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HomeMy WebLinkAbout2006-05-30 Stomwater Mgmt Report I a / I " nnon� QENNONI ASS06kTZ 1n C' CONSULYSNG ENGINEERS 1 ' S rO RIW WA TER, MA NA GEMENT REPORT MERRIMACK COLLEG Elm street campus Entrance DEP File # 90.07 PREPARED FOR: E I i i 1111errimack Col Me I 315 Turnpike Street N. Andover, MA 01845 . ti May 2, 2006 ; Of AM Revised: May 9$ 2006 � l(p,TNLl:�hi Ell. is ClVll. NaQIIL N Prepared by: fi 33 QQ�° Pennoni Associates Inc. 40 Burtt Road, Andover, MA 01 a1 a � E I �6 Project#AAR C 0601 E Andover,MA OI B10 Tel:97i3.749.99Z9 . Fax:978.749.9420 Suite 120 Tel:603•z26.1950 Fax:603•226.3235 } 100 Burtt Road Salem,NH 03079 Suite 20i 93 Stites Road . www.pennani.com enn®ni FENNONI ASSOCIATES INC. C- 5ULTING ENGINEERS AARC 0601 May 24, 2006 Mr, Lincoln Daley, Town Planner Planning Department 400 Osgood Street North Andover, Massachusetts 01845 Re: Merrimack College Elm Street Campus Entrance Planning Board Review Dear Mr. Daley: Merrimack College proposes to relocate the existing campus entrance on Andover Street, No. Andover, 180 feet south to Elm Street, Andover. The new Elm Street Campus Entrance would be an implementation of a portion of the Merrimack College Master Plan and includes new entry drives and walkways, plantings, lighting and drainage improvements. The location of the new Elm Street Campus Entrance 180 feet south of the existing entrance on Andover Street moves the entrance back from the signalized intersection at Andover Street and Route 114, allowing for additional queuing length between the intersection and the entrance. No changes in the amount of trips to and from the campus are anticipated. The proposed work includes demolition of a part of Merrimack College Lot #1 and reconfiguration of a portion of a drive with parallel parking. The demolition and reconfiguration will result in a loss of 25 parking spaces. Over the last year, 12 spaces were added to the Sakowich Campus Center parking. To maintain the overall parking quantity on the campus, the access drive to Lot#1 from Rock Ridge Road will be striped for 13 parallel parking spaces. The project will undergo Site Plan Review in Andover and all the abutters within 300 feet in both North Andover and Andover will be notified of the public hearing on June 13, 2006, On behalf of Merrimack College, Pennoni Associates Inc. requests that the North Andover Planning Board waive Site Plan Review for the proposed project. At the Andover Interdepartmental Review Meeting on May 16, 2006, you were in attendance and recommended that Merrimack College present the proposed project to the North Andover Planning Board on May 30, 2006. Enclosed is the following for distribution prior to the May 301h Planning Board meeting: • 9 copies of this letter • 9 copies of the Site Plans • 9 copies of the Stormwater Management Report, 100 Bum Road Suite 120 Andover,MA 01810 • Tel: 978.749.9929 Fax:978.749.9920 93 Stiles Road • Suite 201 Salem,Nil 03079 • Tel:603.226.1950 Fax: 603.226•3235 www.pennoni.com Page 2 Mr, Lincoln Daley Town Planner May 24, 2006 We look forward to discussing the proposed project with the Planning Board and answering any questions they may have about the project. 