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Stormwater Drainage Report 03-18-2011STORMWATER DRAINAGE REPORT BP AMOCO STATION (Plowe #11 -1318) Chanhassen, MN{ ORIGINAL DATE: March 18, 2011 CITY OF CHANHASSEN HECE.IVED Cv1AR 2 1 2011 tiHANHASSEN PLAUNING DEf-' ?" PLOWS EN GINEERING, INC. 6776 Lake Drive, Suite 110 Lino Lakes, Minnesota 55014 Office (651) 361 -8210 Fax (651) 361 -8701 11 -1318 BP Amoco Site Narrative Date: March 18, 2011 This project will consist of reconstructing an existing BP Amoco site at the intersection of Highway 5 and Great Plains Boulevard in Chanhassen, Minnesota. The existing building, several pumps, the overhead canopy, and some bituminous drive and parking lot are to be removed. A new building and overhead canopy are proposed, as well as a reconfiguration of the existing pumps. The underground gasoline storage tanks are to remain and be re -used for this project. A second automated car wash is to be added adjacent to the existing car wash. Existing drainage is directed into the City's storm sewer system without rate control or water quality. An existing catch basin will collect a fair amount of the parking lot and direct it to an underground detention system. The roof drainage and some of the proposed drive around the building will be directed to a filtration basin on the east side of the site; which in turn will enter the underground detention system. A new manhole with weir wall will be installed over the existing storm sewer leaving the site 'this, in conjunction with the underground detention system, will provide rate control for the site. Not all of the existing parking lot will be disturbed. It is anticipated that the western portion of the parking lot and curb will be saved and that new paving will butt against existing paving. Parcel Area Existing Impervious Proposed Impervious = 49,415 sf (1.134 acres) = 23,580± sf (0.54± acres) = 32,120± sf (0.74± acres) Total Disturbed Area = 38,000± sf (0.9± acres) 11 -1318 BP Amoco Rate Comparison Date: March 18, 2011 STORM EVENT EXISTING 2 -yr 10 -yr 100 -yr. (cam) (cam) (cam) EX 2.19 1 3.99 1 6.62 x( *I EX' Existing Proposed Proposed Underground Storage Subcat' Reach on Link' 11 -1318 Ver 2 Type 11 24 -hr 2 year (2.8) Rainfall =2.80" Prepared by Plowe Engineering, Inc. Printed 3/17/2011 HydroCAD® 8.50 s/n 001574 © 2007 HydroCAD Software Solutions LLC Paa _ Time span= 0.00 -50.00 hrs, dt =0.01 hrs, 5001 points Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv. Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchmentl: Proposed Runoff Area= 23,376 sf 63.03% Impervious Runoff Depth =1.73" Flow Length =120' Tc =7.0 min CN =61/98 Runoff =1.34 cfs 3,365 cf Subcatchment2: Proposed Runoff Area = 11,310 sf 21.88 Impervious Runoff Depth=0.79" Flow Length =120' Tc =7.0 min CN =61/98 Runoff =0.27 cfs 745 d Subcatchment3: Proposed Runoff Area= 14,137 sf 72.93% Impervious Runoff Depth =1.95' Tc =5.0 min CN=61/98 Runoff=0.99 ds 2,301 cf SubeatchmentEx: Existing Runoff Area= 53,423 sf 44.14% Impervious Runoff Depth =1.30" Flow Length =135' Tc =7.8 min CN =61/98 Runoff =2.19 cfs 5,776 cf SubcatchmentR: Building Runoff Area =4,600 sf 100.00% Impervious Runoff Depth =2.57" Tc =2.5 min CN=0/98 Runoff =0.46 crs 985 d Pond CBI: CB1 Peak Elev= 953.52' Storage =239 d Inflow=027 cfs 745 cf Outflow --0.04 ds 745 d Pond PR: Roof Peak EIev= 963.09' Storage =397 d inflow=0.46 ds 985 d Outflow =0.13 cfs 