Loading...
HomeMy WebLinkAboutStormwater Report - 566 MAIN STREET 10/2/2013 Stormwater Management Plan Now School Department Building 566 Main Street North Andover, MA Prepared for: Kang Associates 339 Boston Poet Road Sudbury, MA 01776 Prepared by: DeVellis Zrein Inc. P. O. Box 307 Foxboro, MA 02035 J%k OF a IMAD A ZREIN CIVIL y No. 7231 .0 p S7 �' October 2, 2013 SlplJAL R Starmwater Management Plan 566 Main Street,North Andover Table of Contents 1. Project/Site Information 2, Existing Drainage Conditions 3. Proposed Stonnwater Management List of Figures EX Existing Watershed Map PR Proposed Watershed Map Appendices A Drainage Calculations i Stormwater Management Plan 566 Main Street,North Andover 1 . ro�w6ite Information The project site is located at 566 Main Street(intersection of Main and Osgood Streets, in North Andover,Massachusetts. It is the former North Andover police station. It is bounded by Osgood Street to the east,Main Street to wrest,the intersection of Osgood and Main to the south and a residential development and a single family home to the north. The existing site is approximately 68,190 square feet(SF)and it consists of the former police station building with associated parking and curb cuts on Main Street and Osgood Street. The project's proponent is proposing to demolish the existing building and parking and construct a small office building for the North Andover School Department with associated parking, landscaping and utility services. A single driveway is proposed off of Main Street to access a proposed 34 parking spaces. The proposed development will present a decrease in impervious surfaces compared to the existing conditions,which in turn,will reduce the stormwater runoff off the site. As an added measure to attenuate the stormwater runoff and promote on-site infiltration,low impact design in included in the stormwater design. Stormwater Management Plan 566 Main Sired,North Andover 2. Existing Drainage Conditions The existing site is approximately 68,190 Sl?and it is currently occupied by the former police station and two parking lots. One parking area is to the north of the building and the other is to the south. The existing site has no drainage improvements and the stormwater runoff from the site sheet flow onto Osgood Street before it enters the street drainage system. The total impervious cover is approximately 26,436 SF with the balance being a lawn space. See Figure EX for Existing Watershed Map. 3. Proposed Stmnwater Management The proposed re-development of the site consists of the demolition of the existing building and parking and the construction of an approximately 7,380 SF office building with associated access drive,parking,walkways,utility connections and landscaping areas. See Figure PR for Proposed Watershed Map. The proposed stormwater management system is designed to improve the characteristics of the site drainage discharges over existing conditions by reducing the impervious surfaces,promoting on-site recharge and implementing a low impact drainage design. . The stonnwater runoff from the