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HomeMy WebLinkAbout2019-31 SWMPSTORMWATER MANAGEMENT PLAN 6837 WOODDALE AVE S EDINA, MN DATE: 04-23-2019 CMI PROJECT NO: 0438 PREPARED FOR: Marc Tutt PREPARED BY: Civil Methods, Inc. 1551 Livingston Avenue, Ste. 104 West St. Paul, MN 55118 ENGINEER CERTIFICATION: I hereby certify that this plan, specification, or report was prepared by me or under my direct supervision and that I am a duly licensed Professional Engineer under the laws of the State of Minnesota. Name: Kent Brander, PE Signed: Date: 04-23-2019 Registration: MN No. 44578 06/12/19 ED170948 Scot Jandro 6837 Wooddale – SWMP April 2019 Civil Methods, Inc. Page | i No. 0492 Table of Contents 1. INTRODUCTION ............................................................................................................................................. 1 2. EXISTING SITE CONDITIONS ........................................................................................................................... 1 2.1 OVERVIEW ....................................................................................................................................................... 1 2.2 SOILS .............................................................................................................................................................. 1 3. PROPOSED SITE CONDITIONS ........................................................................................................................ 2 3.1 DRAINAGE PATTERNS ......................................................................................................................................... 2 3.2 RUNOFF RATE CONTROL ..................................................................................................................................... 2 3.3 RUNOFF VOLUME CONTROL ................................................................................................................................ 3 APPENDIX A – DRAINAGE DIAGRAM APPENDIX B – HYDROCAD OUTPUT 06/12/19 ED170948 Scot Jandro 6837 Wooddale – SWMP April 2019 Civil Methods, Inc. Page | 1 No. 0438 1. INTRODUCTION A renovation (addition) is planned for the existing home on the residential lot located at 6837 Wooddale Ave S in Edina, MN. The impervious area on the property will be increased by 2,742 SF to approximately 6,710 SF, or 17.4% of the 38,595 SF property. The property drains to a shared backyard area and will require runoff mitigation measures as stipulated in Category 2 of City Policy No. SP-003-E. This SWMP addresses the stormwater controls necessary to mitigate the effects of the project, per the standards of the City of Edina, including: Regulatory Stormwater Requirements: 1) Match or reduce stormwater discharge rates from the property for the 10-year, Atlas-14 storm event. 2) Infiltrate or otherwise retain the volume of 1.1” of rainfall over the new impervious area draining to private property. 2. EXISTING SITE CONDITIONS 2.1 OVERVIEW The existing property includes the existing house, driveway, sidewalk, patio, appurtenant items, and green space. There are two retaining walls and a shed on the east portion of the property. The front yard, driveway, and a portion of the house drain west toward Wooddale Avenue. The back yard, patio, and remaining property area drains east toward a shared green space. 2.2 SOILS The soil map for the parcel is provided as Attachment 1. The entire parcel is classified as Urban Land, with 51% of the parcel shown in the Malardi complex and 49% shown as Udorthents. The Malardi complex ranges from sandy loam to gravelly sand. Udorthents can vary with regard to drainage characteristics but are generally considered well drained. Based on the descriptions of these soil classifications, the parcel soils are best classified as hydrologic soil group (HSG) B. 2.3 LAND COVER DETAILS Table 1 provides the areas of each land cover under existing conditions. 