HomeMy WebLinkAbout2004-02-05 Stormwater Report I Drainage and Stormwater Quality Report ewd od Shops Eagl Retail Development North .Andover, Massachusetts Prepared for Eaglewood Properties LLC PO Box 337 Topsfield, MA 01983 Prepared by WMNanasse Hangen Brustlin, Inc. Transportation, Land Development, Environmental Services 101 Walnut Street P.O. Box 9151 Watertown,Massachusetts 02471-9151 617 9241770 RECOVED up 1 9 900j NORTH ANI:OVER PLANNIN13 DEPA11TIA PAT September 2003 ; VM Vanasse Hangen Brustlin,Inc. 1 Proposed Conditions ................................................................................................._.............................,............................................................. Summary The project will include the construction of approximately 80,000 square feet of retail and restaurant space.The construction will include vehicular access,paved parking areas,and utility improvements associated with the proposed building construction, The Site surface stormwater drainage system was designed to comply fully with the Massachusetts Stormwater Management Policy as well as general drainage design requirements of the Town of North Andover,Massachusetts. Existing drainage and grading patterns were maintained to the maximum extent possible. The proposed development has been designed to collect stormwater runoff from impervious areas on the site in a closed drainage system.The dosed drainage system collects stormwater runoff in catch basins with 4-foot deep sumps and hooded outlets before discharging into a proposed extended detention pond with sediment forebay.Runoff from the remaining Site open space will be routed into the wetland area via overland flow.A 100-foot BVW Buffer and 25-foot no-build zone restricts development and disturbance in the wetland area. Water Quantity and Quality Control Deep Sump/Hooded Catch Basins. Catch basins at the site are to be constructed with sumps (minimum 4-feet) and hooded outlets to trap debris,sediment and floating contaminants. Extended Detention Basin with Sediment Foreba .The infiltration/detention basin is designed to hold and infiltrate surface stormwater runoff from rainfall events up to 0.5 inch below the outlet culverts.The infiltration volume is in excess of DEP requirements for infiltration for hydrologic soil groups'B'and'C'.The sediment forebay is designed to hold and infiltrate surface stormwater runoff from rainfall events up to 0.1 inch below the outlet culverts, according to DEP guidelines(water quality volume calculations are included in the appendix).Runoff from larger events is collected and treated prior to being discharged through the basin outlet control L.\08354\does\reports\Drainage\08354_DrainageReport-03-09.doc 7 Proposed Conditions vM Vanasse Hangen Bnvstlin,Inc. culvert and weir.Proposed peak discharge rates match or are reduced from existing peak rates of stormwater runoff.The basin surfaces are vegetated with water-tolerant grasses. Based on subsurface investigation of Site soils and groundwater, the proposed extended detention basin elevation may be revised to provide a minimum 2-foot separation from the high groundwater table. Hydrologic Information For the proposed conditions hydrologic analysis,the site was divided into two drainage areas(see Figure 4-5). These areas discharge to the single design point where peak discharge rates were evaluated for both existing and proposed conditions. Drainage Area 1—Thus approximately 11.1 acre area includes all of the proposed development and the Existing Northmark Bank parcel.Stormwater surface runoff from this area is collected in a closed drainage system and routed to the proposed extended detention basin and sediment forebay.Runoff from the detention basin that is not infiltrated is discharged at a reduced rate to the existing wetlands. Drainage Area 2—This approximately 1.1 acre area includes portions of the Site that will not experience an increase in impervious area.Due to the construction of the extended detention basin and sediment forebay,most of this area will be regraded and replanted.Runoff from Drainage Area 2 will continue to discharge via overland flow to the existing wetlands. Table 2 summarizes the key hydrologic parameters for each drainage area used in the proposed conditions analyses. Table 2: Proposed Conditions Hydrologic Data Description Discharge Design Area Curve Time of (Drainage Area#) Location point (acres) Number Concentration(min) 1 Detention 1 11A 88 8.8 Pond 2 Wetlands 1 1.2 70 5.0 The site complies fully with the total suspended solids removal requirement of the Stormwater Management Policy.The calculated TSS removal rates for the site are shown on the Worksheets included in Appendix C. Lr\08354\dots\reports\Drainage\08354_Drainage Report-03-09.doc 8 Proposed Conditions MB Vanasse Hangen Brustlin,Inc. i Table of Contents ProjectSummary....................................................................................................................2 ExistingConditions...............................................................................................................4 ProposedConditions.............................................................................................................6 HydrologicAnalysis............................................................................................................10 StormwaterRegulations.....................................................................................................11 Figure 1:Site Location Map Figure 2: Existing Drainage Areas Figure 3:Proposed Drainage Areas List of Tables Table 1:Existing Conditions Hydrologic Data Table 2:Proposed Conditions Hydrologic Data Table 3: Peak Discharge Bates Appendices Appendix A: Floodplaln Information Appendix B:NRCS Soils Information Appendix C:TSS Removal Worksheet Appendix D: Hydrologic Analysis Appendix F:Long Term Stormwater ON Plan Appendix F:Hydraulic Calculations L:\08354\dots\reports\Drainage\08354_Drainage Report-03-09.doe i Table of Contents Vanasse Hangen Brustlin,Inc. Project Summary The approximately 13.3 acre Site is located along the Salem Turnpike (Route 114) in North Andover,Massachusetts(see Figure 1). The Site is bounded by the Salem Turnpike (Route 114) to the northeast,two residential lots to the south,the Town of Andover municipal boundary to the southwest,Waverly Road to the west,and residential lots to the north.The Site is located within the surface watershed of the Shawsheen River. Wetland Resources on the Site includes approximately 3.4 acres of BVW and associated wetland buffer zones. The Site is presently occupied by residences,and surrounds a parcel occupied by Northmark Bank.Under existing conditions,untreated stormwater runoff flows overland in a westerly direction into the existing wetland area. The proposed development of the site includes approximately 79,000 square feet of retail and restaurant space with paved parking areas and access drives.The Northmark Bank parcel will remain with additional access to the bank included in the design.Under proposed conditions,stormwater runoff will be collected in a closed drainage system and treated prior to discharge into the existing wetlands.The closed drainage system consists of hooded catch basins,storm sewer pipes and a proposed extended detention basin with a sediment forebay. Wherever possible,existing drainage and grading patterns were maintained in the proposed design. Additionally,water quality and quantity