building roof will be collected by a building perimeter drip strip. The drip strip will allow the runoff to first infiltrate into the ground and any overflow will be directed to a grassed swale. The runoff from the parking area will also be directed to the grassed swale,via a break in the curb. The grassed swale is designed with a relatively flat slope and check dams to further promote infiltration and stormwater attenuation. The grassed Swale will terminate at a flared end section that is located in a ponded area for additional stormwater storage. Discharges from the flared end section will connect into an existing drain manhole in Osgood Street. See the site plans for layout and details. The following table compares the proposed and existing drainage areas, including the pertinent information: Tabte 3.1 -Proposed/Existing Conditions orainage Area Characteristics summary Drainage Area AREA CN Value T.(min.) (SF) Existing Site 68,190 87 6.0 Proposed Site 68,190 80 6.0 ■s s ■ WATERSHED LIMIT WATERSHED AREA DISCHARGE POINT <.. DP 14 twX�i O600m 8TTIaET DP—1 a' 3a' so' Asa' Po box M Job Fm�MA EX Drawn by. Checked By: bate: 10.02.13 eVslfis Zrein Inc. r 566 Main Street Scale: 1"=60' Tide: Existing Watershed Map North Andover,MA r r a WATERSHED LIMIT WATERSHED AREA DISCHARGE POINT DP 1~, f; ~4� 41�` 000 .�►a rwrr~rn�rw�.+r a a——————— a a M� oeucx err DA-1 0' W. 60' 120' Job#: ` - 5'roB"U7 suunNa lFo, .HA PR Drawn by: Checked 8y: 'Sae�;ssa3 Date: 1e.02.13 eVeIIRs Zrein Inc. 566 Main Street Scale: S'�-W Title: Proposed Watershed Map North Andover,MA Stormwater Management Plan 566 Maim Street,North Andover The peals flow rates and volumes were calculated for the existing 2-, 10-,and 100-year storm events under proposed conditions,to compare with the existing rates of runoff. It is assumed that the building and all paved areas including sidewalks and parking areas will have impervious cover. The following table(Table 3.2)represents a comparison between existing and proposed conditions of the peak rates of runoff tributary to the discharge point. Table 32-Peak Rates of Runoff Discharge 2-Year Storm 10-Year Storm 100-YearStorm Point Exist. Prop, Exist. Prop. Exist. Prop. (Cfs) (cfs) (cfs) (PA) (cfs) (cfs) DP-1 2.79 2.33 4.89 3.76 8.35 5.67 Stormwater Management Alan 566 Main Street,North Andover Appmdbx A Drainage Calculations i Existing Conditions i Proposed Conditions Stormwater Management Flan 366 Main Street,North Andover Existing Conditions (E)X 1 Site $ubcat Reach on LlI11C Drainage Diagram for Existing Conditions Prepared by DeVellis Zrein Inc. 1013/2093 HydroCAD®7.90 $M 002318 0 2005 HydroCAD Software Solutions LLC 566 Main Street, North Andover Existing Conditions Type 11124-hr2-year RainfaN=�3.40" Prepared by DeVellis Zrein Inc. Page 2 H droCADO 7.10 sln 002318 ©2005 H droCAD Software Solutions LLC 10/3/2013 Time span=0.00-30.00 hrs, dt=0.05 hrs, 601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment EX-1: Site Runoff Area=88,190 sf Runoff Depth=1.56" Tc=6.0 min CN=80 Runoff--2.79 ofs 0.203 of Total Runoff Area = 1.565 ac Runoff Volume=0.203 