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HomeMy WebLinkAboutApplication Applicant 7/23/2024HDG Job #:HOV001Date: Stormwater Management FacilitiesPrivate Stormwater ReportHappy's Car Wash(P) 503 946 6690May 24, 2024 Prepared For: Happy's Carwash I hereby acknowledge and agree that the jurisdiction does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities designed by me.0 Prepared By: 'I hereby certify that this Stormwater Management Report for the Happy's Car Wash project has been prepared by me or under my supervision and meets minimum standards of Springfield and normal standards of engineering practice.110 SE Main St. Suite 200Portland, OR 97214 Table of Contents23456 APPENDICESA Appendix B Support CalculationsB Appendix C Operations and Maintenance PlanC Appendix D Additional Forms & Associated Reports D Project Overview and Description Vicinity Map Methodology Analysis Engineering Conclusions Appendix A Stormwater Facility Details / Exhibits Basin Map Filtration Rain Garden Detail Humber Design Group, Inc 1 Storm Report Watershed Description Tax Map Tax Lot Flood Zone 17032220 N/A Location of Project Site Area/Acreage Nearest Cross Street Property Zoning Project Overview and Description 3358 Gateway Street, Springfield, OR Existing Conditions Proposed Development Willamette 1.51 acres 40,850 sfProposed Impervious Area The existing project is located on pad site A on the south side of the lot. Pad site A was previously graded and prepared for construction during the CFA project just north of the PAD. Erosion control measure, such as silt fences, are in place to prevent soil displacement. Utility stubouts for sanitary,storm, and water are located on the site. The proposed development includes a new carwash building, associated parking lot, queuing lanes, and vaccuum stalls. The site will be split into (2) basin areas and treated via (2) vegetated swales. 001600 & 001300 Gateway Street & Beltline Rd Commercial Subwatershed Humber Design Group, Inc 2 Storm Report Site Location Vicinity MapHumber Design Group, Inc 3 Storm Report Methodology The existing site pad has no drainage systems installed. A shallow stormline stub out to the public main is located on the east side of the lot. PUBLIC Proposed Stormwater Management Techniques A Geotechnical Engineering Investigation dated August 10, 2023 was prepared by Krazan & Associates, Inc. Per the investigation, there is relatively impermeable fine-grained native flood deposit soils estimated to underlie in the upper 10 to 11 feet bgs. Geotech states that on-site infiltration may not be feasible utilizing the native soils. Onsite stormwater will be managed via (2) filtration rain gardens that will manage each manage their associated basin. N/A Drainage Way, River, Storm Only Pipe Infiltration Results PRIVATE Proposed Stormwater Management Techniques Discharge Point Existing Drainage Humber Design Group, Inc 4 Storm Report Table 4 – Catchment Areas and Facility Table Treatment Area (sf) Facility Type/ Function Facility Size 18,550 Rain Garden 580 sf 22,300 Rain Garden 521 sf Ownership (private/ public) Catchment/ Facility ID Source (roof, road, etc.) Private B Pavement/Roof A Pavement Private Humber Design Group, Inc 6 Storm Report Table 1 – Curve Numbers Table 2 – Design Storms Table 3 – Time of Concentration 10-year Post-Developed TOC 79 Post-Developed Impervious CN 3.12 inches WQ Storm (Site Performance Std.)1.4 inches 25-year 5.18 inches Post-Developed Pervious CN 4.46 inches Hydrologic Soil Group Soil Types Predeveloped Pervious CN 79 Predeveloped Impervious CN 98 Analysis HydroCAD models of a SBUH Type 1A Storm were used to calculate the stormwater management facility sizes for the catchment areas. See attached calculations. Below is a summary of the results. 100-year 98 5 min 6.48 inches Predeveloped TOCC Malabon-Urban land complex Computational Method Used 5 min 2-year Stormwater Management Narrative Proposed storm will be designed to meet Springfield SDC 4.3.110 for Stormwater Management. Per 4.3.110(C)(a) The first 1.4" of rainfall from each storm event will be routed to the stormwater facilities and fully infiltrate/evapotranspirate on site. Onsite stormwater will be managed via (2) filtration rain gardens that will manage each manage their associated basin. Basin A will manage 18,550 sf of impervious area for the west portion of the site. Basin B will manage 22,300 sf of impervious area for the east portion of the site along with the runoff from the building roof and a portion of the southern side of the crowned shared driveway. Refer to Appendix A for Basin