Pollutants of Concern The reasonably expected pollutants of concern from this type of development are: • Nutrients • Pesticides, Herbicides, Fungicides Stormwater Analysis Report for Thurston Baptist Church 3 • Metals (Zinc, Copper, Lead, etc.) • Oil, grease and other petroleum • Sediment • Litter • Oxygen demanding materials • Increased thermal loading • Bacteria 4.0 Stormwater Constraints The site is constrained for providing on-site stormwater treatment per Section 3.00 of the City of Springfield Engineering Design Standards & Procedures Manual (2012). The lack of additional capacity in the existing public system constrains the new development per Section 4.00 City of Springfield Engineering Design Standards & Procedures Manual (2012). Therefore, onsite infiltration facilities are designed to treat, and retain all runoff to below existing condition runoff rates for all storm events through the city’s 25-year design storm. The designed system detains the proposed impervious areas to 0.71 cfs compared to the existing conditions runoff rate of 1.25 cfs. 5.0 Proposed Development Stormwater Description The proposed stormwater for the new additions includes two 6-foot-wide approximately 66- foot-long rain gardens with storage aggregate beneath them. The infiltration rates at 3.5 feet below ground surface (BGS) were measured at 20 and 24 inches per hour in the two test holes. The depth to ground water is estimated at 14 feet BGS. Typical city requirements are to have a minimum of 5 feet of separation from bottom of facility to the high groundwater levels. Since the depth to the groundwater is 14 feet and the bottom of the facilities are 3.7 feet below the surface, 10.3 feet of separation is proposed between the bottom of the storage aggregate and the high groundwater table. Well Logs are attached as Appendix D. 6.0 Hydrologic and Hydraulic Analysis 6.1 Computer Model In preparing this Stormwater Management Plan for the project site, SSW Engineers utilized the HydroCAD 10.2 software. This is a computer program used to model, analyze and design hydrosystems of drainage basins. HydroCAD computes Santa Barbara Urban Hydrographs (SBUH) using rainfall data supplied by the designer. The SBUH method is a recognized analysis method by the City of Springfreild and is appropriate for a project site of this size. Once the appropriate data is input to HydroCAD, each drainage basin has a hydrograph and runoff flow for the desired storm event. A copy of the HydroCAD report is included and attached as Appendix B. 6.2 Computer Model Data HydroCAD needs data supplied from the designer that describes the drainage basin in order to create the hydrograph. Data below is used to describe and model the following stormwater basins: Stormwater Analysis Report for Thurston Baptist Church 4 Basin Area (square feet) 25-Year Runoff Rate (cfs) Existing 21,373 1.25 North 9,578 0.71 South 11,795 0.00 o Storm Event For the purposes of this design, the City of Springfield’s design storm events are as follows: Water Quality Event 0.83 inches / 24 hours 5-year Storm Event 3.80 inches / 24 hours 10-year Storm Event 4.30 inches / 24 hours 25-year Storm Event 4.80 inches / 24 hours o Impervious Area Pavement, sidewalks, patios, hardscapes and rooftops are all impervious surfaces. o Pervious Area Lawns and open space are pervious areas. Each drainage basin’s pervious area is all that area that is not impervious. o Runoff Curve Numbers Each drainage basin has a Runoff Curve Number for the impervious areas and the pervious areas. The Runoff Curve Number is based on the type of surface and the Hydrologic Group of the soils. The soils on the site are in Soil Hydrologic Group C. Per the TR-55 table, the Curve Number is 69 for pervious areas and 98 for impervious areas. o Time of Concentration A minimum time of concentration of five minutes was used for the post-developed conditions and ten minutes was used for pre-developed conditions. These times can be observed in the HydroCAD report in Appendix B. 6.3 Infiltration Rates Infiltration rates were tested using the open pit falling head method as described in City of Eugene Stormwater Manual (2014). See Table below for test results. TEST # NORTH RAINGARDEN OPEN PIT TEST RESULTS SOUTH RAINGARDEN OPEN PIT TEST RESULTS 1 24 in/hr 20 in/hr 2 24 in/hr 19 in/hr 3 24 in/hr 20 in/hr FACTOR OF SAFETY 2 2 DESIGN INFILTRATION RATE 12 in/hr 10 in/hr Stormwater Analysis Report for Thurston Baptist Church 5 6.4 Facility Sizing The stormwater treatment and infiltration facilities were sized using the Urban Hydrograph Method and HydroCAD. The rain garden’s dimensions are 6’Wx66’Lx0.7’H. The underlying storage aggregate dimensions are 6’Wx66’Lx2.0’H. 7.0 Operation and Maintenance The rain garden facilities will be operated and maintained by the property owner who will follow the Operation and Maintenance Plan pursuant to the city of Springfield’s code. The operations and maintenance plan is included and can be observed in Appendix C. Stormwater Analysis Report for Thurston Baptist Church 6 APPENDIX A Soil Map and Description Soil Map—Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 1 of 34876920487695048769804877010487704048770704877100487713048771604877190487722048769204876950487698048770104877040487707048771004877130487716048771904877220506650506680506710506740506770506800506830506860 506650 506680 506710 506740 506770 506800 506830 506860 44° 2' 53'' N 122° 55' 1'' W44° 2' 53'' N122° 54' 51'' W44° 2' 43'' N 122° 55' 1'' W44° 2' 43'' N 122° 54' 51'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,500 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:20,000. 