control measures such as parking lot sweeping and rip-rap outlet protection have been designed to protect the surrounding natural resources from potential stormwater runoff impacts. A HydroCAD model,using TR-20 methodology,was developed to evaluate the existing and proposed drainage conditions on the Site. The results of the analyses indicate that there is no increase in peak discharge rates between the pre-and post- development conditions for the 2-, 10-and 100-year storm events.The pre-and post- development peak discharge values are presented in Table 3 at the end of this report. The Stormwater Management flan(the Plan),including Best Management Practices (BMPs)for maintaining stormwater runoff quality both during and after construction,was prepared in accordance with the applicable local,state,and federal regulations. Details of the flan are provided herein. L:\08354\does\reports\Drainage\08354_Drainage Report-03-09.doc 2 Introduction • tr 171 wrff wM�� N lob Mi ® ¢ f Vanasse Hangen Brustlin,Inc. 114 fi, ' �- - 1, •i , 1 Ito its too M off VHB Vanasse Hangen Brustlin,Inc. Existing Conditions ................................................................................................................................................................................. Summary The approximately 13.3 acre Site is located along Route 114 across the street from the Eagle Tribune. Key natural resources in and around the property include 3.4 acres of BVW with a 100-foot wetland buffer. See Figure 4-4. The project is not located within the 100-year flood plain as shown on the Town of North Andover,Massachusetts,Essex County Flood Insurance Rate Map, Community-Panel Number 250098 006 C,June 2,1993,included in Appendix A. The existing site topography varies from a high point of 189 feet at the eastern corner of the site along Route 114, to a low point of 90 feet at the western corner of the site at Waverly Street.Slopes range from almost flat to very steep. The site is partially developed with two existing residences,associated impervious driveways and parking areas.The undeveloped portions of the site are primarily wooded.The soils on the Site are classified by the Natural Conservation Service (NRCS)map as a mix of Charlton,Canton,Paxton,Scituate and Ridgebury soils. These soils are classified as hydrologic soil groups(HSG)B and C,and are described as fine sandy loam.Detailed soils information and map is included in Appendix C. ........................ ................... ............................. .............................................. Hydrologic Information For the existing conditions hydrologic analysis,the site was analyzed as one drainage area,contributing to one design point,where peak discharge rates were evaluated (see Figure 4-4).This 12.25 acre area was defined by Route 114 to the northeast, wetlands to the west,and Site boundaries on all other sides.This area includes developed and undeveloped portions of the existing Site,as well as the Northmark Bank parcel,including rooftops,pavement,woods and open space. Table 1 summarizes the key hydrologic parameters for each drainage area used in the existing conditions analysis. L:\08354\docs\reports\Drainage\08354—Drainage Report-03-09,doc 4 Existing Conditions i �g Vanasse Hangen Brustfin,Inc. i Table 1: Existing Conditions Hydrologic Data Description Discharge Design Area Curve Time of (Drainage Area#) Location Point (acres) Number Concentration(min) 1 Wetlands 1 12.25 67 28.8 1 i i L:\08354\does\reports\Drainage\08354_Drainage Report-03-09.ctoc 5 Existing Conditions 1 vim Vanasse Hangen Erustlin,Inc. Hydrologic/ Hydraulic Analysis Hydrologic Analysis The rainfall-runoff response of the Site under existing and proposed conditions was evaluated for storm events with recurrence intervals of 2-,10-and 100-years. Rainfall volumes used for this analysis were based on the Natural Resources Conservation Service(NRCS)Type III,24-hour storm event; they were 3.1,4.5 and 6.4 inches, respectively. Runoff coefficients for the pre-and post-development conditions,as previously shown in Tables 1 and 2 respectively,were determined using NRCS Technical Release 55(TR-55)methodology as provided in HydroCAD. Drainage areas used in the analyses were described in previous sections and shown on Figures 2 and 3.The HydroCAD model is based on the NRCS Technical Release 20(TR-20)Model for Project Formulation Hydrology. Detailed printouts of the HydroCAD analyses are included in Appendix D. Table 3 presents a summary of the existing and proposed conditions peak discharge rates. Table 3: Peak Discharge Rates (cfs*) Design Point 2-year 10-year 100-year Design Point 1,Wetlands Existing 4.3 11.5 23.2 Proposed 4.3 7.1 21.0 "expressed in cubic feet per second The results of the analysis indicate that there is no increase in peak discharge rates between the pre-and past-development conditions for the 2-,10-and 100-year storm events. L:\08354\does\reports\Drainage\08354_Drautage Report-03-09.doc 10 Hydrologic/ Hydraulic Analysis i vB Vanasse Hangen Brusttin,Inc, Appendix A: Floodplain. Information L:\083541docs\reports\Drainage\08354_Drainage Report-03-09.doe 11 5tormwater Management Plan i WAVERL_Y ROAD APPROXIMATE 5CALi 400 0 400 FEET NA7IQNA1 FLOOD INSURANCE PROGRAM ZONE X 114 FIRS[ FLOQUNSURANCE RATE MAP Project Site TOWN OF NORTH ANDOVER, MASSACHUSETTS ESSEX COUNTY PANEL 8 OF 15 G (SEE MAP IN OEX FOR PANELS NOT PR INTeW PANELLOCATION P COMMUNITY-PANEL IUMBER 250098 0006 0 MAP REVISED: ' JUNE,2, 1993 G Z Federal Emergency Management Agency This is an official copy of a portion of the above referenced flood map. It was extracted using F-MIT On Une. This map does not reflect changes or amendments which may ha%m been made subsequent to the date on the title block. For the latest product information about National Flood Insurance Program flood maps check the FEMA Flood Map Store at www.msc_fema.gav Full[irim I Vanasse Hangen Bmstfin,Inc. Appendix B: NRCS Soil Survey Information L:\08354\does\reports\Drainage\08354_DrainageReport-03-09.doc 12 Stormwater Management Plan low Ail �!:, YV t'c.. -�t'i V. '✓ - : ,apt. r J B '_Z� - Yvs � �r4 - � '�. x r•r� �� b ri ��+ t ry. 3- ��� r s �s � Y `S.��f: � y'��rc:�x 'sv^�- t3�t.rx �,� ¢- •��,cr ��, _3�� � �x rCIk' C r l-Z �< � -� too" iyhk �f v � �25c- �r ',MJMM a..� 5] .X- k4 S_ C's - 3 r i v �eass xr,.s M, P' log s x r 1 'L ] ���,, f ``'� f)" � i �r `- -11�!r�7 S's� rr..r+� is i� ° � -����r•` x §�. i _ iu f a �� � t,di -Y+s _ I '� , L Fs h £+ ,.aa �S .�� ,� 1s t: 3'q,,, ! ��i r�,> ,. ��✓sc�`i. K r'� r l�f � -.�Y�'s-t 4 -��'�' � 1 axs `r. b `i- �. .Na ,: 'jS ,.gt t 7ykh 'n a"ttt -Yam} 7ta j 'e'S.JLS 4�n v W; } {_ } 1�;.i s'f, .� �t'3� Y - .i r! 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R ;�,t f' i 1'i t t _"ty . sm d ¢,r 3' 3�� � x � � i`j 1 �s r-.ei `f l.JJ} � L dYT�' b. - t b " � Ya, ,v -5.,'. n, ..�, - - r ( t '! @'S � � '1 F ' ., 91_¢Bt.� Y-it`v"' k_ _rtr; tr:f' s>j 3., s, d r• r zs9 S zf �i�Q. rrz„r" `'>...,�'e r 5r.M, rut s s t i �a,� tr "s srEt rr its �' r 15� W6 a.�r`€,3'�r ,€� a F; F*'�`� r u y- a�x'~,< ��'�-� rl trz i-n th - n ,< ', ���. 3�. :1�r -r< 4�T het i � � r��� i"� s �' { ,•4� 3.'Y CC��: N r isFxd !, �k ti �'1y, 10� ^r-'-.i•; _1 dip._ 'gn£' _3 - �t � ia. �3���"w._ s JFs''f"-.., 4r w �.g� -.. Q N dy t \ i v � r�--? � e�s 1�"rr -IVIV 6 `, �a1 ya-�lt: s E -5°. c zc'iz i t 7� z -- 6 0`3 Y•s ' s~` ,%.''�:�` i ` _$ a. Ez •.@ - t ! r s -?* 7" `� - i Onil O O r d L4 �� �zt ! �y"'�? - V� ,t.