Map. Humber Design Group, Inc 5 Storm Report Engineering Conclusions Downstream / Upstream Impacts 100 year storm There are no upstream or downstream impacts created by this proposed development. The 100 year storm will be safely conveyed away from structures and will overflow to the public stormwater system. Water Quantity The proposed development will meet the provisions for water quantity per Springfield SDC Chapter 4.3.110 Stormwater Management, amended Nov 20, 2023. The preceding methodologies and calculations presented indicate compliance with the current jurisdictional stormwater management codes and requirements. A summarized breakdown is presented below: The proposed development will meet the provisions for water quality per Springfield SDC Chapter 4.3.110 Stormwater Management, amended Nov 20, 2023. Water Quality Humber Design Group, Inc 7 Storm Report Basin Map Filtration Rain Garden Detail Appendix A Stormwater Facility Details / Exhibits 1. Provide protection from all vehicle traffic, equipment staging, and foot traffic in proposed infiltration areas prior to, during, and after construction. 2.Dimensions: a.Depth of rain garden: 6" minimum and 12” maximum b. Flat bottom width: 2' min. c. Side slopes of Rain Garden: 3:1 maximum. 3. Setbacks: a.Infiltration rain gardens must be 10' from foundations and 5' from property lines. Filtration Rain Garden do not require a setback with an approved waterproof liner. 4. Overflow: a. Overflows are required unless sized to fully infiltrate the flood control design storm. b.Inlet elevation must allow for 2” of freeboard, minimum. 5.Piping: Minimum 3” pipe required for up to 1,500 sq ft of impervious area, otherwise 4” min. Piping material, slopes and installation shall follow the Uniform Plumbing Code. 6.Drain rock: a. Size: 3/4"-2-1/2" washed b.Depth: 12” Minimum 7. Drain rock later shall be separated form the growing medium and the surround soils by a geotextile filter fabric. 8. Growing medium: a. In 0-2 year TOTZ, a 24" minimum with at least 50% organic material b. In all other areas, 12" minimum c. Import topsoil or amended native soil FILTRATION RAIN GARDEN TYPICAL DETAILS Exhibit B, Page 24 of 98 Appendix B Support Calculations 1S West Basin 2S East Basin 3P West WQ (2in/hr Soil Media) 4P East WQ(2in/hr Soil Media) Routing Diagram for Storm Calcs Prepared by Hewlett-Packard Company, Printed 5/24/2024 HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Subcat Reach Pond Link Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 2HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 0.938 98 Paved parking, HSG A (1S, 2S) 0.938 98 TOTAL AREA Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 3HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.938 HSG A 1S, 2S 0.000 HSG B 0.000 HSG C 0.000 HSG D 0.000 Other 0.938 TOTAL AREA Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 4HydroCAD® 10.00-15 s/n 09142 © 2015 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 0.938 0.000 0.000 0.000 0.000 0.938 Paved parking 1S, 2S 0.938 0.000 0.000 0.000 0.000 0.938 TOTAL AREA Type IA 24-hr WQ Rainfall=1.40"Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 5HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SBUH method, Split Pervious/Imperv. Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=18,550 sf 100.00% Impervious Runoff Depth>1.10"Subcatchment 1S: West Basin Tc=5.0 min CN=0/98 Runoff=0.13 cfs 0.039 af Runoff Area=22,300 sf 100.00% Impervious Runoff Depth>1.10"Subcatchment 2S: East Basin Tc=5.0 min CN=0/98 Runoff=0.16 cfs 0.047 af Peak Elev=100.41' Storage=280 cf Inflow=0.13 cfs 0.039 afPond 3P: West WQ (2in/hr Soil Media) Discarded=0.04 cfs 0.039 af Primary=0.00 cfs 0.000 af Outflow=0.04 cfs 0.039 af Peak Elev=100.43' Storage=0.008 af Inflow=0.16 cfs 0.047 afPond 4P: East WQ(2in/hr Soil Media) Discarded=0.05 cfs 0.047 af Primary=0.00 cfs 0.000 af Outflow=0.05 cfs 0.047 af Total Runoff Area = 0.938 ac Runoff Volume = 0.086 af Average Runoff Depth = 1.10" 0.00% Pervious = 0.000 ac 100.00% Impervious = 0.938 ac Type IA 24-hr WQ Rainfall=1.40"Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 6HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: West Basin Runoff = 0.13 cfs @ 7.91 hrs, Volume= 0.039 af, Depth> 1.10" Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type IA 24-hr WQ Rainfall=1.40" Area (sf) CN Description 18,550 98 Paved parking, HSG A 18,550 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 1S: West Basin Runoff Hydrograph Time (hours) 48474645444342414039383736353433323130292827262524232221201918171615141312111098765Flow (cfs)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 0.010 Type IA 24-hr WQ Rainfall=1.40" Runoff Area=18,550 sf Runoff Volume=0.039 af Runoff Depth>1.10" Tc=5.0 min CN=0/98 0.13 cfs Type IA 24-hr WQ Rainfall=1.40"Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 7HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: East Basin Runoff = 0.16 cfs @ 7.91 hrs, Volume= 0.047 af, Depth> 1.10" Runoff by SBUH method, Split Pervious/Imperv., Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type IA 24-hr WQ Rainfall=1.40" Area (sf) CN Description 22,300 98 Paved parking, HSG A 22,300 98 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 2S: East Basin Runoff Hydrograph Time (hours) 48474645444342414039383736353433323130292827262524232221201918171615141312111098765Flow (cfs)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 0.010 Type IA 24-hr WQ Rainfall=1.40" Runoff Area=22,300 sf Runoff Volume=0.047 af Runoff Depth>1.10" Tc=5.0 min CN=0/98 0.16 cfs Type IA 24-hr WQ Rainfall=1.40"Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 8HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Summary for Pond 3P: West WQ (2in/hr Soil Media) Inflow Area = 0.426 ac,100.00% Impervious, Inflow Depth > 1.10" for WQ event Inflow = 0.13 cfs @ 7.91 hrs, Volume= 0.039 af Outflow = 0.04 cfs @ 9.23 hrs, Volume= 0.039 af, Atten= 72%, Lag= 79.1 min Discarded = 0.04 cfs @ 9.23 hrs, Volume= 0.039 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 100.41' @ 9.23 hrs Surf.Area= 783 sf Storage= 280 cf Plug-Flow detention time= 56.9 min calculated for 0.039 af (100% of inflow) Center-of-Mass det. time= 56.1 min ( 785.6 - 729.5 ) Volume Invert Avail.Storage Storage Description #1 100.00' 574 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 100.00 580 0 0 100.75 950 574 574 Device Routing Invert Outlet Devices #1 Discarded 100.00'2.000 in/hr Exfiltration over Surface area #2 Primary 100.50'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.04 cfs @ 9.23 hrs HW=100.41' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.04 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=100.00' (Free Discharge) 2=Orifice/Grate ( Controls 0.00 cfs) Type IA 24-hr WQ Rainfall=1.40"Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 9HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Pond 3P: West WQ (2in/hr Soil Media) Inflow Outflow Discarded Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086Flow (cfs)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 0.010 Inflow Area=0.426 ac Peak Elev=100.41' Storage=280 cf 0.13 cfs 0.04 cfs 0.04 cfs 0.00 cfs Type IA 24-hr WQ Rainfall=1.40"Storm Calcs Printed 5/24/2024Prepared by Hewlett-Packard Company Page 10HydroCAD® 10.00-15 s/n 09142 © 2015 HydroCAD Software Solutions LLC Summary for Pond 4P: East WQ(2in/hr Soil Media) Inflow Area = 0.512 ac,100.00% Impervious, Inflow Depth > 1.10" for WQ event Inflow = 0.16 cfs @ 7.91 hrs, Volume= 0.047 af Outflow = 0.05 cfs @ 9.01 hrs, Volume= 0.047 af, Atten= 68%, Lag= 65.8 min Discarded = 0.05 cfs @ 9.01 hrs, Volume= 0.047 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 100.43' @ 9.01 hrs Surf.Area= 0.025 ac Storage= 0.008 af Plug-Flow detention time= 56.0 min calculated for 0.047 af (100% of inflow) Center-of-Mass det. time= 55.1 min ( 784.6 - 729.5 ) Volume Invert Avail.Storage Storage Description #1 100.00' 0.017 af 2.50'W x 208.00'L x 0.75'H Prismatoid Z=3.0 Device Routing Invert Outlet Devices #1 Discarded 100.00'2.000 in/hr Exfiltration over Surface area #2 Primary 100.50'8.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.05 cfs @ 9.01 hrs HW=100.43' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.05 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=100.00' (Free Discharge) 2=Orifice/Grate ( Controls 0.00 cfs) Pond 4P: East WQ(2in/hr Soil Media) Inflow Outflow Discarded Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086Flow (cfs)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 0.010 Inflow Area=0.512 ac Peak Elev=100.43' Storage=0.008 af 0.16 cfs 0.05 cfs 0.05 cfs 0.00 cfs Appendix C Operations and Maintenance Plan Date: Prepared By: Stormwater Management Facilities Private Operations & Maintenance Plan Happy's Car Wash 110 SE Main St. Suite 200 Portland, OR 97214 (P) 503 946 6690 May 24, 2024 Facility Size (sf)Source 580 Pavement 521 Pavement Roof Filtration Rain Garden Filtration Rain Garden Table 1 - Facility Description Table Discharge PointFacility Name Site O&M Responsible Party 18,550 Site/Public Storm 22,300 This facility is to be maintained by property owner Happy's Carwash. Happy's Carwash contact is Alex Dzyuba, , 503-705-3995. Onsite