06/12/19 ED170948 Scot Jandro 6837 Wooddale – SWMP April 2019 Civil Methods, Inc. Page | 2 No. 0438 Table 1. Existing Coverage Details Coverage Existing Area (SF) Driveway & Walk 1303 House Footprint 2017 Patio 625 Steps on North Side 23 Total Impervious 3968 Total Lot Area 38595 % Impervious 10.3% 3. PROPOSED SITE CONDITIONS 3.1 DRAINAGE PATTERNS The proposed property will include the construction of the addition and some additional modifications. The property drainage patterns will remain generally unchanged, with some of the runoff discharging to the west toward Wooddale Avenue and some discharging to the east. A raingarden is proposed in the backyard to infiltrate and restrict the site runoff. The raingarden has been sized to manage the increased impervious area draining to the shared yard space. Drainage patterns are indicated on the attached grading plan (Attachment 2) 3.2 LAND COVER DETAILS Table 2 provides the areas of each land cover under proposed conditions. Table 2. Proposed Coverage Details Coverage Existing Area (SF) Driveway & Walk 1633 House Footprint 4203 Porch 147 Patios 704 Steps on North Side 23 Total Impervious 6710 Total Lot Area 38595 % Impervious 17.4% 3.3 RUNOFF RATE CONTROL As indicated above, adequate stormwater controls must be implemented so as not to i ncrease the discharge rate of runoff from the property for the 10-year, 24-hour design storm. This rate 06/12/19 ED170948 Scot Jandro 6837 Wooddale – SWMP April 2019 Civil Methods, Inc. Page | 3 No. 0438 control will be provided by the rain garden, and the storage volume and overflow outlet as indicated in the construction plans. The site has been modeled with the HydroCAD modeling software to ensure this rate control requirement is met. The simulations have been run for Atlas-14 rainfall totals using the SCS method for runoff generation during the design rainfall events. The HydroCAD model output information is provided as Attachment 3. Under existing conditions, the peak discharge rate of runoff flowing to private property for the 10-year storm is 0.55 cfs. Under proposed conditions, prior to implementing runoff controls, the peak discharge rate would be 0.60 cfs. With the proposed raingarden in place, the peak discharge rate would be reduced to 0.52 cfs, meeting the rate control requirement. 3.4 RUNOFF VOLUME CONTROL Under proposed conditions, 2742 SF of impervious area will be added to the site. Using this value to calculate the MIDS volume control requirement of 1.1” depth, the raingarden would need to store and infiltrate 251 CF of runoff. The raingarden as designed provides a storage volume of 287 CF, exceeding the indicated requirement. It should also be noted that this is a conservative design, because not all of the new impervious area will be draining to private property, as a portion of it will actually be discharging to the street. However, the raingarden is sized to accommodate all of the additional impervious if needed. 06/12/19 ED170948 Scot Jandro Attachment 1 : Soil Map 06/12/19 ED170948 Scot Jandro Soil Map—Hennepin County, Minnesota (6837 Wooddale Ave, Edina) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/16/2019 Page 1 of 34969420 4969430 4969440 4969450 4969460 4969470 49694804969420 4969430 4969440 4969450 4969460 4969470 4969480473120 473130 473140 473150 473160 473170 473180 473190 473200 473210 473220 473120 473130 473140 473150 473160 473170 473180 473190 473200 473210 473220 44° 52' 41'' N 93° 20' 25'' W44° 52' 41'' N93° 20' 20'' W44° 52' 39'' N 93° 20' 25'' W44° 52' 39'' N 93° 20' 20'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 15N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:509 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale.Soil Map may not be valid at this scale. 06/12/19 ED170948 Scot Jandro 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 1:12,000. 