�r Y,i-•�4 �'� � a �`� yam` a3 srs .rt t@ r z - ,+3_{, «Y r. .4 TAT - s � 1 i ESSEX COUNTY, MASSACHUSETTS, NORTHERN PART 47. subsoil. This soli is wet throughout the. earl spring, often in late spring, and sometimes in the tallart • ously cleared areas h Most areas of this soil have been farmed, Some previ- Most areas of this soil have been farmed. Some revl- ome have reverted to ously cleared areas have reverted to or been Planted to ine residential dof the evelopment.age stiff! is fa or been planted to . frees, Some of the acreage still is farmed, and some is farmed, and some is in residential development. t nt. The soil is suited to cultivated crops, ha Y, and pasture, This soil is well suited to cultivated crops, ha and Good filth is easily maintained in cultivated areas. A P Y, moderately severe erosion hazard and pasture. Wetness is a main limitation, and the erosion hazard is moderate. Good filth is easily maintained in main limitations. Where this snit is farmed, mininess are the .cultivated areas. The main management needs include ]age and the use of cover crops and ' minimum tiff- erosion control and drainage. Where this soil is farmed, control umes a ohe doMixing cropresidue grasses and le- manure into the erosion tillage and the use of cover crops and rases PPing system help to reduce runoff and and legumes In the cropping system help to grasses surface layer Improves tiff h and increases the.organic runoff aril Control- erosion. Mixing crap residue an matter content of this soil. The use of proper stocking manure into the surface layer improves filth and i d rates, deferred grazing, creases organic matter content. The use o€proper g 9, and pasture rotation help to maintain.desirable pasture plant species. stock- ing rates, deferred grazing, and The soil is suitable for trees and o enland. maintain desirable pasture plant speciesre rotation help The and has few limitations for trails. Slo e wildlife The soil is suitable for trees and openfand wildlife slow permeability in the substratum are Ilmiptatfo d for habitat and has few limitations for picnic areas and trolls, most other types of recreational development. The Slow permeability is a limitation for camp areas and perched wafeow able permeability s in the substratum, the seasonal playgrounds. susceptibility to frost action, and The slow permeability in the substratum, the seasonal site for waste disposal facilities, slope limit the soil for residential development and as a perched water table, and a susceptibility to frost actionubcl limit the soil for residential development and as a site . This unit is in capability subclass file. Q and for waste disposal facilities. Lateral water movement Shl3•—Scituate Verystony . along the top of the substratum causes seepage in some excavations. ny fine sandy loam, 3.to,8 percent slopes. This deep, gently sloping, moderately This unit is in capability subclass Ilw. well drained soil is mainly on the tops, and sides of drumlins. The areas are irregular in shape and range W—•Scituate fine sandy !oa„�, g to 15 from 5 to 50 acres. Slopes are smooth or undulating, are slopes. This deep, moderately sloping, moderately well ti surface is covered percent slightly. concave, and are 200 to 600 feet long. The. drained soil is typically an the sides of drumlins and by stones"I to 3 feet in diameter that ridges. The soil is in rectangular areas that range from 5 are 30 to i00 feet apart, to 20 acres and dark is n irregularly areas shaped areas that range Typically,. the surface layer is very friable, very from i0 to 40 acres. Slopes are smooth or as t slight- grayish brown fine sandy loam-about 5 inches thick. The ly concave and 100 to 400 feet long,' g' g subsoil is fine sandy loam 22 Inches thick. It is very Typically' the surface layer is very friable, and very friable and yellowish brown in the u is lark grayish brown fine sandy loam about i0 inches inches. The sub peer 11.inches and Is rY friable and mottled light olive brown in the lower 11 hick. The subsoil is fine sandy loam 17 inches thick. It is sand to a de re The friable and yellowish brown in. fine upper 6 inches Stratum is firm, olive.gray, mottled loamy :nd is friable and mottled light olive brown fn the lower depth of 60 inches or more. I inches. The substratum is olive gray, mottle included with this soil of ma are oils bury and Whitman soils. Alsonfgn laded arle areas of 'aMY sand to a depth of 60 Inches or more. d, firm soils with slopes of 0 to 3 percent and-areas with rock Included with this soil in ma in outcrops more than 200 feet apart. Included soils'make idgebu mapping are small areas of up about 25 percent of this map unit. �', Hollis and Montauk soils. Also included are eas With a few stones an the surface and areas with The permeability of this soil is moderately rapid in the sK outcrops more than 200 feet a art. Included soils subsoil and slow in the substratum. Available water ca- ke UP about 20 percent of this ma-unit. Pacity is moderate, and reaction ranges from very the permeability of this soft is moderately rapid in the strongly acid to medium acid. The rooting zone extend `soil and slow in the substratum. Available water ca- _ to the substratum, but root growth is restricted by a 'ity is moderate, and reaction ' ranges from .very Seasonal perched water table in the lower part of the Ingly acid -to medium acid. The roofing zone extends subsoil. .This soft is wet throughout the earl the substratum, but root.growth is restricted by a spMosf often in (ate spring, and sometimes in the fall sonal Perched water table in- the lower part of the areas of this soil are in woodland. Some areas This soil .is wet throughout'*the earl are to residential development. 9, often in Late spring, and sometimes in the fall. #o Cultivated The crops.on the surface make the soil poorly suited crops. The use of proper stocking rates, z2 6� �- `� i g soltr sURvE� Included w€th this soil-in mapping are small areas of (erred grazing, helps maintain desirable pasture plant Deerfield and Wareham soils that make up about 15 species. percent of this map unit. • The soil is generally suitable for recreational-and resk The permeability of this soil- is very rapid. Available dential development, but slope is a limitation for-play- water capacity is very low. In unlimed areas the soil is grounds and�the moderate or moderately rapid perme- strongly acid to extremely acid. The rooting zone ex- k ability limits use for sanitary landfills. The soil is also tends into the substratum. suitable for trees and for openlarid and woodland wildlife- Most areas of this soil are.