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: Lane County Area, Oregon Survey Area Data: Version 21, Mar 13, 2023 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 12, 2019—Jun 19, 2019 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. Soil Map—Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 32 Coburg-Urban land complex 0.0 2.8% 119 Salem-Urban land complex 0.4 97.2% Totals for Area of Interest 0.4 100.0% Soil Map—Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 3 of 3 Lane County Area, Oregon 32—Coburg-Urban land complex Map Unit Setting National map unit symbol: 2369 Elevation: 100 to 1,300 feet Mean annual precipitation: 30 to 60 inches Mean annual air temperature: 50 to 55 degrees F Frost-free period: 160 to 235 days Farmland classification: Farmland of statewide importance Map Unit Composition Coburg and similar soils:55 percent Urban land:30 percent Minor components:4 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Coburg Setting Landform:Stream terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Loamy alluvium over clayey alluvium Typical profile H1 - 0 to 18 inches: silty clay loam H2 - 18 to 53 inches: silty clay H3 - 53 to 65 inches: fine sandy loam Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Moderately well drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high (0.20 to 0.57 in/hr) Depth to water table:About 18 to 30 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: High (about 11.0 inches) Interpretive groups Land capability classification (irrigated): 2w Land capability classification (nonirrigated): 2w Hydrologic Soil Group: C Ecological site: R002XC006OR - Stream Terrace Group Forage suitability group: Moderately Well Drained < 15% Slopes (G002XY004OR) Map Unit Description: Coburg-Urban land complex---Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 1 of 2 Other vegetative classification: Moderately Well Drained < 15% Slopes (G002XY004OR) Hydric soil rating: No Description of Urban Land Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8 Hydric soil rating: No Minor Components Conser Percent of map unit:4 percent Landform:Stream terraces Hydric soil rating: Yes Data Source Information Soil Survey Area: Lane County Area, Oregon Survey Area Data: Version 21, Mar 13, 2023 Map Unit Description: Coburg-Urban land complex---Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 2 of 2 Lane County Area, Oregon 119—Salem-Urban land complex Map Unit Setting National map unit symbol: 2341 Elevation: 300 to 800 feet Mean annual precipitation: 40 to 60 inches Mean annual air temperature: 52 to 54 degrees F Frost-free period: 165 to 210 days Farmland classification: Farmland of statewide importance Map Unit Composition Salem and similar soils:50 percent Urban land:40 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Salem Setting Landform:Stream terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Gravelly mixed alluvium Typical profile H1 - 0 to 7 inches: gravelly silt loam H2 - 7 to 26 inches: gravelly clay loam H3 - 26 to 60 inches: very gravelly sand Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.57 to 1.98 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: Low (about 4.8 inches) Interpretive groups Land capability classification (irrigated): 2s Land capability classification (nonirrigated): 2s Hydrologic Soil Group: B Ecological site: R002XC006OR - Stream Terrace Group Forage suitability group: Well drained < 15% Slopes (G002XY002OR) Other vegetative classification: Well drained < 15% Slopes (G002XY002OR) Map Unit Description: Salem-Urban land complex---Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 1 of 2 Hydric soil rating: No Description of Urban Land Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8 Hydric soil rating: No Data Source Information Soil Survey Area: Lane County Area, Oregon Survey Area Data: Version 21, Mar 13, 2023 Map Unit Description: Salem-Urban land complex---Lane County Area, Oregon Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/22/2023 Page 2 of 2 Stormwater Analysis Report for Thurston Baptist Church 7 APPENDIX B HydroCAD Report 1S South Paving 4S North Paving 10S Existing South Area 11S Existing North Area 12S South Existing Roof Area 2R 6" Pipe 11R Existing 3P South RG 6P North RG 8P Storage Aggregate 9P Storage Aggregate 10P Extended Aggregate Routing Diagram for Design Prepared by SSW Engineers Inc, Printed 11/14/2023 HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 10-Year Rainfall=4.30"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 2HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: South Paving Runoff = 1.31 cfs @ 11.95 hrs, Volume= 0.077 af, Depth> 3.67" Routed to Pond 3P : South RG Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.30" Area (sf) CN Description 10,645 98 Paved parking, HSG C 250 61 >75% Grass cover, Good, HSG B 10,895 97 Weighted Average 250 61 2.29% Pervious Area 10,645 98 97.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: North Paving Runoff = 1.13 cfs @ 11.95 hrs, Volume= 0.066 af, Depth> 3.60" Routed to Pond 6P : North RG Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.30" Area (sf) CN Description 9,118 98 Paved parking, HSG B 460 61 >75% Grass cover, Good, HSG B 9,578 96 Weighted Average 460 61 4.80% Pervious Area 9,118 98 95.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 10S: Existing South Area Runoff = 0.66 cfs @ 11.98 hrs, Volume= 0.047 af, Depth> 2.06" Routed to Reach 11R : Existing Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.30" Type II 24-hr 10-Year Rainfall=4.30"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 3HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Area (sf) CN Description 8,173 69 50-75% Grass cover, Fair, HSG B 2,722 98 Paved roads w/curbs & sewers, HSG C 900 98 Roofs, HSG C 11,795 78 Weighted Average 8,173 69 69.29% Pervious Area 3,622 98 30.