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: Hennepin County, Minnesota Survey Area Data: Version 14, Sep 12, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 26, 2014—Sep 7, 2014 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—Hennepin County, Minnesota (6837 Wooddale Ave, Edina) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/16/2019 Page 2 of 3 06/12/19 ED170948 Scot Jandro Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI L55B Urban land-Malardi complex, 0 to 8 percent slopes 0.3 39.2% L55C Urban land-Malardi complex, 8 to 18 percent slopes 0.1 11.8% U1A Urban land-Udorthents, wet substratum, complex, 0 to 2 percent slopes 0.4 49.0% Totals for Area of Interest 0.9 100.0% Soil Map—Hennepin County, Minnesota 6837 Wooddale Ave, Edina Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/16/2019 Page 3 of 3 06/12/19 ED170948 Scot Jandro Attachment 2 : Grading Plan 06/12/19 ED170948 Scot Jandro BENCHMARK See Survey Documentation DMPDESIGNED: LIC. NO.: DATE: KENT E BRANDER DRAWN: CHECKED: DMP KEB44578 I HEREBY CERTIFY THAT THIS PLAN, SPECIFICATION, OR REPORT WAS PREPARED BY ME OR UNDER MY DIRECT SUPERVISION AND THAT I AM A DULY LICENSEDPROFESSIONAL ENGINEER UNDER THE LAWS OF THE STATE OF MINNESOTA. 09-13-2018 CIVIL METHODS, INC. 1551 Livingston Avenue, Suite 104 West St. Paul, MN 55118 o:763.210.5713 | www.civilmethods.com 6837 WOODDALE AVE S EDINA, MN 55435 DATE / REVISION: C01 OWNER: TITLE: SHEET NO:4/23/2019 11:01 AMPrint Date: File Loc: D:\CMI\Civil Methods, Inc\CMI - Documents\7. Projects\0438_Marc Tutt_6837 Wooddale\08_DRAWINGS AND SPECIFICATIONS\C3D\0438_WR.dwgEDINA, MN 6837 WOODDALE AVE S 1. Perimeter sediment controls shall be installed as indicated prior to site disturbance, and shall be installed to allow for high-flow bypass or overflow to prevent failure during significant rainfall 2. Inlet protection shall be installed at City catch basins within 1 block of project site. 3. Contractor is responsible for keeping sediment from leaving the property, including vehicle tracking. Should sediment be tracked offsite onto adjacent street, Contractor shall sweep at the end of work day. 4. Install silt fence or sediment control log around any soil stockpiles that will be present for more than 7 days. 5. If areas with slopes greater than 3:1, and near water bodies, are disturbed, they shall be protected with temporary vegetation, mulch or other means as soon as practical. 6. Perimeter sediment controls shall be installed as indicated prior to site disturbance, and shall be installed to allow for high-flow bypass or overflow to prevent failure during significant rainfall. 7. Devices shall be inspected weekly and after all rainfall events exceeding 1", and maintained as necessary to keep the intended functional condition. 8. Accumulated sediment shall be removed from sediment control devices when 13 of device height has been reached. 9. After rough grading is completed, and topsoil spread, areas shall be seeded and blanketed or hydromulched (or sodded) within 7 days. Areas not being actively worked must be covered with temporary seed within 14 days. 10. Perimeter sediment controls shall remain in place until vegetation is growing / established in all disturbed areas. SEDIMENT CONTROL & TURF RESTORATION NOTES: GRADING & STORMWATER MANAGEMENT NOTES: 1. Site survey with existing utilities provided by W. Brown Land Surveying, Inc.; Contractor is responsible for identifying location of all utilities in field (which may not be shown), including contacting Gopher State One Call and ensuring utilities are located prior to digging. 2. See survey site plan for additional existing utility and proposed building and lot dimension information. 3. Topsoil from grading areas shall be stripped, salvaged and stockpiled; subcut below final grade and replace salvaged topsoil to a minimum depth of 6". 