€n .woodland. A few areas habitat. are farmed,-and some are used for residential and urban This unit is in capability'supclass Ile. development, ' This soil is suited to cultivated crops, hay, and pasture, CmC-. Carlton fine sandy loam, S to 15 percent but it is droughty. The erosion hazard is slight. The main slopes. This'deep, moderately sloping; well drained soil management needs include irrigation, frequent applica- €s_mostly in rectangularareas on the lower slopes.of hills tions of fertilizer, and cover crops` and ridges, The areas range .from 5 to 20 acres. Slopes Slope and the sandy texture limit this soil for recre- are•typically smooth and convex and are 100 to 400 feet ational development. The soil is poorly su€fed.to trees long. and wildlife Habitat. Typically, the surface layer is very friable, dark brown The soil is generally suitable for residential develop- -fine sandy loam about 4 inches thick. The subsoil is ment. The sides' of .shallow excavations are unstable. friable, brown fine sandy loam in the upper 7 inches and Establishing lawns is usually difficult because of.droughti- -friable, dark yellowish brown gravelly.flne,sandy loam in ness. The so€l has few. limitations for septic tank filter the lower 17 inches. The substratum is friable, olive f€elds, but the very rapid permeability is a limitation for brown gravelly fine sandy loam to a depth of 60 inches most other types of waste disposal facilities. �d or more. .. This unit is in capability,subclass 1Vs: Included with.this soil in mapping are small areas of C¢nF3=Ctarltt�n nine sandy loam, 3 to g�ercer� Sutton and Canton soils that make up.about 20 percent of this map unit. slopes. This deep, gently sloping, well drained soil is The.permeability'of this soil is moderate or moderately mostly in rectangular areas on the lower slopes of hills rapid, and available water capacity is.rnoderate. Reaction and ridges. The areas range frorn 5 to 20 acres. Slopes ranges from very strongly acid to medium acid.' The are typically smooth and convex and range from 100 to 400 feet long. rooting zone extends into th-e substratum. Typically, the surface layer is very friable, dark brown Many areas of this soil are in residential development. fine sandy loam about 4 inches thick. The subsoil is Some of the previously cleared areas have reverted to.or friable, brown sandy loam in the upper 7-inches and been planted to trees. Most areas of the soil have been , fine friable, dark yellowish brown gravelly fine sandy loam in farmed, and some areas still are farmed. the lower 17 inches. The substratum is friable, olive This soil•is suited to cultivated crops, hay, and pasture. brown gravelly fine sandy loam to a depth of 60 inches Good tilth is easily maintained in cultivated areas. The or more. - erosion hazard is moderately severe. Where this soil is included with this soil in mapping are small areas of farmed, striperopping, terracing, minimum tillage, and use Sutton soils and Charlton soils with slopes of 0 to 3 of cover crops and grasses and legumes fn the cropping percent. Included soils make up about 20 percent of this - system help reduce runoff and'erosion and increase or-, map unit.' panic' matter content. Mixing crop residue and manure The permeability of this soil is moderate or moderately into the surface layer improves tilth and also'increases rapid, and available water capacity is moderate. Reaction the organic.mafter content of this soil. The use of proper- ranges from very strongly acid to- medium acid. The stocking rates, 'deferred grazing, and pasture rotation rooting zone extends into the substratum, help maintain desirable pasture plant species. Most areas of this so€1 are used for residential devel- Slope limits the soil for most types of recreational and opment. Some previously cleared areas have•reverted to residential development, and the moderate or moderate- or been planted to trees. Most of the acreage of the soil iy rapid permeability limits use for most types of waste has been farmed, and some areas still are farmed. disposal facilities. The soil is suitable for?trees and for This soil is well suited to cultivated crops, hay, and openland and woodland wildlife habitat. pasture. Good filth is easily maintained in cultivated This unit is in capability subclass Ille, areas. The erosion hazard is moderate. Where this soil is farmed, striperopping, minimum tillage, and use of cover CmD--•-Charlton fine sandy loam, 15 to 25 percent crops and grasses and legumes in the cropping system slopes. This deep, moderately steep, well drained soil is help reduce runoff and erosion and increase organic mostly in rectangular and irregularly shaped areas on the matter content. Use of proper. stocking rates and de- lower slopes of hills and ridges. The areas range from 5 VM Vanasse Hangen Brustiin,Inc. 1i I a i Appendix C: TSS Removal Worksheet L:\08354\dots\repor€s\Drainage\08354_Drainage Report-03-09.doc 13 Storrnwater Management Plan i VHB Vanasse Hangen Brustlin, Inc. TSS Removal Calculation Worksheet Consulting Engineers and Planners 101 Walnut St., Watertown, MA 02471 Name: Eaglewood Shops Proj. No.: 08354 (617) 924-1770 Date: 4/17/03 Location: N. Andover, MA Computed by: EB Checked by: MG A B C D E BMP TSS Removal Starting TSS Amount Remaining Rate Load* Removed (BxC) Load (C-D) Parking Lot 10 1.00 0.1 0.90 Sweeping I E Deep SOmp an Hooded Catch 25 0.90 0.23 0.68 Basin xten e Detention Basin 70 0.68 0.47 0.20 with Foreba Total TSS Removal= 80% Notes: 'Starting TSS Load for first BMP= 1.00. TSS load for subsequent BMP's is equal to the Remaining Load (E)from the previous BMP. -------.... . ......._... I I v Vanasse Hangen Brustlin,Inc. Appendix D: Hydrologic Analysis L:\08354\does\reports\Drainage\08354_Drainage Report-03-09.doc 14 Stormwater Management flan i Vanasse Hangen Brustlin,Inc. HydroCAD Analysis; Existing Conditions L:\08354\does\reports\Drainage\08354_Drainage Report-03-09.doc 15 StOrmwater Management Plan i I t F — s r f - 4 Af � 4 _ ' C J SUbca Read 0l1 Link Drainage Diagram for 8354-ex Prepared by{enter your company name here} 9/18/2003 HydroCADO 6.10 s/n 001236 01986-2002 Applied Microcomputer Systems ►ltu Vanasse Hangen Brustlin,Inc. �I 2-Year Storm Event- Existing I i i 1 I i L:\08354\does\reports\Drainage\08354_Drainage Report 03-09.doc 16 Stormwater Management Plan i 8354-ex Type 11124-hr Rainfall=a 10" Prepared by (enter your company name here) Page 2 H dro.C-.AD4 6.10 s/n 001236 Q 1986-2002 Applied Microcomputer Systems 9/18/2003 _ Subcatchment EX-1: EX-1 Runoff 4.34 cfs @ 12.48 hrs, Volume= 0.649 af, Depth= 0.64" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type III 24-hr Rainfall=3.10" Area ac CN Description 6.135 70 Good Woods Group C 4.320 55 Good Woods Group B 0.815 98 Impervious 0.750 74 Good Grass Group C 0.230 61 Good Grass Group B 12.250 67 Weighted Average To Length Slope Velocity Capacity Description (min) feet __(fdit) (it/sec) (cfis) 9.8 50 0.0370 0.1 Sheet , t Flow, �.�.. Woods: Light underbrush n=0.400 P2=3.10" 19.0 1,375 0.0580 1.2 Shallow Concentrated Flow, Woodland Kv=5.0 fps 28.8 1,425 Total Subcatchment EX-1: EX-1 Hydrograph I 3 f E I ] ! F 1 ! M1 1 i I I E i i I I I I 1 I i k I E I I F i I i I I I p��nQ'f 3 € I ! ! I # S I I € t I 1 I E I 1 1 { € l I ! 1 t E I ; 1 I 2 I I E I E € 1 € I I f 1 I I I # t ! f 1 ! ! € I i 1 I I J 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) 8354-ex Type H/24-hr Rainfall=3.10" Prepared by tenter your company name here) Page 1 H droCAD®6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Time span=0.00-30.00 hrs, dt=0.01 hrs, 3001 points Runoff by SCS TR-20 method, UH=SCS, Type III 24-hr Rainfall=3.10" Reach routing by Stor-Ind+Trans method - Pond routing by Star-Ind method Subcatchment EX-1. EX-1 Runoff Area=12.250 ac Runoff Depth=0.64" length=1,425' Tc=28.8 min CN=67 Runoff=4.34 cfs 0.649 of Total Runoff Area= 12.250 ac Runoff Volume=0.649 of Average Runoff Depth =0.64" I1111 Vanasse Hangen Brustltn,Inc. 10-Year Storm Event- Existing L:\08354\docs\reports\Drainage\08354-Drainage Report-03-49.doc 17 Stormwater Management Plan I 8354-ex Type 11124-hr Rainfall-4.50" Prepared by {enter your company name here} Page 2 H droCAD®6.10 s/n 001236 01986-2002 Applied Mlcrocom uter Systems 9/18/2003 Subcatchment EX-1: EX-1 Runoff - 11.45 cfs @ 12.44 hrs, Volume= 1,494 af, Depth= 1.46" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type III 24-hr Rain#all=4.50" Area (ac) CN Description 6.135 70 Good Woods Group C 4.320 55 Good Woods Group B 0.815 98 Impervious 0,750 74 Good Grass Group C 0.230 61 Good Grass Group B 12,250 67 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (fUft) (ft/sec) (cfs) 9.8 50 0.0370 0.1 Sheet Flow, Woods: Light underbrush n=0.400 P2= 3.10f1 19.0 1,375 0.0580 1.2 Shallow Concentrated Flow, .., Woodland Kv=5.0 fps 28.8 1425 Tot al tal Subcatchment EX-1: EX-1 Hydrograph 12 i1.45:6ts. ! J_...L_L..J__I.._L��--i__L_3_ J__,__L_1_J__L_L_J__I__L_S__I__L_a_J__ 10- 1 I -I--{-- '-->' _E__L_!