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HomeMy WebLinkAbout16628 - SWMP - Tanager Creek 1-18-2022Storm Water Management Plan Calculations & Summaries TANAGER CREEK Orono, MN Project No. 16628 December 5, 2021 I hereby certify that this plan, specifation 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. _____________________________________________ Adam M. Thiele, P.E. Reg. No. 51317 Prepared By: Prepared For: Anderson Engineering of MN, LLC Ethan DeNary 13605 1st Avenue North, Suite 100 PO Box 192 Plymouth, MN 55441 Babbitt, MN 55706 Ph: 763.412.4000 Ph: 612-802-4052 Fax: 763.412.4090 Anderson Engineering of Minnesota, LLC ● 13605 1st Avenue North, Suite 100 ● Plymouth, Minnesota 55441 ● (763) 412-4000 Main ● (763) 412-4090 Fax ● www.ae-mn.com 1 | P a g e Table of Contents Cover / Certification Page Table of Contents Project Overview Existing Site Conditions Soils Proposed Site Conditions Methodology Green Roof Rate Control Volume Control Water Quality Summary Appendix – Exhibits and Calculations A – Existing Drainage Map & HydroCAD Report B – Proposed Drainage Map & HydroCAD Report C – Engineered Plans dated December 5, 2021 D – County Soils Data for Project Area Stormwater Narrative/Summary December 5, 2021 Tanager Creek Orono, MN 2 | P a g e Project Overview Tanager Creek is a proposed 3-lot residential development in Orono, MN. The site encompasses 14.06 acres. The property is located in Hennepin County and within the Minnehaha Creek Watershed District. The project will require an Erosion Control Permit and Stormwater Management Permit from Minnehaha Creek Watershed Distict. The project includes site clearing and demolition of existing structures and pavement found on site. The proposed development will consist of 3 residential lots, each with over a half acre of upland. A private street and cul-de-sac is proposed to provide access off Brown Road. Existing Site Conditions The 14.06-acre property is located on Brown Road (Co Rd 146) in Orono, MN. Runoff is generally directed to the north and east, entering a wetland area that is contiguous with Lake Minnetonka. The existing site features a single-family residence with detached garage and bituminous paved driveway. The area surrounding the residence is vegetated with turf grass with scattered trees beyond. The existing drainage pattern can be seen in Exhibit A: Existing Drainage Map within the appendices of this report. The property is does not have city water or sewer services and is instead served by private well and septic. Soils County Soils data indicates the in-situ soils are Angus Loam which consists of loam and clay loam. These soils area classified as Hydrologic Soil Group C. For our hydrologic modeling we used curve numbers for “B” soils for the existing conditions and “C” soils for the proposed conditions. Proposed Site Conditions The proposed development will consist of 3 single-family residential lots served by a short private street with cul-de-sac. Each lot is proposed to be served by a paved driveway. The post-developed impervious surface area will increase by 14,487sf. Due to the restrictive onsite soils and limited space to implement a conventional stormwater BMP, the project proposed to construct a filtration basin to provide stormwater treatment. The proposed filtration basin includes retention of 2,498 cubic feet of runoff for filtration prior to outletting into the wetland area. The proposed grading plan allows for overland drainage of the private street and front of the proposed lots, as well as all runoff from Lot 1 and an additional area of Lot 2 to be routed to the filtration basin. The grading also takes advantage of an area proposed to remain undisturbed as a filter strip to provide pretreatment of runoff. The proposed drainage pattern can be seen in Exhibit B: Proposed Drainage Map can be found in the appendices of this report. Stormwater Narrative/Summary December 5, 2021 Tanager Creek Orono, MN 3 | P a g e Methodology HydroCAD The hydrologic