4 Please do not hesitate to call me at 978-749-9929 should you have any questions or require additional information. Sincerely, PENNONI ASSOCIATES INC. Kathleen M. Noonan, P.E. Senior Civil Engineer cc: Robert Coppola, Merrimack College Jonathan Austin, Austin Architects I!. Iyy' V; I!. F:1 PROJECTS\Austin Architects-Merrimack College\correspondence\tetlers\Cover letter to Lincoln Daley 05-24-06.doc l i TAB OF CANT - I Report Cover IL -Table of contents pro. of oescription Management'. 111 Water lV Storm g Conditions . Existin proposed Conditions . Stormwater Quantity ater,Recharge Grour w Quality storm ater Calculations water Quality . Storm cries'. Rate Sum►n Street V peak ro Current pect—to Elm I Credit summaryrintouts Master Plan drocad P rainage Calcula Storm Events) VI � )-year 10 & 10 Vll Maps: ocus Map SCSL Soils Map for ent Dralnage M e Pre &post-devetopm eefg0.075Q) tranceonl , Elm Street en 1 tit. PROJEC sc Merrimack College oved ro osed site Changes existing ,Mould be m P ndover.The driveway across the with is the relocation of the tlon would be the osed hereAndover Street, The new loca ork would be �n The work prop from current location• onion of the w entrance driveway its c On1y a small p le south fromAndover. 180 feet to on Elm Street,ed wetland town line, of a vegetat feet of roximately 10,000 square gufler Zone relocation Would ta�o ynst9ng of app The driveway of aVemen , 1 Reduction p areas. areas• parking and drivewaYand parking hardscape)• 2• Re_striping driveway fixtures. trees,#lowers, manholes and of lighting features( catch basins, g Relocation landscaping improve 4. Addition of new e system imp of drainage 5. Installation quality unit)• water q Conditions xisting order o ter Management Plan" for With a Stormwa Conservation Compliance ,Master the Andover here is part of thews approved by The work pro s to Merrimack College, 90-0750. improvement MADE fife n Order of Conditions as follows. Commission and ment under Section 5.� of the C°)lege develop future Merrimack ace subject to the flow and owing This project falls and of this Order, e of Intentating peak er issuance Not+c ose °f evalu proposed 5,�: Alt outlined in the the pure filed where "section Within the watersdCommission for Notice of Intent uffer zone within the prop ctslards of review by the, including any or applicable b standar act , resource area water quality impacts) storm Within a P does not need to be work is located Activity ort to be Town of Andover• summary in an annual�rep ous area increase sf net irn ervi eXCept as a year, p < 2000 �0mmission,the end of each calendar y reported to the with the Commission at filed area by O gg cis far the 100- d reduce the runoff rate for the ar ork woul calculations) quality that Provide The proposed w See Hydrocad year storm event• ( Management Practices for water roject utilizeS Best M In addition,�valprate of 80/o. a a TSS rem 51912©06 Page 3 storlowater Report I IV. STORM MANAGEMENT' References; coed Ed., 1986) -for runoff curve numbers. 