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Stormwater Management Plan 10-17-2014Sambatek Engineering I Surveying I Planning I Environmental Memorandum 10/17/2014 City of Chanhassen 7700 Market Blvd Chanhassen, MN 55317 RE: Stormwater Management Plan 7 & 41 Crossings Center CITY OFCHANHASSEN RECEIVED 007 17 2014 CHANHASSEN PLANNINGAFPI The following is a summary of the stormwater management system for the proposed retail building project located at the 7 and 41 Crossings Center. The project has been designed to meet the requirements of the city as summarized in the following paragraphs. I. Existing Conditions The current site accommodates the Highway 7 and 41 crossings shopping center. The shopping center houses a Walgreens store to the northwest, a SuperAmerica gas station to the northeast, and a strip mall to the south. The remainder of the site is taken up by parking lots and service drives for the shopping center. The east side of the shopping center contains parking space as well as an area of land that has been mass graded, and provided with utility services, in consideration for the construction of another building. The site currently has stormwater BMP's that are in place. Runoff from the Walgreens building and parking lot flows to a rain garden just north of the Walgreens. The SuperAmerica and the strip mall runoff is captured by storm inlets that feed into an existing storm pond to the south of the strip mall. Runoff from the proposed building area flows over land, to the west, and eventually into catch basins that are piped into the storm pond. 1l. Proposed Conditions The new retail building is to be located on the green space to the east of the strip mall parking lot. The site will contain a 3,915 SF building and a drive -thru lane around the back. A patio area and a new sidewalk are also proposed to accommodate the site. Stormwater runoff will sheet flow across the drive -thru lane and into catch basins where it will be piped into the existing stormwater management pond to the south of the strip mall. Ill. Rate Control The proposed site is less than one acre and therefore does not require an NPDES permit from the MPCA. The stormwater management requirement for the City of Chanhassen is that peak discharge rates may not increase from the result of a proposed project. The Walgreens' portion of the site was designed in 2008, which also included the proposal for a retail store to be built in the future. The stormwater management report that was approved in 2008 took into account a future retail development on the site. The details of the future site were not known at the time. Now, the proposed site has been fully implemented into the stormwater management calculations for the shopping center. The HydroCAD model that was approved in 2008 had to be revised to include the details of the new site. A new HydroCAD model has been created which accounted for an additional 1960 SF of impervious surface due to the proposed site. The results of the runoff rate comparison are summarized in the table(s) below, please refer to the attached calculations and drainage diagrams for further detail. Maximum Rate of Runoff (cfs) Storm Event Existing Proposed 2 -year 13.19 13.28 10 -year 20.55 20.39 100 -year 31.43 30.81 IV. Summary The proposed site was taken into consideration in 2008 when the Walgreens store was designed as a part of the shopping center. The approved stormwater model from 2008 now accounts for the proposed site. The city