_..{_-L-L--I--{-€--!__I__j_S__r..._!_3_I__ - } i ...i--! L-i- I 1 `f 7 V r I I..�L_!._ `- L ! I L I j I L .! 6 , q E E ! I ! I t I I_ I t ! 2 1 I I I 1 € f 1 I' F E I Q '0 0 1 2 3 4 5 6 7 6 9 10 11 12 13 34 16 16 17 18 19 20 21 22 23 24 26 26 27 28 29 30 limo (hours) 8354-ex Type if/24-hr Rainfall=4.50" Prepared by {enter your company name here} Page 1 HydroCAD®6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Time span=0.00-30.00 hrs, dt=0.01 hrs, 3001 points Runoff by SCS TR-20 method, UH=SCS, Type III 24-hr Rainfall=4.50" Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment EX-1: EX-1 Runoff Area=12.250 ac Runoff Depth=1.46" Length=1,425' Tc=28.8 min CN=67 Runoff= 11.45 cfs 1.494 of Total Runoff Area= 12.250 ac Runoff Volume= 1.494 of Average Runoff Depth = 1.46" i Vanasse Hangen Brustlin,Inc. 100-Year Storm Event - Existing L:\08354\dots\reports\Drainage\OB354TDrainage Report-43-09.doe 18 Sturmwater Management Plan 9 8354-ex Type 11124-hr Ralnfall=6.30" Prepared by {enter your company name here} Page 2 H droCADO 6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Subcatchment EX-1: EX-1 Runoff — 22.50 cfs @ 12.42 hrs, Volume= 2.816 af, Depth= 2.76" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type III 24-hr Rainfall=6.30" Area (ac) CN Description 6.135 70 Good Woods Group C 4.320 55 Good Woods Group B 0.815 98 Impervious 0.750 74 Good Grass Group C 0.230 61 Good Grass Group B 12250 67 Weighted Average _ Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 9.8 50 0.0370 0.1 Sheet Flow, Woods: Light underbrush n= 0.400 P2=3.10" 19.0 1,375 0.0580 1.2 Shallow Concentrated Flow, Woodland Kv= 5,0 fps 28.8 1,425 Total Subcatchment EX-1: EX-1 Hydrograph -- --7---- ----E--L- - -l-- - -- - E•' f I E I 3 I i S f ! i i ! I } r I 24- ' 23 1__I_-1 _ r-i--E-- �-T--I--�-T-�--i-i-�--t--,--7--F...-. 22 _J_J__i__1_J__I__f _3__?__I__i_ _I__. L_ .A_.,.1__L_.E { 21 _ -.�...-. 20 _4_ -__t-_T_�__ 18 16 f s I I _r__I__! I I i ! -- ---------------.__._________ �' 1 I t 1 I 1 i I ! f 3 �I-��I E I I S 1 ! { I I I I } i I 16 - - --t--+--a--I-- --r--r--�-+ E- - --I--€ -+ -I--r--I,---+--I-- -1--'--� -41-41-- H } I t 1 I 1 t I I t I I E 1 } } ! .F. 14 -y--!--;-7- --1--;- --I-- - - - --,-- - --I--i- --{-- -`- ---E---- Cl 13 3 •' i I i I I I r I I i 3 1 I € I I ( I I I I ! I € S I i I i... y� 12 1L 11 -1_J__t_-r_J__L_i- 1__I_-L-1 I__1_J.....1_...L_ 1.__I..-.L...L-..l _t__L_ __t__L_1 1 3 I t I I 1 1 1 I f F 1 I ! I I I l y 10 _.7_-. -r` --l--r-7 r r --r-Y--r-r-r--I--r-r-z--:--}---r--r- �-�- 9 1.-._i_ 1 I L 1 _I L ._,L --' - I--I--L- --I--t -L- -- -�--E--L-'-J-- I ! I 1 E 1__1 E I I 1 1 _1__!__! F _ 3__I__i ,- f -__F 1 I F I I _S 7 _--_} _,_ __E__i-;_ 1 _1_._. ..{__E�-.! ,r r E 1 6 _------1-- .r7• _i_ I 1 1 I E ! { i -I _i_ I I I i ! I I E I I E -; -�--1-- '',, e ! I 1 0- 0 1 2 3 4 6 6 7 6 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 26 26 27 28 29 30 Time (hours) 8354-ex Type 11l 24-hr Rainfall=6.30" Prepared by f eater your company name here} Page 1 H droCAD®6.10 s/n 001236 © 1986-2002 Apelled Microcomputer Systems 9/18/2003 Time span=0.00-30.00 hrs, dt=0.01 hrs, 3001 points Runoff by SCS TR-20 method, UH=SCS, Type III 24-hr Rainfall=6.30" Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment EX-1: EX-1 Runoff Area=12.250 ac Runoff Depth=2.76" Length=1,425' Tc=28.8 rein CN=67 Runoff=22.50 cfs 2.816 of Total Runoff Area= 12.250 ac Runoff Volume 2.816 of Average Runoff Depth =2.76" y Vanasse Hangen Brustlin,Inc. HydroCAD Analysis: Proposed Conditions 1 I L:\48354\does\reports\Drainage\08354_Drainage Report-03-09.doc 19 5tormwater Management Plan i i i I I N � � _ F I 77 AG4 k!� Y 1-7 3'- } .r R '' ;.: ^4^' ANN ` E v i �f I Stabaal' Reach on �E1 It =HydrCAP=6.10 Drainage Dlagram for 08354-pr-REVISED d by tenter your company name here) 9/18/2003 s/n 001236 01986.2002 Applied Mlcrocompuler Systems VM Vanasse Hangen Brustlin,Inc. 2-Year Storm Event - Proposed L:\08354\docs\reports\Drainage\08354_Drainage Report-03-09.doc 20 Stormwater Management Flan 08354-pr-REVISED Type 11124-hr Ralnfall=3.10" Prepared by (enter your company name here) Page 1 HydroCAD®6.10 sin 001236 ©1986-2002 Applied Microcomputer Systems 9/18/2003 Subcatchment PR-1: PR-1 Runoff - 22.34 cfs @ 12.12 hrs, Volume= 1.748 af, Depth= 1.75" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt= 0.01 hrs Type III 24-hr Rainfall=3.10" Area ac CN Description 1.176 74 >75% Grass cover, Good, HSG C 2.568 61 >75% Grass cover, Good, HSG B 7.100 98 Paved parking & roofs 0.635 74 >75%Grass cover, Good, HSG C 0.518 98 Paved parking & roofs 11.997 86 Weighted Average Tc Length Slope Velocity Capacity Description (min) __- (feet) (ft/ft) (ft/sec) (cfs) 5.3 50 0.0240 0.2 Sheet Flow, Grass: Short n=0.150 P2=3.10" 0.4 40 0.0500 1.6 Shallow Concentrated Flow, Short Grass Pastore Kv= 7.0 fps 1.8 450 0.0400 4.1 Shallow Concentrated Flow, Paved Kv=20.3 fps 1.3 890 0A500 11.0 8.63 Circular Channel (pipe), Diann= 12.0" Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.012 8.8 1,430 Total Subcatchment PR-1: PR-1 Hydrograph I E I I I i _ _ I .�L._ i I 3._...L .,}.__I_....L_.-t U I_j__ F• 1 E E I i I [ I I I E I 1 I i V yl�W! i i I f 1 I I € ��, ��jn01� 2322-�'� 1 E I I I € E I 21 ___.__ .,._ __ __.__..,..________ _____ _ _________ _ __ 1 € I E E I i I E 1 I E i t I I I 1 I ; I 3 i t 1 i i I 2 _�_ __?__;_�__I__L_a__t__L_1 .._1__S_J_-E--t-"-"1__E__L--.J---1---I_..-j._.1..._3__�_.j_.4__ I I I { 1 r_iIr-T-1-'I�Ji I � I 17 T- --�-T- --i--r-T--1- r- _-;- --c--r-T--}--r-r- r-r- --i--r-T- `- 3 1 I i { I ( i 1 I I 14 _I--1"--f--F--r-t--I--t--r-�--F--i---1--i--r-T-7-- •"� •' r � 13 12. _-I__II__ - --11----:--! 1 - 11 4_ 4_ L .- 1FI-yt--- ___ i -i__I__1 E I— _.1_J__L _-__L_L_,1__"E__i-.,,1' -1__k"-.i_-.I__1-_ .J__t_-i_J_-L_L,_-1- 1_J__ -1 r--r--1--r-r--}--F-----r-�-- 7 1__}__L_3__I__L_.L_J__{__' _ I E 1 i i I 1 I 1 I I I I I i i 1 I I � F 3 I 1 1 I 0 1 2 3 4 5 6 7 8 9 10 i 1 12 13 14 15 16 17 16 19 20 21 22 23 24 25 26 27 26 29 30 Time (hours) 08354-pr-REVISED Type I//24-hr Rainfall=3.10" Prepared by {enter your company name here} Page 2 HydroCAD®610 s/n 001236 0 1986-2002 Applied Microcomputer Systems 9/18/2003 Subcatchment PR-2: PR-2 Runoff — 0.92 cfs @ 12.09 hrs, Volume= 0.072 af, Depth= 0.77" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type ill 24-hr Rainfall=3.10" Area ac CN Description 0.340 61 >75% Grass cover, Good, HSG B 0.775 74 >75% Grass cover, Good, HSG C 1.115 70 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment PR-2: PR-2 Hydrograph 1 1 1 1 I 1 V 3 I 1 i 1 ! 1 f 1 1 I 1 I E F 1 3 f7l�unnff I 1 I 1 1 I I I 3 I I I { 1 1 ! S I ! 1 I 1 I 1 1 E I 1 1 I E ¢ I I F I I I } I 1 S 1 1 1 I ! E ! 1 ! ! E It I I ! i t ! 1 I ! 