of Average Runoff Depth = 1.56" 3 s 566 Main Street, North Andover Existing Conditions Type ///24-hr 2-year Rainfall=3.40° Prepared by DeVellis Zrein Inc. Page 3 H droCAD®7.10 sin 002318 0 2005 H droCAD Software Solutions LLC 10/3/2013 Subcatchment EX-1: Site Runoff = 2.79 cfs @ 12.10 hrs, Volume= 0.203 af, Depth= 1.56" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-30.00 hrs,dt= 0.05 hrs Type III 24-hr 2-year Rainfall=3.40" Area(sf) CN Description 26,436 98 Paved parking& roofs 41,754 69 50-75%Grass cover, Fair, HSG B 68,190 80 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment EX-1: Site Hydragraph 3- 2 Type III 24-hr 2-year Rainfall=3.40" 2 Runoff Area=68,190 sf Runoff Volume=0.203 of Runoff Depth=1.56" O U. Tc=6.0 min CN=80 0 0 1 2 3 4 5 6 7 8 8 1D 1 12 13 14 1'5­1'6 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) 566 Main Street, North Andover Existing Conditions Type ///24-hr?0-year Rainfall=4.80" Prepared by DeVellis Zrein Inc. Page 4 ydroCADS 7.10 sln 002318 ®2005 H droCAD Software Solutions LLC /0/312013 Time span=0.00-30.00 hrs, dt=0.05 hr's, 601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment EX-1: Site Runoff Area=88,190 sf Runoff Depth=2.72" Tc=6.0 min CN=80 Runoff--4.89 cfs 0.355 of Total Runoff Area = 1.565 ac Runoff Volume=0.355 of Average Runoff Depth =2.72" 566 Main Street, North Andover Existing Conditions Type /if 24-hr 10 year Rainfall=4.80" Prepared by DeVellis Zrein Inc. Page 5 H droCADS 7.10 s/n 002398 0 2005 H droCAD Software Solutions LLC 10/312013 Subcatchment EX-1: Site Runoff = 4.89 cfs @ 12.09 hrs, Volume= 0.355 af, Depth= 2.72" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-30.00 hrs, dt=0.05 hrs Type III 24-hr 10-year Rainfall=4.80" Area (sf) CN Description 26,436 98 Paved parking&roofs 41,754 69 50-75%Grass cover, Fair HSG 13 68,190 80 Weighted Average Tc Length Slope Velocity Capacity Description min feet (ft/ft) ftlsec cfs 6.0 Direct Entry, Subcatchment EX-1: Site Hydrograph 5 4.W oft I —Runoff Type III 24-hr 10-year 4 Rainfall=4.80" Runoff Alrea=68,190 sf Runoff Volume=0.355 of g Runoff Depth=2,72" " Tc=6.0 min CN=80 1 0 b 1 2 3 4 5 6 7 8 A 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) 666 Main Street, North Andover Existing Conditions Type/H 24-hr 900 year Rainfall=7.00" Prepared by DeVellis Zrein Inc. Page 6 M droCADO 7.10 sln 002318 0 2005 H droCAD Software Solutions LLC 10/3/2013 Time span=0.00-30.00 hrs, dt=0.05 hrs, 601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchrnent EX-1: Site Runoff Area=68,190 sf Runoff Depth=4.69" Tc=6.0 min CN=80 Runoff=8,35 cfs 0.612 of Total Runoff Area=1.565 ac Runoff Volume=0.612 of Average Runoff Depth -4.69" 566 Main Street, North Andover Existing Conditions Type ///24-hr 100-year Rainfall-7.00° Prepared by DeVellis Zrein Inc. Page 7 H droCAD®7.10 s/n 002318 ®2005 H droCAD Software Solutions LLC 1013!2013 Subcatchment EX-1: Site Runoff = 8.35 cfs @ 12.09 hrs, Volume= 0.612 af, Depth= 4.69" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs,dt=0.05 hrs Type lit 24-hr 100-year Rainfall=7.00" Area (sfl CN Description 26,436 98 Paved parking&roofs 41,754 69 50-75% Grass cover, Fair HSG B 68,190 80 Weighted Average Tc Length Slope Velocity Capacity Description Amin)- (feet) (ft/ft) (Ft/sec) (cfs) 6.0 Direct Entry, Subcatchment EX-1: Site Hydrograph g 8.35 cis —Ftunofi Type III 24-hr 100-year 7 Rainfall=7.00" 6 Runoff Area=68,190 sf Runoff Volume=0.612 of Runoff Depth-4.69" .2 4 TC=6.0 min 3 CN=80 P" r.