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Summary for Subcatchment 11S: Existing North Area Runoff = 0.37 cfs @ 11.99 hrs, Volume= 0.024 af, Depth> 1.32" Routed to Reach 11R : Existing Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.30" Area (sf) CN Description 9,578 69 50-75% Grass cover, Fair, HSG B 9,578 69 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Summary for Subcatchment 12S: South Existing Roof Area Runoff = 0.11 cfs @ 11.95 hrs, Volume= 0.006 af, Depth> 3.74" Routed to Pond 10P : Extended Aggregate Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.30" Area (sf) CN Description 900 98 Roofs, HSG B 900 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type II 24-hr 10-Year Rainfall=4.30"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 4HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Summary for Reach 2R: 6" Pipe Inflow Area = 0.470 ac, 96.53% Impervious, Inflow Depth = 0.38" for 10-Year event Inflow = 0.64 cfs @ 12.03 hrs, Volume= 0.015 af Outflow = 0.63 cfs @ 12.04 hrs, Volume= 0.015 af, Atten= 1%, Lag= 0.7 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 6.56 fps, Min. Travel Time= 0.4 min Avg. Velocity = 3.96 fps, Avg. Travel Time= 0.6 min Peak Storage= 15 cf @ 12.04 hrs Average Depth at Peak Storage= 0.25' , Surface Width= 0.50' Bank-Full Depth= 0.50' Flow Area= 0.2 sf, Capacity= 1.29 cfs 6.0" Round Pipe n= 0.011 Length= 150.0' Slope= 0.0381 '/' Inlet Invert= 518.85', Outlet Invert= 513.14' Summary for Reach 11R: Existing Inflow Area = 0.491 ac, 16.95% Impervious, Inflow Depth > 1.73" for 10-Year event Inflow = 1.03 cfs @ 11.99 hrs, Volume= 0.071 af Outflow = 1.03 cfs @ 11.99 hrs, Volume= 0.071 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Pond 3P: South RG Inflow Area = 0.250 ac, 97.71% Impervious, Inflow Depth > 3.67" for 10-Year event Inflow = 1.31 cfs @ 11.95 hrs, Volume= 0.077 af Outflow = 1.29 cfs @ 11.97 hrs, Volume= 0.074 af, Atten= 1%, Lag= 0.7 min Primary = 1.26 cfs @ 11.97 hrs, Volume= 0.048 af Routed to Pond 8P : Storage Aggregate Secondary = 0.03 cfs @ 11.97 hrs, Volume= 0.026 af Routed to Pond 8P : Storage Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 518.01' @ 11.97 hrs Surf.Area= 0.011 ac Storage= 0.005 af Plug-Flow detention time= 30.0 min calculated for 0.074 af (97% of inflow) Center-of-Mass det. time= 16.5 min ( 748.7 - 732.2 ) Type II 24-hr 10-Year Rainfall=4.30"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 5HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 517.35' 0.006 af 3.00'W x 65.00'L x 0.70'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Secondary 517.35'2.500 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 517.85'6.0" Horiz. Orifice/Grate X 4.00 C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.23 cfs @ 11.97 hrs HW=518.00' (Free Discharge) 2=Orifice/Grate (Weir Controls 1.23 cfs @ 1.28 fps) Secondary OutFlow Max=0.03 cfs @ 11.97 hrs HW=518.00' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Summary for Pond 6P: North RG Inflow Area = 0.220 ac, 95.20% Impervious, Inflow Depth > 3.60" for 10-Year event Inflow = 1.13 cfs @ 11.95 hrs, Volume= 0.066 af Outflow = 1.10 cfs @ 11.97 hrs, Volume= 0.064 af, Atten= 2%, Lag= 0.9 min Primary = 1.07 cfs @ 11.97 hrs, Volume= 0.039 af Routed to Pond 9P : Storage Aggregate Secondary = 0.03 cfs @ 11.97 hrs, Volume= 0.025 af Routed to Pond 9P : Storage Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 517.92' @ 11.97 hrs Surf.Area= 0.011 ac Storage= 0.005 af Plug-Flow detention time= 32.1 min calculated for 0.064 af (97% of inflow) Center-of-Mass det. time= 20.2 min ( 753.0 - 732.7 ) Volume Invert Avail.Storage Storage Description #1 517.25' 0.006 af 3.00'W x 67.00'L x 0.70'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Secondary 517.25'2.500 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 517.75'6.0" Horiz. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.05 cfs @ 11.97 hrs HW=517.92' (Free Discharge) 2=Orifice/Grate (Weir Controls 1.05 cfs @ 1.33 fps) Secondary OutFlow Max=0.03 cfs @ 11.97 hrs HW=517.92' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Summary for Pond 8P: Storage Aggregate Type II 24-hr 10-Year Rainfall=4.30"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 6HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Inflow Area = 0.250 ac, 97.71% Impervious, Inflow Depth > 3.56" for 10-Year event Inflow = 1.29 cfs @ 11.97 hrs, Volume= 0.074 af Outflow = 1.25 cfs @ 11.99 hrs, Volume= 0.074 af, Atten= 3%, Lag= 1.5 min Discarded = 0.11 cfs @ 11.99 hrs, Volume= 0.035 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 2R : 6" Pipe Secondary = 1.14 cfs @ 11.99 hrs, Volume= 0.039 af Routed to Pond 10P : Extended Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 514.97' @ 11.99 hrs Surf.Area= 0.011 ac Storage= 0.002 af Plug-Flow detention time= 0.7 min calculated for 0.074 af (100% of inflow) Center-of-Mass det. time= 0.6 min ( 749.3 - 748.7 ) Volume Invert Avail.Storage Storage Description #1 514.35' 0.010 af 3.00'W x 67.00'L x 2.00'H Prismatoid Z=3.0 0.031 af Overall x 33.0% Voids Device Routing Invert Outlet Devices #1 Discarded 514.35'10.000 in/hr Exfiltration over Surface area #2 Primary 515.85'6.0" Round Culvert L= 10.0' Ke= 0.500 Inlet / Outlet Invert= 515.85' / 515.60' S= 0.0250 '/' Cc= 0.900 n= 0.011, Flow Area= 0.20 sf #3 Secondary 514.35'4.0" Round Culvert X 4.00 L= 10.0' Ke= 0.500 Inlet / Outlet Invert= 514.35' / 514.00' S= 0.0350 '/' Cc= 0.900 n= 0.011, Flow Area= 0.09 sf Discarded OutFlow Max=0.11 cfs @ 11.99 hrs HW=514.96' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.11 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=514.35' (Free Discharge) 2=Culvert ( Controls 0.00 cfs) Secondary OutFlow Max=1.12 cfs @ 11.99 hrs HW=514.96' (Free Discharge) 3=Culvert (Inlet Controls 1.12 cfs @ 3.20 fps) Summary for Pond 9P: Storage Aggregate Inflow Area = 0.220 ac, 95.20% Impervious, Inflow Depth > 3.50" for 10-Year event Inflow = 1.10 cfs @ 11.97 hrs, Volume= 0.064 af Outflow = 0.93 cfs @ 12.03 hrs, Volume= 0.064 af, Atten= 16%, Lag= 3.6 min Discarded = 0.29 cfs @ 12.03 hrs, Volume= 0.049 af Primary = 0.64 cfs @ 12.03 hrs, Volume= 0.015 af Routed to Reach 2R : 6" Pipe Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 516.05' @ 12.03 hrs Surf.Area= 0.024 ac Storage= 0.008 af Plug-Flow detention time= 5.2 min calculated for 0.064 af (100% of inflow) Center-of-Mass det. time= 5.1 min ( 758.0 - 753.0 ) Type II 24-hr 10-Year Rainfall=4.30"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 7HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 514.25' 0.010 af 3.00'W x 65.00'L x 2.00'H Prismatoid Z=3.0 0.030 af Overall x 33.0% Voids Device Routing Invert Outlet Devices #1 Discarded 514.25'12.000 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 515.35'6.0" Round Culvert L= 88.0' Ke= 0.500 Inlet / Outlet Invert= 515.35' / 512.95' S= 0.0273 '/' Cc= 0.900 n= 0.011, Flow Area= 0.20 sf Discarded OutFlow Max=0.29 cfs @ 12.03 hrs