984 cf Pond US: UndergroundStorage Peak Bev= 950.04' Storage =391 d Inflow =1.49 ds 5,094 d Outflow--0.94 ds 5,094 d Total Runoff Area = 106,846 sf Runoff Volume = 13,171 cf Average Runoff Depth = 1.48" 47.87 %, Pervious = 51,146 sf 52.13% Impervious = 55,700 sf 11 -1318 Ver 2 Type II 24 -hr 2 year (2.8) Rainfall =2.80" Prepared by Plowe Engineering, Inc. Printed 3/17/2011 HydroCAD® 8.50 s/n 001574 @2007 HvdroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1: Proposed Runoff = 1.34 cis @ 11.98 hrs, Volume= 3,365 cf, Depth= 1.73" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24 -hr 2 year (2.8 ") Rainfall =2.80" Area (sf) CN Description " 14,735 98 Impervious ' 2,475 98 8,641 61 >75% Grass cover, Good, HSG B 61 23,376 84 Weighted Average 69 Weighted Average 8,641 61 Pervious Area Pervious Area 2,475 14,735 98 Impervious Area 0.24 Tc Length Slope Velocity Capacity Description min (feet) (ft/ft) (ftlsec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 4.8 70 0.0700 0.24 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 7.0 120 Total Summary for Subcatchment 2: Proposed Runoff = 0.27 cfs @ 11.99 hrs, Volume= 745 cf, Depth= 0.79" Runoff by SCS TR -20 method, UH =SCS, Split Perviouslimperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24 -hr 2 year (2.8 ") Rainfall =2.80" Area (sf) CN Description ' 2,475 98 Impervious 8,835 61 >75% Grass cover, Good, HSG B 11,310 69 Weighted Average 8,835 61 Pervious Area 2,475 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (f tsec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, 10,310 98 Impervious Area Grass: Short n=0.150 P2=2.80" 4.8 70 0.0700 0.24 Sheet Flow, Grass: Short n=0.150 P2=2.80" 7.0 120 Total Summary for Subcatchment 3: Proposed Runoff = 0.99 cis @ 11.96 hrs, Volume= 2,301 cf, Depth= 1.95" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24 -hr 2 year (2.8 ") Rainfall =2.80" Area (sf) CN Description ' 10,310 98 Impervious 3,827 61 >75% Grass cover, Good, HSG B 14,137 88 Weighted Average 3,827 61 Pervious Area 10,310 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fUsec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Ex: Existing Runoff = 2.19 cfs @ 11.99 hrs, Volume= 5,776 cf, Depth= 1.30" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt 0.01 hrs Type II 24-hr 2 year (2.8 ") Rainfall =2.80" Area (sf) CN Description ' 23,580 98 Impervious 29,843 61 >75% Grass cover, Good, HSG B 53,423 77 Weighted Average 29,843 61 Pervious Area 23,580 98 Impervious Area 11 -1318 Ver 2 Type 1124 -hr 2 year (2.8) Rainfall =2.80" Prepared by Plowe Engineering, Inc. Printed 3/17/2011 HydroCAD0 8.50 s/n. 001574 @ 2007 HydroCAD Software Solutions LLC Page 4 Tc Length Slope Velocity Capacity Description - (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, Grass: Short n=0.150 P2=2.80" 5.6 85 0.0700 0.25 Sheet Flow, Grass: Short n=0.150 P2=2.80" 7.8 135 Total Summary for Subcatchment R: Building Runoff = 0.46 cfs @ 11.93 hrs, Volume= 985 cf, Depth= 2.57' Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24-hr 2 year (2.8 ") Rainfall =2.80' Area (sf) CN Description _ 4,600 98 4,600 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fl/sec) (cfs) 2.5 Direct Entry, Summary for Pond CB1: CB1 [87] Warning: Oscillations may require Finer Routing or smaller dt Inflow Area = 11,310 sf, 21.88% Impervious, Inflow Depth = 0.79" for 2 year (2.8 ") event Inflow = 0.27 cfs @ 11.99 hrs, Volume= 745 cf