1 F �- 0 1 2 3 4 5 6 7 B 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) 08354-pr-REVISED Type 11124-hr Rainfall=3.10" Prepared by (enter your company name here) Page 3 H droCAM 6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 i Reach 1 R: Design Point 1 [40] Hint: Not Described (Outflow=lnflow) Inflow Area = 13,112 ac, inflow Depth 1.38" Inflow - 4.39 cfs 0 12.50 hrs, Volume= 1.512 of Outflow = 4.39 cfs @ 12.50 hrs, Volume= 1.512 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span=0.00-30.00 hrs, dt=0.01 his Reach 1 R: Design Point 1 Hydrograph S 1 4 I 1 i I I ' FMInflow' outilow E v I E 1 1 1 ! 4.39 cF5':1E t i --- E 4- I # I 1 I I r f 1 E _I__L 1 I 1 I E ! 3 2- i I 1 I E € E j 1 - # I I i t i 3 I f 3 E i I { E F 1 ! 1 ! 1 1 3 3 I ! k ! r F r i � Q Q 1 2 3 4 6 6 7 8 9 30 11 12 13 14 16 16 17 18 19 20 21 22 23 24 26 26 27 28 29 30 Time (hours) I 08354-pr-REVISED Type U/24-hr Rainfalf=3.10" Prepared by {enter your company name here} Page 4 H droCADO 6.10 s/n 001236 © 1986-2002 Applied Microcomputer Systems 9/18/2003 Pond 1: Pond 1 Inflow Area = 11.997 ac Inflow Depth = 1.75 Inflow - 22.34 cfs @ 12.12 hrs, Volume= 1.748 of Outflow = 4.19 cfs @ 12.62 hrs, Volume= 1.441 af, Atten= 81%, Lag=30.0 min Primary - 4.19 cfs @ 12.62 hrs, Volume= 1.441 of i Routing by Stor-Ind method, Time Span=0.00-30.00 hrs, dt=0.01 hrs Peak Elev= 125.16' Surf.Area= 15,568 sf Storage= 35,581 cf Plug-Flow detention time= 191.8 min calculated for 1.441 of (82% of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 122.50 11,000 0 0 123.00 12,032 5,758 5,758 124.00 13,633 12,833 18,591 125.00 15,300 14,467 33,057 126.00 17,016 16158 49,215 127.00 18,795 17,906 67,121 128.00 20,621 19,708 86,829 Primary OutFlow Max=4.19 cfs @ 12.62 hrs HW=125.16' (Free Discharge) �1=Culvert (Controls 4.19 cfs) 2=13road-Crested Rectangular Weir (Controls 0.00 cfs) ## Routing Invert Outlet Devices 1 Primary 123,50' 12.0" x 40.0' long Culvert RCP, groove end w/headwall, Ke=0.200 Outlet Invert= 123,07' S=0.0107 '/' n= 0.013 Cc- 0.900 2 Primary 127.30' 8.0' long x 19.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 08354-pir-REVISED Type If/24-hr Rainfall=3,10" Prepared by {enter your company name here} Page 5 HydroCAD®6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Pond 1: Pond 1 Hydrograph _i_a_J.�..I....L_1__ @ fl, , i i I I i ®Inflow 2r- --I- S r t. . --,..-r _r7 --I -r-r-' IPt3ma 2 _1_J__F__I__L_ _J__!__i__L 222:34 tfs _1_ LLJJIL1Ji L_L_J_J ! LL£ I € I I 3 I 2 {-,. 5 --r-r-T .. r------r --r-r-1-1--1--r-?--i--1--r- -T-1--E--r---- _L-L_J_J__I__L_1_J__3__L-L_1-J2 2 --r--1--t--r-r-r'--�____ ._r_ --- - - - -- - ------,--r-r----I--21_.3__E__L_L_J } _L L J J_. ,_ L_ , _ ] __L_L_S_J ___£ ! ! 1 ! E I £ E I £ 19- T-�--f--I -r-T--1 r-r-� I"'}--f -r-..1_,..E__3__r -t L_L_1 _I__L_1_J_J__I__L_3 I I 1 1 } 17-',• ; '-r-�--€--r-r-T-�--l--r-r-T -1--r-r-�--I--r-r-�-�--,--�-r-T-7.._E. .r_r_ 16 L_L_1 __I_-!__L__< _J VC i i I # F--E... [---r'-r'-T €--r-r -1--i-i-r-T--[--F--r -- `~ !_-L._ -J--f--L-r-1 --I--L._L--1_.J-_,__L-S.-.1-_F_._t- _3_-I_ - 14- ! e ! t I . __T-�__}--E---5----{--F_�-�, ,;-_r_T_�_-E�-"1"`�`-�_ 3 12: %�,J £ € {v ! t { i f 4 I l ! I 1 E # , ! # 1 i I S I 1 1 E j-L ,' ,J 9 -3-- T- --E- T-T--I- 1-- -T--1 -1_r_i_...f--€--r-r- 5 IFT£- T 4MFal j ___- ! I I 2- 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) V Vanasse I3angen Brustlin,Inc. I 10-Year Storm Event- Proposed L:\09354\does\reports\Drainage\08354_DrainageReport-03-09.doc 21 Stortxiwater Management Plan 1 08354-pr-REVISED Type M 24-hr Rainfall=4.50" Prepared by (enter your company name here) Page 1 HydroCAD®6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Subcatchment PR-1: PR-1 Runoff _ 38.06 cfs @ 12.12 hrs, Volume= 3.002 af, Depth= 3.00" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type III 24-hr Rainfall=4.50" Area (ac) CN Description 1.176 74 >75% Grass cover, Good, HSG C 2.568 61 >75% Grass cover, Good, HSG B 7.100 98 Paved parking & roofs 0.635 74 >75% Grass cover, Good, HSG C 0.518 98 Paved parking & roofs 11.997 86 Weighted Average To Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cf_s) 5.3 50 0.0240 0.2 Sheet Flow, Grass: Short n= 0.150 P2=3.10" 0.4 40 0.0500 1.6 Shallow Concentrated Flow, Short Grass Pasture Kv=7.0 fps 1.8 450 0.0400 4.1 Shallow Concentrated Flow, Paved Kv=20.3 fps 1.3 890 0.0500 11.0 8.63 Circular Channel (pipe), Diam= 12.0" Area=0.8 sf Perim= 3.1' r=0.25' n=0.012 8.8 1,430 Total Subcatchment PR-1: PR-1 Hydrograph _ I f 42 a- --I--L-1--E-- -s-�-- - - - - "-�-- -+- -- ORunOlt 1 I I I I 3 S I I f I -.38.06cti{- i � `Y 1 I I I l I i I I i I I 36= -j-i-i--I--] -T--I-- -T -- -j -�--i--F- -3-- 34 I I i ! 1 i 1 S _...I,__L...�. _1__ L_1_J__L_L_!__1__L_J__i__�_S._J.. I I I # 3 1 I I E 1 I I 3 I I I I I I i ! I F S t I 3 _.1_J__.__ i_ __1__ _.I__1___..3 -j-_ -_I--;_- -1--I__ _r- - 3__ -.J-_F !__ 28- 1 , 26 ' I I E I 3 I I I I E 1 .-'1-'"1"`f"" '1 '"'1"i"`f""'I'_..E_ _f....�... _T_Y__i__r_T__1__L_T_�__i 24• 1- - i --!-- ._.iI _i......€.,.� It1_..'t �I 1 !� 1 I I I 1 I I I- I 1.. !,_�..i_... J__i__I__I_JI i__1__I__E__E,.' n 20- - p f'rL -"1--I._.w _..1....� E t I '. 1S - - --:--r- r- --r-€-- I- *-- -Tr-m- _r _r- --1 -r- --;---- r-�-- 14. I i i I I I f .....�'".-`.__i.,..,j....1--I--f'-f�._!...._i'..i -!'-T-�--,�.�r-T-`I-`F�T-�--i-�-Z--i-,f--7 j-- 12 f F I - I -1 1 - S € I ______ _ 1__i i i .�I._-F.__......_... _�-_ f � i 1 1 I ' E ! F' .r 10 J- --`-- -..I- - -3--E-- - .1 _l._ _- 1 _ I _I,,,,...i..._! -"1.__..L._1.___._I_._€,.-'j--1--�-1-_- � _3 - -- f 3 F i 3 1 I f I i I 1 E l i I s t I '� I 1 ' i i f ! i ! 1 I i 4 -Y- --. -r--t-.. kf.. - --l-- - --I - --f----E_.-:".....T- _I - r o- 0 1 2 3 A 5 S 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) i i 08354-pr-REVISED Type Ill 24-hr Rainfall=4.50" Prepared by{enter your company name here} Page 2 H droCAD®6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 ! Subcatchment PR-2: PR-2 Runoff — 2.20 cfs @ 12.08 hrs, Volume= 0.156 aft Depth= 1.67" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-30.00 hrs, dt= 0.01 hrs Type III 24-hr Rainfall=4.50" Area (ac) CN Description 0.340 61 >75% Grass cover, Good, HSG B 0.775 74 >75% Grass cover, Good, HSG C 1.115 70 Weighted Average To Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment PR-2: PR-2 Hydrograph 2' ! E I I F ;, I I 3 I E ! I { E I } E 1 ! F 1 F € Q E I ! I I I E ! I I 1 { I F i I I ! I i • i 3 1 } i 5 ! I 1 1 ! I I 1 I { f ! f E E E I F I I I f ! ! 1 I I 1 I 1 F 3 I 1 F i I I I f I I I t i WWI D 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) 1 i i 08354-pr-REVISED Type /if 24-hr Rainfall=4.50' Prepared by (enter your company name here) Page 3 HydroCAD®6. „ 20 10 sln 001236 © 1986-2©02 Applied Microcomputer Systems, 9/1$_/ 03_ Reach 1 R: Design Point 1 [40] Hint: Not Described (Outflow=lnflow) Inflow Area= 13.112 ac, Inflow Depth = 2.61" Inflow — 7,11 cfs @ 12,41 hrs, Volume= 2.$49 of Outflow = 7.11 cfs @ 12.41 hrs, Volume= 2.849 af, Atten=0%, Lag=0.0 min Routing by Stor-Ind+Trans method, Time Span=0.00-30.00 hrs, dt=0.01 hrs Reach 1 R: Design Point 1 Hydrograph I i i 3 3 I ! E I E E E 1 € ? I 1 I I ! F I E { ! ! ! i iFia I 3 1 3 i I i E 1 1 I F 3 I I 1 I fallow :__'--'-- TAWS _I__E____1__f__I__ _L_1_J.__I_._1_,_I- J _ DOulflow 7111C#$� I E f I E 1 E I I E r ! € 1 4 1 i I I I F 1 3 I I t I I { I I 5 ! I t I I ! I I I-_'6_'--#--I--�.r':.. --1' --J--'- y I t 1 E I r I I 1 4- - I - !LL -E I VrL i I I 1 E I ! I V I I ! 