characteristics of the site were modeled using HydroCAD software. TR55/TR20 methods were utilized. Existing and proposed drainage areas were determined based on existing survey and proposed grading. The 2, 10, & 100-year frequency events where analyzed for peak runoff rate control in the existing and proposed conditions. The MSE Type III- 24 hr distribution was used in analysis. Runoff from pervious and impervious surfaces were calculated separately to more accurately model the runoff volume from the site surfaces. For our purposes, only the portion of the property that will be modified as a result of this project has been modeled. Results of this analysis are summarized below, and a report can be seen in Exhibit D: HydroCAD Report. Filtration Basin The project proposes to use a shallow filtration basin to control and treat stormwater runoff. The proposed basin is situated to most efficiently gather a majority of runoff from impervious surfaces prior to discharging to wetland area. The proposed filtration basin will provide 12” of water retention prior to outletting via earthen weir. The bottom of the basin is proposed to be lined with MPCA Filtration Mix C and includes a 6” perforated underdrain. Phosphorus Control Minnehaha Creek Watershed District requires control phosphorus within stormwater runoff. For redevelopment projects, the requirement is considered met if the proposed conditions meet the requirements of the Volume Control regulations. See below for more information. Rate Control Minnehaha Creek Watershed District requires post-development conditions to maintain pre-development peak runoff rates. The table below summarizes the pre- and post-development peak rates for the property: Storm Event Pre Development Rate (CFS) Post Development Rate (CFS) 2yr – 2.86 2.39 1.31 10yr – 4.25 5.91 4.90 100yr – 7.28 15.20 13.21 Volume Control Minnehaha Creek Watershed District requires the retention and infiltration of 1.0” of stormwater runoff from new impervious surfaces, where feasible. Due to restrictive on-site soils, the project has proposed a Stormwater Narrative/Summary December 5, 2021 Tanager Creek Orono, MN 4 | P a g e filtration basin. Per watershed rules, a filtration basin is required to retain twice the volume required for infiltration. The project has a increased impervious surface area of 14,487 square feet, which requires 1,207 cubic feet of volume retention. The proposed filtration basin provides 2,498 cubic feet of retention, more than twice the volume required for infiltration. Summary The implementation of a filtration basin will provide the necessary stormwater control to meet MCWD regulations. 9 3 0 93 5 940940940 94594592 9 9 3 1 93293 3 93 4 9 3 6 93 7 93 8 93 9 941941942942943943944944946946947 947948948945 950 944 94 6 947 948 949 935940945 945 9319329339349369379389399419429439449469469479479 3 0 935 931 932 933 934 936 937 938 939941942 800 BROWN ROAD 920 BROWN ROAD 930 BROWN ROADBROWN ROAD (CO RD 146)N 0 20'40' 2 PLOTTED:COMM. NO. DRAWING NO. ----16628 TANAGER CREEK 1 3 6 0 5 1 s t A v e n u e N . #1 0 0 P l y m o u t h , M N 5 5 4 4 1 | a e -m n .c o m P 7 6 3 .4 1 2 .4 0 0 0 | F 7 6 3 .4 1 2 .4 0 9 0 A n d e r s o n E n g i n e e r i n g o f M i n n e s o t a , L L C DRAWING TITLE CHECKED BY:DRAWN:DESIGNED: ATJRAT 12/05/2021 REVISION LOG DESCRIPTION OF REVISIONSNO.DATE 860 BROWN ROAD ORONO, MN ETHAN DENARY PRELIMINARY PLAT 1 12/05/21 PRELIMINARY PLAT SUBMITTAL PRINT NAME: SIGNATURE: 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. DATE:LICENSE NO.12/05/2021 1X EXISTING CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 1HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1X: EXISTING SITE Runoff = 2.39 cfs @ 12.19 hrs, Volume= 0.150 af, Depth= 0.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2yr Rainfall=2.86" Area (sf) CN Description 108,143 69 50-75% Grass cover, Fair, HSG B * 3,345 98 DRIVEWAY * 1,900 98 HOUSE/GARAGE 113,388 Weighted Average 108,143 95.37% Pervious Area 5,245 4.