-"j.I 2 a 0 1 2 3 A 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) Stormwater Management Plan Stib Main Street,North Andover Propo.Sed Conditions �PRM �PR1 B Detain d Un-Det ined Detention :DP-]1 DP-1 Drainage Diagram tar Proposed Conditions Subcat Reach on 1' l Lnk Prepared by DeVellis zrein Inc. 1013/2013 HydroCAUS 7.10 stn 002318 0 2005 HydroCAD Software Solutions LLC 566 Main Street, North Andover Proposed Conditions Type ///24-hr 2-year Rainfa11=3.40" Prepared by DeVellis Zrein Inc. Page 2 HydroCADO 7.10 sin 002318 ®2005 HydroCAD Software Solutions LLC 1013/8013 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment PR1A: Detained Runoff Area=43,579 sf Runoff Depth=1.77" Tc=6.0 min CN=83 Runoff=2.04 cfs 0.148 of Subcatchment PR1B: Un-Detained Runoff Area=24,611 sf Runoff Depth�0.89" Tc=6.0 min CN=69 Runoff-0.53 oft 0.042 of Reach DP-1: DP-1 Inflow=2.33 eft 0.190 of Outflow=2.33 cfs 0.190 of Pond 1 P: Detention Peak Elev=73.87' Storage=304 of Inflow-2.04 cfs 0.148 of 12.0"x 24.0'Culvert Outflow=1.82 cfs 0.148 of Total Runoff Area =1.565 ac Runoff Volume=0.190 of Average Runoff Depth = 1.46►" 566 Main Street, North Andover Proposed Conditions Type 11124-hr2-year Rainfall=3.40" Prepared by DeVellis Zreln Inc. page 3 HydroCAD®7.10 s/n 002318 0 2005 HydroCAD Software Solutions LLC 901312013 Subcatchment PRIA: Detained Runoff - 2.04 cfs @ 12.09 hrs, Volume= 0.148 af, Depth= 1.77' Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type III 24-hr 2-year Rainfall=3,40" Area (sf) CN Description 21,071 98 Paved parking&roofs 22,508 69 50-75%Grass cover, Fair HSG B 43,579 83 Weighted Average Tc Length Slope Velocity Capacity Description min (feet) ftlf# ft/sec CfS 6.0 Direct;Entry, Subcatchment PR1A: Detained Hydrograph 2.04 cfs —RunoN x- Type III 24-hr 2-year Rainfall=3.40" Runoff Area=43,579 sf Runoff Volume=0.148 of Runoff Depth=1.77" LL Tc=6.0 min CN=83 0 1 2 3 4 5 B 7 B 8 10 11 12 1314151617181920 21 22 2324 25 26 27 26 28 30 3i 32 33 34 35 36 Time (hours) 566 Main Street, North Andover Proposed Conditions Type 11124-hr2-year Rainfal1=3.40" Prepared by DeVellis Zrein Inc. Page 4 HydroCADO 7.10 s/n 002318 0 2005 HydroCAD Software Solutions LLC 10%3/2013 Subcatchment PR1 B: Un-Detained Runoff = 0.53 cfs @ 12.10 hrs, Volume= 0.042 af, Depth= 0.89" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs,dt= 0.05 hrs Type III 24-hr 2-year Rainfall=3.40" Areas CN Descri Lion 24,611 69 50-75%Grass cover, Fair, MSG B Tc Length Slope Velocity Capacity Description min feet ft/ft) (ftsec) (cfs 6.0 Direct Entry, Subcatchment PR1 B: Un-Detained Hydrograph 0.55 0153 crs -•Runoff 0.5 Type III 24-hr 2-year 0.45 Rainfall=3,40" 0.4 Runoff Area=24,611 sf 0.35_ Runoff Volume=0.042 