Outflow = 0.04 cfs @ 12.37 hrs, Volume= 745 cf, Atten= 86 %, Lag = 22.5 min Primary = 0.04 cfs @ 12.37 hrs, Volume= 745 cf Routing by DynStor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 953.52'@ 12.37 hrs Surf.Area= 600 sf Storage= 239 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 85.7 min ( 893.7 - 808:0) Volume Invert Avail-Storage Storage Description , #1 953.00' 588 cf Custom Stage Data (Prismatic) -isted below (Recalc) Elevation Surf.Area Inc.Store Cum.Store. (feet) (sq -ft) (cubic -feet) (cubic -feet) 953.00 327 0 0 953.50 592 230 230 954.00 842 359 588 Device Routing Invert Outlet Devices #1 Primary 953.50' 2.50'W x 1.00' H Vert. Orifice /Grate C= 0.600 #2 Primary 951.50' 6.0" x 30.0' long Culvert Ke= 0.500 Outlet Invert= 951.50' S= 0.00007' Cc= 0.900 n= 0.013 #3 Device 2 953.00' 1.600 in/hr ExFltration over Surface area Primary OutFlow Max =0.04 cfs @ 12.37 hrs HW= 953.52' TW= 949.30' (Dynamic Tailwater) t 1= Orifice /Grate (Orifice Controls 0.02 cfs @ 0.40 fps) 2= Culvert (Passes 0.02 cfs of 0.99 cfs potential flow) t3= Exfl1tration (Exfiltration Controls 0.02 cfs) Summary for Pond PR: Roof Inflow Area = 4,600 sf,100.00% Impervious, Inflow Depth = 2.57" for 2 year (2.8 ") event Inflow = 0.46 cfs @ 11.93 hrs, Volume= 985 cf Outflow = 0.13 cfs @ 12.02 hrs, Volume= 984 cf, Atten= 72 %, Lag= 5.8 min Primary = 0.13 cfs @ 12.02 hrs, Volume= 984 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 963.09'@ 12.02 hrs Surf.Area= 4,600 sf Storage= 397 cf Plug -Flow detention time= 98.4 min calculated for 984 cf (100% of inflow) Center -of -Mass det time= 97.7 min ( 849.9 - 752.2 ) Volume Invert Avail.Storage Storage Description #1 963.00' 1,150 cf Custom Stage Data (Prismatic)_isted below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 963.00 4,600 0 0 963.25 4,600 1,150 1,150 Device Routing Invert Outlet Devices #1 Primary 963.00' 6.0" Horiz. Orifice /Grate Limited to weir flow C=0.600 11 -1318 Ver 2 Type 11 24 -hr 2 year (2.8:) Rainfall =2.80" Prepared by Plowe.Engineering, Inc. Printed 3/17%2011 HydroCAD@) 8.50 s/n 001574 @2007 HydroCAD Software Solutions LLC Pacie 5 - Primary OutFlow Max =0.13 cis @ 12.02 hrs HW= 963.09' TW= 949.99' (Dynamic Tailwater) L1= Orifice /Grate (Weir Controls 0.13 cfs @ 0.96 fps) Summary for Pond US: Underground Storage [87] Warning: Oscillations may require Finer Routing or smaller dt Inflow Area = 39,286 sf, 55.52% Impervious, Inflow Depth = 1.56" for 2 year (2.8 ") event Inflow = 1.49 cfs @ 11.98 hrs, Volume= 5,094 cf Outflow = 0.94 cfs @ 12.06 hrs, Volume= 5,094 cf, Atten= 37 %, Lag= 4.8 min Primary = 0.94 cfs @ 12.06 hrs, Volume= 5,094 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 950.04' @ 12.06 hrs Surf.Area= 577 sf Storage= 391 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 1.6 min ( 803.5 - 801.9 ) Volume Invert Avail.Storage Storage Description #1 949.20' 471 cf 24.0 "D x 150.00'L Horizontal Cylinder #2 949.20' 650 cf 36.0 "D x 46.00% Horizontal Cylinder 2 #3 949.05' 30 cf 12.0 "D x 38.00'L Horizontal Cylinder S= 0.00397 #4 948.90' 11 cf 12.0 "D x 14.00'L Horizontal Cylinder S= 0.0107 T #5 948.90' 47 cf Custom Stage Data (Prismatic) -isted below (Recalc) 1,209 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 948.90 13 0 0 952.50 13 47 47 Device Routing Invert Outlet Devices #1 Primary 948.80' 12.0" x 85.0' long Culvert Ke= 0.500 Outlet Invert= 948.70' S= 0.0012'r Cc= 0.900 n= 0.013 #2 