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1X: EXISTING SITE Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 MSE 24-hr 3 2yr Rainfall=2.86" Runoff Area=113,388 sf Runoff Volume=0.150 af Runoff Depth=0.69" Tc=10.0 min CN=WQ 2.39 cfs EXISTING CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 2HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1X: EXISTING SITE Runoff = 5.91 cfs @ 12.19 hrs, Volume= 0.337 af, Depth= 1.55" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10yr Rainfall=4.25" Area (sf) CN Description 108,143 69 50-75% Grass cover, Fair, HSG B * 3,345 98 DRIVEWAY * 1,900 98 HOUSE/GARAGE 113,388 Weighted Average 108,143 95.37% Pervious Area 5,245 4.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1X: EXISTING SITE Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 MSE 24-hr 3 10yr Rainfall=4.25" Runoff Area=113,388 sf Runoff Volume=0.337 af Runoff Depth=1.55" Tc=10.0 min CN=WQ 5.91 cfs EXISTING CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 3HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1X: EXISTING SITE Runoff = 15.20 cfs @ 12.18 hrs, Volume= 0.845 af, Depth= 3.90" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100yr Rainfall=7.28" Area (sf) CN Description 108,143 69 50-75% Grass cover, Fair, HSG B * 3,345 98 DRIVEWAY * 1,900 98 HOUSE/GARAGE 113,388 Weighted Average 108,143 95.37% Pervious Area 5,245 4.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1X: EXISTING SITE Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MSE 24-hr 3 100yr Rainfall=7.28" Runoff Area=113,388 sf Runoff Volume=0.845 af Runoff Depth=3.90" Tc=10.0 min CN=WQ 15.20 cfs 9 3 0 93 5 940940940 94594592 9 9 3 1 93293 3 93 4 9 3 6 93 7 93 8 93 9 941941942942943943944944946946947 947948948945 950 944 94 6 947 948 949 935940945 945 9319329339349369379389399419429439449469469479479 3 0 935 931 932 933 934 936 937 938 939941942 945941942943944946 935 945 945933934 941 941942 942943 9 4 3 94494 4 94094594593693693793793893893 8 939 941942943944 944 940945939941942943944946946947947948948 800 BROWN ROAD 920 BROWN ROAD 930 BROWN ROADBROWN ROAD (CO RD 146)N 0 20'40' 2 1 PLOTTED:COMM. NO. DRAWING NO. ----16628 TANAGER CREEK 1 3 6 0 5 1 s t A v e n u e N . #1 0 0 P l y m o u t h , M N 5 5 4 4 1 | a e -m n .c o m P 7 6 3 .4 1 2 .4 0 0 0 | F 7 6 3 .4 1 2 .4 0 9 0 A n d e r s o n E n g i n e e r i n g o f M i n n e s o t a , L L C DRAWING TITLE CHECKED BY:DRAWN:DESIGNED: ATJRAT 12/05/2021 REVISION LOG DESCRIPTION OF REVISIONSNO.DATE 860 BROWN ROAD ORONO, MN ETHAN DENARY PRELIMINARY PLAT 1 01/13/22 PRELIMINARY PLAT SUBMITTAL PRINT NAME: SIGNATURE: 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. DATE:LICENSE NO.01/13/2022 1S 2S 1P 1S ROAD & ROW 2S (new Subcat) 3R TOTAL RUNOFF 1P FILTRATION BASIN Routing Diagram for 16628 SWMP Prepared by {enter your company name here}, Printed 12/6/2021 HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Subcat Reach Pond Link PROPOSED CONDITIONS 16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 2HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 1.520 74 >75% Grass cover, Good, HSG C (1S, 2S) 0.083 98 LOT 1 (1S) 0.083 98 LOT 2 (1S, 2S) 0.083 98 LOT 3 (1S, 2S) 0.205 98 ROAD (1S) 1.973 80 TOTAL AREA PROPOSED CONDITIONS 16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 3HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 0.000 HSG B 1.520 HSG C 1S, 2S 0.000 HSG D 0.453 Other 1S, 2S 1.973 TOTAL AREA PROPOSED CONDITIONS 16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 4HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Ground Covers (selected nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 0.000 1.520 0.000 0.000 1.520 >75% Grass cover, Good 1S, 2S 0.000 0.000 0.000 0.000 0.083 0.083 LOT 1 1S 0.000 0.000 0.000 0.000 0.083 0.083 LOT 2 1S, 2S 0.000 0.000 0.000 0.000 0.083 0.083 LOT 3 1S, 2S 0.000 0.000 0.000 0.000 0.205 0.205 ROAD 1S 0.000 0.000 1.520 0.000 0.453 1.973 TOTAL AREA PROPOSED CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 5HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=51,635 