HW=516.04' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.29 cfs) Primary OutFlow Max=0.63 cfs @ 12.03 hrs HW=516.04' (Free Discharge) 2=Culvert (Inlet Controls 0.63 cfs @ 3.19 fps) Summary for Pond 10P: Extended Aggregate Inflow Area = 0.021 ac,100.00% Impervious, Inflow Depth > 26.56" for 10-Year event Inflow = 1.24 cfs @ 11.99 hrs, Volume= 0.046 af Outflow = 0.34 cfs @ 12.17 hrs, Volume= 0.046 af, Atten= 72%, Lag= 11.3 min Discarded = 0.34 cfs @ 12.17 hrs, Volume= 0.046 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 515.27' @ 12.17 hrs Surf.Area= 1,476 sf Storage= 879 cf Plug-Flow detention time= 23.0 min calculated for 0.046 af (100% of inflow) Center-of-Mass det. time= 22.9 min ( 747.9 - 725.0 ) Volume Invert Avail.Storage Storage Description #1 514.50' 2,661 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 514.50 800 0 0 515.50 1,675 1,238 1,238 516.35 1,675 1,424 2,661 Device Routing Invert Outlet Devices #1 Discarded 514.50'10.000 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.34 cfs @ 12.17 hrs HW=515.27' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.34 cfs) Type II 24-hr 25-Year Rainfall=4.80"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 8HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: South Paving Runoff = 1.46 cfs @ 11.95 hrs, Volume= 0.086 af, Depth> 4.12" Routed to Pond 3P : South RG Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=4.80" Area (sf) CN Description 10,645 98 Paved parking, HSG C 250 61 >75% Grass cover, Good, HSG B 10,895 97 Weighted Average 250 61 2.29% Pervious Area 10,645 98 97.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: North Paving Runoff = 1.26 cfs @ 11.95 hrs, Volume= 0.074 af, Depth> 4.04" Routed to Pond 6P : North RG Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=4.80" Area (sf) CN Description 9,118 98 Paved parking, HSG B 460 61 >75% Grass cover, Good, HSG B 9,578 96 Weighted Average 460 61 4.80% Pervious Area 9,118 98 95.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 10S: Existing South Area Runoff = 0.79 cfs @ 11.98 hrs, Volume= 0.055 af, Depth> 2.42" Routed to Reach 11R : Existing Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=4.80" Type II 24-hr 25-Year Rainfall=4.80"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 9HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Area (sf) CN Description 8,173 69 50-75% Grass cover, Fair, HSG B 2,722 98 Paved roads w/curbs & sewers, HSG C 900 98 Roofs, HSG C 11,795 78 Weighted Average 8,173 69 69.29% Pervious Area 3,622 98 30.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Summary for Subcatchment 11S: Existing North Area Runoff = 0.46 cfs @ 11.99 hrs, Volume= 0.030 af, Depth> 1.64" Routed to Reach 11R : Existing Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=4.80" Area (sf) CN Description 9,578 69 50-75% Grass cover, Fair, HSG B 9,578 69 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Summary for Subcatchment 12S: South Existing Roof Area Runoff = 0.12 cfs @ 11.95 hrs, Volume= 0.007 af, Depth> 4.19" Routed to Pond 10P : Extended Aggregate Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=4.80" Area (sf) CN Description 900 98 Roofs, HSG B 900 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type II 24-hr 25-Year Rainfall=4.80"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 10HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Summary for Reach 2R: 6" Pipe Inflow Area = 0.470 ac, 96.53% Impervious, Inflow Depth = 0.46" for 25-Year event Inflow = 0.71 cfs @ 12.03 hrs, Volume= 0.018 af Outflow = 0.71 cfs @ 12.04 hrs, Volume= 0.018 af, Atten= 1%, Lag= 0.6 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 6.73 fps, Min. Travel Time= 0.4 min Avg. Velocity = 3.94 fps, Avg. Travel Time= 0.6 min Peak Storage= 16 cf @ 12.04 hrs Average Depth at Peak Storage= 0.26' , Surface Width= 0.50' Bank-Full Depth= 0.50' Flow Area= 0.2 sf, Capacity= 1.29 cfs 6.0" Round Pipe n= 0.011 Length= 150.0' Slope= 0.0381 '/' Inlet Invert= 518.85', Outlet Invert= 513.14' Summary for Reach 11R: Existing Inflow Area = 0.491 ac, 16.95% Impervious, Inflow Depth > 2.07" for 25-Year event Inflow = 1.25 cfs @ 11.99 hrs, Volume= 0.085 af Outflow = 1.25 cfs @ 11.99 hrs, Volume= 0.085 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Pond 3P: South RG Inflow Area = 0.250 ac, 97.71% Impervious, Inflow Depth > 4.12" for 25-Year event Inflow = 1.46 cfs @ 11.95 hrs, Volume= 0.086 af Outflow = 1.44 cfs @ 11.96 hrs, Volume= 0.083 af, Atten= 1%, Lag= 0.7 min Primary = 1.41 cfs @ 11.96 hrs, Volume= 0.057 af Routed to Pond 8P : Storage Aggregate Secondary = 0.03 cfs @ 11.97 hrs, Volume= 0.027 af Routed to Pond 8P : Storage Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 518.02' @ 11.97 hrs Surf.Area= 0.011 ac Storage= 0.005 af Plug-Flow detention time= 28.2 min calculated for 0.083 af (96% of inflow) Center-of-Mass det. time= 14.6 min ( 746.1 - 731.6 ) Type II 24-hr 25-Year Rainfall=4.80"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 11HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 517.35' 0.006 af 3.00'W x 65.00'L x 0.70'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Secondary 517.35'2.500 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 517.85'6.0" Horiz. Orifice/Grate X 4.00 C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.38 cfs @ 11.96 hrs HW=518.02' (Free Discharge) 2=Orifice/Grate (Weir Controls 1.38 cfs @ 1.33 fps) Secondary OutFlow Max=0.03 cfs @ 11.97 hrs HW=518.02' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Summary for Pond 6P: North RG Inflow Area = 0.220 ac, 95.20% Impervious, Inflow Depth > 4.04" for 25-Year event Inflow = 1.26 cfs @ 11.95 hrs, Volume= 0.074 af Outflow = 1.24 cfs @ 11.97 hrs, Volume= 0.072 af, Atten= 2%, Lag= 1.0 min Primary = 1.21 cfs @ 11.97 hrs, Volume= 0.046 af Routed to Pond 9P : Storage Aggregate Secondary = 0.03 cfs @ 11.97 hrs, Volume= 0.026 af Routed to Pond 9P : Storage Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 517.93' @ 11.97 hrs Surf.Area= 0.012 ac Storage= 0.005 af Plug-Flow detention time= 30.9 min calculated for 0.072 af (97% of inflow) Center-of-Mass det. time= 18.0 min ( 750.2 - 732.2 ) Volume Invert Avail.Storage Storage Description #1 517.25' 0.006 af 3.00'W x 67.00'L x 0.70'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Secondary 517.25'2.500 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 517.75'6.0" Horiz. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.18 cfs @ 11.97 hrs HW=517.93' (Free Discharge) 2=Orifice/Grate (Weir Controls 1.18 cfs @ 1.39 fps) Secondary OutFlow Max=0.03 cfs @ 11.97 hrs HW=517.93' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Summary for Pond 8P: Storage Aggregate Type II 24-hr 25-Year Rainfall=4.80"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 12HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Inflow Area = 0.250 ac, 97.71% Impervious, Inflow Depth > 3.99" for 25-Year event Inflow = 1.44 cfs @ 11.96 hrs, Volume= 0.083 af Outflow = 1.38 cfs @ 11.99 hrs, Volume= 0.083 af, Atten= 4%, Lag= 1.7 min Discarded = 0.12 cfs @ 11.99 hrs, Volume= 0.038 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 2R : 6" Pipe Secondary = 1.26 cfs @ 11.99 hrs, Volume= 0.045 af Routed to Pond 10P : Extended Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 515.08' @ 11.99 hrs Surf.Area= 0.012 ac Storage= 0.002 af Plug-Flow detention time= 0.7 min calculated for 0.083 af (100% of inflow) Center-of-Mass det. time= 0.6 min ( 746.8 - 746.1 ) Volume Invert Avail.Storage Storage Description #1 514.35' 0.010 af 3.00'W x 67.00'L x 2.00'H Prismatoid Z=3.0 0.031 af Overall x 33.0% Voids Device Routing Invert Outlet Devices #1 Discarded 514.35'10.000 in/hr Exfiltration over Surface area #2 Primary 515.85'6.0" Round Culvert L= 10.0' Ke= 0.500 Inlet / Outlet Invert= 515.85' / 515.60' S= 0.0250 '/' Cc= 0.900 n= 0.011, Flow Area= 0.20 sf #3 Secondary 514.35'4.0" Round Culvert X 4.00 L= 10.0' Ke= 0.500 Inlet / Outlet Invert= 514.35' / 514.00' S= 0.0350 '/' Cc= 0.900 n= 0.011, Flow Area= 0.09 sf Discarded OutFlow Max=0.12 cfs @ 11.99 hrs HW=515.07' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.12 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=514.35' (Free Discharge) 2=Culvert ( Controls 0.00 cfs) Secondary OutFlow Max=1.25 cfs @ 11.99 hrs HW=515.07' (Free Discharge) 3=Culvert (Inlet Controls 1.25 cfs @ 3.57 fps) Summary for Pond 9P: Storage Aggregate Inflow Area = 0.220 ac, 95.20% Impervious, Inflow Depth > 3.92" for 25-Year event Inflow = 1.24 cfs @ 11.97 hrs, Volume= 0.072 af Outflow = 1.02 cfs @ 12.03 hrs, Volume= 0.072 af, Atten= 18%, Lag= 3.8 min Discarded = 0.31 cfs @ 12.03 hrs, Volume= 0.054 af Primary = 0.71 cfs @ 12.03 hrs, Volume= 0.018 af Routed to Reach 2R : 6" Pipe Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 516.17' @ 12.03 hrs Surf.Area= 0.025 ac Storage= 0.009 af Plug-Flow detention time= 5.3 min calculated for 0.072 af (100% of inflow) Center-of-Mass det. time= 5.1 min ( 755.3 - 750.2 ) Type II 24-hr 25-Year Rainfall=4.80"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 13HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 514.25' 0.010 af 3.00'W x 65.00'L x 2.00'H Prismatoid Z=3.0 0.030 af Overall x 33.0% Voids Device Routing Invert Outlet Devices #1 Discarded 514.25'12.000 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 515.35'6.0" Round Culvert L= 88.0' Ke= 0.500 Inlet / Outlet Invert= 515.35' / 512.95' S= 0.0273 '/' Cc= 0.900 n= 0.011, Flow Area= 0.20 sf Discarded OutFlow Max=0.31 cfs @ 12.03 hrs HW=516.15' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.31 cfs) Primary OutFlow Max=0.70 cfs @ 12.03 hrs HW=516.15' (Free Discharge) 2=Culvert (Inlet Controls 0.70 cfs @ 3.57 fps) Summary for Pond 10P: Extended Aggregate Inflow Area = 0.021 ac,100.00% Impervious, Inflow Depth > 30.53" for 25-Year event Inflow = 1.37 cfs @ 11.99 hrs, Volume= 0.053 af Outflow = 0.36 cfs @ 12.19 hrs, Volume= 0.053 af, Atten= 74%, Lag= 11.9 min Discarded = 0.36 cfs @ 12.19 hrs, Volume= 0.053 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 515.37' @ 12.19 hrs Surf.Area= 1,562 sf Storage= 1,028 cf Plug-Flow detention time= 25.7 min calculated for 0.052 af (100% of inflow) Center-of-Mass det. time= 25.5 min ( 750.1 - 724.6 ) Volume Invert Avail.Storage Storage Description #1 514.50' 2,661 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 514.50 800 0 0 515.50 1,675 1,238 1,238 516.35 1,675 1,424 2,661 Device Routing Invert Outlet Devices #1 Discarded 514.50'10.000 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.36 cfs @ 12.19 hrs HW=515.37' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.36 cfs) Type II 24-hr WQ Rainfall=0.83"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 14HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: South Paving Runoff = 0.22 cfs @ 11.96 hrs, Volume= 0.012 af, Depth> 0.57" Routed to Pond 3P : South RG Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr WQ Rainfall=0.83" Area (sf) CN Description 10,645 98 Paved parking, HSG C 250 61 >75% Grass cover, Good, HSG B 10,895 97 Weighted Average 250 61 2.29% Pervious Area 10,645 98 97.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: North Paving Runoff = 0.19 cfs @ 11.96 hrs, Volume= 0.010 af, Depth> 0.56" Routed to Pond 6P : North RG Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr WQ Rainfall=0.83" Area (sf) CN Description 9,118 98 Paved parking, HSG B 460 61 >75% Grass cover, Good, HSG B 9,578 96 Weighted Average 460 61 4.80% Pervious Area 9,118 98 95.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 10S: Existing South Area Runoff = 0.06 cfs @ 11.98 hrs, Volume= 0.004 af, Depth> 0.18" Routed to Reach 11R : Existing Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr WQ Rainfall=0.83" Type II 24-hr WQ Rainfall=0.83"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 15HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Area (sf) CN Description 8,173 69 50-75% Grass cover, Fair, HSG B 2,722 98 Paved roads w/curbs & sewers, HSG C 900 98 Roofs, HSG C 11,795 78 Weighted Average 8,173 69 69.29% Pervious Area 3,622 98 30.