Device 1 948.80' 6.0" Vert. Orifice /Grate C= 0.600 #3 Device 1 950.80' 1.50'W x 1.20'H Vert. Orifice /Grate C= 0.600 Primary OutFlow Max =0.94 cfs @ 12.06 hrs HW= 950.04' (Free. Discharge) t 1= Culvert (Passes 0.94 cfs of 2.04 cfs potential flow) � 2= Orifice /Grate (Orifice Controls 0.94 cfs @ 4.79 fps) 3= Orifice /Grate ( Controls 0.00 cfs) - - 11 -1318 Ver 2 Type 11 24 -hr 10 -year (4.2) Rainfall =4.20" Prepared by Plowe Engineering, Inc. Printed' 3/1'7/2011 HydroCAD@) 8:50 stn 001574 © 2007 HydroCAD Software Solutions LLC Page 6 Time span =0.00 -50;00 hrs, dt =0.01 hrs,'5001.pbints Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv. Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchmentl: Proposed Runoff Area = 23,376 sf 63.03% Impervious Runoff Depth =2.84" Flow Lenglh =120' Tc =7.0 min CN =61/98 Runoff- cfs 5,528 d Subcatchment2: Proposed Runoff Area = 11,310 sf 21.88% Impervious Runoff Depth =1.58" Flow Length =120' Tc=7.O min CN=61/98 Runoff=0.62 cfs 1,492 cf Subcatchment3: Proposed Runoff Area = 14,137 sf 72.93% Impervious Runoff Depth =3.14" Tc =5.0 min CN=61/98 Runoff =1.59 cis 3,698 d SubcatchmentEx: Existing Runoff Area = 53,423 sf 44.14% Impervious Runoff Depth =2.26" Flow Lenglh =135' Tc=7.8 min CN =61/98 Runoff =3.99 cfs 10,069 cf SubcatchmentR: Building Runoff Area =4,600 sf 100.00% Impervious Runoff Depth =3.96" Tc =2.5 min CN=0/98 Runoff =0.70 cfs 1,520 cf Pond CB1: CB1 Peak Elev= 953.65' Storage =325 ef Inflow=0.62 ds 1,492 cf Outflow - -0.50 ds 1,492 cf Pond PR: Roof Peak Elev= 963.12' Storage =570 cf Inflow=0.70 cis 1,520 cf Outflow -022 ds 1,519 cf Pond US: UndergroundStorage Peak Elev=951.OT Storage d Inflow- ds 8,539 cf Outflow cis 8,539 cf Total Runoff Area = 106,846 sf Runoff Volume = 22,308 cf Average Runoff Depth = 2.51" 47.87% Pervious = 51,146 sf 52.13% Impervious = 55,700 sf 11 -1318 Ver 2 Type 11 24-hr. 10 -year (4.2) Rainfall =4.20" Prepared by Plowe Engineering, Inc: Printed 3/17/2011 HydroCAD® 8.50 sin 001574. © 2007 HydroCAD Software Solutions LLC Pa0e7 Summary for'$ubcatchment 1: Proposed Runoff = 2.24 cfs @ 11.98 hrs, Volume= 5,528 of, Depth= 2.84" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24 -hr 10 -year (4.2 ") Rainfall =4.20" Area (sf) CN Description ' 14,735 98 Impervious 8,641 61 >75% Grass cover, Good, HSG B 23,376 84 Weighted Average 8,641 61 Pervious Area 14,735 98 Impervious Area To Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, 98 Impervious Area 98 To Length Slope - Velocity Capacity Grass: Short n=0.150 P2=2.80" 4.8 70 0.0700 0.24 Sheet Flow, Sheet Flow, ; Grass: Short n= .0.150 P2=2.80" . . Grass: Short n=0.150 P2=2.80" 7.0 120 Total Grass: Short n=0.150 P2=2.80" Summary for Subcatchment 2: Proposed Runoff = 0.62 cfs @ 11.99 hrs, Volume= 1,492 cf, Depth= 1.58" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24-hr 10 -year (4.2 ") Rainfall =4.20" Area (sf) CN Description Description " 2,475 98 Impervious Impervious 8,835 61 >75% Grass cover, Good HSG B 11,310 69 Weighted Average 88 8,835 61 Pervious Area 61 2,475 98 Impervious Area 98 To Length Slope - Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) (ft/sec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, ; Grass: Short n= .0.150 P2=2.80" . . 