of 0.3 Runoff'Depth=0.89" 0.25- Tc=6.0 min 0.2 CN=69 0.15 0.1 0.05 0 0 1 731"M4' 5 B 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 265 27 28 29 30 31 32 33 34 35 36 Time (hours) a P X 566 Main Street, North Andover Proposed Conditions Type 11124-hr2-year Rainfall=3.40" Prepared by DeVellis Zrein Inc. Page 5 H drOCADO 7.10 s/n 002318 ®2005 H droCAD Software Solutions LLC 10/3/2013 Reach DP-i: DP-1 Inflow Area= 1.565 ac, Inflow Depth = 1.46" for 2-year event Inflow - 2.33 cfs @ 12.12 hrs, Volume= 0.190 of Outflow = 2.33 cfs @ 12.12 hrs, Volume= 0.190 af, Atten= 0%, Lag=0.0 min Routing by Star-Ind+Trans method, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Reach DP-1: DP-1 Hydrograph 2-33 afs -Inflow OuHlow Inflow Area=1 .565 ac 2- N O LL 1 0 0'.1.....1.1....J1. ......I.. .... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 26 28 30 3132 33 34 35 36 'rime (hours) 566 Main Street, North Andover Proposed Conditions Type if/24-hr2 year Ralnfall=3.40" Prepared by DeVellis Zrein Inc. Page 6 W droCADO 7.10 s/n 002318 ®2005 W droCAD Software Solutions LLC 101312013 Pond 1 P: Detention Inflow Area= 1.000 ac, Inflow Depth = 1.77" for 2-year event Inflow - 2.04 cfs @ 12.09 hrs, Volume= 0.148 of Outflow = 1.82 cfs @ 12.14 hrs, Volume= 0.148 af, Allen= 11%, Lag=2.5 min Primary = 1.82 cfs @ 12.14 hrs, Volume= 0.148 of Routing by Stor-Ind method,Time Span=0.00-36.00 hrs, dt= 0.05 hrs Peak Elev=73.87'@ 12.14 hrs Surf.Area= 551 sf Storage= 304 cf Plug-Flow detention time= 4.5 min calculated for 0.148 of(100% of inflow) Center-of-Mass det. time= 4.5 min (834.6-830.1 ) Volume Invert Avail.Storage Storage Description _ #1 73.00' 2,614 cf Custom Stage Data(Prismatic)Listed below(Recalc) Elevation Surf,Area Inc.Store Cum.Stare feet s -ft cubicfeet (cubic-feet) 73.00 145 0 0 74.00 611 378 378 75.00 1,825 1,218 1,596 75.50 2,245 1,018 2,614 Device Routing Invert Outlet Devices #1 Primary 73.00' 12.0" x 24.0' long Culvert CPP, projecting, no headwall, Ke=0.900 Outlet Invert= 72.00' S=0.0417'/' Cc=0.900 n=0.013 Primary OutFlow Max=1.79 cis @ 12.14 hrs HW=73.88' (t=ree Discharge) L1=Culvert (Inlet Controls 1.79 efs @ 2.5 fps) 566 Main Street, North Andover Proposed Conditions Type 11124-hr2-year Rainfal1=140" Prepared by DeVellis Zrein Inc. Page 7 HydroCAD®7.10 s/n 002318 0 2005_HydroCAD Software Solutions LLC 10/3/2013 Pond 1 P: Detention Nydrograph 2.04 cfs Inflow —Primary 2 �� Inflow Area=1.008 ac Peak Elev=73.87' Storage=304 cf '12.0" x 24.0' Culvert 3 LL 1 01-1 0 1 2 3 4 5 8 7 8 9 1011 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 38 Time (hours) 566 Main Street, North Andover Proposed Conditions Type 11124-hr 10-year Rainfall=4.80" Prepared by DeVellis Zrein Inc. Page 8 H droCADO 7.10 sfn 002318 ®2005 H droCAD Software Soluflons LLC 10/312013 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor Ind method Subcatchment PR1 A: Detained Runoff Aream43,579 sf Runoff Depth=2,99" Tc=6.0 min CN=83 Runoff-3.43 cfs 0.250 of Subcatchment PR1B: Un-Detained RunoffAtea=24,611 sf RunoffDepth=1,81" Tc=6.0 min CN=69 Runoff-1.15 cfs 0.085 of Reach