4. Unless noted otherwise, all proposed contours indicate finished grades. 5. Contractor is responsible for maintaining flow paths indicated, with roof runoff directed to the street, not to adjacent private properties. 6. Sediment control devices shall not redirect or back water up onto adjacent properties. 7. All grading and erosion control shall adhere to City requirements. 1. Concrete washout shall not be permitted onsite, unless done per MPCA standard. 2. Vehicle or equipment washing will not be performed on site. 3. All solid waste must be disposed of in accordance with all applicable federal and state regulations. 4. All hazardous materials must be properly stored to prevent spills or leaks; dispose per all applicable regulations, including MN Rule Ch. 7045. 5. Pesticides, herbicides, fertilizers, cleaners, paints, treatment chemicals, etc., must be stored under cover to prevent pollutant discharge (or similarly protected to prevent contact with stormwater). 6. DEWATERING, if necessary, shall be done in a manner so as to not discharge sediment-laden water or cause downstream nuisance conditions of standing water or erosion. 6.1. Discharge dewatering towards street. 6.2. Dewatering water shall be inspected for turbidity (cloudy with sediment); if present, filtration mechanism shall be installed at pump inlet and/or outlet to remove sediment. This may include pumping from a perforated barrel lined with a filter fabric, pumping to a sediment filter sack or temporary settling basin (lined dumpster, pit, etc.) with in-line Chitosan sock (or similar non-toxic flocculant) and discharge from the surface, or similar filtration mechanism approved by the City. 6.3. Dewatering must be done to MPCA standards. POLLUTION PREVENTION NOTES: 1. PRIMARY: Ph: EROSION CONTROL SUPERVISOR: REINFORCED OVERFLOW LEGEND: SITE DATA: 1. PROPERTY AREA:2 2. EXISTING IMPERV.:2 3. PROPOSED IMPERV.:2 4. NET NEW IMPERVIOUS: + 198 FT2 RAIN GARDEN BASIN STABILIZED CONSTRUCTION ENTRANCE SILT FENCE OR SEDIMENT CONTROL LOG PROPOSED CONTOUR EXISTING CONTOUR Feet 0 15 30 NOTE: This is a partial list; other wet-tolerant, full-sun, native plants may be suitable. 18" DEPTH TO OUTLET ELEVATION (OE) NOTE: INSTALL NATIVE PLANT PLUGS (SIZE 2") FROM LIST (OR SIMILAR) SPACED PER SUPPLIER INSTRUCTIONS. 3 1 MAX. SLOPE VARIES REPLACE TOPSOIL (6" MIN), SOD OR SEED & MULCH GRADED AREAS OUTSIDE PLANTING AREA RAIN GARDEN ADD 2" COMPOST AND LOOSEN / TILL NATIVE SOIL TO DEPTH OF 8", MINIMUM. PLACE 6" OF SANDY TOPSOIL IF NOT PRESENT 2" THICK LAYER OF WOOD SLASH MULCH OR HYDROMULCH IN PLANTING AREA TILL SUBGRADE TO DEPTH OF 8" (MIN.) OE = C D 4" MIN. A B NOTE: REINFORCED OVERFLOW CAN BE RIVER ROCK , GEOFABRIC, OR OTHER APPROVED STABILIZATION BERM ELEV = C+D REINFORCED BASIN OVERFLOW A B C D 2.0' 4.0' 871.5 0.5' 12" MIN. SILT FENCE - PREASSEMBLED DIRECTION OF RUNOFF FLOW 18" MIN.POSTAT 6' MAXIMUM SPACING 5' MINIMUM LENGTH POSTS STAPLES (TYP.) GEOTEXTILE FABRIC, WOVEN, 36" WIDTH EMBEDMENT6"x 6" FABRIC ANCHOR TRENCH, BACKFILL IWTH TAMPED NATURAL SOIL CRUSHED ROCK,OF 3" TO 6"12" MINIMUM DEPTH 15' MIN.AS REQUIRED PUBLIC STREET RADIUS AS REQUIRED 15' MIN. CLEAR OR WASHED,OVER GEOTEXTILE FABRIC STABILIZED CONSTRUCTION ENTRANCE 8 IN. - 10 IN. DEEP 1 IN. X 2 IN. X 24 IN. LONG WOODEN STAKES. STAKES SHALL BE DRIVEN THROUGH THE BACK HALF OF THE SEDIMENT CONTROL LOG AT AN ANGLE OF 45 DEGREES WITH THE TOP OF THE STAKE POINTING UPSTREAM. (FOR TYPES: STRAW, WOOD FIBER, OR COIR. FOR WOODCHIP,COMPOST, OR ROCK ROLLS STAKE ON OUTSIDE & NO TRENCH REQ'D) PLACE SEDIMENT CONTROL LOG IN SHALLOW TRENCH (1 TO 2 IN. DEPTH) BACKFILL AND COMPACT SOIL FROM TRENCH ON UPGRADIENT SIDE OF SEDIMENT CONTROL LOG SEDIMENT CONTROL LOGS RAIN GARDEN BOTTOM EL 870 OVERFLOW EL 871.5 BERM EL 872 STORAGE VOL = 287 CF 06/12/19 ED170948 Scot Jandro Attachment 3: HydroCAD Output 06/12/19 ED170948 Scot Jandro EX1 Existing