1. SCS - TR55 (Se Handbook 2. SCS- Rainfall Distribution o Handbook(Vol.s 1 & 2), Hydrology 3. DEP— Stormwate a closed system to achieve e system was designed utilizing ed area with the abutting f The proposed drainag Y courses.The similar drainage pattern to the existing This is The- reduced rates of runoff at the bound, drainageof the developed- ear events). r 2 10 & 100Y roadway, and would maintain e ill rainfalls ( Management guidelines. All methodology is SCS TR-20�Type uirements of DEP's Stormwater ana ed utilizing were develop consistent with the req resented in the following pages pertinent calculations rep software. f4ydrocad Stormwater modeling Existing Condltions: rid a series, described by SCS as follows: The on soils consist of Woodb g level to �� " consist of [earlyeormed in oodbridge series (SCS Classificati°n C ) W t moderately well drained soils on d dli loam or sandy loam steep, deep (5 feet},m° e soils have friable fine sa Y fine sandy loam compact glacial till. Woodbridg slow subsoil with moderate permeability h ha 1r slow or very surface soil an at 1S to 38 inches ston surface or sandy loam substratum stony or extremely YThey Woodbridge soils have a veTY permeability. oved, and have stones below the or limitations a� except where stones have been re stoniness and slope, seasonal high water table at 18 to 2`1 inches. have a perched, permeability in the substratum, are related to wetness,slow p ear used a hydrologic soil group°f licit tion, the design eng�n Based on the SCS descrip Drainage for the calculations. ment The existing drai s nage pattern on site is depicted on the Predevelo dove Street Map , North A shown, the entire site's surface run included here• off flows to Andover{known as Elm Street in Andover}. 519/2006 Page 4 Stonnwater Report Proposed Conditions: vement in water quality, With the Nation provide an irrrpro for water quality The proposed work would$ mps and oil hoods, and a Stormcep lace as pre- catch basins with deep the project area would flow to Nh r s in Compliance with me of treatment euni the Sheet drainage system.Theproposed developm d Master Stormwater Management Plan. the preViously approve stem in prior to entering the drainage system reduction of stormwater flows. water would be controlled and treated Storm Elm Street,which will experience Management Policy. Therefore, the project is subject to DEP's Stormwater This Provide g0%TSS and groundwater recharge. drainage system Is required top e Project complies with Massachusetts under pEP#g0--075a. For a full descussion of how nt Policy standards, see the plans and report f Managem stormwater Quantity Controls: e character rmwater qistics-and reducing impervious, the site By improving groundwater recharg quantity. will experience a reduction in sto Groundwater Recharge' 00 s.f. in impervious area would generate osed reduction of approximately '10,0 The prop groundwater recharge a natural Increase in g Stormwater Quality Controls: ,10%. n a scheduled basis.TSS Removal ndaredirect to be done o Sumps to capture, 1. Street Sweeping— TSS Removal Rate =25% 2. ting Catch Basins with Oil Hoods and d Dee system. I Rate = 71% stormwaee{aoW toward treatment unit.TSS Remova 3. Stormc p for the Elm Street relocation alit treatment discussed here is only Note: Stormwater quality for entire site analysis. project. See original filing i 5/912006 page 5 Stormwater Report I I� l Water Quality Calculations: i Note: All calculations are based on the area of proposed construction activities. Additional improvements