required that the proposed stormwater runoff rates did not exceed the existing runoff rates. The stormwater requirements are met for the proposed site, with the exception of the proposed 2 -year runoff rate exceeding the existing runoff rate by 0.08 cfs. If you have any questions or comments regarding this report, please feel free to contact me at bbusselman @sambatek.com or 763- 476 -6010. Sincerely, Sambatek, Inc. Brady Busselman, P.E. q,q a 8F LLI v�F- W 0: LU w ua a z a z w a2 U � V Z ? W I- Jw II 0 J w Q 2 w 2 QV U - t O ' 0111111110` "�' L111 inc � Y, a z w o LU Vf Ln A O E LLI y a O cr �x zoo .za a o U N W 2 z U f0m O> H� Z Z Z N z= z E = CC U o °Cz° W a IlU U C H¢ VI 14A a` - t O ' 0111111110` "�' L111 inc � Y, a Existing Runoff (Overall Mall Area - Discharges to Pond) Subcat Reach on Link 17252- Existing - Anxon- Chanhassen Prepared by {enter your company name here) Page 2 HydroCAD ®8 00 s/n 002790 © 2006 HydroCAD Software Solutions LLC 9/16/2008 Area Listing (all nodes) Area (acres) CN Description (subcats) 1.840 61 >75% Grass cover, Good, HSG B - Pervious Islands (2S) 4.880 98 Paved parking & roofs (2S) 6.720 17252- Existing - Anxon- Chanhassen Prepared by {enter your company name Type 11 24 -hr 1 " Rainfall= 1. 00" Page 3 Time span =0.00 -48.00 hrs, dt =0.05 hrs, 961 points Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv. Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 2S: Existing Runoff (Overall Mall Area - Dischar Runoff Area =6.720 ac Runoff Depth = 0.57" Flow Length =955' Tc =19.0 min CN =61/98 Runoff =4.23 cfs 0.322 of Total Runoff Area = 6.720 ac Runoff Volume = 0.322 of Average Runoff Depth = 0.57" 27.38% Pervious Area =1.840 ac 72.62% Impervious Area = 4.880 ac 17252 - Existing - Anxon- Chanhassen Prepared by {enter your company name Type 1124 -hr 1 " Rainfall= 1. 00" Page 4 Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Runoff = 4.23 cfs @ 12.11 hrs, Volume= 0.322 af, Depth= 0.57" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr l" Rainfall = 1.00" Area (ac) CN Description 4.880 98 Paved parking & roofs 1.840 61 >75% Grass cover, Good HSG B - Pervious Islands 6.720 88 Weighted Average 1.840 61 Pervious Area 4.880 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.3 100 0.0200 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" 0.8 55 0.0200 1.14 Sheet Flow, Smooth surfaces n=0.011 P2=2.80" 2.9 800 0.0100 4.54 3.56 Circular Channel (pipe), Diam= 12.0" Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 19.0 955 Total Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Hydrograph 6.23015 --------- Type 1124 -hr 1,. 4 Rainfall- 1.00" Runoff Area =6.720 ac 3 Runoff', Volume =0.322 of Runoff Depth =0.57' i; LL 2 LJ�L= o 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 17252 - Existing- Anxon- Chanhassen Prepared by {enter your company name Type// 24 -hr 2 -Year Rainfall= 2.80" Page 5 Time span =0.00 -48.00 hrs, dt =0.05 hrs, 961 points Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv. Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 2S: Existing Runoff (Overall Mall Area - Dischar Runoff Area =6.720 ac Runoff Depth= 1.95" Flow Length =955' Tc =19.0 min CN =61/98 Runoff =13.19 cfs 1.090 of Total Runoff Area = 6.720 ac Runoff Volume= 1.090 of Average Runoff Depth= 1.95" 27.38% Pervious Area =1.840 ac 72.62% Impervious Area = 4.880 ac 17252 - Existing - Anxon- Chanhassen Type 1124 -hr2 -Year Rainfall =280" Prepared by (enter your company name here) Page 6 HydroCAD® 8.00 s/n 002790 © 2006 HydroCAD Software Solutions LLC 9/16/2008 Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Runoff = 13.19 cfs @ 12.11 hrs, Volume= 1.090 af, Depth= 1.95" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 2 -Year Rainfall= 2.80" Area (ac) CN Description 4.880 98 Paved parking & roofs i 4AA C1 79ZO /_ (gone nnver (_nnA WQr] R _ Pon,iniic Ichnrlc 6.720 88 Weighted Average 1.840 61 Pervious Area 4.880 98 Impervious Area Tc Length Slope Velocity Capacity Description 15.3 100 0.0200 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" 0.8 55 0.0200 1.14 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.80" 2.9 800 0.0100 4.54 3.56 Circular Channel (pipe), Diam= 12.0" Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 19.0 955 Total Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Hydrograph p 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 10� 9 V 8 - e a 6 5 3 Hydrograph p 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 17252- Existing- Anxon- Chanhassen Prepared by (enter vour comoanv name Type 1124 -hr 10 -Year Rainfall= 4.10" Page 7 Time span =0.00 -48.00 hrs, dt =0.05 hrs, 961 points Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv. Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 2S: Existing Runoff (Overall Mall Area - Dischar Runoff Area =6.720 ac Runoff Depth= 3.04" Flow Length =955' Tc =19.0 min CN =61/98 Runoff =20.55 cfs 1.704 of Total Runoff Area = 6.720 ac Runoff Volume = 1.704 of Average Runoff Depth = 3.04" 27.38% Pervious Area = 1.840 ac 72.62% Impervious Area = 4.880 ac 17252 - Existing- Anxon- Chanhassen Type 1124 -hr 10 -Year Rainfall = 4.10" Prepared by (enter your company name here) Page 8 HydroCAD® 8.00 s/n 002790 © 2006 HydroCAD Software Solutions LLC 9/16/2008 Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Runoff = 20.55 cfs @ 12.11 hrs, Volume= 1.704 af, Depth= 3.04" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 10 -Year Rainfall= 4.10" Area (ac) CN Description 4.880 98 Paved parking & roofs 1.840 61 >75% Grass cover, Good, HSG B - Pervious Islands 6.720 88 Weighted Average 1.840 61 Pervious Area 4.880 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.3 100 0.0200 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" 0.8 55 0.0200 1.14 Sheet Flow, Smooth surfaces n=0.011 P2=2.80" 2.9 800 0.0100 4.54 3.56 Circular Channel (pipe), Diam= 12.0" Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 19.0 955 Total Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Hydrograph 23 ... _ _ !. - -- - - _ - - - ❑Runoff 22 21 2o 20 55 Type-112A_ qtr 10 "Year 18 - - Rainfall = 4.10' . 16 Runoff. Area =6.720 ac - 16 - _ - -- - - - 'Runoff Volume_j.704. af. 14 - -- - 13 12- Runoff Depfh_3.04" 3 " 0 u Flow Lengfh:=:955' 10 - - - Tc 9.0 min e =l 6 -CN =61/98 5 - --- 3 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 17252- Existing - Anxon- Chanhassen Prepared by {enter your company name here} Type 1124 -hr 100 -Year Rainfall =5. g0" Page 9 Time span =0.00 -48.00 hrs, dt =0.05 hrs, 961 points Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv. Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment 2S: Existing Runoff (Overall Mall Area - Dischar Runoff Area =6.720 ac Runoff Depth = 4.64" Flow Length =955' Tc =19.0 min CN =61/98 Runoff =31.43 cfs 2.600 of Total Runoff Area = 6.720 ac Runoff Volume = 2.600 of Average Runoff Depth = 4.64" 27.38% Pervious Area =1.840 ac 72.62% Impervious Area = 4.880 ac 17252 - Existing - Anxon- Chanhassen Type 1124 -hr 100 -Year Rainfall = 5.90" Prepared by {enter your company name here) Page 10 HydroCADO 8.00 s/n 002790 © 2006 HvdroCAD Software Solutions LLC 9/16/2008 Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) Runoff = 31.43 cfs @ 12.11 hrs, Volume= 2.600 af, Depth= 4.64" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 100 -Year Rainfall= 5.90" Area (ac) CN Description 4.880 98 Paved parking & roofs 1.840 61 >75% Grass cover, Good HSG B - Pervious Islands 6.720 88 Weighted Average 1.840 61 Pervious Area 4.880 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.3 100 0.0200 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" 0.8 55 0.0200 1.14 Sheet Flow, Smooth surfaces n=0.011 P2=2.80" 2.9 800 0.0100 4.54 3.56 Circular Channel (pipe), Diam= 12.0" Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 19.0 955 Total Subcatchment 2S: Existing Runoff (Overall Mall Area - Discharges to Pond) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) \| � \ w : \| § \ § § § ° L q / § j ) / U \ (A �2k a )) | i) }w / /§\3§% LA=z \ §k\ ■ Walgreens Roof Raingarden 4R Pipe to Pond from Rain Ga den 2S N V 3R Runoff (Overall Mall Discharge to Existing Area - Flows to Pond) Pond Subcat Reach Am 1Li JEB REVISED 10 -7- 201417252- Proposed - Anxon -Chanh Type// 24 -hr 2 -Year Rainfall = 2.80" Prepared by {enter your company name here} Printed 10/15/2014 .. . .... — I ,..., — � ... — , ,-- n- o..,.., n Summary for Subcatchment 1 S: Walgreens Roof Runoff = 1.19 cfs @ 12.01 hrs, Volume= 0.075 af, Depth= 2.01" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 2 -Year Rainfall= 2.80" Area (ac) CN Description 0.340 98 Paved parking & roofs 0.110 61 >75% Grass cover, Good, HSG B 0.450 89 Weighted Average 0.110 61 24.44% Pervious Area 0.340 98 75.56% Impervious Area Tc Length Slope Velocity Capacity Description 10.0 Direct Entry, JEB REVISED 10 -7 -2014 17252 - Proposed - Anxon -Chanh Type 1124 -hr 2 -Year Rainfall =2.80" Prepared by {enter your company name here} Printed 10/15/2014 HydroCAD@ 10.00 s/n 00887 @2012 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 2S: Runoff (Overall Mall Area - Flows to Pond) Runoff = 12.88 cfs C 12.11 hrs, Volume= 1.062 af, Depth= 2.00" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /] mperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 2 -Year Rainfall= 2.80" Area (ac) CN Description 4.780 98 Paved parking & roofs 1.580 61 >75% Grass cover, Good HSG B - Pervious Islands 6.360 89 Weighted Average 1.580 61 24.84% Pervious Area 4.780 98 75.16% Impervious Area Tc Length Slope Velocity min) (feet) (ft/ft) (ft/sec) 15.3 100 0.0200 0.11 0.8 55 0.0200 1.14 2.9 800 0.0100 4.54 19.0 955 Total Description Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" Sheet Flow, Smooth surfaces n= 0.011 P2= 2.80" 3.56 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' JEB REVISED 10 -7- 201417252- Proposed - Anxon -Chanh Type 1124 -hr 2- Year Rainfall= 2.80" Prepared by (enter your company name here) Printed 10/15/2014 Summary for Reach 3R: Discharge to Existing Pond [40] Hint: Not Described (Outflow = Inflow) Inflow Area = 6.810 ac, 75.18% Impervious, Inflow Depth = 1.98" for 2 -Year event Inflow = 13.28 cfs @ 12.11 hrs, Volume= 1.123 of Outflow = 13.28 cfs @ 12.11 hrs, Volume= 1.123 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs JEB REVISED 10 -7- 201417252- Proposed - Anxon -Chanh Type 11 24 -hr 2 -Year Rainfall = 2.80" Prepared by {enter your company name here} Printed 10/15/2014 Summary for Reach 4R: Pipe to Pond from Rain Garden [52] Hint: Inlet/Outlet conditions not evaluated Inflow Area = 0.450 ac, 75.56% Impervious, Inflow Depth = 1.62" for 2 -Year event Inflow = 0.42 cfs @ 12.17 hrs, Volume= 0.061 of Outflow = 0.42 cfs @ 12.26 hrs, Volume= 0.061 af, Atten= 0 %, Lag= 5.2 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Max. Velocity= 4.59 fps, Min. Travel Time= 2.7 min Avg. Velocity = 1.95 fps, Avg. Travel Time= 6.4 min Peak Storage= 69 cf @ 12.21 hrs Average Depth at Peak Storage= 0.17' Bank -Full Depth= 1.00' Flow Area= 0.8 sf, Capacity= 6.37 cfs 12.0" Round Pipe n= 0.013 Length= 750.0' Slope= 0.0320 7' Inlet Invert= 990.00', Outlet Invert= 966.00' JEB REVISED 10 -7- 201417252- Proposed- Anxon -Chanh Type 1124 -hr 2 -Year Rainfall= 2.80" Prepared by f enter your company name here} Printed 10/15/2014 Summary for Pond 1 P: Raingarden Inflow Area = 0.450 ac, 75.56% Impervious, Inflow Depth = 2.01" for 2 -Year event Inflow = 1.19 cfs @ 12.01 hrs, Volume= 0.075 of Outflow = 0.43 cfs @ 12.17 hrs, Volume= 0.072 af, Atten= 64 %, Lag= 9.9 min Discarded = 0.01 cfs @ 12.17 hrs, Volume= 0.011 of Primary = 0.42 cfs @ 12.17 hrs, Volume= 0.061 of Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Peak Elev= 993.58' @ 12.17 hrs Surf.Area= 1,320 sf Storage= 1,158 cf Flood Elev= 995.50' Surf.Area= 3,018 sf Storage= 3,940 cf Plug -Flow detention time= 188.6 min calculated for 0.072 of (96% of inflow) Center -of -Mass det. time= 163.4 min ( 929.0 - 765.5 ) Volume Invert Avail.Storage Storage Description #1 993.00' 3,163 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 988.00' 777 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,590 cf Overall x 30.0% Voids 3,940 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 993.00 518 0 0 994.00 1,009 764 764 995.00 1,693 1,351 2,115 995.50 2,500 1,048 3,163 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 988.00 518 0 0 993.00 518 2,590 2,590 Device Routing Invert Outlet Devices #1 Primary 990.50' 12.0" Round Culvert L= 45.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet/ Outlet Invert= 990.50'/ 990.24' S=0.0058'/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 994.75' 24.0" Horiz. Orifice /Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 990.50' 4.0" Round Culvert L= 80.0' RCP, groove end projecting, Ke= 0.200 Inlet/ Outlet Invert= 990.50'/ 990.50' S= 0.0000 'P Cc= 0.900 n=0.010 PVC, smooth interior, Flow Area= 0.09 sf #4 Secondary 995.00' 2.5' long x 5.0' 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 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #5 Discarded 988.00' 0.250 in /hr Exfiltration over Horizontal area JEB REVISED 10 -7- 201417252- Proposed - Anxon -Chanh Type 1124 -hr 2 -Year Rainfall= 2.80" Prepared by {enter your company name here) Printed 10/15/2014 Discarded OutFlow Max =0.01 cfs @ 12.17 hrs HW= 993.57' (Free Discharge) t- -5= Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max =0.42 cfs @ 12.17 hrs HW= 993.57' (Free Discharge) t--1--Culvert (Passes 0.42 cfs of 5.85 cfs potential flow) �2 =Orifice /Grate ( Controls 0.00 cfs) 3= Culvert (Barrel Controls 0.42 cfs @ 4.81 fps) Secondary OutFlow Max =0.00 cfs @ 0.00 hrs HW= 988.00' (Free Discharge) = Broad- Crested Rectangular Weir ( Controls 0.00 cfs) JEB REVISED 10 -7- 201417252- Proposed -Anxon -Chan Type 11 24 -hr 10 -Year Rainfall =4.10" Prepared by {enter your company name here} Printed 10/15/2014 Summary for Subcatchment 1S: Walgreens Roof Runoff = 1.84 cfs @ 12.01 hrs, Volume= 0.117 af, Depth= 