4.8 70 0.0700 0.24 Sheet Flow, Grass: Short n=0.150 P2=2.80" 7.0 120 Total Summary for Subcatchment 3: Proposed Runoff = 1.59 cis @ 11.96 hrs, Volume= 3,698 of, Depth= 3.14" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type 11 24 -hr 10 -year (4.2 ") Rainfall =4.20" Area (sf) CN Description " 10,310 98 Impervious _ 3,827 61 >75% Grass cover, Good, HSG B 14,137 88 Weighted Average 3,827 61 Pervious Area 10,310 98 Impervious Area To Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Ex: Existing Runoff = 3.99 cfs @ 11.99 hrs, Volume= 10,069 of, Depth= 2.26" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24 -hr 10 -year (4.2 ") Rainfall =4.20" Area (sf) CN Description ' 23,580 98 Impervious 29,843 61 >75% Grass cover, Good, HSG B 53,423 77 Weighted Average 29,843 61 Pervious Area 23,580 98 Impervious Area 11 -1318 Ver 2 Type 11 24 -hr 10 -year (4.2) Rainfall= 4.20" Prepared by Rowe Engineeririg, Inc. Printed 3/17/2091 HydroCAM 8:50 's/n 001574 @ 2007 HydroCAD Software Solutions LLC paw Tc Length Slope?. Velocity Capacity Description _(min) (feet) (f tft) (ft/sec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, Grass: Short n=0.150 P2=2.80" 5.6 85 0.0700 0.25 Sheet Flow, Grass: Short n=0.150 P2=2.80" 7.8 135 Total Summary for Subcatchment R: Building Runoff = 0.70 cfs @ 11.93 hrs, Volume= 1,520 cf, Depth= 3.96" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24-hr 10 -year (4.2") Rainfall =4.20" Area (sf) CN Description ' 4,600 98 4,600 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (f /sec) (cfs) 2.5 Direct Entry, Summary for Pond CB1: CB1 Inflow Area = 11,310 sf, 21.88% Impervious, Inflow Depth = 1.58" for 10 -year (4.2 ") event Inflow = 0.62 crs @ 11.99 hrs, Volume= 1,492 cf Outflow = 0.50 cfs @ 12.04 hrs, Volume= 1,492 cf, Atten= 20 %, Lag= 3.1 min Primary = 0.50 cfs @ 12.04 hrs, Volume= 1,492 of Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev 953.65'@ 12.04 hrs Surf.Area= 668 sf Storage= 325 of Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det time= 74.9 min ( 884.4 - 809.5 ) Volume Invert Avail.Storage Storage Description #1 953.00' 588 of Custom Stage Data (Prismatic)-.isted below,(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 953.00 327 0 0 953.50 592 230 230 954.00 842 359 588 Device Routing Invert Outlet Devices #1 Primary 953.50' 2.50'W x 1.00'H Vert. Orifice /Grate C= 0.600 #2 Primary 951.50' 6.0" x 30.0' long Culvert Ke= 0.500 Outlet Invert= 951.50' S= 0.00007 Cc= 0.900 n= 0.013 #3 Device 2 953.00' 1.600 in/hr Exfiltration over Surface area Primary OutFlow Max =0.50 cfs @ 12.04 hrs HW= 953.65' TW= 951.03' (Dynamic Tailwater) t 1= Orifice /Grate (Orifice Controls 0.47 cfs @ 1.25 fps) 2= Culvert (Passes 0.02 cfs of 1.03 cfs potential flow) t3= Exfiltration ( Exfiltration Controls 0.02 cfs) Summary for Pond PR: Roof Inflow Area = 4,600 sf,100.00% Impervious, Inflow Depth = 3.96" for 10 -year (4.2 ") event Inflow = 0.70 cfs @ 11.93 hrs, Volume= 1,520 cf Outflow = 0.22 cfs @ 12.02 hrs, Volume= 1,519 cf, Atten= 68 %, Lag= 5.5 min Primary = 0.22 cfs @ 12.02 hrs, Volume= 1,519 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 963.12'@ 12.02 hrs Surf.Area= 4,600 sf Storage= 570 of Plug -Flow detention time= 85.3 min calculated for 1,519 cf (100 %, of inflow) Center -of -Mass det. time= 84.8 min ( 828.6 - 743.8 ) Volume Invert Avail.Storage Storage Description #1 963.00' 1,150 cf Custom Stage Data (Prismatic)_isted below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 963.00 4,600 0 0 963.25 4,600 1,150 1,150 Device Routing Invert Outlet Devices #1 Primary 963.00' 6.0" Horiz. Orifice /Grate Limited