1 I 1 I , 1 V 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) 08354-pr-REVISED Type 11124-hr Rainfall=4.50" Prepared by (enter your company name here} Page 4 H droCADO 6.10 s/n 001236 U 1986-2002 Applied Microcomputer Systems 9/18/2003 Pond 1: Pond 1 Inflow Area= 11.997 ac, Inflow Depth = 3.00" Inflow = 38.06 cfs @ 12.12 hrs, Volume= 3.002 of Outflow _ 6.58 cfs @ 12.63 hrs, Volume= 2.693 af, Atten=83%, Lag=30.6 min Primary 6.58 cfs @ 12.63 hrs, Volume= 2.693 of Routing by Star-Ind method, Time Span=0.00-30.00 hrs, dt=0.01 hrs Peak Elev= 126.75' Surf.Area= 18,351 sf Storage=62,647 cf Plug-Flow detention time= 172.8 min calculated for 2.693 of (90%of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store feet s -ft cubic-feet cubic-feet 122.50 11,000 0 0 123.00 12,032 5,758 5,758 124.00 13,633 12,833 18,591 125.00 15,300 14,467 33,057 126.00 17,016 16,158 49,215 127.00 18,795 17,906 67,121 128.00 20,621 19,708 86,829 Primary OutFlow Max=6.58 cfs @ 12.63 hrs HW=126.75' (Free Discharge) �1=Culvert (Controls 6.58 ofs) 2=Broad-Crested Rectangular Weir (Controls 0.00 cfs) # Routing Invert Outlet Devices 1 Primary 123.50 12.0 x 40.0 long Culvert RCP, groove end w/headwal _' I, Ke=0.200 Outlet Invert= 123.07' S= 0.0107 '/' n=0.013 Cc=0.900 2 Primary 127.30' 8.0' long x 19.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 i 08354-pr-REVISED Type lil 24-hr Rainfall 4.50" Prepared by {enter your company name here} Page 6 H droCADO 6,10 s/n 001236 01986-2002 Applied Microcomputer Sy stems 9/1 8/2003 i Pond 1: Pond 1 Hydrograph I --I F.-♦---� �__,_ F-i -1-- !_�, _�.._+_.;...._,__€_ _{.-.,_._,_._,_._�. _.� � 19�Inflow 3 I l I I 42 T i I-T T --, L- .�C19 -Il--i--3 T 19Prfma 40- ! ! I ! I ! I 1 I I - I I 1 1 I 1 3 1 f I I I € 1 € I [ ! 38 _1_J_J__I__L_1_J__I__L_i_-i __f__L_.L_.J J-_T,,. L 1 J _!_-L_L __ --A--._-f_, 36 i--1--1-- -+- --E--E-- -_- --{--�--- 34' ! ! I E 1 I • _r_�_-I__1__r_Y_�__r__E-_�_.T _I__r--r_7-i_-,--r_t_7--_I_-�-t----I-_F__r_T._.. '32 I I f 1 1 ! I 1 F I ! € I I ! 1 1 I I S ! 1 1 I { ! ! O; 1 s 1 { I ! I ! ! I F s I 28- -k- +- '-- -I-..;._.a._.-s- 1- 4 -a--I--I--�- - 28. I I i F 1 E _T_-1_-f_-i--_f__"_f-1--1__"r._T.."T _.I..."r�r-Y�i�-;-r---�_.�1�_.�-r-T-�--F_---r..,. 2422 = '''' 1 L_L_S _L_L_1__I__1__L_1_J__F__I.._E_S__I__€__L___ ?r - 1 1 1 I O 2a= a----l--�'-+--1--l-- -�'-a� 1--+-i--=----t- 1 p i 1 f I f I I I 1 ! 1 I f I' I i I i 1 ! ! I € I -- 16- 1 I 14- • � 1 12- ' - -4--4--E-- -=- --I--~- i o- - - --r---F--€---r-r--r--r- 7----r--'7--I_._,'---_-_ , 8 1 ! 1 E I €---------------- - - ., 1 1 -1- 6- _L_J_J____L_1_J__I_J__L_ __ __I__I_.,,F_._L_1_.l.-_.I_.-E__,L_1_J-_f_.. {. E ! 4- r 2- {f' 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) Vanasse Hangers Brustlin,Inc. i 100-Year Storm Event - Proposed L:\08354\does\reports\Drainage\08354_DrainageReport-03-09.doc 22 Stormwater Management Plan 1 08354-pr-REVISED Type 11124-hr Rainfall=6.30" Prepared by (enter your company name here) Page 1 HydroCAD®6.10 s/n 001236 © 1986-2002 Applied Microcomputer Systems 9/1812003 Subcatchment PR-1: PR-1 Runoff = 58.51 cfs @ 12.12 hrs, Volume= 41694 af, Depth= 4.70" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type III 24-hr Rainfall=6.30" Area (ac) CN Description 1.176 74 >75% Grass cover, Good, HSG C 2.568 61 >75% Grass cover, Good, HSG B 7.100 98 Paved parking & roofs 0.635 74 >75% Grass cover, Good, HSG C 0.518 98 Paved parking & roofs 11.997 86 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) {ft/sec) (cfs) 5.3 50 0.0240 0.2 Sheet Plow, Grass: Short n=0.150 P2=3.10" 0.4 40 0.0500 1.6 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 1.8 450 0.0400 4.1 Shallow Concentrated Flow, Paved Kv=20.3 fps 1.3 890 0.0500 11.0 8.63 Circular Channel (pipe), Diam= 12.0" Area= 0.8 sf Perim=3.1' r=0.25' n=0.012 8.8 1,430 Total Subcatchment PR-1: PR-1 Hydrograph 1 i 50 t f I t { 1 { I [ � 1 - 45 ! I 1 I 40 r _ _r_1__I__r._t.,. _1__r_Y__ N i I I E 3 35 3 -�-�--r-r--#-_E__r-�--I---E--*_ ,' -r-r--r--i--I-- r--1--r-r-�--r-r-rt--I--r-�-�-- G 30 V I ! v E I I � F - "'T`y_`F""r_.T. 25 I I I ...1.. r_T_1__i_T. 2 1 I I I 1 I i t I I I i I i I I I � _ T_,__._T_.7.__1__E._T__{__E_.. . T_.1__r__r____I__3_T_,__�_7__3 15 E i ! I I r_-r__I__r_T__!__r_.r 10 I I I - --i-}'._"7--I-"'T....._€._-i... ..E-.., - ...T...-1....._1.__.r-T,-!-`F-T- `..,r_..,.��._-7 - 5 E I I I I I 3 f F t € E 0 1 2 3 4 5 6 7 B 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) E I I 08354-pr-REVISED Type /H 24-hr Rainfall=6.30" Prepared by {enter your company name here) Page 2 H droCAD®6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Subcatchment PR-2: PR-2 Runoff _ 4.11 cfs @ 12.08 hrs, Volume= 0.283 af, Depth= 3.05" I Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-30.00 hrs, dt=0.01 hrs Type III 24-hr Rainfall=6.30" Area ac CN Description I 0.340 61 >75% Grass cover, Good, HSG B 0.775 74 >75% Grass cover, Good, HSG C 1.115 70 Weighted Average To Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment PR-2. PR-2 Hydrograph I I ! E I { 1 4.11 0s'. I I ! S I I I f 3 ! I I # 1 4 ! 1 ! } 1 { 1 I € I 1 I 1 I I I f E I I 1 • I E I i 1 1 I I - I 3 1 i I ! I I I { € ! 1 ! f � • 1 1 I 1 I f I I I ! ] 1 1 1 € I I I I 1 F I f ! N t ! t E E E I E I I E I ! 1 ! 1 4 I 1 t I 1 F I F I v E € 1 1 I I I E 1 ! 1 F I t I € 1 I s F 1 F I I. I € _ r_T_1__I__i __[__� T_-1__F__i_7__I__r_T_1__3__�_T_-l_..�_r—_ rz I E € f S 1 I I { I LL I _i__ _1__L_S_J__I__L_S_J__L_S_J__I__L_A 1 F F i I i I 3 F I } ! I E I I I 1 I 1 1 3 } f 1 1 F I I € t I t ! I ! 1 # 1 1 E 0- 0 1 2 3 4 5 6 7 6 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Time (hours) I II 08354-pr-REVISED Type !l124-hr Rainfall=6.34" Prepared by (enter your company name here) Page 3 HydroCAD®6.10 sin 001236 @ 1986-2002 Applied Microcomputer Systems 9/18/2003 Reach 1 R: Design Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 13.112 ac, Inflow Depth = 4,27" Inflow — 21.64 cfs @ 12.43 hrs, Volume= 4.666 of Outflow _ 21.64 cfs @ 12.43 hrs, Volume= 4.666 af, Atten=0%, Lag=0.0 min Routing by Stor-1nd+Trans method, Time Span= 0.00-30.00 hrs, dt=0.01 hrs Reach 1 R: Design Point 1 Hydrograph -; -r ;- i -I--?- r - Olnflow 24;' a_ 1 _: a_a _I_ L_� L-3_ a _I__L _ 1 A- r El Outflow 1 t I E 1 ! 21.64 cfs ik I I I ! € E 3 I I I I F I I 21 23- r .64 cfs I t 22- -i-1--F- -- -L- I # I 3 I I € I I I I I E I € I I I 1 I 1 21-- -r--- .2 A L_ _i__L...R_J_,_I__,1-,_L_I_ I ? L_1_ E I I ! I I I 3 I 1 I 1 E I I 3 I € I I I 1 -F-rt-- 1Q E I__1 E__L _S_. __E__I__i_ L_E 1__1_1 L IWr I I 1 I ! I I f 3 I I I I I I I I I I E I iQ- - --E---- ------i-- - T T-T T..T.E --L- € ----E----1 = T_I I.. 14 � 13 ..E-_t- 1_;_-1--I_-r.. C 11= 1U-' .• -r-�--I--I--r-;- 1--,--r-; -r-�-�--1--r- r-,--{--r-r-; .,.._I_ .i_ ...,._t__ _1.._L ;' -J..-t-..I..-L...1."_F--''.._L_1-,__I__I__Lm.A__ _ •7 _ E 3 I L _t__L_�_ €_i__I__L_i_J_.J_._I_-1 ! I E----!- I - I t I f > I ! I t r E 41 --- -- r- -€--�-t t --€ - -K- { I 4 I I 1 I I I E ~1 I 1 1 1 2 I-A pop 0 0 1 2 3 4 6 fi 7 Q 9 10 11 12 13 14 16 i6 17 18 19 20 2i 22 23 24 26 2fi 27 28 29 W Time (hours) 08354-pr-REVISED Type Ill 24-hr Rainfall=6.30" Prepared by (enter your company name here) Page 4 HydroCAD®_6.10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Pond 1: Pond 1 Inflow Area= 11.997 ac, Inflow Depth = 4.70" Inflow - 58.51 cfs @ 12.12 hrs, Volume= 4.694 of Outflow - 20.45 cfs @ 12.44 hrs, Volume= 4.383 af, Atten=65%, I-ag='19.1 min Primary = 20.45 cfs @ 12.44 hrs, Volume= 4.383 of Routing by Stor-Ind method, Time Span=0.00-30.00 hrs, dt=0.01 hrs Peak Elev= 128.00' Surf.Area=20,619 sf Storage= 86,802 of Plug-Flow detention time= 151.4 min calculated for 4.383 of (93%of inflow) Storage and wetted areas determined by Prismatic sections Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 122.50 11,000 0 0 123A0 12,032 5,758 5,758 124.00 13,633 12,833 18,591 125.00 16,300 14,467 33,057 126.00 17,016 16,158 49,215 127.00 18,795 17,906 67,121 128.00 20,621 19,708 86,829 Primary OutFlow Max=20,45 cfs @ 12.44 hrs HW=128.00' (Free Discharge) T__ 1=Cuivert (Controls 7.97 cfs) 2=Broad-Crested Rectangular Weir (Controls 12.48 cfs) # Routing Invert Outlet Devices 1 Prima 123.50 12.0 x 40.0 Ion Culvert RCP, groove end w/headwall, K.