3.13" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 10 -Year Rainfall= 4.10" Area (ac) CN Description 0.340 98 Paved parking & roofs 0.450 89 Weighted Average 0.110 61 24.44% Pervious Area 0.340 98 75.56% Impervious Area Tc Length Slope Velocity Capacity Description 10.0 Direct Entry, JEB REVISED 10 -7- 201417252- Proposed -Anxon -Chan Type 1124 -hr 10 -Year Rainfall = 4.10" Prepared by {enter your company name here) Printed 10/15/2014 Summary for Subcatchment 2S: Runoff (Overall Mall Area - Flows to Pond) Runoff = 19.96 cfs @ 12.11 hrs, Volume= 1.653 af, Depth= 3.12" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type 1124-hr 10 -Year Rainfall= 4.10" Area (ac) CN Description 4.780 98 Paved parking & roofs 1.580 61 >75% Grass cover. Good, HSG B - Pervious Islands 6.360 89 Weighted Average 1.580 61 24.84% Pervious Area 4.780 98 75.16% Impervious Area Tc Length Slope Description 15.3 100 0.0200 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" 0.8 55 0.0200 1.14 Sheet Flow, Smooth surfaces n=0.011 P2=2.80" 2.9 800 0.0100 4.54 3.56 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 19.0 955 Total JEB REVISED 10 -7- 2014 17252- Proposed -Anxon -Chan Type 1124 -hr 10 -Year Rainfall = 4.10" Prepared by {enter your company name here) Printed 10/15/2014 Summary for Reach 3R: Discharge to Existing Pond [401 Hint: Not Described (Outflow= I nf low) Inflow Area = 6.810 ac, 75.18% Impervious, Inflow Depth = 3.09" for 10 -Year event Inflow = 20.39 cfs @ 12.11 hrs, Volume= 1.755 of Outflow = 20.39 cfs @ 12.11 hrs, Volume= 1.755 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs JEB REVISED 10 -7- 201417252- Proposed -Anion -Chan Type 1124 -hr 10 -Year Rainfall = 4.10" Prepared by (enter your company name here) Printed 10/15/2014 Summary for Reach 4R: Pipe to Pond from Rain Garden [52] Hint: Inlet/Outlet conditions not evaluated Inflow Area = 0.450 ac, 75.56% Impervious, Inflow Depth = 2.72" for 10 -Year event Inflow = 0.47 cfs @ 12.22 hrs, Volume= 0.102 of Outflow = 0.47 cfs @ 12.30 hrs, Volume= 0.102 af, Atten= 0 %, Lag= 5.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Max. Velocity= 4.73 fps, Min. Travel Time= 2.6 min Avg. Velocity = 2.26 fps, Avg. Travel Time= 5.5 min Peak Storage= 74 cf @ 12.26 hrs Average Depth at Peak Storage= 0.18' Bank -Full Depth= 1.00' Flow Area= 0.8 sf, Capacity= 6.37 cfs 12.0" Round Pipe n= 0.013 Length= 750.0' Slope= 0.03207' Inlet Invert= 990.00', Outlet Invert= 966.00' JEB REVISED 10 -7- 201417252- Proposed -Anion -Chan Type 1124 -hr 10 -Year Rainfall= 4.10" Prepared by {enter your company name here) Printed 10/15/2014 Summary for Pond 1 P: Raingarden Inflow Area = 0.450 ac, 75.56% Impervious, Inflow Depth = 3.13" for 10 -Year event Inflow = 1.84 cfs @ 12.01 hrs, Volume= 0.117 of Outflow = 0.48 cfs @ 12.22 hrs, Volume= 0.114 af, Atten= 74 %, Lag= 12.6 min Discarded = 0.01 cfs @ 12.22 hrs, Volume= 0.012 of Primary = 0.47 cfs @ 12.22 hrs, Volume= 0.102 of Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Peak Elev= 994.22'@ 12.22 hrs Surf.Area= 1,674 sf Storage= 1,774 cf Flood Elev= 995.50' Surf.Area= 3,018 sf Storage= 3,940 cf Plug -Flow detention time= 140.7 min calculated for 0.114 of (97% of inflow) Center -of -Mass det. time= 124.1 min ( 884.6 - 760.5 ) Volume Invert Avail.Storage Storage Description #1 993.00' 3,163 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 988.00' 777 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,590 cf Overall x 30.0% Voids_ 3,940 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 993.00 518 0 0 994.00 1,009 764 764 995.00 1,693 1,351 2,115 995.50 2,500 1,048 3,163 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 988.00 518 0 0 993.00 518 2,590 2,590 Device Routing Invert Outlet Devices #1 Primary 990.50' 12.0" Round Culvert L= 45.