to weir flow C=0.600 Primary OutFlow Max =0.22 cfs @ 12.02 hrs HW= 963.12' TW= 950.89' (Dynamic Tailwater) t1= Orifice /Grate (Weir Controls 0.22 cfs @ 1.15 fps) 114318 Ver 2 Type 1124-hr.10 -year (4.2') Rainfall =4.20" Prepared by Plowe Engineering, Inc: Printed 3/17/2011 HydroCAM.8.50 s/n 001574 ©2007 HydroCAQ Software Solutions LLC pagg� . r ' Summary The Pond US: Underground Storage [87] Warning: Oscillations may require Finer Routing or smaller dt Inflow Area = 39,286 sf, 55.52% Impervious, Inflow Depth = 2.61" for 10 -year (4.2 ") event Inflow = 2.79 cis @ 12.00 hrs, Volume= 8,539 of Outflow = 2.04 cis @ 12.06 hrs, Volume= 8,539 cf, Atten= 27 %, Lag= 3.9 min Primary = 2.04 cis @ 12.06 hrs, Volume= 8,539 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 951.OT @ 12.06 hrs Surf.Area= 426 sf Storage= 956 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 3.2 min ( 799.9 - 796.7 ) Volume Invert Avail.Storage Storage Description #1 949.20' 471 cf 24.0 "D x 150.001 Horizontal Cylinder #2 949.20' 650 cf 36.0 "D x 46.00'L Horizontal Cylinder 2 #3 949.05' 30 cf 12.0 "D x 38.00'L Horizontal Cylinder S= 0.0039 7 #4 948.90' 11 cf 12.0 "D x 14.00% Horizontal Cylinder S= 0.01107T #5 948.90' 47 cf Custom Stage Data (Prismatic)-isted below (Recalc) 1,209 cf Total Available Storage Elevation Surf.Area Inc.Store Cum,Store (feet) (sq - ft) (cubic (cubic - feet) 948.90 13 0 0 952.50 13 47 47 Device Invert Outlet Devices #1 Primary 948.80' 12.0" x 85.0' long Culvert Ke= 0.500 Outlet Invert= 948.70' S= 0.0012T Cc= 0.900 n= 0.013 #2 Device 1 948.80' 6.0" Vert. Orifice /Grate C= 0.600 #3 Device 1 950.80' 1.50'W x 1.20'H Vert. Orifice /Grate C= 0.600 Primary OutFlow Max =2.03 cis @ 12.06 hrs HW= 951.OT (Free Discharge) t11 Culvert (Passes 2.03 cis of 3.62 cfs potential flow) F-2= Orifice /Grate (Orifice Controls 1.34 @ 6.85 fps) 3 Orifice /Grate (Orifice Controls 0.69 cis @ 1.68 fps) 11 -1318 Ver 2 Type 11 24 -hr 100 year (6.0') . Rainfall =6.00" Prepared by Plowe Engineering, lnc. Printed 3/17/2011 HydroCAD® 8.50 s/n 001574. ©200T HydroCAD`Software Solutions LLC' - Pam 10 Time span = 0:00-50;00 hrs, dt =0.01 hrs, 5001 points Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv. Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchmentl: Proposed Runoff Area = 23,376 sf 63.03% Impervious Runoff Depth=4.37" Flow Length =120' Tc =7.0 min CN =61/98 Runoff =3.47 ds 8,519 d Subcatchment2: Proposed Runoff Area = 11,310 sf 21.88% Impervious Runoff Depth =2.83" Flow Length =120' Tc =7.0 min CN =61/98 Runoff =1.16 ds 2,665 d Subcatchment3: Proposed Runoff Area = 14,137 sf 72.93% Impervious Runoff Depth =4.74" Tc =5.0 min CN=61 /98 Runoff =2.41 ds 5,590 d SubcatchmentEx: Existing Runoff Area= 53,423 sf 44.14% Impervious Runoff Depth =3.66" Flow Length =135' Tc=7.8 min CN =61/98 Runoff =6.62 ds 16,310 d SubcatchmentR: Building Runoff Area =4,600 sf 100.00% Impervious Runoff Depth =5.76" Tc =2.5 min CN=0/98 Runoff =1.01 ds 2,209 d Pond CB1: CB1 Peak EIev= 953.76 Storage =400 d Inflow =1.16 ds 2,665 d Outflow ds 2,665 d Pond PR: Roof Peak EIev 963.1T Storage =778 d Inflow =1.01 ds 2,209 d Outflow --0.36 ds 2,207 d Pond US: UndergroundStorage Peak EIev - 951.84' Storage =1,156 d Inflow - -4.84 ds 13,392 d Outflow -4.51 ds 13,392 d Total Runoff Area = 106,846 sf Runoff Volume = 35,292 cf Average Runoff Depth = 3.96" 47.87% Pervious = 51,146 sf 52.13% Impervious = 55,700 sf 11 -1318 Ver 2 Type 11.24 -hr 100 year (6.0:) Rainfall= 6.00 Prepared by Rowe Engineering, Inc. Printed.3 /17/2011 HydraCAD®8.50. s(n 001574 0)2007 HydroCAD Software Solutions LLC Pad; 11 Summary for $ ubcatchment 1: Proposed Runoff = 3.47 cis @ 11.98 hrs, Volume= 8,519 cf, Depth= 4.37" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/lmperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24-hr 100 year (6.0 ") Rainfall =6.00" 14,735 98 23,376 84 Weighted Average 8,641 61 Pervious Area 14,735 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ftfft) (fUsec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, 2,475 98 Impervious Area Grass: Short n=0.150 P2=2.80' 4.8 70 0.0700 0.24 Sheet Flow, 4.8 70 0.0700 Grass: Short n=0.150 P2=2.80" 7.0 120 Total Summary for Subcatchment 2: Proposed Runoff = 1.16 cfs @ 11.99 hrs, Volume= 2,665d, Depth= 2.83" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24-hr 100 year (6.0 ") Rainfall =6.00" Area (sf) CN Description ` 2,475 98 Impervious 8,835 61 >75% Grass cover, Good, HSG B 11,310 69 Weighted Average 8,835 61 Pervious Area 2,475 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fUsec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 4.8 70 0.0700 0.24 Sheet Flow, Grass: Short n=0.150 P2=2.80" 7.0 120 Total Summary for Subcatchment 3: Proposed Runoff = 2.41 cis @ 11.96 hrs, Volume= 5,590 cf, Depth= 4.74" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt 0.01 hrs Type II 24-hr 100 year (6.0 ") Rainfall =6.00" Area (sf) CN Description ` 10,310 98 3,827 61 >75% Grass cover, Good, HSG B 14,137 88 Weighted Average 3,827 61 Pervious Area 10,310 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (f /ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Ex: Existing Runoff = 6.62 cfs @ 11.99 hrs, Volume= 16,310 cf, Depth= 3.66" Runoff by SCS TR -20 method, UH =SCS, Split Pervious /] mperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24 -hr 100 year (6.0 ") Rainfall= 6.00" Area (sf) CN DescriDtlon 23,580 98 Impervious 29,843 61 >75% Grass cover, Good, HSG B 53,423 77 Weighted Average 29,843 61 Pervious Area 23,580 98 Impervious Area 11 -1318 Ver 2 Type ll 24 -hr 100 year (6.0) Rainfall= 6.00" Prepared by Plowe Engineering, Inc. Printed 3/17/2011 HydroCAM 8.50 s/n 001574 .@2007 HydroCAD Software Solutions LLC Pace' 12 Tc Length Slope Velocity Capacity Description (min) (feet) (f tft) (fl/sec) (cfs) 2.2 50 0.2500 0.38 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 5.6 85 0.0700 0.25 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 7.8 135 Total Summary for Subcatchment R: Building Runoff = 1.01 cfs @ 11.93 hrs, Volume= 2,209 cf, Depth= 5.76" Runoff by SCS TR -20 method, UH =SCS, Split Pervious/Imperv., Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Type II 24-hr 100 year (6.0 ") Rainfall =6.00" Area (sf) CN Description 4,600 98 4,600 98 Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (f fsec) (cfs) 2.5 Direct Entry, Summary for Pond CB1: CB1 Inflow Area = 11,310 sf, 21.88% Impervious, Inflow Depth = 2.83" for 100 year (6.0 ") event Inflow = 1.16 cfs @ 11.99 hrs, Volume= 2,665 of Outflow = 1.09 cis @ 12.01 hrs, Volume= 2,665 cf, Atten= 6 %, Lag= 1.7 min Primary = 1.09 cfs @ 12.01 hrs, Volume= 2,665 of Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 953.76'@ 12.01 hrs Surf.Area= 722 sf Storage= 400 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 63.1. min ( 869.2 - 806.1) - Volume Invert