Stormwater System Description Onsite stormwater will be managed via (2) filtration rain gardens that will manage each manage their associated basin. Impervious Area Managed (sf) Site/Public Storm Infiltration Testing Results A Geotechnical Engineering Investigation dated August 10, 2023 was prepared by Krazan & Associates, Inc. Per the investigation, there is relatively impermeable fine-grained native flood deposit soils estimated to underlie in the upper 10 to 11 feet bgs. Geotech states that on-site infiltration may not be feasible utilizing Type Swale B Swale A Humber Design Group, Inc 1 Operation and Maintenance Plan After major rainfall events: Thereafter: Within 48 hours of major rainfall events (more than 1 inch of rain over a 24- hour period) All stormwater facilities must be inspected at least: Inspection & Maintenance Schedule First two years:Quarterly Twice a year Humber Design Group, Inc 2 Operation and Maintenance Plan ● ● ● ● ● Spill Prevention Spill prevention measures shall be exercised when handling substances that can contaminate stormwater. Virtually all sites, including residential and commercial, present dangers from spills. It is important to exercise Inspection & Stormwater Maintenance Prodecures The following items shall be inspected and maintained as stated. Overflow Drains, Area Drains, and Piped Storm System Sediment shall be removed biannually. Debris shall be removed from inlets and outlets quarterly. Quarterly inspection for clogging shall be performed. Employees shall be trained on spill control measures. Shut-off valves shall be tested quarterly. Releases of pollutants shall be corrected within 12 hours. Access Access shall be maintained for all facilities so O&M can be performed as regularly scheduled. Best Management Practices (BMPs) BMPs prevent pollutants from mixing with stormwater. Typical nonstructural control measures include raking and removing leaves, street sweeping, vacuum sweeping, and limited and controlled application of The proper authority and the property owner shall be contacted immediately if a spill is observed. A spill kit shall be kept near spill-prone operations and refreshed annually. Vectors Stormwater facilities shall not harbor mosquito larvae or rats that pose a threat to public health or that undermine the facility structure. Monitor standing water for small wiggling sticks perpendicular to the water's Humber Design Group, Inc 3 Operation and Maintenance Plan Maintenance Record date, description, and contractor (if applicable) for all structural repairs, landscape maintenance, and facility cleanout activities. Percent Vegetation Coverage Record percent cover of desirable, dead, and invasive vegetation. Condition of Structural Components Record type and size of missing or broken components (i.e. width of cracks and/or extent of settling.) Inspection & Maintenance Logs Take and record measurement at catch basins, conveyance systems, inlets, outlets and within the facility itself. Inspection Log Record the date and the personnel who conducted the site inspection. Record the infiltration rate if water continues to pond longer than 48 hours after storm event, a description of any and all spills and vector issues, The facility owner shall keep a log to record all inspection and maintenance activities (see Sample Log). Record date, description, and contractor (if applicable) for all inspections and any maintenance or repairs performed. Keep work orders and invoices on file and make available upon request of the city inspector. Depth of Sediment & Oil Pollution Prevention All sites shall implement BMPs to prevent hazardous wastes, litter, or excessive oil and sediment from contaminating stormwater. Record time/date, weather, and site conditions if site activities are found to Vectors (mosquitoes and rodents) Stormwater facilities shall not harbor mosquito larvae or rats that pose a threat to public health or that undermine the facility structure. Monitor standing water for small wiggling sticks perpendicular to the water's Humber Design Group, Inc 4 Operation and Maintenance Plan Date: Time: Initial: Work performed by: Work performed: Details: Date: Time: Initial: Work performed by: Work performed: Details: Sample Log Form Humber Design Group, Inc 5 Operation and Maintenance Plan Date: Time: Initial: Work performed by: Work performed: Details: Date: Time: Initial: Work performed by: Humber Design Group, Inc 6 Operation and Maintenance Plan Work performed: Details: Humber Design Group, Inc 7 Operation and Maintenance Plan Additional Forms & Associated Reports Appendix D