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Summary for Subcatchment 11S: Existing North Area Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Reach 11R : Existing Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr WQ Rainfall=0.83" Area (sf) CN Description 9,578 69 50-75% Grass cover, Fair, HSG B 9,578 69 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Summary for Subcatchment 12S: South Existing Roof Area Runoff = 0.02 cfs @ 11.96 hrs, Volume= 0.001 af, Depth> 0.59" Routed to Pond 10P : Extended Aggregate Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr WQ Rainfall=0.83" Area (sf) CN Description 900 98 Roofs, HSG B 900 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type II 24-hr WQ Rainfall=0.83"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 16HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Summary for Reach 2R: 6" Pipe Inflow Area = 0.470 ac, 96.53% Impervious, Inflow Depth = 0.00" for WQ event Inflow = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 0.00 fps, Min. Travel Time= 0.0 min Avg. Velocity = 0.00 fps, Avg. Travel Time= 0.0 min Peak Storage= 0 cf @ 5.00 hrs Average Depth at Peak Storage= 0.00' Bank-Full Depth= 0.50' Flow Area= 0.2 sf, Capacity= 1.29 cfs 6.0" Round Pipe n= 0.011 Length= 150.0' Slope= 0.0381 '/' Inlet Invert= 518.85', Outlet Invert= 513.14' Summary for Reach 11R: Existing Inflow Area = 0.491 ac, 16.95% Impervious, Inflow Depth > 0.10" for WQ event Inflow = 0.06 cfs @ 11.98 hrs, Volume= 0.004 af Outflow = 0.06 cfs @ 11.98 hrs, Volume= 0.004 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Pond 3P: South RG Inflow Area = 0.250 ac, 97.71% Impervious, Inflow Depth > 0.57" for WQ event Inflow = 0.22 cfs @ 11.96 hrs, Volume= 0.012 af Outflow = 0.17 cfs @ 12.06 hrs, Volume= 0.012 af, Atten= 23%, Lag= 6.3 min Primary = 0.15 cfs @ 12.06 hrs, Volume= 0.002 af Routed to Pond 8P : Storage Aggregate Secondary = 0.02 cfs @ 12.06 hrs, Volume= 0.010 af Routed to Pond 8P : Storage Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 517.89' @ 12.06 hrs Surf.Area= 0.010 ac Storage= 0.004 af Plug-Flow detention time= 47.4 min calculated for 0.012 af (100% of inflow) Center-of-Mass det. time= 46.8 min ( 804.1 - 757.3 ) Type II 24-hr WQ Rainfall=0.83"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 17HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 517.35' 0.006 af 3.00'W x 65.00'L x 0.70'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Secondary 517.35'2.500 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 517.85'6.0" Horiz. Orifice/Grate X 4.00 C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.13 cfs @ 12.06 hrs HW=517.88' (Free Discharge) 2=Orifice/Grate (Weir Controls 0.13 cfs @ 0.60 fps) Secondary OutFlow Max=0.02 cfs @ 12.06 hrs HW=517.88' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.02 cfs) Summary for Pond 6P: North RG Inflow Area = 0.220 ac, 95.20% Impervious, Inflow Depth > 0.56" for WQ event Inflow = 0.19 cfs @ 11.96 hrs, Volume= 0.010 af Outflow = 0.06 cfs @ 12.16 hrs, Volume= 0.010 af, Atten= 67%, Lag= 12.0 min Primary = 0.04 cfs @ 12.16 hrs, Volume= 0.001 af Routed to Pond 9P : Storage Aggregate Secondary = 0.02 cfs @ 12.16 hrs, Volume= 0.010 af Routed to Pond 9P : Storage Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 517.77' @ 12.16 hrs Surf.Area= 0.010 ac Storage= 0.004 af Plug-Flow detention time= 51.0 min calculated for 0.010 af (100% of inflow) Center-of-Mass det. time= 50.6 min ( 807.9 - 757.3 ) Volume Invert Avail.Storage Storage Description #1 517.25' 0.006 af 3.00'W x 67.00'L x 0.70'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Secondary 517.25'2.500 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 517.75'6.0" Horiz. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.04 cfs @ 12.16 hrs HW=517.77' (Free Discharge) 2=Orifice/Grate (Weir Controls 0.04 cfs @ 0.44 fps) Secondary OutFlow Max=0.02 cfs @ 12.16 hrs HW=517.77' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.02 cfs) Summary for Pond 8P: Storage Aggregate Type II 24-hr WQ Rainfall=0.83"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 18HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Inflow Area = 0.250 ac, 97.71% Impervious, Inflow Depth > 0.57" for WQ event Inflow = 0.17 cfs @ 12.06 hrs, Volume= 0.012 af Outflow = 0.15 cfs @ 12.09 hrs, Volume= 0.012 af, Atten= 12%, Lag= 1.9 min Discarded = 0.06 cfs @ 12.09 hrs, Volume= 0.010 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 2R : 6" Pipe Secondary = 0.09 cfs @ 12.09 hrs, Volume= 0.002 af Routed to Pond 10P : Extended Aggregate Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 514.45' @ 12.09 hrs Surf.Area= 0.006 ac Storage= 0.000 af Plug-Flow detention time= 0.5 min calculated for 0.012 af (100% of inflow) Center-of-Mass det. time= 0.4 min ( 804.6 - 804.1 ) Volume Invert Avail.Storage Storage Description #1 514.35' 0.010 af 3.00'W x 67.00'L x 2.00'H Prismatoid Z=3.0 0.031 af Overall x 33.0% Voids Device Routing Invert Outlet Devices #1 Discarded 514.35'10.000 in/hr Exfiltration over Surface area #2 Primary 515.85'6.0" Round Culvert L= 10.0' Ke= 0.500 Inlet / Outlet Invert= 515.85' / 515.60' S= 0.0250 '/' Cc= 0.900 n= 0.011, Flow Area= 0.20 sf #3 Secondary 514.35'4.0" Round Culvert X 4.00 L= 10.0' Ke= 0.500 Inlet / Outlet Invert= 514.35' / 514.00' S= 0.0350 '/' Cc= 0.900 n= 0.011, Flow Area= 0.09 sf Discarded OutFlow Max=0.06 cfs @ 12.09 hrs HW=514.44' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.06 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=514.35' (Free Discharge) 2=Culvert ( Controls 0.00 cfs) Secondary OutFlow Max=0.09 cfs @ 12.09 hrs HW=514.44' (Free Discharge) 3=Culvert (Inlet Controls 0.09 cfs @ 1.05 fps) Summary for Pond 9P: Storage Aggregate Inflow Area = 0.220 ac, 95.20% Impervious, Inflow Depth > 0.56" for WQ event Inflow = 0.06 cfs @ 12.16 hrs, Volume= 0.010 af Outflow = 0.06 cfs @ 12.18 hrs, Volume= 0.010 af, Atten= 6%, Lag= 1.2 min Discarded = 0.06 cfs @ 12.18 hrs, Volume= 0.010 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 2R : 6" Pipe Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 514.28' @ 12.18 hrs Surf.Area= 0.005 ac Storage= 0.000 af Plug-Flow detention time= 0.4 min calculated for 0.010 af (100% of inflow) Center-of-Mass det. time= 0.3 min ( 808.2 - 807.9 ) Type II 24-hr WQ Rainfall=0.83"Design Printed 11/14/2023Prepared by SSW Engineers Inc Page 19HydroCAD® 10.20-3f s/n 13139 © 2023 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 514.25' 