DP-1: DP-1 Inflow=376 cfs 0.335 of Outflow=3.76 cfs 0.335 of Pond 113: Detention Peak Elev=74.32' Storage=636 cf Inflow=3.43 cfs 0.250 of 12.0"x 24.0'Culvert Outflow=2.70 cfs 0.250 of Total Runoff Area= 1.565 ac Runoff Volume =0.335 of Average Runoff Depth = 2.57" 566 Main Street, North Andover Proposed Conditions Type 111 24-hr 10-year Rainfall=4.80" Prepared by DeVellis Zrein Inc. Page 9 H droCADO 7.10 s/n 002318 ®2005 H droCAD Software Solutions LLC 10/3,12013 Subcatchment PR1A: Detained Runoff = 3,43 cfs @ 12.09 hrs, Volume= 0.250 af, Depth= 2.99" Runoff by SCS TR-20 method, UH=SCS,Time Span= 0.00-36.00 hrs, dt=0.05 hrs Type 111 24-hr 10-year Rainfall=4,80" Areas CN Description 21,071 98 Paved parking&roofs 22,508 69 50-75%Grass cover, Fair HSG B 43,579 83 Weighted Average Te Length Slope Velocity Capacity Description min feet ftlft ft/seo cfs 6.0 Direct Entry, Subcatchment PR1A: Detained Hyd rogra ph 3.43 cfs —Runoff Type III 24-hr 10 year 3 Rainfall=4.80" Runoff Area=43,579 sf Runoff Volume-0.250 of Runoff Depth=2.99" Tc=6.0 min CN=83 01 w 0 1 2 3 4 5 9 7 8 9 10 11 12 73 14 15 18 17 19 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Time (hours) 566 Main Street, North Andover Proposed Conditions Type!1124-hr 10 year Rainfall=4.80" Prepared by DeVellis Zrein Inc. Page 10 H droCADO 7.10 sln 002318 0 2005 H droCAD Software Solutions LLC 10!312013 Subcatchment PR1 B: Un-Detained Runoff = 1.15 cfs @ 12.10 hrs, Volume= 0.085 af, Depth= 1.81" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type III 24-hr 10-year Rainfall=4.80" Area (so CN Description 24,611 69 50-75%Grass cover, Fair, HSG B Tc Length Slope Velocity Capacity Description min feet ft/ft (ft/sec) cfs 6.0 Direct Entry, Subcatchment PR1 B: Un-Detained Hydrograph 1.15 cfs —Rwnof{ Type III 24-hr 10-year Rainfall=4.80" Runoff Area=24,611 sf w Runoff Volume=0.085 of a Runoff Depth=1.81" Tc=6.0 min CN=69 .............. ......... 0 1 2 3 4 5 6 7 8 9 1011 12131415161718192021222324252627282930313233343536 Time thours) n 566 Main Street, North Andover Proposed Conditions Type 11I 24-hr 10-year Rainfall=4.80" Prepared by DeVellis Zrein Inc. Page 11 HydroCADO 7.10 sln 002318 0 2005 HydroCAD Software Solutions LLC - 110/3/2013 Reach DP-1: DP-1 Inflow Area= 1.565 ac, Inflow Depth = 2.57' for 10-year event Inflow - 3.76 ofs Q 12.12 hrs, Volume= 0.335 of Outflow = 3.76 cfs Q 12.12 hrs, Volume= 0.335 af, Atten= 0%, Lag= 0.0 min Routing by Sior-Ind+Trans method, Time Span=0.00-36.00 hrs, dt= 0.05 hrs Reach DP-1. DP-1 Hydrograph 4 3.76 cfs I I_In%w Outflow Inflow Area=1 .565 ac 3-- m 2 LL i• 0 0 1 2 3 4 5 6 7 8 9 101112131415161718192021222 3 24 25 26 27 28 29 30 3132 33 34 35 3a Time (hours) 566 Main Street, North Andover Proposed Conditions Type!1124-hr 70 year Rafnfa11-4.80" Prepared by DeVellis Zrein Inc. Page 12 H droCADO 7.10 sln 002318 ®2005 H droCAD Software Solutions LLC 1013/2013 Pond 9 P: Detention Inflow Area= 1.000 ac, Inflow Depth = 2.99" for 10-year event Inflow - 3.43 cfs @ 12.09 hrs, Volume= 0.250 of Outflow = 2.70 cfs @ 12.16 hrs, Volume= 0.250 af, Atten= 21%, Lag=4.0 min