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Home My WebLink AboutStormwater Report - 870 GREAT POND ROAD 3/15/2007 Sullivan Engineering Group, LLC Civil Engineers&Land Development Consultants Watershed Protection District Drywell System Design For 870 Great Pond Road In North Andover, Massachusetts March 15, 2007 Prepared For: Ronald McCluskey 870 Great Pond Road North Andover, MA 01845 22 Mount Vernon Road Boxford, Massachusetts 01921 — (978)352-7871-Phone 978352-7871 -Fax 1S Prop. Addi ions - Roof Ar as ';;!7 1R 4" PVC oof Drain 1P 500 Gallon Drywell w/ 18" Stone Surrounding Subcat Reach Pon Link Drainage Diagram for 870 Great Pond Road,North Andover Prepared by Jack Sullivan, P.E. 3/15/2007 HydroCAD®7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 870 Great Pond Road, North Andover Type ///24-hr 100 yr Rainfall=6.40" Prepared by Jack Sullivan, P.E. Page 2 HydroCADO 7.00 s/n 001433 01986-2003 Applied Microcomputer Systems 3/15/2007 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Prop.Additions-Roof Areas Runoff Area=458 sf Runoff Depth=5.69" Tc=6.0 min CN=98 Runoff=0.06 cfs 217 cf Reach 1R: 4" PVC Roof Drain Peak Depth=0.08' Max Vet=3.7 fps Inflow=0.06 cfs 217 cf D=4.0" n=0.011 L=120.0' S=0.0412 '/' Capacity=0.46 cfs Outflow=0.06 cfs 217 cf Pond 1 P: 500 Gallon Drywell w/18"Stone Surro Peak Elev=126.93' Storage=84 cf Inflow=0.06 cfs 217 cf Outflow=0.01 cfs 216 cf Total Runoff Area=458 sf Runoff Volume= 217 cf Average Runoff Depth = 5.69" 870 Great Pond Road, North Andover Type 111 24-hr 100 yr Rainfall=6.40" Prepared by Jack Sullivan, P.E. Page 3 HydroCAD®7.00 s/n 001433 01986-2003 Applied Microcomputer Systems 3/15/2007 Subcatchment 1S: Prop. Additions - Roof Areas Runoff = 0.06 cfs @ 12.09 hrs, Volume= 217 cf, Depth= 5.69" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 yr Rainfall=6.40" Area (sf) CN Description 458 98 Roof Areas of Proposed Additions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, From Roof Subcatchment IS: Prop. Additions - Roof Areas Hydrograph 0.07 ®Runoff 0.06 cfs 0.065_ Type III 24-h r 100 yr 0.06 0.055 Rainfall=6.40" 0.05- Runoff Area=458 sf 0.045 Runoff Volume=217 cf 42 0.04 0.035 Runoff Depth=5.69" 0.03 Tc=6.0 min 0.025 0.02 C N=98 0.015 0.01- 0.005 ; w 0- 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 870 Great Pond Road, North Andover Type 111 24-hr 100 yr Rainfal1=640" Prepared by Jack Sullivan, P.E. Page 4 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 3/15/2007 Reach 1 R: 4" PVC Roof Drain [52] Hint: Inlet conditions not evaluated [82] Warning: Early inflow requires earlier time span Inflow Area = 458 sf, Inflow Depth = 5.69" for 100 yr event Inflow = 0.06 cfs @ 12.09 hrs, Volume= 217 cf Outflow = 0.06 cfs @ 12.10 hrs, Volume= 217 cf, Atten= 2%, Lag= 0.9 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 3.7 fps, Min. Travel Time= 0.5 min Avg. Velocity= 1.4 fps, Avg. Travel Time= 1.4 min Peak Depth=0.08' @ 12.09 hrs Capacity at bank full= 0.46 cfs Inlet Invert= 133.00', Outlet Invert= 128.05' 4.0" Diameter Pipe n= 0.011 Length= 120.0' Slope= 0.0412 '/' Reach 1 R: 4" PVC Roof Drain Hydrograph ®Inflow 0.07' 0.06 cfs M Outflow 0.065 0.06ds Inflow Area=458 sf Peak Depth=0.08' °.055. 0.05 Max Vet=3.7 fps 0.045- 0.04 n=0.011 0 0.035- LL 0.03- L=120.0' 0.025 S=0.0412 '/' 0.02. Capacity=0.46 cfs 0.015-- 0.01- - 0.005 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 870 Great Pond Road, North Andover Type ///24-hr 100 yr Rainfall=6.40" Prepared by Jack Sullivan, P.E. Page 5 HydroCAD®7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 3/15/2007 Pond 1 P: 500 Gallon Drywell w/ 18" Stone Surrounding Field Percolation Rate of Soil = 7 MPI A factor of safety of 3x was used for the design rate Therefore, design rate of 21 MPI used for exfiltration rate. Inflow Area= 458 sf, Inflow Depth = 5.69" for 100 yr event Inflow = 0.06 cfs @ 12.10 hrs, Volume= 217 cf Outflow = 0.01 cfs @ 11.25 hrs, Volume= 216 cf, Atten= 92%, Lag= 0.0 min Discarded = 0.01 cfs @ 11.25 hrs, Volume= 216 cf Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 126.93' @ 13.05 hrs Surf.Area= 81 sf Storage= 84 cf Plug-Flow detention time= 121.1 min calculated for 216 cf(99% of inflow) Center-of-Mass det. time= 118.4 min ( 853.7-735.3) # Invert Avail.Storage Storage Description 1 124.80' 103 cf 9.00'W x 9.00'L x 4.00'H Prismatoid 324 cf Overall -67 cf Embedded = 257 cf x 40.0% Voids 2 125.80' 67 cf 5.33'D x 3.00'H Vertical Cone/Cylinder Inside#1 170 cf Total Available Storage # Routing Invert Outlet Devices 1 Discarded 0.00' 0.003968 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.01 cfs @ 11.25 hrs HW=124.84' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0.01 cfs) 870 Great Pond Road, North Andover Type 111 24-hr 100 yr Rainfall=6.40" Prepared by Jack Sullivan, P.E. Page 6 HydroCAD®7.00 s/n 001433 01986-2003 Applied Microcomputer Systems 3/15/2007 Pond 1P: 500 Gallon Drywell w/ 18" Stone Surrounding Hydrograph 0.07 In K.w o.os crs E Discarded 0.065 Inflow Area-458 sf 0.06 0.055 Peak Elev=126.93' 0.05-: Storage=84 cf 0.045 0.04 3 0.035 0 u 0.03 0.025 0.02 0.015 0.01 o.o�ds 0.005 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours)