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HomeMy WebLinkAboutStormwater Report - 498 CHICKERING ROAD 11/2/2007 PROPOSED RETAIL FA CILI T Y NORTHANDOVER, MASSACHUSETTS PROJECT DRAINAGE REPORT 2001 DATE: NOVEMBER 2 , 2007 P`-pNc1�NG PREPARED FOR: PARK STREET REDEVELOPMENT, LLC 231 Sutton Street—Suite 1 B North Andover, MA 01845 OF Aja6 VLADIMIR L. � m NEMCHENOK o No.39 Q ¢SS/ONAL F��. Merrimack Engineering Services, Inc. Email: merreng @aol.com 66 Park Street Phone: (978)-475-3555 Andover,MA 0 18 10 Fax: (978)-475-7448. PROPOSED RETAIL FA CILITY NORTHANDOVER, MASSACHUSETTS < TABLE OF CONTENTS > SECTION 1.0 INTRODUCTION SECTION 2.0 LOCUS MAPS SECTION 3.0 SUMMARY SECTION 4.0 STORM DRAINAGE CALCULATIONS Description of Drainage System 4.1 Pre vs. Post-Development Analysis 4.2.1 Pre-Development —2, 10 & 100-Year Storm Event 4.2.2 Post-Development—2, 10 & 100-Year Storm Event SECTION 5.0 APPENDIX 5.1 Rainfall Data Maps 5.2 National Resources Conservation Service (MRCS)— Soil Description with Classification Merrimack Engineering Services, Inc. 66 Park Street Phone: (978)475-3555 Andover,MA 01810 Fax: (978)475-7448 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 1.0 > INTRODUCTION The project consists of a proposed retail facility(total foot print-5,042 S.F.)with appurtenant parking lot and grading,on a 0.72 acre parcel located at 498 Chickering Road(Rte 125),North Andover,MA.The subject parcel is mostly paved with some grass and shrubs areas along the south(Park Street),west and north(Franklin Street)sides of the site.The site is a former gas station and contains a building and canopy to be removed.A new building(retail facility)will be built approximately at the center of the lot,to the east of the existing building.There are no wetlands on the site or within 100' of the site. Topographic elevations at the site range from a high of 138±at the southwest corner of the at Park Street to a low of 123±at northeast corner of the parcel toward Franklin Street,a difference of 15±feet. The parcel is above the 100-year flood elevation of 95.0(Zone AE)as depicted on Flood Insurance Rate Map, Community Panel 250098 0003C, dated June 02, 1993. Soils within the vicinity of the project have been mapped by USDA-NRCS(formerly SCS) and consist of Udorthents smoothed soils(68.5%)and Woodbridge fine sandy loam,which is classified within the SCS Hydrological Soils Group C. For a more detailed description of the soils at this site see Section 5.2 of this report. These calculations will determine Pre-Development and Post-Development runoff rates using the SCS-TR20 Runoff Method,as implemented by the HydroCad computer model.The calculations will be performed for the 2, 10 and 100-year storm event. Merrimack Engineering Services, Inc. Section 1 —Page 1 Printed: November 1,2007 PROPOSED RE TAIL FA CILI T Y NORTHANDOVER, MASSACHUSETTS < SECTION 2.0 > LOCUS MAPS Merrimack Engineering Services, Inc. Section 2—Page 1 Printed: November 1,2007 � I i 1 1 --I y„ ri 5� MA5 .tcy C WWk t � t rvieln Strevt 7 d AR, - Rf X i m f �ci- - Irnaye MaesGl�,Carntnomaoalth"of FAa�cachuseUS EUErk 4,,2007�T I,�A66 i �`� X2007 Eurrpo Ynchnolaylev ea s F'olntat 42.41`,39. 3 N s71 07'11.70' N av,127?ft 10-WOPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 2.0 > USGS Map f 6i i1:/ �fiA RENO ! t �� ,��1 .lit " ..3 fip '� ' � �(!r{ ' �r/ -\ � t�\ r• r 1 �'�.o • 8 � III' � � ! t c" �, r�-'n"`' 'Doup� 6Fk 1P� '�♦ `•,c, I< f� k�{r� f�ia%�@ t(t` �� ku To • T` ," s 1 � _ ';l� ��v \ f iii Site Merrimack Engineering Services,Inc. Section 2—Page 3 Printed: November 1,2007 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 2.0 > Site Soils Map (,lain5 s ESSf_X COUNTY MASSACHUSETTS N hrxri 2:1) tFl/u �1tfC` P�43 tP4 x' I�E 77=777 ,t OlFr --. -...M... _ _1110 P11D Par) Far - O3nooF9 rr 1'0r"l �1 V1r Ci -C:mk3 ` p�(i Rdh- V > 'R16— a i 1d `Fr" Wi�fi WFt'} �: r iLQ(4f •, — - (03 '(,r; WI ..� f r� � <� SITE h1C1CITH wt SAE r f L F t aC n 51rut�s 4V.,Q_ Nrfi tlil<'ii' �Fltitl7 ^.±'" .. N4A i {t k°2C� Sii6 wh 5�.1'...i � �� :fie K � U C '�•; CUC M(; `Wt' Fsa . tJrA ,c e, Y f21E3 WrC} 48 I aC; <i 11C) }"tsiA F'FF[F r _ `.. - ✓ (:ufi :�'" UD —Udorthents, smoothed. WrB—Woodbridge fine sandy loam, 0 to 8 percent slopes. Merrimack Engineering Services, Inc. Section 2—Page 4 Printed: November 1,2007 R OPOSED RE TAIL FA CILI T Y NORTHANDOVER, MASSACHUSETTS < SECTION 3.0 > Summary As indicated in the Introduction,the objective of the project design is to mitigate any increase in storm drainage flow rate as the result of the site modifications. The procedure utilized as follows: 1) The area to be modified is currently paved and was used for gas station in the past. It was determined 31,425 square feet and will be modified with the demolition of the old building,construction with the new retail facility,and re- paving of the site. The runoff rate was calculated during the 2, 10,and 100-year storm and the runoff hydrograph was developed. 2) The runoff from the proposed roof will be directed to the proposed underground detention facility with connection via 12"HDPE pipe to the existing stormwater drainage system. 3) This design will not allow any increase in the runoff rate as a result of the project. The proposed structure has been designed according to generally accepted engineering principles with an emergency outlet to allow flows in excess of 100 year storm. The following chart is a summary of pre and post-development peak flow rates for 2, 10 and 100-year storm events of the accumulative design point(Catch Basin R1), as shown on the accompanying drainage plans. Rainfall /Storm Event Structure/ Design Point 2—YR cfs 10—YR (cfs 100—YR cfs Pre Post Change Pre Post Change Pre Post Change RI 2.85 2.81 -0.04 4.54 4.42 -0.12 6.84 6.29 -0.55 Merrimack Engineering Services, Inc. Section 3—Page I Printed: November 1,2007 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 4.0 > Storm drainage calculations The proposed drainage system is a closed system.Decreases in peak flow will be obtained through the use of an underground detention facility. The closed system will discharge into an underground detention facility which is essentially a 7,500 gallon Commercial Line Tank,which will serve to detain, store,and transfer the runoff to the existing stormwater drainage system. Pre and Post-Development Drainage Area Maps accompany these calculations. Merrimack Engineering Services, Inc. Section 4—Page 1 Printed: November 1,2007 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 4.1 > Pre vs. Post Development Hydrologic Analysis & Design 2, 10 & 100—Year Storm Event Merrimack Engineering Services, Inc. Section 4—Page 2 Printed: November 1,2007 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 4.2.1 > PRE - DEVELOPMENT — 2, 10, & 100 — Year STORM EVENT Merrimack Engineering Services, Inc. Section 4—Page 3 Printed: November 1,2007 w E o �, N C0 a � Q E t0 U O N U C U _ Y Q. CL Q U U o° (\J _ M - (D 1 04 c � C am 0 N L E e 0)CU CO _C E ca fn cn ca 0 ` O U U = -0o U � UN M U M ono < a�i N M o U m m _ N (D N� i N r U) C r c C%4 o (h 0 Y �.. O C '= N .� � C J �— o N � U M � V � V � }' 0) v U c ._n .N U) X W W W m U 498 Chickering Road Pre Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 1 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment S1: (Subcatchment 1 -Existing Conditions) Runoff Area=33,573 sf Runoff Depth=2.44" Flow Length=377' Tc=9.7 min CN=94 Runoff=1.85 cfs 0.157 of Subcatchment S2: (Subcatchment 2 -Existing Conditions) Runoff Area=5,100 sf Runoff Depth=2.45" Flow Length=212' Tc=5.0 min CN=94 Runoff=0.32 cfs 0.024 of Subcatchment S3: (Subcatchment 3 -Existing Conditions) Runoff Area=19,641 sf Runoff Depth=1.53" Flow Length=400' Tc=7.8 min CN=83 Runoff--0.75 cfs 0.057 of Reach P2: (20'-12" RCP) Peak Depth=0.24' Max Vet=7.1 fps Inflow=1.02 cfs 0.081 of D=12.0" n=0.011 L=20.0' S=0.0370'/' Capacity=8.10 cfs Outflow=1.02 cfs 0.081 of Reach P3: (56'-12" CSP) Peak Depth=0.38' Max Vet=2.7 fps Inflow--0.75 cfs 0.057 of D=12.0" n=0.024 L=56.0' S=0.0155 '/' Capacity=2.41 cfs Outflow=0.73 cfs 0.057 of Reach R1: (Reach 1 -Catch Basin#1) Inflow--2.85 cfs 0.238 of Outflow=2.85 cfs 0.238 of Reach R2: (Reach 2-Catch Basin#2) Inflow=1.02 cfs 0.081 of Outflow=1.02 cfs 0.081 of Reach R3: (Reach 3 - Catch Basin #3) Inflow=0.75 cfs 0.057 of Outflow=0.75 cfs 0.057 of Total Runoff Area= 1.339 ac Runoff Volume= 0.238 of Average Runoff Depth = 2.13" 498 Chickering Road Pre Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 2 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S1: (Subcatchment 1 - Existing Conditions) Runoff = 1.85 cfs @ 12.13 hrs, Volume= 0.157 af, Depth= 2.44" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 7,016 79 50-75% Grass cover, Fair, HSG C 26,557 98 Paved parking & roofs 33,573 94 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.1 Sheet Flow, Subcatchment-1 Woods: Light underbrush n= 0.400 P2= 3.10" 0.2 50 0.0650 5.2 Shallow Concentrated Flow,Subcatchment- 1 Paved Kv= 20.3 fps 0.7 150 0.0337 3.7 Shallow Concentrated Flow, Subcatchment-1 Paved Kv= 20.3 fps 0.5 57 0.0700 1.9 Shallow Concentrated Flow,Subcatchment-1 Short Grass Pasture Kv= 7.0 fps 0.2 70 0.0681 5.3 Shallow Concentrated Flow, Subcatchment-1 Paved Kv= 20.3 fps 9.7 377 Total Subcatchment S1: (Subcatchment 1 - Existing Conditions) Hydrograph 2® 1 .85 Cfs E] Runoff Type III 24-hr 2-yr Rainfall=3.10" Runoff Area=33,573 sf Runoff Volume=0.157 of Runoff Depth=2.44" 1 Flow Length=377' —° Tc=9.7 min u. CN=94 i . 4 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 2-yr Rainfall=3.90" Prepared by Merrimack Engineering Services Page 3 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S2: (Subcatchment 2 - Existing Conditions) Runoff = 0.32 cfs @ 12.07 hrs, Volume= 0.024 af, Depth= 2.45" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 1,200 79 50-75% Grass cover, Fair, HSG C 3,900 98 Paved parking & roofs 5,100 94 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.5 50 0.0420 1.6 Sheet Flow, Subcatchment- 2 Smooth surfaces n= 0.011 P2= 3.10" 0.1 34 0.0588 4.9 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 0.5 60 0.0750 1.9 Shallow Concentrated Flow, Subcatchment-2 Short Grass Pasture Kv= 7.0 fps 0.2 68 0.0555 4.8 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 3.7 Direct Entry, (Adjust for min. Sminute Tc) 5.0 212 Total Subcatchment S2: (Subcatchment 2 - Existing Conditions) Hydrograph 0.35 0.32 cfs El Runoff Type 111 24-hr 2-yr 0.3 Rainfall=3.10" 0.25 Runoff Area=5,100 sf Runoff Volume=0.024 of 0 2 Runoff Depth=2.45" .. Flow Length=212' �° 0.15- Tc=5.0 min CN=94 0.1 ,x 0.05- 0� . . o , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 4 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Existing Conditions) Runoff = 0.75 cfs @ 12.12 hrs, Volume= 0.057 af, Depth= 1.53" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 15,405 79 50-75% Grass cover, Fair, HSG C 4,236 98 Paved parking & roofs 19,641 83 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.2 Sheet Flow, Subcatchment-3 Grass: Short n= 0.150 P2= 3.10" 0.9 72 0.0332 1.3 Shallow Concentrated Flow,Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.8 59 0.0305 1.2 Shallow Concentrated Flow,Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 1.0 81 0.0386 1.4 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 42 0.0564 1.7 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 96 0.0428 4.2 Shallow Concentrated Flow, Subcatchment-3 Paved Kv= 20.3 fps 7.8 400 Total 498 Chickering Road Pre Type 111 24-hr 2-yr Rainfall=3.90" Prepared by Merrimack Engineering Services Page 5 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Existing Conditions) Hydrograph 0.0- 10.75 cfs 0 Runoff Type III 24-hr 2-yr 0.7-. Rainfall=3.10" 0.6- Runoff Area=19,641 sf Runoff Volume=0.057 of 0.5 . Runoff Depth=1.53" 0.4- Flow Length=400' ° FL Tc=7.8 min 0.3 CN=83 0.2 0.1 _ e f o i e 6 ' . Z < s . N 0 2 '4' . 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type ///24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 6 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P2: (20'-12" RCP) Inflow Area = 0.568 ac, Inflow Depth = 1.71" for 2-yr event Inflow = 1.02 cfs @ 12.11 hrs, Volume= 0.081 of Outflow - 1.02 cfs @ 12.11 hrs, Volume= 0.081 af, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 7.1 fps, Min. Travel Time= 0.0 min Avg. Velocity= 2.3 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.24' @ 12.11 hrs Capacity at bank full= 8.10 cfs Inlet Invert= 115.97', Outlet Invert= 115.23' 12.0" Diameter Pipe n= 0.011 Length= 20.0' Slope= 0.0370 '/' Reach P2: (20'-12" RCP) Hydrograph Inflow Inflow Area=O. 1 .02 cfs 0 outflow 1_ Peak Depth=0.24' Max Vet=7.1 fps 4 ,_. D=12.0" N n=0.011 3 L=20.0' f o �- S=0.0370 T Capacity=8.10 cfs 0- , . . . E 6- -2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 7 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P3: (56'-12" CSP) Inflow Area = 0.451 ac, Inflow Depth = 1.53" for 2-yr event Inflow = 0.75 cfs @ 12.12 hrs, Volume= 0.057 of Outflow = 0.73 cfs @ 12.13 hrs, Volume= 0.057 af, Atten= 3%, Lag= 0.6 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.7 fps, Min. Travel Time= 0.3 min Avg. Velocity= 1.0 fps, Avg. Travel Time= 0.9 min Peak Depth= 0.38' @ 12.12 hrs Capacity at bank full= 2.41 cfs Inlet Invert= 116.89', Outlet Invert= 116.02' 12.0" Diameter Pipe n= 0.024 Length= 56.0' Slope= 0.01557' Reach P3: (56'-12" CSP) Hydrograph El Inflow 0.8 Inflow Area=O. 0.73 CfS 0 Outflow 0.7- Peak Depth=0.38' Max Vet=2.7 fps 0.6j .r D=12.0" 0.5 _ n=0.024 #' 3 0.4 L=56.0' 0.3 ' S=0.0155 '/" 0.2 Capacity=2.41 cfs ' 0.1 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 8 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 1111/2007 Reach R1: (Reach 1 - Catch Basin #1) Inflow Area = 1.339 ac, Inflow Depth = 2.13" for 2-yr event Inflow = 2.85 cfs @ 12.12 hrs, Volume= 0.238 of Outflow = 2.85 cfs @ 12.12 hrs, Volume= 0.238 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R1: (Reach 1 - Catch Basin #1) Hydrograph Inflow 3 2.85 CfS p Outflow Inflow Area=1 . _ z# N 2 V C LL 1 f 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 9 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R2: (Reach 2 - Catch Basin #2) Inflow Area = 0.568 ac, Inflow Depth = 1.71" for 2-yr event Inflow = 1.02 cfs @ 12.11 hrs, Volume= 0.081 of Outflow = 1.02 cfs @ 12.11 hrs, Volume= 0.081 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R2: (Reach 2 - Catch Basin #2) Hydrograph Inflow 1 Inflow Area=O. 1 .02 cfs 0 Outflow O 0 i , . . " , . . . s . . . . , . . . . , . , . 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type ///24-hr 2-yr Rainfall=3.10° Prepared by Merrimack Engineering Services Page 10 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R3: (Reach 3 - Catch Basin #3) Inflow Area = 0.451 ac, Inflow Depth = 1.53" for 2-yr event Inflow = 0.75 cfs @ 12.12 hrs, Volume= 0.057 of Outflow - 0.75 cfs @ 12.12 hrs, Volume= 0.057 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R3: (Reach 3 - Catch Basin #3) Hydrograph 0 Inflow 0 8_ 0.75 cfs 0 Outflow Inflow Area=d. 0.7- 0.6 0.5 . 3 0.4 0 0.3 0.2- 0.1 0 , . . . . . , , . . . . . ., 6 . . , , . , , . . r , , , . 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 11 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment S1: (Subcatchment 1 - Existing Conditions) Runoff Area=33,573 sf Runoff Depth=3.81" Flow Length=377' Tc=9.7 min CN=94 Runoff=2.81 cfs 0.245 of Subcatchment S2: (Subcatchment 2 - Existing Conditions) Runoff Area=5,100 sf Runoff Depth=3.81" Flow Length=212' Tc=5.0 min CN=94 Runoff=0.49 cfs 0.037 of Subcatchment S3: (Subcatchment 3-Existing Conditions) Runoff Area=19,641 sf Runoff Depth=2.72" Flow Length=400' Tc=7.8 min CN=83 Runoff=1.34 cfs 0.102 of Reach P2: (20'-12" RCP) Peak Depth=0.32' Max Vet=8.2 fps Inflow--1.76 cfs 0.139 of D=12.0" n=0.011 L=20.0' S=0.0370'/' Capacity=8.10 cfs Outflow=1.76 cfs 0.139 of Reach P3: (56'-12" CSP) Peak Depth=0.53' Max Vet=3.1 fps Inflow=1.34 cfs 0.102 of D=12.0" n=0.024 L=56.0' S=0.0155 '/' Capacity=2.41 cfs Outflow=1.31 cfs 0.102 of Reach R1: (Reach 1 -Catch Basin #1) Inflow=4.54 cfs 0.384 of Outflow=4.54 cfs 0.384 of Reach R2: (Reach 2-Catch Basin #2) Inflow=1.76 cfs 0.139 of Outflow=1.76 cfs 0.139 of Reach R3: (Reach 3 - Catch Basin#3) Inflow=1.34 cfs 0.102 of Outflow=1.34 cfs 0.102 of Total Runoff Area = 1.339 ac Runoff Volume= 0.384 of Average Runoff Depth = 3.44" 498 Chickering Road Pre Type 11/24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 12 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S1: (Subcatchment 1 - Existing Conditions) Runoff = 2.81 cfs @ 12.13 hrs, Volume= 0.245 af, Depth= 3.81" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 7,016 79 50-75% Grass cover, Fair, HSG C 26,557 98 Paved parking & roofs 33,573 94 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.1 Sheet Flow, Subcatchment- 1 Woods: Light underbrush n= 0.400 P2= 3.10" 0.2 50 0.0650 5.2 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.7 150 0.0337 3.7 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.5 57 0.0700 1.9 Shallow Concentrated Flow, Subcatchment-1 Short Grass Pasture Kv= 7.0 fps 0.2 70 0.0681 5.3 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 9.7 377 Total Subcatchment S1: (Subcatchment 1 - Existing Conditions) Hydrograph 3- 2.81 Cfs El Runoff Type Ili 24-hr 10-yr Rainfall=4.50" Runoff Area=33,573 sf .. 2 Runoff Volume=0.245 of Runoff Depth=3.81" 3 Flow Length=377' -° Tc=9.7 min u. - 1 CN=94 07 - ; . , , . , , , , , . . . . . , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 13 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S2: (Subcatchment 2 - Existing Conditions) Runoff = 0.49 cfs @ 12.07 hrs, Volume= 0.037 af, Depth= 3.81" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 1,200 79 50-75% Grass cover, Fair, HSG C 3,900 98 Paved parking & roofs 5,100 94 Weighted Average Tc Length Slope Velocity Capacity Description _ (min) (feet) (ft/ft) (ft/sec) (cfs) 0.5 50 0.0420 1.6 Sheet Flow, Subcatchment-2 Smooth surfaces n= 0.011 P2= 3.10" 0.1 34 0.0588 4.9 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 0.5 60 0.0750 1.9 Shallow Concentrated Flow, Subcatchment-2 Short Grass Pasture Kv= 7.0 fps 0.2 68 0.0555 4.8 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 3.7 Direct Entry, (Adjust for min. 5minute Tc) 5.0 212 Total Subcatchment S2: (Subcatchment 2 - Existing Conditions) Hydrograph 0.55-6 0.49 Cfs 10 Runoff 0.5 - Type III 24-hr 10-yr 0.45 : Rainfall=4.50" 0.4 a Runoff Area=5,100 sf 0.35 Runoff Volume=0.037 of 0.3 Runoff Depth=3.81 c 0.25- Plow Length=212' s s Tc=5.0 min 0.2- CN=94 0.15 0.1 _ 0.05 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 90-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 14 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Existing Conditions) Runoff = 1.34 cfs @ 12.11 hrs, Volume= 0.102 af, Depth= 2.72" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 15,405 79 50-75% Grass cover, Fair, HSG C 4,236 98 Paved parking & roofs 19,641 83 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.2 Sheet Flow, Subcatchment-3 Grass: Short n= 0.150 P2= 3.10" 0.9 72 0.0332 1.3 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.8 59 0.0305 1.2 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 1.0 81 0.0386 1.4 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 42 0.0564 1.7 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 96 0.0428 4.2 Shallow Concentrated Flow, Subcatchment-3 Paved Kv= 20.3 fps 7.8 400 Total 498 Chickering Road Pre Type 111 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 15 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Existing Conditions) Hydrograph 1 .34 Cfs D Runoff Type III 24-hr 10-yr Rainfall=4.50" Runoff Area=19,641 sf 1_ Runoff Volume=0.102 of Runoff Depth=2.72" Flow Length=400' 0 Tc=7.8 min CN=83 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 90-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 16 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P2: (20'-12" RCP) Inflow Area = 0.568 ac, Inflow Depth = 2.95" for 10-yr event Inflow 1.76 cfs @ 12.11 hrs, Volume= 0.139 of Outflow - 1.76 cfs @ 12.11 hrs, Volume= 0.139 af, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 8.2 fps, Min. Travel Time= 0.0 min Avg. Velocity= 2.6 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.32' @ 12.11 hrs Capacity at bank full= 8.10 cfs Inlet Invert= 115.97', Outlet Invert= 115.23' 12.0" Diameter Pipe n=0.011 Length= 20.0' Slope= 0.0370 '/' Reach P2: (20'-12" RCP) Hydrograph Inflow Inflow Area=O. 1 .76 cfs 0 Outflow Peak Depth=0.32' Max Vet=8.2 fps ' D=12.0" n=0.011 3 1 L=20.0' 0 �- S=0.0370 '/' Capacity=8.10 cfs 0 , . . b . . , . e . . o , . <, , . . . . , . . . , . , . 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type ///24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 17 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P3: (56'-12" CSP) Inflow Area = 0.451 ac, Inflow Depth = 2.72" for 10-yr event Inflow = 1.34 cfs @ 12.11 hrs, Volume= 0.102 of Outflow = 1.31 cfs @ 12.12 hrs, Volume= 0.102 af, Atten= 2%, Lag= 0.5 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.1 fps, Min. Travel Time= 0.3 min Avg. Velocity = 1.2 fps, Avg. Travel Time= 0.8 min Peak Depth= 0.53' @ 12.12 hrs Capacity at bank full= 2.41 cfs Inlet Invert= 116.89', Outlet Invert= 116.02' 12.0" Diameter Pipe n= 0.024 Length= 56.0' Slope= 0.0155T Reach P3: (56'-12" CSP) Hydrograph -- p Inflow Inflow Area=O. 1 .31 ds 0 Outflow Peak Depth=0.53' Max Vet=3.1 fps 1 D=12.0" �m n=0.024 3 L=56.0' 0 E: S=0.0155 '/' r Capacity=2.41 cfs i , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 18 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R1: (Reach 1 - Catch Basin#1) Inflow Area = 1.339 ac, Inflow Depth = 3.44" for 10-yr event Inflow = 4.54 cfs @ 12.12 hrs, Volume= 0.384 of Outflow 4.54 cfs @ 12.12 hrs, Volume= 0.384 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R1: (Reach 1 - Catch Basin #1) Hydrograph 0 Inflow 5- 4.54 cfs Q Outflow Inflow Area=1. s 4 V 33 2 1 0- � , , s , y . � , : � . . � �� � ,, , � � , , : , , , , , , , , , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 19 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R2: (Reach 2 - Catch Basin #2) Inflow Area = 0.568 ac, Inflow Depth = 2.95" for 10-yr event Inflow = 1.76 cfs @ 12.11 hrs, 'Volume= 0.139 of Outflow = 1.76 cfs @ 12.11 hrs, Volume= 0.139 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R2: (Reach 2 - Catch Basin #2) Hydrograph r El Inflow 1 .76 Cfs 0 outflow Inflow Area=O. t 1_ W 3 o 2 1 w:: 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type ///24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 20 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach 113: (Reach 3 - Catch Basin #3) Inflow Area = 0.451 ac, Inflow Depth = 2.72" for 10-yr event Inflow = 1.34 cfs @ 12.11 hrs, Volume= 0.102 of Outflow = 1.34 cfs @ 12.11 hrs, Volume= 0.102 af, Atten=0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R3: (Reach 3 - Catch Basin #3) Hydrograph 0 Inflow X1 .34 cfs El Outflow Inflow Area=O. o - 0 2 4 6' '' '8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type /// 24-hr 900-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 21 H droCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment S1: (Subcatchment 1 -Existing Conditions) Runoff Area=33,573 sf Runoff Depth=5.69" Flow Length=377' Tc=9.7 min CN=94 Runoff=4.10 cfs 0.365 of Subcatchment S2: (Subcatchment 2 -Existing Conditions) Runoff Area=5,100 sf Runoff Depth=5.69" Flow Length=212' Tc=5.0 min CN=94 Runoff=0.72 cfs 0.056 of Subcatchment S3: (Subcatchment 3 -Existing Conditions) Runoff Area=19,641 sf Runoff Depth=4.46" Flow Length=400' Tc=7.8 min CN=83 Runoff--2.16 cfs 0.168 of Reach P2: (20'-12" RCP) Peak Depth=0.40' Max Vet=9.3 fps Inflow=2.78 cfs 0.223 of D=12.0" n=0.011 L=20.0' S=0.0370 '/' Capacity=8.10 cfs Outflow=2.78 cfs 0.223 of Reach 123: (66'-12" CSP) Peak Depth=0.74' Max Vet=3.5 fps Inflow=2.16 cfs 0.168 of D=12.0" n=0.024 L=56.0' S=0.0155 '1' Capacity=2.41 cfs Outflow=2.13 cfs 0.168 of Reach R1: (Reach 1 -Catch Basin#1) Inflow=6.84 cfs 0.588 of Outflow=6.84 cfs 0.588 of Reach R2: (Reach 2 -Catch Basin#2) Inflow=2.78 cfs 0.223 of Outflow=2.78 cfs 0.223 of Reach R3: (Reach 3 - Catch Basin#3) Inflow=2.16 cfs 0.168 of Outflow=2.16 cfs 0.168 of Total Runoff Area= 1.339 ac Runoff Volume= 0.688 of Average Runoff Depth = 6.27" 498 Chickering Road Pre Type 11124-hr 900-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 22 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S1: (Subcatchment 1 - Existing Conditions) Runoff = 4.10 cfs @ 12.13 hrs, Volume= 0.365 af, Depth= 5.69" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 7,016 79 50-75% Grass cover, Fair, HSG C 26,557 98 Paved parking & roofs 33,573 94 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.1 Sheet Flow, Subcatchment- 1 Woods: Light underbrush n= 0.400 P2= 3.10" 0.2 50 0.0650 5.2 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.7 150 0.0337 3.7 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.5 57 0.0700 1.9 Shallow Concentrated Flow, Subcatchment- 1 Short Grass Pasture Kv= 7.0 fps 0.2 70 0.0681 5.3 Shallow Concentrated Flow, Subcatchment-1 _ Paved Kv= 20.3 fps 9.7 377 Total Subcatchment S1: (Subcatchment-1 - Existing Conditions) Hyd rog raph 4.10 Cfs- Runoff 4-a Type III 24-hr 100-yr Rainfall=6.40" Runoff Area=33,573 sf 3- Runoff Volume=0.365 of Runoff Depth=5.69" Flow Length=377' 0 2- Tc=9.7 min CN=94 0 , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 23 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S2: (Subcatchment 2 - Existing Conditions) Runoff = 0.72 cfs @ 12.07 hrs, Volume= 0.056 af, Depth= 5.69" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 1,200 79 50-75% Grass cover, Fair, HSG C 3,900 98 Paved parking & roofs 5,100 94 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (fUft) (ft/sec) (cfs) 0.5 50 0.0420 1.6 Sheet Flow, Subcatchment-2 Smooth surfaces n= 0.011 P2= 3.10" 0.1 34 0.0588 4.9 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 0.5 60 0.0750 1.9 Shallow Concentrated Flow, Subcatchment-2 Short Grass Pasture Kv=7.0 fps 0.2 68 0.0555 4.8 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 3.7 Direct Entry, (Adjust for min. 5minute Tc) 5.0 212 Total Subcatchment S2: (Subcatchment 2 - Existing Conditions) Hydrograph 0.8 0.72 CfS Runoff 0.7 Type III 24-hr 100-yr Rainfall=6.40" 0.6 Runoff Area=5,100 sf 0 5 Runoff Volume=0.056 of Runoff Depth=5.69" 3 0.4 Flow Length=212' —° - Tc=5.0 min �- 0.3 CN=94 0.2- 0.1 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type Ill 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 24 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Existing Conditions) Runoff = 2.16 cfs @ 12.11 hrs, Volume= 0.168 af, Depth= 4.46" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 15,405 79 50-75% Grass cover, Fair, HSG C 4,236 98 Paved parking & roofs 19,641 83 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.2 Sheet Flow, Subcatchment-3 Grass: Short n= 0.150 P2= 3.10" 0.9 72 0.0332 1.3 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.8 59 0.0305 1.2 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 1.0 81 0.0386 1.4 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 42 0.0564 1.7 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 96 0.0428 4.2 Shallow Concentrated Flow, Subcatchment-3 Paved Kv= 20.3 fps 7.8 400 Total 498 Chickering Road Pre Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 25 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Existing Conditions) Hydrograph 2.16 cfs 10 Runoff Type III 24-hr 100-yr 2 Rainfall=6.40" Runoff Area=19,641 sf Runoff Volume=0.168 of Runoff Depth=4.46" Flow Length=400' —° 1 Tc=7.8 min u_ CN=83 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 26 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P2: (20'-12" RCP) Inflow Area = 0.568 ac, Inflow Depth = 4.71" for 100-yr event Inflow = 2.78 cfs @ 12.11 hrs, Volume= 0.223 of Outflow = 2.78 cfs @ 12.11 hrs, Volume= 0.223 af, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 9.3 fps, Min. Travel Time= 0.0 min Avg. Velocity= 3.0 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.40' @ 12.11 hrs Capacity at bank full= 8.10 cfs Inlet Invert= 115.97', Outlet Invert= 115.23' 12.0" Diameter Pipe n= 0.011 Length= 20.0' Slope=0.0370 '/' Reach P2: (20'-12" RCP) Hydrograph Inflow 3 Inflow Area=O. 2.78 cfs p Outflow Peak Depth=0.40' Max Vet=9.3 fps 2 D=12.0" n=0.011 3 L=20.0' j 0 �- S=0.0370 '/' 1 Capacity=8.10 cfs 0- . .. . , o . , . , : , . � 6 - 7 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 27 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P3: (56'-12" CSP) Inflow Area = 0.451 ac, Inflow Depth = 4.46" for 100-yr event Inflow = 2.16 cfs @ 12.11 hrs, Volume= 0.168 of Outflow = 2.13 cfs @ 12.12 hrs, Volume= 0.168 af, Atten= 2%, Lag= 0.5 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.5 fps, Min. Travel Time= 0.3 min Avg. Velocity= 1.3 fps, Avg. Travel Time= 0.7 min Peak Depth= 0.74' @ 12.11 hrs Capacity at bank full= 2.41 cfs Inlet Invert= 116.89', Outlet Invert= 116.02' 12.0" Diameter Pipe n= 0.024 Length= 56.0' Slope= 0.01557' Reach P3: (56'-12" CSP) Hydrograph Inflow Inflow Area=O. 2.13 cfs Outflow 2- Peak Depth=0.74' �x Max Vet=3.5 fps r D=12.0 N n=0.024 c 1 L=56.0' �- S=0.0155 Capacity=2.41 cfs 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 28 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R1: (Reach 1 - Catch Basin #1) Inflow Area = 1.339 ac, Inflow Depth = 5.27" for 100-yr event Inflow = 6.84 cfs @ 12.12 hrs, Volume= 0.588 of Outflow = 6.84 cfs @ 12.12 hrs, Volume= 0.588 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R1: (Reach 1 - Catch Basin #1) Hydrograph Inflow _ Inflow Area=1. 6.84 cfs outflow �7 rj 5 _ 4 3 2 1 0__ 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 29 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R2: (Reach 2 - Catch Basin #2) Inflow Area = 0.568 ac, Inflow Depth = 4.71" for 100-yr event Inflow = 2.78 cfs @ 12.11 hrs, Volume= 0.223 of Outflow = 2.78 cfs @ 12.11 hrs, Volume= 0.223 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R2: (Reach 2 - Catch Basin #2) Hydrograph 0 Inflow 3 2.78 CfS 0 Outflow Inflow Area=O. N 2-- v v O 1 0 2 4 6 8 10 1 i2 14 16 18 20 22 24 Time (hours) 498 Chickering Road Pre Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 30 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R3: (Reach 3 - Catch Basin #3) Inflow Area = 0.451 ac, Inflow Depth = 4.46" for 100-yr event Inflow = 2.16 cfs @ 12.11 hrs, Volume= 0.168 of Outflow = 2.16 cfs @ 12.11 hrs, Volume= 0.168 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R3: (Reach 3 - Catch Basin #3) Hydrograph 0 Inflow Inflow Area=O. 2.16 cfs Outflow 2 o u.. i i a 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 4.2.2 > POST - DEVELOPMENT— 2, 10, & 100 — Year STORM EVENT Merrimack Engineering Services, Inc. Section 4—Page 4 Printed: November 1,2007 o N o o N N U) O r Q a) a o CL V o o ° ? 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C a O Q (D o a �-a CL 498 Chickering Road Post Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 31 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment PR: (Proposed building roof) Runoff Area=5,046 sf Runoff Depth=2.87" Tc=5.0 min CN=98 Runoff=0.35 cfs 0.028 of Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Runoff Area=25.123 sf Runoff Depth=2.55" Flow Length=350' Tc=5.0 min CN=95 Runoff=1.64 cfs 0.122 of Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Runoff Area=2,513 sf Runoff Depth=2.16" Flow Length=109' Tc=5.0 min CN=91 Runoff=0.15 cfs 0.010 of Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Runoff Area=23.740 sf Runoff Depth=1.82" Flow Length=400' Tc=7.8 min CN=87 Runoff=1.08 cfs 0.083 of Reach P2: (20'-12" RCP) Peak Depth=0.27' Max Vet=7.5 fps Inflow=1.26 cfs 0.121 of D=12.0" n=0.011 L=20.0' S=0.0370 '/' Capacity=8.10 cfs Outflow=1.26 cfs 0.121 of Reach P3: (56'-12" CSP) Peak Depth=0.47' Max Vet=3.0 fps Inflow=1.08 cfs 0.083 of D=12.0" n=0.024 L=56.0' S=0.0155 '/' Capacity=2.41 cfs Outflow=1.06 cfs 0.083 of Reach P4: (112' - 12" HDPE) Peak Depth=0.08' Max Vet=2.8 fps Inflow=0.08 cfs 0.028 of D=12.0" n=0.011 L=112.0' S=0.0224 '/' Capacity=6.30 cfs Outflow=0.08 cfs 0.028 of Reach R1: (Reach 1 -Catch Basin #1) Inflow=2.81 cfs 0.243 of Outflow=2.81 cfs 0.243 of Reach R2: (Reach 2 -Catch Basin #2) Inflow=1.26 cfs 0.121 of Outflow=1.26 cfs 0.121 of Reach R3: (Reach 3 - Catch Basin#3) Inflow=1.08 cfs 0.083 of Outflow=1.08 cfs 0.083 of Pond CT: (7,500 Gal. Commercial Line Tank) Peak Elev=121.29' Storage=355 cf Inflow=0.35 cfs 0.028 of Outflow=0.08 cfs 0.028 of Total Runoff Area = 1.295 ac Runoff Volume= 0.243 of Average Runoff Depth = 2.25" 498 Chickering Road Post Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 32 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment PR: (Proposed building roof) Runoff = 0.35 cfs @ 12.07 hrs, Volume= 0.028 af, Depth= 2.87° Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 5,046 98 Paved parking & roofs Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Roof runoff Subcatchment PR: (Proposed building roof) Hydrograph 0.35 0 Runoff 0.35 _ Type III 24-hr 2-yr Rainfall=3.10" 0.3-- Runoff Area=5,046 sf 0.25= Runoff Volume=0.028 of Runoff Depth=2.87°° 0.2 Tc=5.0 min 0 �- 0.15= CN=98 0.05- 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 33 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Runoff = 1.64 cfs @ 12.07 hrs, Volume= 0.122 af, Depth= 2.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0,00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 4,360 79 50-75% Grass cover, Fair, HSG C 20,763 98 Paved parking & roofs 25,123 95 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.9 50 0.0100 0.9 Sheet Flow, Subcatchment- 1 Smooth surfaces n= 0.011 P2= 3.10" 0.5 92 0.0217 3.0 Shallow Concentrated Flow, Subcatchment-1 Paved Kv= 20.3 fps 0.1 50 0.0800 5.7 Shallow Concentrated Flow, Subcatchment-1 Paved Kv= 20.3 fps 0.3 41 0.0963 2.2 Shallow Concentrated Flow, Subcatchment-1 Short Grass Pasture Kv= 7.0 fps 0.4 117 0.0495 4.5 Shallow Concentrated Flow, Subcatchment-1 Paved Kv= 20.3 fps 2.8 Direct Entry,Adjust for min. 5 minute Tc 5.0 350 Total Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Hydrograph 1 .64 cfs Q Runoff Type III 24-hr 2-yr Rainfall=3.10" Runoff Area=25,123 sf Runoff Volume=0.122 of 1_ Runoff Depth=2.55" 3 Flow Length=350' ° Tc=5.0 min u. CN=95 0 I . , , , „ p . , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type ///24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 34 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Runoff = 0.15 cfs @ 12.07 hrs, Volume= 0.010 af, Depth= 2.16" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 938 79 50-75% Grass cover, Fair, HSG C 1,575 98 Paved parking & roofs 2,513 91 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.6 50 0.1400 0.3 Sheet Flow,Subcatchment-2 Grass: Short n= 0.150 P2= 3.10" 0.2 59 0.0555 4.8 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 2.2 Direct Entry, (Adjust for min. 5minute Tc) 5.0 109 Total Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Hydrograph 0.16 10.15 cfs in Runoff 0.14 _ Type 111 24-hr 2-yr Rainfall=3.10" 0.12 - Runoff Area=2,513 sf Runoff Volume=0.010 of 0.1 Runoff Depth=2.16" 0.08' Flow Length=109' ° _ Tc=5.0 min " 0.06- CN=91 0.04-- 0.02- 0 7 , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 35 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Runoff = 1.08 cfs @ 12.11 hrs, Volume= 0.083 af, Depth= 1.82" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.10" Area (sf) CN Description 13,798 79 50-75% Grass cover, Fair, HSG C 9,942 98 Paved parking & roofs 23,740 87 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.2 Sheet Flow, Subcatchment-3 Grass: Short n= 0.150 P2= 3.10" 0.9 72 0.0332 1.3 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.8 59 0.0305 1.2 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 1.0 81 0.0386 1.4 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 42 0.0564 1.7 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 96 0.0428 4.2 Shallow Concentrated Flow, Subcatchment-3 Paved Kv= 20.3 fps 7.8 400 Total 498 Chickering Road Post Type Ill 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 36 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Hydrograph 1 .08 cfs ❑ Runoff Type 11124-hr 2-yr 1 Rainfall=3.10" Runoff Area=23,740 sf Runoff Volume=0.083 of Runoff Depth=1.82" Flow Length=400' —° Tc=7.8 min v_ CN=87 0- . , . . , . , . . . . . E . . , . , . . . . . 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 37 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P2: (20'-12" RCP) Inflow Area = 0.719 ac, Inflow Depth = 1.99" for 2-yr event Inflow = 1.26 cfs @ 12.12 hrs, Volume= 0.119 of Outflow - 1.26 cfs @ 12.12 hrs, Volume= 0.119 af, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 7.5 fps, Min. Travel Time= 0.0 min Avg. Velocity= 2.7 fps, Avg. Travel Time= 01 min Peak Depth= 0.27' @ 12.12 hrs Capacity at bank full= 8.10 cfs Inlet Invert= 115.97', Outlet Invert= 115.23' 12.0" Diameter Pipe n= 0.011 Length=20.0' Slope= 0.0370 '/' Reach P2: (20'-12" RCP) Hydrograph Inflow 1 .26 ds p Outflow Inflow Area=O. Peak Depth=0.27' 1 Max Vet=7.5 fps D=7 2.0" n=0.071 3 L=20.0' �- S=0.0370 '/' y Capacity=8.10 cfs 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 38 HLdroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P3: (56'-12" CSP) Inflow Area= 0.545 ac, Inflow Depth = 1.82" for 2-yr event Inflow = 1.08 cfs @ 12.11 hrs, Volume= 0.083 of Outflow = 1.06 cfs @ 12.12 hrs, Volume= 0.083 af, Atten= 2%, Lag= 0.6 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.0 fps, Min. Travel Time= 0.3 min Avg. Velocity= 1.1 fps, Avg. Travel Time= 0.9 min Peak Depth= 0.47' @ 12.12 hrs Capacity at bank full= 2.41 cfs Inlet Invert= 116.89, Outlet Invert= 116.02' 12.0" Diameter Pipe n= 0.024 Length= 56.0' Slope= 0.0155 '/' Reach P3: (56'-12" CSP) Hydrograph 0 Inflow Inflow Area=O. 1 .06 cfs 0 Outflow 1-r Peak Depth=0.47' Max Vet=3.0 fps .. D=12.0" N n=0.024 c L=56.0' �- S=0.0155 Capacity=2.41 cfs on 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type /// 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 39 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P4: (112' - 12" HDPE) [52] Hint: Inlet conditions not evaluated Inflow Area = 0.116 ac, Inflow Depth = 2.86" for 2-yr event Inflow = 0.08 cfs @ 12.45 hrs, Volume= 0.028 of Outflow = 0.08 cfs @ 12.47 hrs, Volume= 0.028 af, Atten= 0%, Lag= 1.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.8 fps, Min. Travel Time= 0.7 min Avg. Velocity = 1.5 fps, Avg. Travel Time= 1.3 min Peak Depth= 0.08' @ 12.46 hrs Capacity at bank full= 6.30 cfs Inlet Invert= 118.58', Outlet Invert= 116.07' 12.0" Diameter Pipe n= 0.011 Length= 112.0' Slope= 0.0224 '/' Reach P4: (112' - 12" HDPE) Hydrograph Inflow 0.09 0.08 ds - 0 Outflow Inflow Area=O. Cal 0.08 :. Peak Depth=0.08' 0.07 Max Vei=28 fps s 0.06 D12 '± ,0�� 0.05- n=0.011 3 L=112.0' , r y o 0.04 �- S=0.0224 '/' 0.03 Capacity=6.30 cfs 0.02 = r j 0.01- 0 i a 4 8 1 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 40 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R1: (Reach 1 - Catch Basin #1) Inflow Area = 1.295 ac, Inflow Depth = 2.24" for 2-yr event Inflow = 2.81 cfs @ 12.09 hrs, Volume= 0.241 of Outflow 2.81 cfs @ 12.09 hrs, Volume= 0.241 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R1: (Reach 1 - Catch Basin #1) Hydrograph El Inflow 3 2.81 CfS El Outflow Inflow Area=1. w 2 O 0 ! 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type /// 24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 41 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 1 1/1/2007 Reach R2: (Reach 2 - Catch Basin #2) Inflow Area = 0.719 ac, Inflow Depth = 1.99" for 2-yr event Inflow = 1.26 cfs @ 12.12 hrs, Volume= 0.119 of Outflow = 1.26 cfs @ 12.12 hrs, Volume= 0119 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R2: (Reach 2 - Catch Basin #2) Hydrograph 0 Inflow Inflow Area-0. 1 .26 Cfs 0 Outflow 1 - v - v 3 o u.. 0i � , . p 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 42 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R3: (Reach 3 - Catch Basin #3) Inflow Area = 0.545 ac, Inflow Depth = 1.82" for 2-yr event Inflow = 1.08 cfs @ 12.11 hrs, Volume= 0.083 of Outflow = 1.08 cfs @ 12.11 hrs, Volume= 0.083 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R3: (Reach 3 - Catch Basin #3) Hydrograph Inflow Inflow Area=O. 1 .08 cfs 0 outflow 1— V 3 _O 0—. 1 . . . 1 , — 1 - 111 . . . , , , . , . . . 0 2 6 8 10 12 14 16 18 2e0 22 24 Time (hours) 498 Chickering Road Post Type l//24-hr 2-yr Rainfall=3.10" Prepared by Merrimack Engineering Services Page 43 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Pond CT: (7,500 Gal. Commercial Line Tank) Inflow Area = 0.116 ac, Inflow Depth = 2.87" for 2-yr event Inflow = 0.35 cfs @ 12.07 hrs, Volume= 0.028 of Outflow = 0.08 cfs @ 12.45 hrs, Volume= 0.028 af, Atten= 77%, Lag= 23.0 min Primary = 0.08 cfs @ 12.45 hrs, Volume= 0.028 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 121.29' @ 12.45 hrs Surf.Area= 0 sf Storage= 355 cf Plug-Flow detention time=41.3 min calculated for 0.028 of(99% of inflow) Center-of-Mass det. time= 39.2 min ( 795.0 - 755.8) # Invert Avail.Storage Storage Description 1 118.83' 1,008 cf Custom Stage Data Listed below Elevation Cum.Store (feet) (cubic-feet) 118.83 0 122.33 504 125.83 1,008 # Routing invert Outlet Devices 1 Primary 118.83' 1.0"Vert. Orifice/Grate X 2.00 C= 0.600 Primary OutFlow Max=0.08 cfs @ 12.45 hrs HW=121.29' (Free Discharge) t1=Orifice/Grate (Orifice Controls 0.08 cfs @ 7.5 fps) Pond CT: (7,500 Gal. Commercial Line Tank) Hydrograph 0.35 Cfs E Inflow 0.35 _ Inflow Area=0.116 ac B Primary - Peak Elev=121.29' 0.3- Storage=355 cf N 0.25- 0.2_ 0 LL 0.15- 0.1- 0.08 Cfs 0.05- y 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type ///24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 44 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment PR: (Proposed building roof) Runoff Area=5,046 sf Runoff Depth=4.26" Tc=5.0 min CN=98 Runoff=0.51 cfs 0.041 of Subcatchment S1: (Subcatchment 1 -Proposed Conditions) Runoff Area=25.123 sf Runoff Depth=3.92" Flow Length=350' Tc=5.0 min CN=95 Runoff=2.47 cfs 0.189 of Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Runoff Area=2,513 sf Runoff Depth=3.50" Flow Length=109' Tc=5.0 min CN=91 Runoff=0.23 cfs 0.017 of Subcatchment S3: (Subcatchment 3 -Proposed Conditions) Runoff Area=23.740 sf Runoff Depth=3.10" Flow Length=400' Tc=7.8 min CN=87 Runoff=1.82 cfs 0.141 of Reach P2: (20'-12" RCP) Peak Depth=0.35' Max Vet=8.6 fps Inflow=2.08 cfs 0.198 of D=12.0" n=0.011 L=20.0' S=0.0370 '/' Capacity=8.10 cfs Outflow=2.08 cfs 0.198 of Reach P3: (56'-12" CSP) Peak Depth=0.65' Max Vet=3.4 fps Inflow=1.82 cfs 0.141 of D=12.0" n=0.024 L=56.0' S=0.0155'/' Capacity=2.41 cfs Outflow=1.79 cfs 0.141 of Reach P4: (112' - 12" HDPE) Peak Depth=0.09' Max Vet=3.0 fps Inflow=0.10 cfs 0.041 of D=12.0" n=0.011 L=112.0' S=0.0224 '/' Capacity=6.30 cfs Outflow=0.10 cfs 0.041 of Reach R1: (Reach 1 -Catch Basin #1) Inflow=4.42 cfs 0.387 of Outflow=4.42 cfs 0.387 of Reach R2: (Reach 2 -Catch Basin #2) Inflow=2.08 cfs 0.198 of Outflow=2.08 cfs 0.198 of Reach R3: (Reach 3 - Catch Basin #3) Inflow=1.82 cfs 0.141 of Outflow=1.82 cfs 0.141 of Pond CT: (7,500 Gal. Commercial Line Tank) Peak Elev=122.77' Storage=567 cf Inflow=0.51 cfs 0.041 of Outflow=0.10 cfs 0.041 of Total Runoff Area = 1.295 ac Runoff Volume = 0.387 of Average Runoff Depth = 3.59" 498 Chickering Road Post Type 111 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 45 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment PR: (Proposed building roof) Runoff = 0.51 cfs @ 12.07 hrs, Volume= 0.041 af, Depth= 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 5,046 98 Paved parking & roofs Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Roof runoff Subcatchment PR: (Proposed building roof) Hydrograph 0.55 - 0.51 10 Runoff 0.5- Type III 24-hr 10-yr 0.45 Rainfall=4.50" 0.4 - Runoff Area=5,046 sf Runoff Volume=0.041 of 0.35- Runoff Depth=4.26" �- 0.3 Tc=5.0 min o 0.25- CN=98 U. 0.2-- 0.15- 0.1 a 0.05 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type ///24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 46 HydroCADD 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Runoff = 2.47 cfs @ 12.07 hrs, Volume= 0.189 af, Depth= 3.92" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 4,360 79 50-75% Grass cover, Fair, HSG C _ 20,763 98 Paved parking & roofs 25,123 95 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.9 50 0.0100 0.9 Sheet Flow, Subcatchment- 1 Smooth surfaces n= 0.011 P2= 3.10" 0.5 92 0.0217 3.0 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.1 50 0.0800 5.7 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.3 41 0.0963 2.2 Shallow Concentrated Flow, Subcatchment-1 Short Grass Pasture Kv= 7.0 fps 0.4 117 0.0495 4.5 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 2.8 Direct Entry,Adjust for min. 5 minute Tc 5.0 350 Total Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Hydrograph 2.47 10 Runoff Type III 24-hr 10-yr Rainfall=4.50" 2 Runoff Area=25,123 sf Runoff Volume=0.189 of Runoff Depth=3.92" 3 Flow Length=350' ° Tc=5.0 min u_ 1 CN=95 O-L . . . . . . . . . ; , 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 10-yr Rainfall=4.50° Prepared by Merrimack Engineering Services Page 47 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Runoff = 0.23 cfs @ 12.07 hrs, Volume= 0.017 af, Depth= 3.50" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 938 79 50-75% Grass cover, Fair, HSG C 1,575 98 Paved parking & roofs 2,513 91 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.6 50 0.1400 0.3 Sheet Flow, Subcatchment- 2 Grass: Short n= 0.150 P2= 3.10" 0.2 59 0.0555 4.8 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps 2.2 Direct Entry, (Adjust for min. 5minute Tc) 5.0 109 Total Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Hydrograph - 0.23 cfs 0 Runoff 0.24 0.22- Type 111 24-hr 10-yr 0.2 - Rainfall=4.50" 0.18: Runoff Area=2,513 sf 0.16-- Runoff Volume=0.017 of 0.14 _ Runoff Depth=3.50" c 0.12-- Flow Length=109' 0 0.1 Tc=5.0 min 0.08- CN=91 0.06 0.04 0.02 0- 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type ///24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 48 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Runoff = 1.82 cfs @ 12.11 hrs, Volume= 0.141 af, Depth= 3.10" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.50" Area (sf) CN Description 13,798 79 50-75% Grass cover, Fair, HSG C _ 9,942 98 Paved parking & roofs 23,740 87 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.2 Sheet Flow, Subcatchment-3 Grass: Short n= 0.150 P2= 3.10" 0.9 72 0.0332 1.3 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.8 59 0.0305 1.2 Shallow Concentrated Flow, Subcatchment 3 Short Grass Pasture Kv= 7.0 fps 1.0 81 0.0386 1.4 Shallow Concentrated Flow, Subcatchment- 3 Short Grass Pasture Kv= 7.0 fps 0.4 42 0.0564 1.7 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 96 0.0428 4.2 Shallow Concentrated Flow, Subcatchment- 3 Paved Kv= 20.3 fps 7.8 400 Total 498 Chickering Road Post Type 111 24-hr 10-yr Rainfall=4.50° Prepared by Merrimack Engineering Services Page 49 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Hydrograph 2 1 .82 Cfs Runoff Type III 24-hr 10-yr Rainfall=4.50" Runoff Area=23,740 sf Runoff Volume=0.141 of Runoff Depth=3.10" Flow Length=400' O 3 LL Tc=7.8 min CN=87 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 50 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P2: (20'-12" RCP) Inflow Area = 0.719 ac, Inflow Depth = 3.29" for 10-yr event Inflow = 2.08 cfs @ 12.11 hrs, Volume= 0.197 of Outflow = 2.08 cfs @ 12.12 hrs, Volume= 0.197 af, Atten= 0%, Lag=0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 8.6 fps, Min. Travel Time= 0.0 min Avg. Velocity= 3.1 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.35' @ 12.11 hrs Capacity at bank full= 8.10 cfs Inlet Invert= 115.97', Outlet Invert= 115.23' 12.0" Diameter Pipe n= 0.011 Length= 20.0' Slope= 0.03707' Reach P2: (20'-12" RCP) Hydrograph p Inflow Inflow Area=O. 2.08 cfs 0 outflow 2f Peak Depth=0.35' Max Vet=8.6 fps .. D=12.0" n=0.071 c 1 v L=20.0' LL S=0.0370 '/' Capacity=8.10 cfs = 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type Ill 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 51 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P3: (56'-12" CSP) Inflow Area = 0.545 ac, Inflow Depth = 3.10" for 10-yr event Inflow = 1.82 cfs @ 12.11 hrs, Volume= 0.141 of Outflow = 1.79 cfs @ 12.12 hrs, Volume= 0.141 af, Atten= 2%, Lag= 0.5 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.4 fps, Min. Travel Time= 0.3 min Avg. Velocity = 1.2 fps, Avg. Travel Time= 0.8 min Peak Depth= 0.65' @ 12.11 hrs Capacity at bank full= 2.41 cfs Inlet Invert= 116.89', Outlet Invert= 116.02' 12.0" Diameter Pipe n= 0.024 Length= 56.0' Slope= 0.01557' Reach P3: (56'-12" CSP) Hydrograph Inflow 2- 1 .79 cfs El Outflow Inflow Area=O. Peak Depth=0.65' Max Vet=3.4 fps D=12.0" 1 n=0.024 c 1- L=56.0' �- S=0.0155 '/' Capacity=2.41 cfs 0 t 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 52 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P4: (112' - 12" HDPE) Inflow Area = 0.116 ac, Inflow Depth = 4.25" for 10-yr event Inflow = 0.10 cfs @ 12.49 hrs, Volume= 0.041 of Outflow = 0.10 cfs @ 12.51 hrs, Volume= 0.041 af, Atten= 0%, Lag= 1.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.0 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.6 fps, Avg. Travel Time= 1.1 min Peak Depth= 0.09' @ 12.50 hrs Capacity at bank full= 6.30 cfs Inlet Invert= 118.58', Outlet Invert= 116.07' 12.0" Diameter Pipe n= 0.011 Length= 112.0' Slope= 0.02247' Reach P4: (112' - 12" HDPE) Hyd rog raph Inflow 0.11 0.10 cfs Outflow Inflow Area=O. 0.1 _ Peak Depth=0.09' ; 0.09 Max Vet=3.0 fps 0.08 D=12.0" 0.07 n=0.011 0.06" 3 L=112.0' 0 0.05 0.04- U- S=0.0224 '/' 0.03= Capacity=6.30 cfs 0.02 0.01 Q E i i 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 53 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R1: (Reach 1 - Catch Basin #1) Inflow Area = 1.295 ac, Inflow Depth = 3.57" for 10-yr event Inflow = 4.42 cfs @ 12.09 hrs, Volume= 0.385 of Outflow = 4.42 cfs @ 12.09 hrs, Volume= 0.385 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R1: (Reach 1 - Catch Basin #1) Hyd rog raph Inflow 4.42 cfs 0 Outflow Inflow Area=1. 3 4 3_ uo. 2--. 1- 0 2 4 61 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 54 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R2: (Reach 2 - Catch Basin #2) Inflow Area = 0.719 ac, Inflow Depth = 3.29" for 10-yr event Inflow = 2.08 cfs @ 12.11 hrs, Volume= 0.197 of Outflow = 2.08 cfs @ 12.11 hrs, Volume= 0.197 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R2: (Reach 2 - Catch Basin #2) Hydrograph Inflow Inflow Area=O. 2.08 cfs El outflow 2 lu .in 0 1 0-- - 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type /// N-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 55 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R3: (Reach 3 - Catch Basin #3) Inflow Area = 0.545 ac, Inflow Depth = 3.10" for 10-yr event Inflow = 1.82 cfs @ 12.11 hrs, Volume= 0.141 of Outflow = 1.82 cfs @ 12.11 hrs, Volume= 0.141 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R3: (Reach 3 - Catch Basin #3) Hydrograph 0 Inflow 2 1 .82 CfS El Outflow Inflow Area=O. 3 1 0 Zi PIP u. 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 10-yr Rainfall=4.50" Prepared by Merrimack Engineering Services Page 56 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Pond CT: (7,500 Gal. Commercial Line Tank) Inflow Area = 0.116 ac, Inflow Depth = 4.26" for 10-yr event Inflow = 0.51 cfs @ 12.07 hrs, Volume= 0.041 of Outflow = 0.10 cfs @ 12.49 hrs, Volume= 0.041 af, Atten= 80%, Lag= 25.1 min Primary = 0.10 cfs @ 12.49 hrs, Volume= 0.041 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 122.77' @ 12.49 hrs Surf.Area= 0 sf Storage= 567 cf Plug-Flow detention time= 51.5 min calculated for 0.041 of (100% of inflow) Center-of-Mass det. time=49.4 min ( 798.0- 748.6 ) # Invert Avail.Storage Storage Description 1 118.83' 1,008 cf Custom Stage Data Listed below Elevation Cum.Store (feet) (cubic-feet) 118.83 0 122.33 504 125.83 1,008 # Routing Invert Outlet Devices 1 Primary 118.83' 1.0"Vert. Orifice/Grate X 2.00 C= 0.600 Primary OutFlow Max=0.10 cfs @ 12.49 hrs HW=122.76' (Free Discharge) t-1=0rifice/Grate (Orifice Controls 0.10 cfs @ 9.5 fps) Pond CT: (7,500 Gal. Commercial Line Tank) Hydrograph 0.51 cfs Inflow 0.55" El Primary Inflow Area=0.116 ac 0.5- Peak Elev=122:77' 0.45 Storage-567 cf 4 0.35" 0.3- 0 0.25" U. 0.2 : 0.15- _ 0.10 cfs 0.1 0.05 Q 1 . g i . . g 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 57 HydroCADB 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment PR: (Proposed building roof) Runoff Area=5,046 sf Runoff Depth=6.16" Tc=5.0 min CN=98 Runoff=0.73 cfs 0.059 of Subcatchment S1: (Subcatchment 1 -Proposed Conditions) Runoff Area=25.123 sf Runoff Depth=5.81" Flow Length=350' Tc=5.0 min CN=95 Runoff=3.58 cfs 0.279 of Subcatchment S2: (Subcatchment 2 -Proposed Conditions) Runoff Area=2,513 sf Runoff Depth=5.35" Flow Length=109' Tc=5.0 min CN=91 Runoff=0.34 cfs 0.026 of Subcatchment S3: (Subcatchment 3 -Proposed Conditions) Runoff Area=23.740 sf Runoff Depth=4.90" Flow Length=400' Tc=7.8 min CN=87 Runoff=2.82 cfs 0.222 of Reach P2: (20'-12" RCP) Peak Depth=0.41' Max Vet=9.4 fps Inflow=2.85 cfs 0.307 of D=12.0" n=0.011 L=20.0' S=0.0370'/' Capacity=8.10 cfs Outflow=2.85 cfs 0.307 of Reach P3: (56'-12" CSP) Peak Depth=1.00' Max Vet=3.5 fps Inflow=2.82 cfs 0.222 of D=12.0" n=0.024 L=56.0' S=0.0155'/' Capacity=2.41 cfs Outflow=2.61 cfs 0.222 of Reach P4: (112' - 12" HDPE) Peak Depth=0.10' Max Vet=3.2 fps Inflow=0.13 cfs 0.059 of D=12.0" n=0.011 L=112.0' S=0.0224 '/' Capacity=6.30 cfs Outflow=0.13 cfs 0.059 of Reach R1: (Reach 1 -Catch Basin #1) Inflow=6.29 cfs 0.586 of Outflow=6.29 cfs 0.586 of Reach R2: (Reach 2 -Catch Basin #2) Inflow=2.85 cfs 0.307 of Outflow=2.85 cfs 0.307 of Reach R3: (Reach 3 - Catch Basin #3) Inflow=2.82 cfs 0.222 of Outflow=2.82 cfs 0.222 of Pond CT: (7,500 Gal. Commercial Line Tank) Peak Elev=124,91' Storage=875 cf Inflow=0.73 cfs 0.059 of Outflow=0.13 cfs 0.059 of Total Runoff Area = 1.295 ac Runoff Volume = 0.587 of Average Runoff Depth a 5.43" 498 Checkering Road Post Type Ill 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 58 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment PR: (Proposed building roof) Runoff = 0.73 cfs @ 12.07 hrs, Volume= 0.059 af, Depth= 6.16" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 5,046 98 Paved parking & roofs Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Roof runoff Subcatchment PR: (Proposed building roof) Hydrograph 0.8 0.73 cfs D Runoff 0.7 _ Type III 24-hr 100-yr Rainfall=6.40" 0.6 Runoff Area=5,046 sf Runoff Volume=0.059 of 0.5 _ Runoff Depth=6.16" 3 0.4-= Tc=5.0 min ° 0.3 CN=98 �- 0.2 0.1- 0, 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 59 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Runoff = 3.58 cfs @ 12.07 hrs, Volume= 0.279 af, Depth= 5.81" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 4,360 79 50-75% Grass cover, Fair, HSG C 20,763 98 Paved parking & roofs 25,123 95 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.9 50 0.0100 0.9 Sheet Flow, Subcatchment- 1 Smooth surfaces n= 0.011 P2= 3.10" 0.5 92 0.0217 3.0 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 0.1 50 0.0800 5.7 Shallow Concentrated Flow, Subcatchment-1 Paved Kv= 20.3 fps 0.3 41 0.0963 2.2 Shallow Concentrated Flow, Subcatchment-1 Short Grass Pasture Kv= 7.0 fps 0.4 117 0.0495 4.5 Shallow Concentrated Flow, Subcatchment- 1 Paved Kv= 20.3 fps 2.8 Direct Entry, Adjust for min. 5 minute Tc 5.0 350 Total Subcatchment S1: (Subcatchment 1 - Proposed Conditions) Hydrograph 4 3.5$ Cfs U Runoff Type III 24-hr 100-yr Rainfall=6.40" 3 Runoff Area=25,123 sf ., Runoff!Volume=0.279 of Runoff Depth=5.81" 3 2-- Flow Length=350' ° Tc=5.0 min u. CN=95 1 0 0. 2 4 6 $, . 10 . . 1`2 , 14 16 . 18 . 20 22 " 24 Time (hours) 498 Chickering Road Post Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 60 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Runoff = 0.34 cfs @ 12.07 hrs, Volume= 0.026 af, Depth= 5.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 938 79 50-75% Grass cover, Fair, HSG C _ 1,575 98 Paved parking & roofs 2,513 91 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.6 50 0.1400 0.3 Sheet Flow, Subcatchment-2 Grass: Short n= 0.150 P2= 3.10" 0.2 59 0.0555 4.8 Shallow Concentrated Flow, Subcatchment-2 Paved Kv= 20.3 fps _ 2.2 Direct Entry, (Adjust for min. 5minute Tc) 5.0 109 Total Subcatchment S2: (Subcatchment 2 - Proposed Conditions) Hydrograph 0.34 Cfs 0 Runoff 0.35- Type III 24-hr 100-yr 0.3 Rainfall=6.40" Runoff Area=2,513 sf 0.25= Runoff Volume=0.026 of Runoff Depth=5.35" 0.2-- Flow Length=109' ° Tc=5.0 min M 0.15- CN=91 0.1- 0.05 .. 0 . 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 61 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Runoff = 2.82 cfs @ 12.11 hrs, Volume= 0.222 af, Depth= 4.90" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=6.40" Area (sf) CN Description 13,798 79 50-75% Grass cover, Fair, HSG C _ 9,942 98 Paved parkinq & roofs 23,740 87 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.2 Sheet Flow, Subcatchment-3 Grass: Short n= 0.150 P2= 3.10" 0.9 72 0.0332 1.3 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.8 59 0.0305 1.2 Shallow Concentrated Flow,Subcatchment- 3 Short Grass Pasture Kv= 7.0 fps 1.0 81 0.0386 1.4 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 42 0.0564 1.7 Shallow Concentrated Flow, Subcatchment-3 Short Grass Pasture Kv= 7.0 fps 0.4 96 0.0428 4.2 Shallow Concentrated Flow, Subcatchment-3 Paved Kv= 20.3 fps 7.8 400 Total 498 Chickering Road Post Type ///24-hr 900-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 62 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 1111/2007 Subcatchment S3: (Subcatchment 3 - Proposed Conditions) Hydrograph 3- 2.82 Cfs 0 Runoff Type III 24-hr 100-yr Rainfall=6.40" Runoff Area=23,740 sf 2 Runoff Volume=0.222 of Runoff Depth=4.90" 3 Flow Length=400' 0 Tc=7.8 min 1 CN=87 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 63 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P2: (20'-12" RCP) Inflow Area = 0.719 ac, Inflow Depth = 5.10" for 100-yr event Inflow = 2.85 cfs @ 12.20 hrs, Volume= 0.306 of Outflow = 2.85 cfs @ 12.20 hrs, Volume= 0.306 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 9.4 fps, Min. Travel Time= 0.0 min Avg. Velocity= 3.5 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.41' @ 12.20 hrs Capacity at bank full= 8.10 cfs Inlet Invert= 115.97', Outlet Invert= 115.23' 12.0" Diameter Pipe n= 0.011 Length= 20.0' Slope= 0.0370 '/' Reach P2: (20'-12" RCP) Hydrograph El Inflow 2.85 cfs ❑ Outflow 3- Inflow Area=O. Peak Depth=0.41' Max Vet=9.4 fps 2 D=1 2.0" k 0 n=0.011 c L=20.0' LL S=0.0370 T 1 Capacity=8.10 cfs 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 64 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P3: (56'-12" CSP) Inflow Area = 0.545 ac, Inflow Depth = 4.90" for 100-yr event Inflow = 2.82 cfs @ 12.11 hrs, Volume= 0.222 of Outflow = 2.61 cfs @ 12.18 hrs, Volume= 0.222 af, Atten= 7%, Lag=4.5 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.5 fps, Min. Travel Time= 0.3 min Avg. Velocity = 1.4 fps, Avg. Travel Time= 0.7 min Peak Depth= 1.00' @ 12.13 hrs Capacity at bank full= 2.41 cfs Inlet Invert= 116.89', Outlet Invert= 116.02' 12.0" Diameter Pipe n= 0.024 Length= 56.0' Slope= 0.0155 '/' Reach P3: (56'-12" CSP) Hydrograph 2.82 cfs 0 Inflow 3- inflow Area=0.j 2 Outflow .61 cfs Peak Depth=l. Max Vet=3.5 fps ,. 2- D=1 2.0" n=0.024 = c L=56.0' S=0.0155 '/' 1 Capacity=2.41 cfs 0- 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 65 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach P4: (112' - 12" HDPE) Inflow Area = 0.116 ac, Inflow Depth = 6.14" for 100-yr event Inflow = 0.13 cfs @ 12.52 hrs, Volume= 0.059 of Outflow = 0.13 cfs @ 12.54 hrs, Volume= 0.059 af, Atten= 0%, Lag= 1.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.2 fps, Min. Travel Time= 0.6 min Avg. Velocity= 1.8 fps, Avg. Travel Time= 1.0 min Peak Depth= 0.10' @ 12.52 hrs Capacity at bank full= 6.30 cfs Inlet Invert= 118.58', Outlet Invert= 116.07' 12.0" Diameter Pipe n= 0.011 Length= 112.0' Slope= 0.0224T Reach P4: (112' - 12" HDPE) Hydrograph Inflow 0.14 0.13 cfs D outflow Inflow Area=O. 0.12f Peak Depth=0.10' Max Vet=3.2 fps 0.1 , x D-12.0" f N � 0.08-- n=0.011 . 0.06 L=112.0' �- -S=0:0224 T. 0.04 Capacity=6.30 cf 0.02 -J 1 0 s r a E i i 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 111 24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 66 HydroCADO 7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R1: (Reach 1 - Catch Basin #1) Inflow Area = 1.295 ac, Inflow Depth = 5.42" for 100-yr event Inflow = 6.29 cfs @ 12.08 hrs, Volume= 0.585 of Outflow = 6.29 cfs @ 12.08 hrs, Volume= 0.585 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R1: (Reach 1 - Catch Basin #1) Hydrograph Inflow 7 6.29 CFS Outflow - Inflow Area=1. 6- _ 5 - r= H _ r 4- 0 3- LL 2 _ 1= 0 2 4 6' 8 10 12 1!4 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type ///24-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 67 HydroCAD®7 00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Reach R2: (Reach 2 -Catch Basin #2) Inflow Area = 0.719 ac, Inflow Depth = 5.10" for 100-yr event Inflow = 2.85 cfs @ 12.20 hrs, Volume= 0.306 of Outflow = 2.85 cfs @ 12.20 hrs, Volume= 0.306 af, Atten=0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R2: (Reach 2 - Catch Basin #2) Hydrograph r El Inflow 2.85 Cfs jj El outflow 3- Inflow Area=O. 4 2. lu 0 u. 0 0 2 4 6 . . ,$ 1;0 „ 12 < < 14 , 16 . . 18 20 2`2 „ 24 Time (hours) 498 Chickening Road Post Type 11124-hr 100-yr Rainfall=6.40" Page 68 Prepared by Merrimack Engineering Services 11/1/2007 H droCAD®7.00 s/n OOQ899 © 1986-2003 Applied Microcom uter Systems Reach R3: (Reach 3 - Catch Basin #3) Inflow Area = 0.545 ac, Inflow Depth = 4.90" for 100-yr event Inflow = 2.82 cfs @ 12.11 hrs, Volume= 0.222 of Outflow = 2.82 cfs @ 12.11 hrs, Volume= 0.222 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach R3: (Reach 3 - Catch Basin #3) Hydrograph E Inflow 2.82 Cfs El Outflow 3- Inflow Area=O. ._ 2 v 0 0-ij LL _ - 1 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 498 Chickering Road Post Type 11124-hr 100-yr Rainfall=6.40" Prepared by Merrimack Engineering Services Page 69 HydroCAD®7.00 s/n 000899 © 1986-2003 Applied Microcomputer Systems 11/1/2007 Pond CT: (7,500 Gal. Commercial Line Tank) Inflow Area = 0.116 ac, Inflow Depth = 6.16" for 100-yr event Inflow = 0.73 cfs @ 12.07 hrs, Volume= 0.059 of Outflow = 0.13 cfs @ 12.52 hrs, Volume= 0.059 af, Atten= 82%, Lag= 26.8 min Primary = 0.13 cfs @ 12.52 hrs, Volume= 0.059 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 124.91' @ 12.52 hrs Surf.Area= 0 sf Storage= 875 cf Plug-Flow detention time= 64.4 min calculated for 0.059 of(99% of inflow) Center-of-Mass det. time= 62.3 min ( 805.2- 742.9 ) # Invert Avail.Storage Storage Description 1 118.83' 1,008 cf Custom Stage Data Listed below Elevation Cum.Store (feet) (cubic-feet) 118.83 0 122.33 504 125.83 1,008 # Routing Invert Outlet Devices 1 Primary 118.83' 1.0"Vert. Orifice/Grate X 2.00 C= 0.600 Primary OutFlow Max=0.13 cfs @ 12.52 hrs HW=124.90' (Free Discharge) 't--1=Orifice/G rate (Orifice Controls 0.13 cfs @ 11.8 fps) Pond CT: (7,500 Gal. Commercial Line Tank) Hydrograph 0.73 Cfs Inflow 0.8 Inflow Area=0.116 ac Primary 0.7- .Peak Elev-124.91' 0.6 Stora -875 cf 9;a 0.5 v 0.4 0 0.3- 0.2- 0.13 Cfs 0.1 Q 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 5.0 > APPENDIX Merrimack Engineering Services, Inc. Section 5—Page 1 Printed: November 1,2007 PREVOPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 5.1 > RAINFALL DATA MAPS Merrimack Engineering Services, Inc. Section 5—Page 2 Printed: November 1,2007 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS < SECTION 5.1 > Rainfall Data Map 2 8" ESSEX r FRANKLIN+ rr MIDDLESEX 3•2 SUFFOLK . HAMPSHIRE OI�CESTER �c 3 V! tb RAINFALL: DATA M-AP, NS LE 2--Y.EAR,'.24 'HOUR "PRECIPITATION (INCHES) �4 DUKES y O NANTUCKET —4.2" 4 5" 4 31 ESSEX 4<6i' ' FRANKLIN " f�+ MIDOL-ESrX r SUFFOLK' 4.7; ' HAAiP$gig WpRCE5TER. ' HAIAPDENO � /, p DARNS? LE 10-YEAR, 2,4 HOUR PRECIPITATION (INCHES) .4, 9,Q .pQ 'err^ 1 DUKES C7 NANTUCKET ' Merrimack Engineering Services, Inc. Section 5 —Page 3 Printed: November 1,2007 PROPOSED RETAIL FA CILI T Y NORTHANDOVER, MASSACHUSETTS < SECTION 5.1 > Rainfall Data Map } yj J Merrimack Engineering Services, Inc. Section 5—Page 4 Printed: November 1,2007 PROPOSED RETAIL FA CILI T Y NORTHANDOVER, MASSACHUSETTS < SECTION 5.2 > NATIONAL RESOURCES CONSERVATION SERVICE - SOIL DESCRIPTION WITH CLASSIFICATION Merrimack Engineering Services,Inc. Section 5—Page 5 Printed: November 1,2007 PROPOSED RETAIL FACILITY NORTHANDOVER, MASSACHUSETTS Soils description: Woodbridge series soils The Woodbridge series consists of coarse-loamy,mixed,mesic Typic Fragiochrepts. These deep and moderately well drained soils are on uplands. The soils formed in compact glacial till derived mainly from schist and granite. Slopes range from 0 to 25 percent. Woodbridge soils formed in the same kind of material as well drained Paxton soils,poorly drained Ridgebury soils,and very poorly drained Whitman soils. They are similar to the Scituate,and Sutton soils. Woodbridge soils have less sand in the substratum than the Scituate soils.They have a fragipan,which the Sutton soils do not have. Typical pedon of Woodbridge fine sandy loam,3 to 8 percent slopes,in the town of Georgetown,in a field 700 feet southwest of the junction of Andover and West Streets: Ap-0 to 9 inches;very dark grayish brown(I OYR 3/2)fine sandy loam;very weak fine and medium granular structure; friable;many fine roots; 10 percent angular coarse fragments 2 to 20 millimeters in diameter;medium acid; abrupt smooth boundary. B21-9 to 16 inches;yellowish brown(10YR 5/4)fine sandy loam that fades to light olive brown(2.5Y 5/4)with depth; very weak fine and medium granular structure; friable;common fine roots;many small worm holes filled with very dark grayish brown material from Ap horizon; 10 percent angular gravel;medium acid; clear wavy boundary. B22-16 to 23 inches;olive brown(2.5Y 4/4)fine sandy loam;common fine distinct gray to light gray(5Y 6/1)and yellowish brown(I OYR 5/6)mottles;weak medium subangular blocky structure;friable;few fine herbaceous roots; 10 percent angular gravel, 3 percent stones;medium acid;abrupt wavy boundary. A'2-23 to 26 inches; light olive gray(5Y 6/2)fine sandy loam;common fine distinct strong brown(7.5YR 5/6) and yellowish red(5YR 5/6)mottles;weak medium subangular blocky structure;firm; few fine roots; 15 percent angular and subrounded gravel,3 percent stones;strongly acid;abrupt wavy boundary. Cx-26 to 60 inches;light olive brown(2.5Y 5/4)fine sandy loam;common fine distinct strong brown(7.5YR 5/6) mottles;moderate to strong thick platy structure; very firm; 10 percent angular.gravel,3 percent stones;strongly acid. The depth to the firm or very firm fragipan ranges from 21 to 29 inches.The depth to mottling ranges 16 to 29 inches. The content of coarse fragments in the solum and substratum ranges from 5 to 30 percent.The reaction ranges from strongly acid to medium acid.The surface layer is slightly acid to neutral where limed. The Ap horizon has hue of l OYR,value of 3 or 4,and chroma of 2 or 3.The Al horizon is 1 unit lower in value or chroma or both.The texture of the A horizon is fine sandy loam or loam. The B21 horizon has hue of 7.5YR or l OYR,value of 4 or 5,and chroma of 4 to 6. It is fine sandy loam or loam. The B22 horizon has hue of l OYR or 2.5Y with value and chroma of 4 to 6 and is distinctly mottled.It is sandy loam,fine sandy loam,or loam. Some pedons do not have an A'2 horizon. The Cx horizon has hue of 2.5Y or 5Y,value of 4 or 5,and chroma of 3 or 4.It is sandy loam, fine sandy loam,or loam or thin gravely analogues. Merrimack Engineering Services,Inc. Section 5—Page 6 Printed: November 1,2007 N � ; r ,r. a Y- i ATM. a s Q C cl cl o t G U c a CfS a En 7K �`"fir r,=';°� E •" O u —° � X 1�% w o x o M G. Cd e O y K N Z m w .� a. rnayo y� o ' v ov N G O E U 00 ` r� ' V a v t o S a�i i e '' °•' � _ o tD o _� d x Q Location: Owner's Name: z0� MapRarcel• Addr= Wr Installers Tc1� Nn+'(��_liepslr . Dar--_I - `' . Wetlands --- Zone u— Sol.l Sjznbol LI Sall Mme2POW114C SoU Mu Deep-Obsematign Sole Logs EIM-Rtion Depth Soil Hpcimn Soil Trsture son Color Soil htottling. %Gravel,Stoners eta 5't rstrcntA[�tetW.�`lii�• DerRhq&dn �_st lti�lYstsrintbe8ala �fiscp4t�icowlllF�a gGLtf �' •ef a-t fit, ZA- _14 Ir Y'areatMatetW '• -t 1.. ikpthts8eir.dS .�.. 6p�dlo=tYsterfatl�aH�lc —' tYeeptn=[raatltFaee -- ESHGtYc 2� Date I'crcolation Tests '� ObsercntionHole� Depth of Pare Stut N"asl: Ttmc stt 124 Time at 9"' Time at 6" Time Rate Ni Onch°• -' Performed B�: . F � ' ' Witnrssed Bti� U2 0a