Primary 2.70 cfs @ 12.16 hrs, Volume= 0.250 of Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Peak Elev= 74.32' @ 12.16 hrs Surl.Area= 1,000 sf Storage=636 cf Plug-Flow detention time= 4.6 min calculated for 0.250 of(100%of inflow) Center-of-Mass det. time= 4.1 min (819.2-815.1 ) Volume Invert Avail.Stora a Storage Description #1 73.00` 2,614 of Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 73.00 145 0 0 74.00 611 378 378 75.00 1,825 1,218 1,596 75.50 2,245 1,018 2,614 Device Routing _ Invert Outlet Devices #1 Primary 73.00' 12.0" x 24.0'long Culvert CPP, projecting, no headwall, Ke=0.900 Outlet Invert= 72.00' S=0.0417T Cc-- 0.900 n= 0.013 Primary OutFlow Max=2.69 cfs @ 12.16 hrs HW=74.31' (Free Discharge) L1=Culvert (inlet Controls 2.69 cfs @ 3.4 fps) 556 Main Street, North Andover Proposed Conditions Type ff!24-hr 10 year Rafnfaff=4.8Q" Prepared by DeVellis Zrein Inc. Page 13 HydroCADO 7.10 sin 002318 C 2005 HydroCAD Software Solutions LLC. _ 10/3/2013 Pond 1 P: Detention Hydrograph 3.43 cfs Inflow Prfnwry Inflow-Area=1 .000 arc 3 2.7°� Peak Elev=74.32' Storage=636 cf 2- 12.0" x 24.0' Culvert 1 0 0 1 2 3 4 5 6 7 8 9 1011 li 1314151617181920 21 22232425262728293031323334353E Time 1houra) F 566 Main Street, North Andover Proposed Conditions Type 11124-hr 900 year Rainfall=7.00" Prepared by DeVellis Zrein Inc. Page 14 H droCADO 7.10 s/n 002318 ®2005 H droCAD Software Solutions LLC 110/3/2013 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind*Trans method - Pond routing by Stor-Ind method Subcatchment PR1A: Detained Runoff Area=43,579 sf Runoff Depth=5.03" Tc=6.0 min CN=83 Runoff-5.66 cfs 0.419 of Subcatchment PR1B: Un-Detained Runoff Area=24,611 sf Runoff Depth=3.51" Tc=6.0 min CN=69 Runoff--2.28 cfs 0.165 of Reach DP-1: DP-1 Inflow--5.67 cfs 0.585 of Outflow=5.67 cfs 0.585 of Pond 1P: Detention Peak Elev=74.97' Storage=1,547 cf Inflow=5.66 cfs 0.419 of 12.0"x 24.0'Culvert Outflow=3.62 cfs 0.419 of Total Runoff Area= 1.565 ac Runoff Volume=0.585 at Average Runoff Depth =4.48" V 566 Main Street, North Andover Proposed Conditions Type 11124-hr 140 year Rainfall=7.40" Prepared by DeVellis Zrein Inc. Page 15 HydroCAD®7.10 s/n 002318 ®2005 HydroCAD Software Solutions LLC 10/3/2013 Subcatchment PRIA: Detained Runoff = 5.66 ofs @ 12.09 hrs, Volume= 0.419 af, Depth= 5.03" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt=0.05 hrs Type III 24-hr 100-year Rainfall=7.00° Area (sf) CN Description 21,071 98 Paved parking& roofs ........,..._ 22,608 69 50-75% Grass cover, Fair HSG B 43,579 83 Weighted Average Te Length Slope Velocity Capacity Description min feet ft/ft fl/sec cfs 6.0 Direct Entry, Subcatchment PR1A: Detained Hydrograph G S.6S cfs —Runoll Type III 24-hr 100-year Rainfall=7.00" 4 Runoff Area=43,579 sf Runoff Volume=0,419 of 0 3 Runoff Depth=5.03" Tc=6,0 min 2 GN=83 1 0 0 1 2 3 4 5 6 7 6 9 10 11 12 13 14 15 1 B 17 18 19 20 21 22 23 24 25 26 27 23 20 30 31 32 33 34 35 36 Time (hours) I 556 Main Street, North Andover Proposed Conditions Type 11124-hr 10Q year Rainfall=7.00" Prepared by DeVellis Zrein Inc. Page 16 H droCADO 7.10 sin 002318 ©2005 H droCAD Software Solufions I-LC 10/3/2013 Subcatchment PR1B: Un-Detained Runoff = 2.28 cfs @ 12.09 hrs, Volume= 0.165 a€, Depth= 3.51" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt=0.05 hrs Type III 24-hr 100-year Rainfall=7.00" Area (sf) CN Description 24,611 69 50-75%Grass cover, Fair, HSG B Tc Length Slope Velocity Capacity Description min? (feet) (ft/fl) (ftisec) (cfs) 6.0 Direct Entry, —..... . .................._ ._...._..