to the existing site development are indicated on previous Site Plans. Calculations: TSS Removal Average Annual Load: 1.00 x Street Sweeping removal rate (0.10) = 0.10 Load Remaining = 1.00 - 0.10 = 0.90 Remaining Load: 0.90 x Catch Basin removal rate (0.25) = 0.23 Load Remaining = 0.90— 0,23 = 0.67 Remaining Load: 0.67 x Stormceptor removal rate (0.71) = 0.48 Load Remaining = 0.67—0.48 0.19 TSS Removal Rate = 80% The BMPS to be used are: -RUNOff WATER W'IT11 SEO]IJENT GRAVEL(12"ON.GEPTII) 38' NIR. mill � LI1—L�I�f`: • , �h�=III�I�J ' '' WIRE MESH 5E9E UIT MTEREU WATER Inlet Protection X�— 4LT JE a 6 HAY 6MC 9AP-S xrs X 3 Stormwater Report Page 6 5/9/2006 i DOUBLE CATCH BASIN TRAUE G GRAIL Nws4 NOTES: CRAOE B'T 4H'DNA. 8` 5.BASE SECpQ'F SHnLl B[VONOGIHIC KITH A 1B'I-M DIAMETER. 2.Ail SECTIONS SHALL BE DESIGNED FOR ! 51:E i 8S-25 LOAO m NOSE 7 T 3.CONCRETE SHALL BE COWAFSS W 'OP STRENG111 4000 P9,TYPE 11 CEVENT, SLAB 4.FRAMES AND CRATES SHALL BE MAW fi0'g0.1a—...,.... CATCH B'19N� WM AIM DES!GHTO FOR HS70 LOAdh& SECTION A-A 5.PROME''f KNOCKOUTS FOR PEES MIR 2'MAY CLEARANCE TO OUTSIDE OF PIPE. NM—ALL PIPE CONNECLMS. D WiiLC[AIpT BA4N F,J014T SCAW4I 43E TPCC14 MtCAST SECTI0115 SHALL BE W71 PMBBCR. 'RAW&GRAIE -nmsi A4 7,STAROARO CATCH BASH FRAME AHD li GRADE GRATE SNALL OE SCT III FllLL MOIITAR BED. ADAl51 TO"R C W"CLAY ORCK ANL ! WORTAR(2&RII L CWRSES TIPICALLY, 5 F.C.COI1R5E5 uAx'MMv) SEE H.ON ALL CO'S,PROWE AN ADSORB[NT SOCK NOTE 7- OR FLOATER TW S Ag 1.48'dA^I —SEE NOTE 6 i 90'DIA CATCH BASIN WHET I i a � A� -CATCH BASIN TR yA IRARON L-219-1 ------- 1 LION-SNR�N% � GRONT TIP. 11'[DUPACI£D ACCEPTPBCC 3VB0RADE AS GR0.LLL BORRON DETEAM'RCO BY ML F]I--. DOUBLE CATCH BASIN VATH HOODED TRAP !.. N.7.R FRAME h GRATE TOP OF OWE ADAUSTBLS e HANDLE FOR 4"0 PVC PIPE REMOVABLE V14.15"HIG VAR ES fNIME AF10 TEE y/1"CEP SIORYCCTHOR IT INSERT W PA4 iHlEl' _____ SEE NOTE 2 �! I O�iEt 4"0 PLC PIPE CIEANOUT/VENT PIPE 4"0 OUTLET RISER PIPE iv�E'i I I 4"0 fNLET 4°0 OUTLET s ��• _ I I WI�Lt !. DOWN P,PE RISER PIPE I __-- (RCMOVAHB} I'If NEEDED INSERT COME AND TEE HERE !, 8 (TEE OPBIINGS 10 FACE SIDE RAILS) SECION THRU CHAMBER SECTION THRU PLAN VIEW N07E: I 1.THE USE OF FLEABL£CONNECTIONS IS RECOUtAENCE0 AT THE OUTLET MERE APPLICABLE. ' 2.THE COVER SHOULD BE POSITIONED OVER THE 4"0 CLEANOUT/VENT PIPE AND ME 4"0 INLET DOWI4 PIPE, ! S.THE STORIACEPTOR SYSTEM IS PROTECTED BY ONE OR NORE OFF THE FOLLOWING U.S.PATENTS: #4085148,#5498331. #5725760,#5753115,95849181. 4.CONTRACTOR TO PROVIDE CRANE TO SET UNIT(HEAVIEST SECTION WEIGHS 5000 L8) STORMCEPTOR StorniNvater Report Page 7 5/9/2006 Stormceptor Sizing Table Version 3.0.0 i Particle Size Distribution Selected Rainfall Station �_- - ~o Velocity fills) -- - - ` Diameter(um) Percent(/o) State MASSACHUSETTS 0.0013 BIRCH 20 20.0 CH HILL DAM Name 0.0052 ID 666 6D 20.0 Etev.(ft) 864 38 min 20.0 0.0351 Latitude N 42 deg 150 Longitude W 72 deg 7 min 400 20.0 0.2116 Site Parameters 2000 20.0 0.9416 ` - Note:Sizing Results vary with particle size 2 comparisons must use the distribution.SNIP comp Total Area(ac) 70 same particle size dlstritAl please ith 'r dWributlons imperviousness No) 0 (B00)909-77e3 for sizing impervious Area(ac) Stormceptor Sizing Table -� %TSS Removal o/oRunoff Treated Stormceptor Model 71 0 82.8 STC 4501 79.9 93.2. STC 900___- 80.0 STC 1200 93.2 80A _ 93.2 STC 1800 ---� 84.2 96.6 STC 2400 85.0 96.6 STC 3600 87.9 98.6 STC 4800 88.3 98.6 STC 6000 90.2 99.3 ----- STC 7200 92.8 99.5 STC 11000 93.0 STC 99.5 13000 94.3 99.7 - - STC 16000 Comments: Merrimack Coilege Model Selected:STC 4501 Total TSS Removal 1of 0,0%based on: Street Sweeping @ peep Sump C13s @ 250% Stormceptor @ 71 P i I' 11. Peak Date Summaries N ote: All rates are shown in cubic feet per second (CFS). Storm Pre-Deveto ment Post-Devet0 meet Point of Ana! sis S 5.6 2-Year 6.17 10.16 10-Year 10.81 16.58 Urn Street ea 17.27 100-Yr t. 5/9/2006 Page 8 stonnwater Report ennoni Hydrocad PRE-DEVELOPMENT. 2, 10 & 100-Year Storms E F Amendment to OOC.doc Page 7 5/l/2006. i k A t" Z Eirn street Flowso l e QEagram for p,ARC 0641 -pred 51112006 n �I Drafnag lnc. aC�l -<p Ltnk:. droCAPrepared D@ 7 10 sin 002,66 0 2005 HydrocA 5oflware Solulians LtG Subca. Re .. HY Architects-Merrimack CollegeWrainage� Type Ill 24-hr 2-Year Rainfall=3gea2 pROJECTSWustin A 01 - Predevebp rrlent 51112006 ARC 06 es Inc. c ciat LL 550 solutions- repared by Penn oni A sot droGAD®7.10 sin 002166 ©2005 N droCAD Software 0.00 hrs, dt=0.05 hrs, 301 points Time span=5.00-2 Runoff by SCS TR-20 method, t fH=SC b Star-Ind method Reach routing by Stor-Ind+Trans method - Pond routing y a-131,844 sf Runoff Depth>1•40" Runoff Are chment 1 S: Flows to Elm Street Flow Length--475' Tc=3.0 min CN=84 Runoff-6.17 cfs 0.375 of 5uhcat th Total Runoff Area-3.027 ac Runoff Volume=0.375 of Average Runoff Dep o: i i i k: V'. Vi i. i r I I' i; 1 j; I. eldrainagel Type III 24-hr 2-Year Rainfall=3.10" Page 3 PROJECTS1Austine elopcmenterrirnackColleg 51112006 NRC 0601 - Pred epared by Pennon: 5 H Associates, Inc. Software Solut(ons ILL droCApp 7.10 sin 002166 ©200 droCAD S to Elm Street Subcatchment 1 S; Flow 12,05 hrs, Volume= 0.375 af, Depth> 1,41" wnoff - 6.17 cfs @ runoff by SCS TR-20 method, UH=SCS,Time Span::' 5*00-20.00 hrs, dt=0.05 hrs Type III 24-hr 2-Year Rainfall=3.10" Areas CN Descri tion 77'874 74 >75% Grass cover, Good, HSG C 53 970 98 Paved arAver Average ofs 131,844 84 Weighted Velocity Capacity Description To Length Slope cfs feet ftlsec sheet Flow, 3,10" min 1,0 0.011 P2= 0.4 25 0.0200 Smooth surfaces n= Shallow Concentrated Flow, 2.6 450 0.0200 2 Paved Kv= 20.3 f s 3.0 475 Total Subcatchment 1S: Flows to Elm Street liydrograph p Runoff 1 , t - - ar I_ 11 -- - Yee Q RainFafI=3.1_ - -- i 844'sf _,- - - s- --- Hoff Area=13 1 II I 1 ' 10- >7-5- - a f 5 _ Runof ,Vohume- ' .4,Runo4 DeIpth .,4 5�- t I E , I ; , I t 1-. .� , �loiiv-Lengt f 2 t 1 y E I 2,0, V 13 14 10 15 16 17 18 ._ 11 6 7 8 9 Time (hours) jl ,I. I I' t f Architects-Merrimack Collegeldrainagel Type 11124-hr 10-year Rat'nfallPeo4' PROJECTS1Aust�n 5/112006 ARC 0601 - Predeve{op ment epared by Pennont Associates, Inc. 7.10 sin 002166 OO 2005 H droCAD Software Solutions LLC droCADO Dints Time span=5.00-20.00 hrs, dt=p.Q5 UH SCS Runoff by SC S TR-20 method, b Stor-Ind method Reach routing by Stor-Ind+Trans method - Pond routing Y Runoff Depth>2.64" Runoff Area=131,844 sf Flow Length=475' Tc=3.0 min CN=84 Runoff-10'81 cfs 0.686 of ;ubcatchment 1S: F1ows to Elm Street ''. = Volume =0.666 of Average Runoff Depth _2.64" Total Runoff Area 3.027 ac Runoff ; i, 1. i-, E i Type 11124-hr 10-Year RainfallP,50"9 _PRO.IECTS1Austin Architects Merrimack CoNege\drainage\ 06 ARC 060'1 - Predevelopme 511120 -epared by Pennoni Associates, Inc. droCAl]®7.10 s/n 002165 ©2005 H droCAD Software Solutions LLC Subcatchment is: Flows to Elm Street 12.05 hrs, Volume 0.666 af, Depth' 2.6N, runoff = 10.81 cfs @ -20 method, UH=SCS, Time Span= 5.00-20.00 hrs,dt=0.05 hrs Zunoff by SCS TR f ype III 24-hr 10-Year Rainfall=4.5011 Areas CN Descri lion 77,874 74 >76% Grass cover, Good, HSG C 53 g70 98 Paved ar4cin &roofs 131,844 84 Weighted Average Slope Velocity Capacity Description Tc Length ftlsec cfs min feet 1 0 Sheet Flow, 3.1011 0.4 25 0.0200 Smooth surfaces n=0.N P2= 2 9 Shallow Concentrated Flow, 2.6 450 0.0200 Paved Kv=20.3 f is 3.0 475 tal To Subcatchment is-. Flows to Elm Street ---Hydrograph -, 7 Runoff ---- j __ 1 -^ 3 12 -- - '----- - f-_-- Yezar--- ---- ---Typo-Ill-24-hr-iO- 11 FZainfall-4.�l0'"- - -- - - 10 -R J31;844�S -- unof qr�a_ ! =O:666i1af.-- - - �I v -i LVOf e 8 - -- Runoff l , -- >2.64-- ---- - -- Ronoff Depth 7 _ --- Flow Length=415' u. _ - T =3irp in- 5 ----- --CN-84- 4 ---1 - 3 _ t t , 1 1 17 18 1g 20 .�°� .', 12 13 14 15 0 5 , _ .. 6 7 8 _ S 10 91 Time (hours) I is 1': i ,i_PR©JECTS1Austin Architects-Merrimack Collegeldrainagel ARC 0601 - Predevelopment Type !U 24-hr 100-Year .Rainfall=6.40" repared by Pennoni Associates, Inc. Page 6 droCADO7.10 s/n 002166 2005 f1 droCAD Software Solutions LLC 5/1/2006 Time span=5.00-20.00 hrs,dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method �ubcatchment 1S: Flows to Elm Street Runoff Area=131,844 sf Runoff Depth>4.31" Flow Length=475' Tc=3.0 min CN=84 Runoff=17.27 cfs 1.088 of Total Runoff Area=3.027 ac Runoff Volume= 1.088 of Average Runoff Depth =4.31" i i 8 i 3 m iz�:1_PROJECTSIAustin Architects- Merrimack Collegeldrainagel AARC 0601 - Predevelopment Type 11124-hr 100-Year Rainfall=6.40" Prepared by Pennoni Associates, Inc. Page 7 H droCAD©7.10 sln 002166 ©2005 H droCAD Software Solutions LLC 5/1/2006 Subcatchment 18: Flows to Elm Street e Runoff _ 17.27 cfs @ 12.05 hrs, Volume= 1.088 af, Depth> 4.31" Runoff by SCS TR-20 method, UH=SCS,Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 1 Type III 24-hr 100-Year Rainfall=6.4011 Areas CN Description 77,874 74 >75% Grass cover, Good, HSG C 53,970 98 Paved parking & roofs 131,844 84 Weighted Average Tc Length Slope Velocity Capacity Description min feet fUft ftlsec cfs 0.4 25 0,0200 1.0 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.10" 2.6 450 0,0200 2.9 Shallow Concentrated Flow, Paved Kv= 20.3 fps 3.0 475 Total Subcatchment 1S: Flows to Elm Street Hydrograph 19 --- - i ---�--- :- --- -- -- �Runoft 17 - --- -- - - -- --Type !lll 24-hr'100 Year--- 15 --- --------- - _-,._.J-- ---E --- -- ! 14 --------- l--- - ------- Runoff Ar a '13'1 -844;sf- i ----- ------ -- ---= -'- -- ---- ---- - 13 ----- t , ' i f 12 '. -- E-- --- -;-- --- Runoffr',V-o1..ume=t088-kaf-- .. - Ru hof -Depth?4.3',o ._ n gth=4T5'�. . - I - - - -- -- ---- - -- Tc-3P0-nin- 6 - —8 f ! 4 -- --- --- --- --- -- ..._ f E - . 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ennoni Hydrocad POST-DEVELOPMENT: 2, 10 & 100-Year Storms i l i' Page 8 5/l/2006 Aniend►nent to OOC.doc I t y� z r v �?a vian y a � S Y I Flows to Elm Street Subaa= Reach 01� , LIn Drainage Diagram for AARC 0601 -Postdeveiopment Prepared by Pennoni Associates, Inc. 5/1/2006 HydroCAD@)7.10 s/n 002166 ©2005 HydroCAD Software Solutions LLC F:1_PROJECTS1Austin Architects-Merrimack Collegeldrainagel AARC 0601 - Postdevelopment Type III 24-hr 2-Year Rainfall=3,90" Prepared by Pennon! Associates, Inc. Page 2 H droCAD®7.10 sln 002166 ©2005 H droCAD Software Solutions LLC 5I112006 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind*Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Flows to Elm Street Runoff Area=131,844 sf Runoff Depth>1.35" Flow Length=475' Tc=3.0 min CN=82 Runoff=5.61 cfs 0.341 of Total Runoff Area=3.027 ac Runoff Volume=0.341 of Average Runoff Depth = 1.35" F:1_PROJECTS1Austin Architects-Merrimack Collegeldrainagel AARC 0601 - Postdevelopment Type/1/24-hr 2-Year Rainfall=3.10" Prepared by Pennon! Associates, Inc. Page 3 H droCAD®7.10 sln 002166 ©2005 H droCAD Software Solutions LLC 5/1/2006 Subcatchment 1 S: Flows to Elm Street Runoff - 5.61 cfs @ 12.05 hrs, Volume= 0.341 af, Depths 1.35' Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt=0.05 hrs Type III 24-hr 2-Year Rainfall=3.10" Area (sfl CN Description 87,635 74 >75% Grass cover, Good, HSG C 44,209 98 Paved parking & roofs 131,844 82 Weighted Average Tc Length Slope Velocity Capacity Description min feet OR) ft/sec) (cfs 0.4 25 0.0200 1.0 Sheet Flow, Smooth surfaces n=0.011 P2= 3.10" 2.6 450 0.0200 2.9 Shallow Concentrated Flow, Paved Kv=20.3 fps 3.0 475 Total Subcatchment 1 S: Flows,to Elm Street Hydrograph I f . 1 I f 6 Type III 24,hr 2-Y6ar -- -- Rainfall=3, " 6 j Runoff Aroa='131-,844.'ISf_- E ; Ru6off,Volume-0.341 ;af 4 a I F I i i f f f 1 Runoff Depth>1 .35"... . 3 ;E Flow Le6gth=475' -- ---- -- -- --- _____-- - - T-c-30 min - ; ------ 2 ' CN=82 1 f E 04 ` 5 g 7 �g ,,g- 10 11 12 13 14 15 16 17 18 19 20 Time (hours) :1 PROSECTS\Austin Architects-Merrimack Coliegeldrainagel Type /it 24-hr '10-year Rainfall .50 Page 4 ARC 0601 - Postdevelopment 51112006 prepared by Pennoni Associates, Inc. A droCAD®7.10 s1n 002166 O 2005 H droCAD Software solutions LLC hrs,dt=-0.05 hrs, 301 points Time span=5.00-20.00 Runoff by SCS TR-20 method, UH=SCS Star-Ind method Reach routing by Stor-Ind+Trans method - Pond routing by Runoff Area=131,84 Runoff 0.16 cDfsP0.622 of Subcatchment IS: Flows to Elm Street Flow Length=�475' Tc=3.0 min CN=82 Runoff ffV plume=0.622 of Average Runoff Depth =2.47'0 Iota! Runoff Area-' 3.02 7a c Run off i i i it i. i. 1 Iq. i1: - S1Austin Architects-Merrimack Cnllege\drainagel T e 111 24-hr 10-Year Rainfa11=4.50" -:1_PROJECT YP -Page 5 AARC 0601 - PoondevellopmeAssociates,nnc. 511/2006 Prepared by den H droCA166 O 2005 H droCAD Software Solutions LLC D0 7.10 sln 002 Subcatchment IS: Flows to Elm Street Runoff - e= 0.622 af, Depth> 2.47" 10.16 cfs @ 12.05 hrs, Volum CS TR-20 method, UH=SCS,Time Span= 5,00-20.00 hrs, dt=0.05 hrs Runoff by S �i - .50 _ ' fall-4 _ ar Rain -type 1}1 24 hr 10 Ye Areas CN Descri tion $7 635 74 >75% Grass cover, Good, HSG C 44 209 98 Paved parking &roofs 131,844 82 Weighted Average Tc Length Slope Velocity Capacity aps Description min feet ftlft Sheet Flow, 0.4 25 0.0200 1.0 Smooth surfaces n= 0.011 P2= 3.10 2 6 45© 0©204 2 g Shallow Concentrated Flow, Paved Kv=20.3 f s 3.0 475 Total Subcatchment IS: Flows,to Elm Street Hydrograph - i 1 ;--- - -- -- ; ;,o:,ss _-- ---T p 111 Z4-hr 10-Ye'ar - Y ----T---- io -------- ,- Rainfall=4.50" --- . 