sf 26.21% Impervious Runoff Depth=1.29"Subcatchment 1S: ROAD & ROW Tc=10.0 min CN=WQ Runoff=2.12 cfs 0.128 af Runoff Area=34,325 sf 18.06% Impervious Runoff Depth=1.15"Subcatchment 2S: (new Subcat) Tc=10.0 min CN=WQ Runoff=1.26 cfs 0.075 af Inflow=1.31 cfs 0.203 afReach 3R: TOTAL RUNOFF Outflow=1.31 cfs 0.203 af Peak Elev=934.06' Storage=2,685 cf Inflow=2.12 cfs 0.128 afPond 1P: FILTRATION BASIN Outflow=0.42 cfs 0.128 af Total Runoff Area = 1.973 ac Runoff Volume = 0.203 af Average Runoff Depth = 1.24" 77.04% Pervious = 1.520 ac 22.96% Impervious = 0.453 ac PROPOSED CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 6HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ROAD & ROW Runoff = 2.12 cfs @ 12.18 hrs, Volume= 0.128 af, Depth= 1.29" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2yr Rainfall=2.86" Area (sf) CN Description * 8,933 98 ROAD * 3,600 98 LOT 1 * 500 98 LOT 2 * 500 98 LOT 3 38,102 74 >75% Grass cover, Good, HSG C 51,635 Weighted Average 38,102 73.79% Pervious Area 13,533 26.21% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1S: ROAD & ROW Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 MSE 24-hr 3 2yr Rainfall=2.86" Runoff Area=51,635 sf Runoff Volume=0.128 af Runoff Depth=1.29" Tc=10.0 min CN=WQ 2.12 cfs PROPOSED CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 7HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: (new Subcat) Runoff = 1.26 cfs @ 12.18 hrs, Volume= 0.075 af, Depth= 1.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 2yr Rainfall=2.86" Area (sf) CN Description 28,125 74 >75% Grass cover, Good, HSG C * 3,100 98 LOT 2 * 3,100 98 LOT 3 34,325 Weighted Average 28,125 81.94% Pervious Area 6,200 18.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 2S: (new Subcat) Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 MSE 24-hr 3 2yr Rainfall=2.86" Runoff Area=34,325 sf Runoff Volume=0.075 af Runoff Depth=1.15" Tc=10.0 min CN=WQ 1.26 cfs PROPOSED CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 8HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Reach 3R: TOTAL RUNOFF [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.973 ac, 22.96% Impervious, Inflow Depth = 1.24" for 2yr event Inflow = 1.31 cfs @ 12.18 hrs, Volume= 0.203 af Outflow = 1.31 cfs @ 12.18 hrs, Volume= 0.203 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Reach 3R: TOTAL RUNOFF Inflow Outflow Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Inflow Area=1.973 ac 1.31 cfs1.31 cfs PROPOSED CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 9HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Pond 1P: FILTRATION BASIN Inflow Area = 1.185 ac, 26.21% Impervious, Inflow Depth = 1.29" for 2yr event Inflow = 2.12 cfs @ 12.18 hrs, Volume= 0.128 af Outflow = 0.42 cfs @ 12.59 hrs, Volume= 0.128 af, Atten= 80%, Lag= 24.7 min Primary = 0.42 cfs @ 12.59 hrs, Volume= 0.128 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 934.06' @ 12.59 hrs Surf.Area= 3,221 sf Storage= 2,685 cf Plug-Flow detention time= 377.4 min calculated for 0.128 af (100% of inflow) Center-of-Mass det. time= 377.7 min ( 1,172.7 - 795.0 ) Volume Invert Avail.Storage Storage Description #1 933.00' 6,290 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 933.00 1,850 0 0 935.00 4,440 6,290 6,290 Device Routing Invert Outlet Devices #1 Primary 934.00'10.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 933.00'0.800 in/hr Exfiltration over Surface area Primary OutFlow Max=0.42 cfs @ 12.59 hrs HW=934.06' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 0.36 cfs @ 0.61 fps) 2=Exfiltration (Exfiltration Controls 0.06 cfs) PROPOSED CONDITIONS MSE 24-hr 3 2yr Rainfall=2.86"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 10HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Pond 1P: FILTRATION BASIN Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Inflow Area=1.185 ac Peak Elev=934.06' Storage=2,685 cf 2.12 cfs 0.42 cfs PROPOSED CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 11HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=51,635 sf 26.21% Impervious Runoff Depth=2.37"Subcatchment 1S: ROAD & ROW Tc=10.0 min CN=WQ Runoff=3.99 cfs 0.234 af Runoff Area=34,325 sf 18.06% Impervious Runoff Depth=2.19"Subcatchment 2S: (new Subcat) Tc=10.0 min CN=WQ Runoff=2.49 cfs 0.144 af Inflow=4.90 cfs 0.377 afReach 3R: TOTAL RUNOFF Outflow=4.90 cfs 0.377 af Peak Elev=934.24' Storage=3,282 cf Inflow=3.99 cfs 0.234 afPond 1P: FILTRATION BASIN Outflow=3.02 cfs 0.234 af Total Runoff Area = 1.973 ac Runoff Volume = 0.377 af Average Runoff Depth = 2.29" 77.04% Pervious = 1.520 ac 22.96% Impervious = 0.453 ac PROPOSED CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 12HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ROAD & ROW Runoff = 3.99 cfs @ 12.18 hrs, Volume= 0.234 af, Depth= 2.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10yr Rainfall=4.25" Area (sf) CN Description * 8,933 98 ROAD * 3,600 98 LOT 1 * 500 98 LOT 2 * 500 98 LOT 3 38,102 74 >75% Grass cover, Good, HSG C 51,635 Weighted Average 38,102 73.79% Pervious Area 13,533 26.21% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1S: ROAD & ROW Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 MSE 24-hr 3 10yr Rainfall=4.25" Runoff Area=51,635 sf Runoff Volume=0.234 af Runoff Depth=2.37" Tc=10.0 min CN=WQ 3.99 cfs PROPOSED CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 13HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: (new Subcat) Runoff = 2.49 cfs @ 12.18 hrs, Volume= 0.144 af, Depth= 2.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 10yr Rainfall=4.25" Area (sf) CN Description 28,125 74 >75% Grass cover, Good, HSG C * 3,100 98 LOT 2 * 3,100 98 LOT 3 34,325 Weighted Average 28,125 81.94% Pervious Area 6,200 18.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 2S: (new Subcat) Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 MSE 24-hr 3 10yr Rainfall=4.25" Runoff Area=34,325 sf Runoff Volume=0.144 af Runoff Depth=2.19" Tc=10.0 min CN=WQ 2.49 cfs PROPOSED CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 14HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Reach 3R: TOTAL RUNOFF [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.973 ac, 22.96% Impervious, Inflow Depth = 2.29" for 10yr event Inflow = 4.90 cfs @ 12.24 hrs, Volume= 0.377 af Outflow = 4.90 cfs @ 12.24 hrs, Volume= 0.377 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Reach 3R: TOTAL RUNOFF Inflow Outflow Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)5 4 3 2 1 0 Inflow Area=1.973 ac 4.90 cfs4.90 cfs PROPOSED CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 15HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Pond 1P: FILTRATION BASIN Inflow Area = 1.185 ac, 26.21% Impervious, Inflow Depth = 2.37" for 10yr event Inflow = 3.99 cfs @ 12.18 hrs, Volume= 0.234 af Outflow = 3.02 cfs @ 12.27 hrs, Volume= 0.234 af, Atten= 24%, Lag= 5.4 min Primary = 3.02 cfs @ 12.27 hrs, Volume= 0.234 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 934.24' @ 12.27 hrs Surf.Area= 3,453 sf Storage= 3,282 cf Plug-Flow detention time= 249.1 min calculated for 0.234 af (100% of inflow) Center-of-Mass det. time= 249.7 min ( 1,039.2 - 789.5 ) Volume Invert Avail.Storage Storage Description #1 933.00' 6,290 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 933.00 1,850 0 0 935.00 4,440 6,290 6,290 Device Routing Invert Outlet Devices #1 Primary 934.00'10.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 933.00'0.800 in/hr Exfiltration over Surface area Primary OutFlow Max=2.89 cfs @ 12.27 hrs HW=934.23' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.83 cfs @ 1.23 fps) 2=Exfiltration (Exfiltration Controls 0.06 cfs) PROPOSED CONDITIONS MSE 24-hr 3 10yr Rainfall=4.25"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 16HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Pond 1P: FILTRATION BASIN Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=1.185 ac Peak Elev=934.24' Storage=3,282 cf 3.99 cfs 3.02 cfs PROPOSED CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 17HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=51,635 sf 26.21% Impervious Runoff Depth=5.01"Subcatchment 1S: ROAD & ROW Tc=10.0 min CN=WQ Runoff=8.49 cfs 0.495 af Runoff Area=34,325 sf 18.06% Impervious Runoff Depth=4.78"Subcatchment 2S: (new Subcat) Tc=10.0 min CN=WQ Runoff=5.48 cfs 0.314 af Inflow=13.21 cfs 0.809 afReach 3R: TOTAL RUNOFF Outflow=13.21 cfs 0.809 af Peak Elev=934.45' Storage=4,042 cf Inflow=8.49 cfs 0.495 afPond 1P: FILTRATION BASIN Outflow=7.93 cfs 0.495 af Total Runoff Area = 1.973 ac Runoff Volume = 0.809 af Average Runoff Depth = 4.92" 77.04% Pervious = 1.520 ac 22.96% Impervious = 0.453 ac PROPOSED CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 18HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ROAD & ROW Runoff = 8.49 cfs @ 12.17 hrs, Volume= 0.495 af, Depth= 5.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100yr Rainfall=7.28" Area (sf) CN Description * 8,933 98 ROAD * 3,600 98 LOT 1 * 500 98 LOT 2 * 500 98 LOT 3 38,102 74 >75% Grass cover, Good, HSG C 51,635 Weighted Average 38,102 73.79% Pervious Area 13,533 26.21% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 1S: ROAD & ROW Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 MSE 24-hr 3 100yr Rainfall=7.28" Runoff Area=51,635 sf Runoff Volume=0.495 af Runoff Depth=5.01" Tc=10.0 min CN=WQ 8.49 cfs PROPOSED CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 19HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: (new Subcat) Runoff = 5.48 cfs @ 12.17 hrs, Volume= 0.314 af, Depth= 4.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100yr Rainfall=7.28" Area (sf) CN Description 28,125 74 >75% Grass cover, Good, HSG C * 3,100 98 LOT 2 * 3,100 98 LOT 3 34,325 Weighted Average 28,125 81.94% Pervious Area 6,200 18.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment 2S: (new Subcat) Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 MSE 24-hr 3 100yr Rainfall=7.28" Runoff Area=34,325 sf Runoff Volume=0.314 af Runoff Depth=4.78" Tc=10.0 min CN=WQ 5.48 cfs PROPOSED CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 20HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Reach 3R: TOTAL RUNOFF [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.973 ac, 22.96% Impervious, Inflow Depth = 4.92" for 100yr event Inflow = 13.21 cfs @ 12.20 hrs, Volume= 0.809 af Outflow = 13.21 cfs @ 12.20 hrs, Volume= 0.809 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Reach 3R: TOTAL RUNOFF Inflow Outflow Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=1.973 ac 13.21 cfs13.21 cfs PROPOSED CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 21HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Summary for Pond 1P: FILTRATION BASIN Inflow Area = 1.185 ac, 26.21% Impervious, Inflow Depth = 5.01" for 100yr event Inflow = 8.49 cfs @ 12.17 hrs, Volume= 0.495 af Outflow = 7.93 cfs @ 12.21 hrs, Volume= 0.495 af, Atten= 7%, Lag= 2.3 min Primary = 7.93 cfs @ 12.21 hrs, Volume= 0.495 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 934.45' @ 12.21 hrs Surf.Area= 3,727 sf Storage= 4,042 cf Plug-Flow detention time= 136.3 min calculated for 0.494 af (100% of inflow) Center-of-Mass det. time= 137.1 min ( 917.9 - 780.9 ) Volume Invert Avail.Storage Storage Description #1 933.00' 6,290 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 933.00 1,850 0 0 935.00 4,440 6,290 6,290 Device Routing Invert Outlet Devices #1 Primary 934.00'10.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 933.00'0.800 in/hr Exfiltration over Surface area Primary OutFlow Max=7.78 cfs @ 12.21 hrs HW=934.44' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 7.71 cfs @ 1.74 fps) 2=Exfiltration (Exfiltration Controls 0.07 cfs) PROPOSED CONDITIONS MSE 24-hr 3 100yr Rainfall=7.28"16628 SWMP Printed 12/6/2021Prepared by {enter your company name here} Page 22HydroCAD® 10.00-25 s/n 00837 © 2019 HydroCAD Software Solutions LLC Pond 1P: FILTRATION BASIN Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=1.185 ac Peak Elev=934.45' Storage=4,042 cf 8.49 cfs 7.93 cfs