____ Subcatchment PRIG; Un-Detained Hydrograph 228 cfs —r2unofC 2 Type III 24-hr 100-year Rainfall=7.00" Runoff Area=24,611 sf Runoff Volume=0.165 of u. Runoff Depth=-3.51" Tc=6.0 min CN=69 0 1 2 3 4 5 B 7 8 8 10 11 12 13 14 i5 16 17 18 19 20 21 22 23 24 25 26 27 24 29 30 31 32 33 34 35 36 Time (hours) r 566 Main Street, North Andover Proposed Conditions Type 11124-hr 900 year Rainfalf=7.010" Prepared by DeVellis Zrein Inc. Page 17 HydroCADS 710 sln 002318 G 2005 HydroCAD_Software Solutions LLC 10/3/2013 Reach DP-1: DP-1 Inflow Area= 1.565 ac, Inflow Depth= 4.48" for 100-year event Inflow - 5.67 cfs @ 12.11 hrs, Volume= 0.585 of Outflow - 5.67 efs @ 12.11 hrs, Volume= 0.585 af, Atten= 0%, Lag= 0.0 min Routing by Star-Ind+Trans method, Time Span=0.00-36.00 hrs, dt=0.05 hrs Reacts DP-1: DP-1 Hydrograph 6 5.fi7.at ^F inflow �utlfow Inflow Area=1 .565 ac 4- 10 3: 3 0 LL 2- Q.. 0 1 2 3 4 5 6 7 .6 $ .10 11 12 13 1.E154B17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Time (hours) 566 Main Street, North Andover Proposed Conditions Type fff 24-hr 100 year Rainfall=7.00" Prepared by DeVellis Zrein Inc_ Page 18 H droCAD®7.10 s/n 002318 ®2005 H droCA❑Software Solutions LLC 1013/2013 Pond 1P: Detention Inflow Area = 1.000 ac, Inflow Depth= 5.03" for 100-year event Inflow - 5.66 cfs @ 12.09 hrs, Volume= 0.419 of Outflow = 3.62 cfs @ 12.19 hrs, Volume= 0.419 af, Atten= 36%, Lag=6.2 min Primary - 3.62 cfs @ 12.19 hrs, Volume= 0.419 of Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Peak Slev= 74.97'@ 12.19 hrs Surf.Area= 1,792 sf Storage= 1,547 of Plug-Flow detention time= 4.5 min calculated for 0.419 of(100%of inflow) Center-of-Mass det. time= 4.5 min (805.0-800.4) Volume Invert Avaii.Stora a Storage Description #1 73.00' 2,614 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 73.00 145 0 0 74.00 611 378 378 75.00 1,825 1,218 1,596 75.50 2,245 1,018 2,614 Device Routing Invert Outlet Devices #1 Primary 73.00' 12.0" x 24.0'long Culvert CPP, projecting, no headwall, Ke=0.900 Outlet Invert= 72.00' S=0,0417T Cc- 0.900 n=0.013 Primary Outflow Max--3.62 cfs @ 12.19 hrs HW=74.97' (Free Discharge) L1=Culvert (Inlet Controls 3.62 cfs @ 4.6 fps) 566 Main Street, North Andover Proposed Conditions Type 11124-hr 900 year Rainfall=7.00" Prepared by DeVellis Zrein Inc. Page 19 H droCAD®7,10 s/n 002318 ®2005 H droCAD Software Solutions LLC 10/3/2013 Pond 1 P. Detention Hydrograph B S. crs I--Inflow --Wrlmery Inflow Area=1.000 ac 5 Peak Elev=74.97' 4 3 Storage=1,547 cf 12.011 x 24.0' Culvert 3 W 1 4 0 1 2 3 4 5 6. 7 B 6 10 11 12 13 14 15 16 17 16 19 20 21 22 23 24 25 25 27 20 23 30 31 32 33 34 35 36 Time (hours)