Avail.Storage Storage Description #1 953.00' 588 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 953.00 327 0 0 953.50 592 230 230 954.00 842 359 588 Device Invert Outlet Devices #1 Primary 953.50' 2.50'W x 1.00' H Vert. Orifice /Grate C= 0.600 #2 Primary 951.50' 6.0" x 30.0' long Culvert Ke= 0.500 Outlet Invert= 951.50' S= 0.0000'/' Cc= 0.900 n= 0.013 #3 Device 2 953.00' 1.600 in/hr Exfiltration over Surface area Primary OutFlow Max =1.08 cis @ 12.01 hrs HW= 953.76' TW= 951.83' (Dynamic Tailwater) t 1= Orifice /Grate (Orifice Controls 1.06 cfs @ 1.63 fps) 2= Culvert (Passes 0.03 cfs of 1.06 cfs potential flow) t3= Exfiltration (Exfiltration Controls 0.03 cfs) Summary for Pond PR: Roof Inflow Area = 4,600 sf,100.00% Impervious, Inflow Depth = 5.76" for 100 year (6.0 ") event Inflow = 1.01 cfs @ 11.93 hrs, Volume= 2,209 cf Outflow = 0.36 cfs @ 12.01 hrs, Volume= 2,207 of, Atten= 65 %, Lag= 5.2 min Primary = 0.36 cfs @ 12.01 hrs, Volume= 2,207 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 963.1T @ 12.01 hrs Surf.Area= 4,600 sf Storage= 778 cf Plug -Flow detention time = 75.1 min calculated for 2,207 cf (100% of inflow) Center -of -Mass det. time= 75.0 min ( 812.7 - 737.7 ) V_ olume Invert Avail.Storage Storage Description #1 963.00' 1,150 cf Custom Stage Data (Prismatic)_isted below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 963.00 4,600 0 0 963.25 4,600 1,150 1,150 Device Routing Invert Outlet Devices #1 Primary 963.00' 6.0" Horiz. Orifice /Grate Limited to weir flow C=0.600 Primary OutFlow Max =0.36 cfs @ 12.01 hrs HW= 963.17' TW= 951.83' (Dynamic Tailwater) t1 =0rifice/Grate (Weir Controls 0.36 cfs @ 1.34 fps) 11 -1318 Ver 2 - Type 1i 24 -hr 100 year (6.0) Rainfall= 6.00 ": Prepared by Plowe'Engineering, Inc. Printed 3/17/2611 HvdroCAD® 8:50: s/n 001574 © 2007 HydroCAD Software Solutions LLC - Page 13 Summary for Pond US' Storage Inflow Area = 39,286 sf, 55.52% Impervious, Inflow Depth = 4.09" for 100 year (6.0 ") event Inflow = 4.84 cfs @ 11.99 hrs, Volume= 13,392 cf Outflow = 4.51 cis @ 12.02 hrs, Volume= 13,392 cf, Atten= 7 %", Lag= 1.9 min Primary = 4.51 cfs @ 12.02 hrs, Volume= 13,392 cf Routing by DynStor -Ind method, Time Span= 0.00 -50.00 hrs, dt= 0.01 hrs Peak Elev= 951.84'@ 12.02 hrs Surf.Area= 193 sf Storage= 1,156 of Plug -Flow detention time= 3.2 min calculated for 13,392 of (100% of inflow) Center -of -Mass det time= 3.2 min ( 794.6 - 791.4 ) Volume Invert Avail.Storage Storage Description #1 949.20' 471 cf 24.0 "D x 150.00'L Horizontal Cylinder #2 949.20' 650 cf 36.0 "D x 46.00'L Horizontal Cylinder 2 #3 949.05' 30 of 12.0 "D x 38.00'L Horizontal Cylinder S= 0.0039 'P #4 948.90' 11 of 12.0 "D x 14.00'L Horizontal Cylinder S= 0.0107 T #5 948.90' 47 of Custom Stage Data (Prismatic).isted below (Recale) 1,209 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store _ (feet) (sq -ft) (cubic -feet) (cubic -feet) 948.90 13 0 0 952.50 13 47 47 Device Routing Invert Outlet Devices #1 Primary 948.80' 12.0" x 85.0' long Culvert Ke= 0.500 Outlet Invert= 948.70' S= 0.0012? Cc= 0.900 n= 0.013 #2 Device 1 948.80' 6.0" Vert. Orifice /Grate C= 0.600 #3 Device 1 950.80' 1.50' W x 1.20'H Vert. Orifice /Grate C= 0.600 Primary OutFlow Max =4.51 cfs @ 12.02 hrs HW= 951.84' (Free Discharge) t-1 =Culvert (Barrel Controls 4.51 cfs @ 5.74 fps) = Orifice /Grate (Passes < 1.58 cfs potential flow) L 12 3= Orifice /Grate (Passes < 5.08 cfs potential flow)