to east PR1 Proposed to east 1P Raingarden Routing Diagram for 0438 Prepared by {enter your company name here}, Printed 4/23/2019 HydroCAD® 10.00-21 s/n 07283 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link 06/12/19 ED170948 Scot Jandro 0438 Printed 4/23/2019Prepared by {enter your company name here} Page 2HydroCAD® 10.00-21 s/n 07283 © 2018 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.337 61 >75% Grass cover, Good, HSG B (EX1, PR1) 0.090 98 Impervious (EX1, PR1) 0.427 69 TOTAL AREA 06/12/19 ED170948 Scot Jandro MSE 24-hr 3 10-Year Rainfall=4.26"0438 Printed 4/23/2019Prepared by {enter your company name here} Page 3HydroCAD® 10.00-21 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-96.00 hrs, dt=0.01 hrs, 9601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=0.225 ac 15.56% Impervious Runoff Depth=1.31"Subcatchment EX1: Existing to east Flow Length=100' Slope=0.1000 '/' Tc=5.6 min CN=67 Runoff=0.55 cfs 0.025 af Runoff Area=0.202 ac 27.23% Impervious Runoff Depth=1.57"Subcatchment PR1: Proposed to east Flow Length=100' Slope=0.1000 '/' Tc=5.6 min CN=71 Runoff=0.60 cfs 0.027 af Peak Elev=871.67' Storage=296 cf Inflow=0.60 cfs 0.027 afPond 1P: Raingarden Outflow=0.52 cfs 0.021 af Total Runoff Area = 0.427 ac Runoff Volume = 0.051 af Average Runoff Depth = 1.43" 78.92% Pervious = 0.337 ac 21.08% Impervious = 0.090 ac 06/12/19 ED170948 Scot Jandro MSE 24-hr 3 10-Year Rainfall=4.26"0438 Printed 4/23/2019Prepared by {enter your company name here} Page 4HydroCAD® 10.00-21 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment EX1: Existing to east Runoff = 0.55 cfs @ 12.14 hrs, Volume= 0.025 af, Depth= 1.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-96.00 hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (ac) CN Description 0.190 61 >75% Grass cover, Good, HSG B * 0.035 98 Impervious 0.225 67 Weighted Average 0.190 61 84.44% Pervious Area 0.035 98 15.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.2 Direct Entry, Rooftop_flow 5.4 100 0.1000 0.31 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 5.6 100 Total Summary for Subcatchment PR1: Proposed to east Runoff = 0.60 cfs @ 12.13 hrs, Volume= 0.027 af, Depth= 1.57" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-96.00 hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (ac) CN Description 0.147 61 >75% Grass cover, Good, HSG B * 0.055 98 Impervious 0.202 71 Weighted Average 0.147 61 72.77% Pervious Area 0.055 98 27.23% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.2 Direct Entry, Rooftop 5.4 100 0.1000 0.31 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 5.6 100 Total Summary for Pond 1P: Raingarden Inflow Area = 0.202 ac, 27.23% Impervious, Inflow Depth = 1.57" for 10-Year event Inflow = 0.60 cfs @ 12.13 hrs, Volume= 0.027 af Outflow = 0.52 cfs @ 12.16 hrs, Volume= 0.021 af, Atten= 13%, Lag= 1.9 min Primary = 0.52 cfs @ 12.16 hrs, Volume= 0.021 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-96.00 hrs, dt= 0.01 hrs 06/12/19 ED170948 Scot Jandro MSE 24-hr 3 10-Year Rainfall=4.26"0438 Printed 4/23/2019Prepared by {enter your company name here} Page 5HydroCAD® 10.00-21 s/n 07283 © 2018 HydroCAD Software Solutions LLC Peak Elev= 871.67' @ 12.16 hrs Surf.Area= 321 sf Storage= 296 cf Plug-Flow detention time= 103.2 min calculated for 0.021 af (79% of inflow) Center-of-Mass det. time= 31.9 min ( 853.9 - 822.0 ) Volume Invert Avail.Storage Storage Description #1 870.00' 413 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 0.85 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 870.00 49 0 0 871.50 334 287 287 872.00 462 199 486 Device Routing Invert Outlet Devices #1 Primary 871.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 Width (feet) 2.00 4.00 Primary OutFlow Max=0.52 cfs @ 12.16 hrs HW=871.67' (Free Discharge) 1=Custom Weir/Orifice (Weir Controls 0.52 cfs @ 1.31 fps) 06/12/19 ED170948 Scot Jandro