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet/ Outlet Invert= 990.50'/ 990.24' S=0.00587' Cc= 0.900 n=0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 994.75' 24.0" Horiz. Orifice /Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 990.50' 4.0" Round Culvert L= 80.0' RCP, groove end projecting, Ke= 0.200 Inlet/ Outlet Invert= 990.50'/ 990.50' S=0.00007' Cc= 0.900 n=0.010 PVC, smooth interior, Flow Area= 0.09 sf #4 Secondary 995.00' 2.5' long x 5.0' 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 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #5 Discarded 988.00' 0.250 in /hr Exfiltration over Horizontal area JEB REVISED 10 -7- 201417252- Proposed -Anxon -Chan Type 1124 -hr 10 -Year Rainfall = 4.10" Prepared by {enter your company name here) Printed 10/15/2014 Discarded OutFlow Max =0.01 cfs @ 12.22 hrs HW= 994.21' (Free Discharge) t 5 =Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max =0.47 cfs @ 12.22 hrs HW= 994.21' (Free Discharge) ttCulvert (Passes 0.47 cfs of 6.61 cfs potential flow) 2= Orifice /Grate ( Controls 0.00 cfs) =Culvert (Barrel Controls 0.47 cfs @ 5.34 fps) econdary OutFlow Max =0.00 cfs @ 0.00 hrs HW= 988.00' (Free Discharge) =Broad- Crested Rectangular Weir ( Controls 0.00 cfs) JEB REVISED 10 -7- 201417252- Proposed - Anxon -Cha Type 1124 -hr 100 -Year Rainfall =5.90" Prepare_ d by (enter your company name here) Printed 10/15/2014 Summary for Subcatchment 1S: Walgreens Roof Runoff = 2.80 cfs @ 12.01 hrs, Volume= 0.178 af, Depth= 4.75' Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 100 -Year Rainfall = 5.90" Area (ac) CN Description 0.340 98 Paved parking & roofs 0.450 89 Weighted Average 0.110 61 24.44% Pervious Area 0.340 98 75.56% Impervious Area Tc Length Slope Velocity Capacity Description 10.0 Direct Entry, JEB REVISED 10 -7- 201417252- Proposed - Anxon -Cha Type 1124 -hr 100 -Year Rainfall = 5.90" Prepared by {enter your company name here) Printed 10/15/2014 Summary for Subcatchment 2S: Runoff (Overall Mall Area - Flows to Pond) Runoff = 30.32 cfs @ 12.11 hrs, Volume= 2.511 af, Depth= 4.74" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /] mperv., Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Type II 24 -hr 100 -Year Rainfall= 5.90" Area (ac) CN Description 4.780 98 Paved parkinq & roofs 6.360 89 Weighted Average 1.580 61 24.84% Pervious Area 4.780 98 75.16% Impervious Area Tc Length Slope Velocity Capacity Description 15.3 100 0.0200 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.80" 0.8 55 0.0200 1.14 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.80" 2.9 800 0.0100 4.54 3.56 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 19.0 955 Total JEB REVISED 10 -7- 201417252- Proposed - Anxon -Cha Type 1124 -hr 100 -Year Rainfall= 5.90" Prepared by {enter your company name here] Printed 10/15/2014 Summary for Reach 3R: Discharge to Existing Pond [40] Hint: Not Described (Outflow = Inflow) Inflow Area = 6.810 ac, 75.18% Impervious, Inflow Depth = 4.71" for 100 -Year event Inflow = 30.81 cfs @ 12.11 hrs, Volume= 2.673 of Outflow = 30.81 cfs @ 12.11 hrs, Volume= 2.673 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs JEB REVISED 10 -7- 201417252- Proposed - Anxon -Cha Type 1124 -hr 100 -Year Rainfall =5.90" Prepared by {enter your company name here] Printed 10/15/2014 Summary for Reach 4R: Pipe to Pond from Rain Garden [52] Hint: Inlet/Outlet conditions not evaluated [79] Warning: Submerged Pond 1 P Primary device # 1 OUTLET by 0.03' Inflow Area = 0.450 ac, 75.56% Impervious, Inflow Depth = 4.32" for 100 -Year event Inflow = 1.07 cfs @ 12.17 hrs, Volume= 0.162 of Outflow = 0.97 cfs @ 12.25 hrs, Volume= 0.162 af, Atten= 10 %, Lag= 4.9 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Max. Velocity= 5.90 fps, Min. Travel Time= 2.1 min Avg. Velocity = 2.55 fps, Avg. Travel Time= 4.9 min Peak Storage= 127 cf @ 12.21 hrs Average Depth at Peak Storage= 0.27' Bank -Full Depth= 1.00' Flow Area= 0.8 sf, Capacity= 6.37 cfs 12.0" Round Pipe n= 0.013 Length= 750.0' Slope= 0.0320'P Inlet Invert= 990.00', Outlet Invert= 966.00' JEB REVISED 10 -7- 201417252- Proposed - Anxon -Cha Type 1124 -hr 100 -Year Rainfall = 5.90" Prepared by (enter your company name here) Printed 10/15/2014 Summary for Pond 1 P: Raingarden Inflow Area = 0.450 ac, 75.56% Impervious, Inflow Depth= 4.75" for 100 -Year event Inflow = 2.80 cfs @ 12.01 hrs, Volume= 0.178 of Outflow = 1.08 cfs @ 12.17 hrs, Volume= 0.175 af, Atten= 61 %, Lag= 9.8 min Discarded = 0.01 cfs @ 12.17 hrs, Volume= 0.013 of Primary = 1.07 cfs @ 12.17 hrs, Volume= 0.162 of Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor -Ind method, Time Span= 0.00 -48.00 hrs, dt= 0.05 hrs Peak Elev= 994.84' @ 12.17 hrs Surf.Area= 2,104 sf Storage= 2,634 cf Flood Elev= 995.50' Surf.Area= 3,018 sf Storage= 3,940 cf Plug -Flow detention time= 111.2 min calculated for 0.175 of (98% of inflow) Center -of -Mass det. time= 100.3 min ( 856.9 - 756.6 ) Volume Invert Avail.Storage Storage Description #1 993.00' 3,163 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 988.00' 777 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,590 cf Overall x 30.0% Voids _ 3,940 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 993.00 518 0 0 994.00 1,009 764 764 995.00 1,693 1,351 2,115 995.50 2,500 1,048 3,163 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 988.00 518 0 0 993.00 518 2,590 2,590 Device Routing Invert Outlet Devices #1 Primary 990.50' 12.0" Round Culvert L= 45.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 990.50'/ 990.24' S= 0.0058'/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Device 1 994.75' 24.0" Horiz. Orifice /Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 990.50' 4.0" Round Culvert L= 80.0' RCP, groove end projecting, Ke= 0.200 Inlet/ Outlet Invert= 990.50'/ 990.50' S=0.0000'/' Cc= 0.900 n=0.010 PVC, smooth interior, Flow Area= 0.09 sf #4 Secondary 995.00' 2.5' long x 5.0' 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 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #5 Discarded 988.00' 0.250 in /hr Erfiltration over Horizontal area JEB REVISED 10 -7- 201417252- Proposed - Anxon -Cha Type 1124 -hr 100 -Year Rainfall= 5.90" Prepared by {enter your company name here} Printed 10/15/2014 iscarded OutFlow Max =0.01 cfs @ 12.17 hrs HW= 994.83' (Free Discharge) = Exfiltration (Exfiltration Controls 0.01 cfs) rimary OutFlow Max =0.99 cfs @ 12.17 hrs HW= 994.83' (Free Discharge) Culvert (Passes 0.99 cfs of 7.26 cfs potential flow) 2= Orifice /Grate (Weir Controls 0.48 cfs @ 0.94 fps) 3=Culvert (Barrel Controls 0.51 cfs @ 5.81 fps) econdary OutFlow Max =0.00 cfs @ 0.00 hrs HW= 988.00' (Free Discharge) = Broad- Crested Rectangular Weir ( Controls 0.00 cfs)