0.010 af 3.00'W x 65.00'L x 2.00'H Prismatoid Z=3.0 0.030 af Overall x 33.0% Voids Device Routing Invert Outlet Devices #1 Discarded 514.25'12.000 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 515.35'6.0" Round Culvert L= 88.0' Ke= 0.500 Inlet / Outlet Invert= 515.35' / 512.95' S= 0.0273 '/' Cc= 0.900 n= 0.011, Flow Area= 0.20 sf Discarded OutFlow Max=0.06 cfs @ 12.18 hrs HW=514.28' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.06 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=514.25' (Free Discharge) 2=Culvert ( Controls 0.00 cfs) Summary for Pond 10P: Extended Aggregate Inflow Area = 0.021 ac,100.00% Impervious, Inflow Depth > 1.53" for WQ event Inflow = 0.10 cfs @ 12.09 hrs, Volume= 0.003 af Outflow = 0.09 cfs @ 12.11 hrs, Volume= 0.003 af, Atten= 13%, Lag= 1.0 min Discarded = 0.09 cfs @ 12.11 hrs, Volume= 0.003 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 514.51' @ 12.11 hrs Surf.Area= 808 sf Storage= 7 cf Plug-Flow detention time= 1.3 min calculated for 0.003 af (100% of inflow) Center-of-Mass det. time= 1.2 min ( 767.1 - 765.9 ) Volume Invert Avail.Storage Storage Description #1 514.50' 2,661 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 514.50 800 0 0 515.50 1,675 1,238 1,238 516.35 1,675 1,424 2,661 Device Routing Invert Outlet Devices #1 Discarded 514.50'10.000 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.15 cfs @ 12.11 hrs HW=514.51' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.15 cfs) Stormwater Analysis Report for Thurston Baptist Church 8 APPENDIX C Operations and Maintenance Plan Appendix 3A-1 Rev 01/27/17 Page 1 of 1     EDSP Adopted December 03, 2012 Notice of Operations and Maintenance Agreement Private Stormwater Management and Treatment System The undersigned owner(s), is hereby given notice that stormwater runoff from the “Property” described below requires stormwater management facilities to be located, designed, and constructed in compliance with the City of Springfield’s Engineering Design and Procedures Manual. Said facilities shall be operated and maintained in accordance with the Operations and Maintenance Agreement (O&M Agreement) on file with the City of Springfield, Development and Public Works Department. Thurston Baptist Church_ (Property Owner/Developer) acknowledges and agrees to maintain private stormwater treatment facilities listed in this document. The maintenance of the stormwater facilities listed in this document is required as part of the Development Agreement with the City of Springfield. This facility will be operated and maintained in accordance with the requirements stated in this document and in the latest edition of the City of Springfield Engineering Design Standards and Procedures Manual, Chapter 3. The City reserves the right to enter and inspect any stormwater facility located on the “Property” to ensure the facilities are operating as designed. Failure of the responsible party to inspect and maintain the facilities can result in an adverse impact to the public stormwater system and the quality of receiving waters. The requirement to operate and maintain the stormwater treatment facilities in accordance with the approved site development agreement and the site O&M Agreement is binding on all current and future owners of the property. The Agreement and its O&M Plan may be modified under written consent of new owners with written approval by and re-filing with the City. The O&M Agreement and O&M Plan for facilities constructed pursuant to this notice are available at the Development and Public Works Department, 225 Fifth St, Springfield Oregon, or call (541)-736-3753, between the hours of 8 a.m. and 5 p. m., Monday through Friday. The Subject premises, is legally described as follows: (Tax lot number cannot be used to describe the property. Legal descriptions may be obtained from the county assessor's office). SEE EXHIBIT “A” ATTACHED HERETO AND INCORPORATED HEREIN BY REFERENCE By signing below, the signer accepts and agrees to the terms and conditions contained in the Operations and Maintenance Plan and in any documents attached. This instrument is intended to be binding upon the parties hereto, their heirs, successors, and assigns. In Witness whereof, the undersigned has executed this instrument on this ________day of ________________, 20____. Owner(s): Signature ____________________________________ ___________________________________________ Print Name ___________________________________ ___________________________________________ STATE OF OREGON, County of Lane, This instrument as acknowledged before me on ___________________________, by _____________________________________________________________, owner(s) of the above described premises. This instrument as acknowledged before me on ___________________________, by _____________________________________________________________, as _____________________________________________________________ of _____________________________________________________________, owner(s) of the above described premises. _______________________________________________________ ___________________________________ Notary Public for Oregon My Commission Expires RETURN TO: CITY OF SPRINGFIELD DEVELOPMENT & PUBLIC WORKS DEPT. 225 FIFTH ST. SPRINGFIELD, OREGON 97477  RESERVE THIS SPACE FOR RECORDING STICKER **Avoid $20 nonstandard doc FEE (font too small)… Print this form on Legal size paper.** EXHIBIT A Appendix 3A-2 Rev 01/26/16 Page 1 of 1 EDSP Adopted December 03, 2012 Operations and Maintenance Agreement Private Stormwater Management and Treatment System Land Development Application Number:___________________________________________________ Owner's Name:________________________________________________________________________ Phone No.:___________________________________ Mailing Address:_______________________________________________________________________ City_____________________________ State_____________ Zip________________ Site Address:__________________________________________________________________________ City_____________________________ State_____________ Zip________________ Site Map and Tax lot No.:________________________________________________________________ (Or attach document with additional lot information if the facility crosses more than one lot) Type of Facility(ies)____________________________________________________________________ Requirements 1) Stormwater Management Site Plan, (min. 8 1/2" x 11" attached to this form) showing the location of the facility(ies) in relation to building structures or other permanent monuments on the site, sources of runoff entering the facility(ies), and where stormwater will be discharged to after leaving the facility(ies). Landscape and vegetation should be clear on the Plan submitted or submit a separate Landscape Plan document showing vegetation type, location, and quantity (landscape plan). These can be the same Plans submitted for development review. The stormwater management facility(ies) shown on the Site Plan are a required condition of development approval for the identified property. The owner of the identified property is required to operate and maintain the facility(ies) in accordance with the Facility Specific Operation and Maintenance Plan(s) (O&M Plan(s)) attached to this form and on file with the City. The O&M Plan for the facility(ies) will be available at the Development and Public Works Department, 225 5th Street, Springfield, Oregon between the hours of 8 a.m. and 5 p.m., Monday through Friday. 2) Financially responsible party (circle one): Property Owner Homeowner Association Other (describe) __________________________ 3) Party(ies) responsible for maintenance (only if other than owner). Daytime phone no. (______) _______ -_______ Emergency/after-hours contact phone no. (______) _______ - _______ Maintenance Contact Party(ies) Name & Business Address: _____________________________ ______________________________________________________________________________ 4) Maintenance practices and schedule for the stormwater facility(ies) are included in the Facility Specific O&M Plan(s) attached to this form and filed with the Development and Public Works Department, City of Springfield. The operation and maintenance practices are based on the version of the City of Eugene's Stormwater Management Manual in effect at the date of development application, as modified by any plans attached to this document at the time of signing. Application Date: By signing below, Filer accepts and agrees to the terms and conditions contained in the Operations and Maintenance Plan(s) and in any document executed by Filer and recorded with it. Filer Signature: Print Name: Appendix 3A-4 Page 15 of 31 EDSP Adopted December 03, 2012 Rain Gardens Operations and Maintenance Plan A vegetated Infiltration Basin or rain garden is a vegetated depression created by excavation, berms, or small dams to provide for short-term ponding of surface water until it percolates into the soil. The basin shall infiltrate stormwater within 24 hours. All facility components and vegetation shall be inspected for proper operations and structural stability, at a minimum, quarterly for the first 2 years from the date of installation, 2 times per year thereafter, and within 48 hours after each major storm event. The facility owner must keep a log, recording all inspection dates, observations, and maintenance activities. The following items shall be inspected and maintained as stated: Basin Inlet shall assure unrestricted stormwater flow to the vegetated basin. • Sources of erosion shall be identified and controlled when native soil is exposed or erosion channels are present. • Inlet shall be cleared when conveyance capacity is plugged. • Rock splash pads shall be replenished to prevent erosion. Embankment, Dikes, Berms and Side Slopes retain water in the infiltration basin. • Structural deficiencies shall be corrected upon discovery: o Slopes shall be stabilized using appropriate erosion control measures when soil is exposed/ flow channels are forming. o Sources of erosion damage shall be identified and controlled. Overflow or Emergency Spillway conveys flow exceeding reservoir capacity to an approved stormwater receiving system. • Overflow shall be cleared when 25% of the conveyance capacity is plugged. • Sources of erosion damage shall be identified and controlled when soil is exposed. • Rocks or other armament shall be replaced when only one layer of rock exists. Filter Media shall allow stormwater to percolate uniformly through the infiltration basin. If water remains 36-48 hours after storm, sources of possible clogging shall be identified and corrected. • Basin shall be raked and, if necessary, soil shall be excavated, and cleaned or replaced. • Infiltration area shall be protected from compaction during construction. Sediment/ Basin Debris Management shall prevent loss of infiltration basin volume caused by sedimentation. Gauges located at the opposite ends of the basin shall be maintained to monitor sedimentation. • Sediment and debris exceeding 3 inch in depth shall be removed every 2-5 years or sooner if performance is affected. Debris and Litter shall be removed to ensure stormwater infiltration and to prevent clogging of overflow drains and interference with plant growth. • Restricted sources of sediment and debris, such as discarded lawn clippings, shall be identified and prevented. Vegetation shall be healthy and dense enough to provide filtering while protecting underlying soils from erosion. • Mulch shall be replenished as needed to ensure healthy plant growth • Vegetation, large shrubs or trees that limit access or interfere with basin operation shall be pruned or removed. • Grass shall be mowed to 4”-9” high and grass clippings shall be removed no less than 2 times per year. • Fallen leaves and debris from deciduous plant foliage shall be raked and removed if build up is damaging vegetation. • Nuisance or prohibited vegetation (such as blackberries or English Ivy) shall be removed when discovered. Invasive vegetation contributing up to 25% of vegetation of all species shall be removed. • Dead vegetation shall be removed to maintain less than 10% of area coverage or when infiltration Stormwater Analysis Report for Thurston Baptist Church 9 APPENDIX D Well Logs