3 -- ---j-- - 9 -- - --' -- -- �- Aria-'131,844'sf Runoff 8 Runoff,Volume=0.622`af 7 _ Ru,n o ep 2 6 -a-- De __--h=475' Flow ngt c=30 min C I 2 d 117 ' s � r; 14 16 17 �g 49 20 0 15 5 6 . <. 7 .' 8 9_ . 10 11 Time (hours) y, 1'. t r, i ack Colle eldrainagel Merrimack g • PRO.fECTSIAustin Architects _ -Year Ralnfall=6,4011 �•� Type 11124 hr ?00 AARC 060'I - Postdevelopment page 6 Prepared by Pennon! Associates, Inc. 5i112006 droCADO 7.10 s/n 002166 © Ff 2005 droCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SC S TR-20 method, UH=SCS Reach routing by Stor-End+Trans method - Pond routing by Stor-Ind method Subcatchment 1 S: Mows to.Elm Street Runoff Area=131,844 sf Runoff Depth>4.10" Flow Length-475' Tc=3.0 min CN=82 Runoff=16.58 cfs 1.034 of Total Runoff Area =3.027 ac Runoff Volume=1.034 of Average Runoff Depth=4.10" f l I 1 F:1—PROJICTS1Austin Architects- Merrimack Collegeldrainagel AARC 0601 - Postdevelopment Type 11124-hr 100-Year Rainfall=6-40" Prepared by Pennoni Associates, Inc. Page 7 H droCADO 7.10 sfn 002166 ©2005 H droCAD Software Solutions LLC 5/1/2006 Subcatchment IS: Flows to Elm Street Runoff = 16.58 cfs @ 12.05 hrs, Volume= 1.034 af, Depth> 4.10" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5,00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Areas CN Description 87,635 74 >75%Grass cover, Good, HSG C 44,209 98 Paved parkhg_&roofs__ 131,844 82 Weighted Average Tc Length Slope Velocity Capacity Description min feet ftlft) (ft/sec) (cfs 0.4 25 0.0200 1.0 Sheet Flow, Smooth surfaces n=0,011 P2= 3.10" 2.6 450 0,0200 2.9 Shallow Concentrated Flow, _ Paved Kv= 20.3 f2s _ 3.0 475 Total Subcatchment 1S: Flows to Elm Street Hydrograph Runoff 1868 ifs` 3 17 f 16 T e FIII 24 hr_100-Ye'ar -- -----I- ,-- --- ---- Yp- J_ - , - I 40 15 --- --------- ---- - --- . - --- ---- -- "�- -I--- - Raiirifiall-=6-. - 14- - - _----__--- --- - --- - --- -,-- 13 _ _Runoff_Ar_ba-13.1,8.44;sf__ --- ' RunoffVolume='I;0 12 -----I--------... .... ........ ' - I ---, - -- ii ` 10 Runoff D :._ p . e` th?4.10'.. . I a g ow Le gth=475' r 7 f ---------------------; --- --- _- r- ------ - -- T,c=3 0 njin 6 ___ -- '- -- ---- - -1--------- --- ----'--- w' t- 5 - i - - CN=82 I I 4 3 ----,-----1----- ---------- ----.. -'F---- - _... ..-.... -- :- --_ ; 2 ..---'- - -- 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Timo (hours) ennoni i MAPS: Amendment to OOC.doc Page 9 5/1/2006 ��, s rr �) ��• � � /SST;/! ���f' 4Er�a'f-.'+llwTi 1 - t 44 11 DU Rim- VA EVA w VIA Al. k RMv Rw f r, xp IRROM4 t�2 IN ri, . :, {JQinssheat23) 2 F ESSEX' COUNTY, MASSACH ��,. - r � f"'� i�ry�•���lt }r4 '°*Tx�i��FvY ny� �+r �r�e � �,�'�` �fi r i, ) ;.. rcy," "j 5 �tt # i �;3 x Sys A� � ¢¢r �,, � ��, 7�'� �f �x � ,� 3 4' �'•sue trx. r 3 - t& -tbA 'r �! d ��•��tiT'� � Te�i-y� '* �Y 5 ; 1 �l �- �1�tz.� �z• �$5�12' � t�r ,ft bk., r 5� +�� �`�„ t-C � '� l rh; 1're%�t'��3`• �` .. � R'�sKst '� "* � I'M c qx- 1' �,z 1 N�•. �� ��'�. .' 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