= _Primary " g e-0.200 Outlet Invert= 123,07' S= 0.0107 '/' n=0.013 Cc=0,900 2 Primary 127.30' 8.0' long x 19.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2,70 2.70 2.64 2.63 2.64 2.64 2.63 1 08354-pr-REVISED Type 11124-hr Rainfall=6.30' Prepared by tenter your company name here) Page 5 HydroCADO6,10 s/n 001236 01986-2002 Applied Microcomputer Systems 9/18/2003 Pond 1: Pond 1 Hydrograph -�- El ow 85 QPiimasy 5 � '-T- --i--1-1-T-7--1--r-r--T -€--r-T- -�--�-r-'-T-7-'-!--"r_"T-""T-`r-`I--r-r-" E I I I I I I S 1 ! 1 I ! ! I ! I 1 l I 1 I I ! i f ! I I I I I I ! 1 I I ! 3 r ! I ! [ f 1 1 I ! 1 E 3 E ! i 7 3 1 1 t ! i I ! € ! ! ! ' _ E € _I _'__i- -'--'---1----' -..E.._!__ _ 3__i-..1-- - -'- -`--1- i_ !_-1--L _L 50- i — I I i I i 1 ! _ I I I I E t I I 1 [ I I E I 1 1 t I f 1 -1_-€_.�I i...1_.J__I--l._ .: _I--L_i-J--i__!__l-_-A-J ..L-,,.L_J_1__1__L___ 45- I ; 1 F 1 I I 3 1 i I 'I � 40_,' -_;-_..d..,.�.__.I�_.1'.....L_,...F__!_._r.,_;. ...1 -1-- 1 F i C. - � r'- I ! v35 r i_ , t-y__.I _ ! 1 e t I O 30-- i--T-7-1--1-r-T-7--1--r---7 -1--r-7-7--;__._,-, LL 25 - 3 -I--1--I-F-T I 1 I �- -!--r---7----.--j -- - 2Q45d5. 20- 3 I 1 I I I 1 I l I I 3 I t l .. ,I_, 1_.. I� 10= 5 l 0 0 1 2 3 4, 5 8 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 28 27 28 29 30 Time (hours) vM Vanasse Hangen Brustlin,Inc. Infiltration Calculations Sediment Forebay Calculations Water Quality Volume Calculations L:\08354\does\reports\Drainage\08354_Drainage Report-03-09,doe 23 Stormwater Management Plan i i VHB Wiltration Volume Calculations Project Name: Eagiewood Shops Retail Proj. No.: 8354.0 Project Location: North Andover, MA Date: 4/16/03 Calculated by: EJB Proposed Impervious Surface Summary Net Proposed Impervious Areas by Hydrologic Soil Group(HSG) in acres Subcatchment HSG A HSG B HSG C HSG D Total Area 1 2.80 3.90 6.70 2 0.00 TOTAL 0.00 2.80 3.90 0.00 6.70 Required Infiltration Volume (Cubic Feet) HSG Area Recharge Depth Volume (acres) (in.) c.f. A 0.0 0.40 0 B 2.8 0.25 2,541 C 3.9 0.10 1,416 D 0.0 0.00 0 TOTAL 3,957 Assumptions: 1. Massachusetts DEP Infiltration requirement:HSG A=0.4 In;HSG B=0.26 in;HSG C=0.1 in;HSG D=0 in. Provided Infiltration Volume (Cubic Feet) Infiltration Volume Provided in Extended Detention Basin (below lowest overflow outlet -see attached sheets) Basin 1 12,922 c.f. i Y HWater Quality Volume Calculations Project Name: Eaglewood Shops Proj. No.: 08354 Project Location: N.Andover, MA Date: 9/1812003 Calculated by: TD Water Quality Basin 1 (runoff from Area PR-1) Net Proposed Impervious Area 5.87 Acres Required: Runoff Depth to Required be Treated(in.) Volume(c.f.) Forebay Volume 0.1 2,131 Water Quality Volume 0.5 10,654 Provided. Cumulative Forebay Elevation Area(s.f.) Volume(c.f.) 124.5 218 0 125.0 316 134 126.0 581 582 127.0 927 1,336 128.0 1,328 2,464 Cumulative Basin Elevation Area(s.f.) Volume (c.f.) 122.5 11,400 0 123.0 12,187 5,897 123.5 12,989 12,191 Page 1 of 1 HB Vanasse Hangen Bnusktan,Inc. i i i i I Appendix E: Long Term StormwaterMgt. O&M Information U\08354\does\reports\Drainage\08354_Drainage Deport-03-09.doc 24 Stormwo ter Management Plan I i Vanasse Hangen Brustun,Inc. i ............................................................................................ ........................... . Long Term Stormwater Maintenance Program I The following maintenance program is proposed to ensure the continued effectiveness of the structural water quality controls previously described. ) Inspect extended detention basin once annually,in the spring,for cracking or erosion of side slopes,embankments,and accumulated sediment. Necessary sediment removal,earth repair,and/or reseeding will be performed immediately upon identification. Inspect sediment forebay monthly for erosion.of side slopes and accumulated sediment.Necessary sediment removal,earth repair and/or reseeding shall be performed immediately upon identification.Clean traps/ forebays approximately four times per year or as needed. ) Clean all catch basins twice annually to remove accumulated sand,sediment, and floatable products or as needed based on use. Paved areas will be swept regularly. Routinely pick up and remove litter from the parking areas,islands and perimeter landscape areas in addition to regular pavement sweeping. Routinely inspect all dumpster and compactor locations for spills.Remove all trash litter from the enclosure and dispose of properly. L:\08354\does\reports\Drainage\08354_Drainage Report-03-09.doc 25 Stormwater Management Plan i 1 Eaglewood Shops Operations and Maintenance Plan This Revised Operation and Maintenance Plan identify inspection and maintenance requirements for the proposed Eagle Wood Shopping Center in North Andover,Massachusetts.The Plan addresses requirements contained in the Stormwater Management Policy developed by the Massachusetts DEP and CZM, Project Eagle Wood Shopping Center Salem Turnpike (Route 114) North Andover,Massachusetts Developer/Responsible Party Developer: Owner/Manager: Eaglewood Properties,LLC Eaglewood Properties,LLC PO Box 337 PO Box 337 Topsfield,Massachusetts 01983 Topsfield,Massachusetts 01983 Pavement Sweeping All paved surfaces shall be swept and cleaned quarterly between April 1 and November 30,depending on weather conditions and equipment availability.The site will also be swept immediately after any chemical release of 5 gallons or more. Between December and May,the site will be swept at least once monthly. Pavement sweeping will be conducted with a combination brush and vacuum type sweeper. L:V08354WOC*epoAs4EHF_ExpandoIO4 gncFill_0_Dmimg©.dw Appendix B i Catch Basin Maintenance Inspect all drainage structures monthly during the first 12-month period following the completion of construction and quarterly thereafter.Accumulated debris in the deep-sump catch basins will be removed. Catch basins will be cleaned with a vacuum or clamshell type apparatus annually or more frequently as needed based on quarterly inspections. Cleaning will be conducted between April 1 and November 30.Any structural damage to the catch basins or indication of malfunction will be recorded in the maintenance log and repaired j accordingly. All drainage structures shall be thoroughly cleaned immediately after any chemical release involving 5 gallons or more. All removed sediments shall be disposed of in a proper manner. Liquids collected from the catch basins may be decanted at the site and allowed to drain back into the catch basins.Liquids removed from the site shall be taken to a water treatment plant for disposal.Solids collected form the catch basins are classified as a solid waste and will be disposed of properly at a solid waste landfill facility.Analytical testing of the collected solids may be required by the receiving facility prior to acceptance for disposal. 5orbent pillows have been placed in each catch basin to adsorb petroleum hydrocarbons. Replacement of sorbent pillows within catch basins will be undertaken at least four times per year on a quarterly basis at the same time as the catch basin inspection. The attached site plan illustrates the locations of the catch basins on site. Drainage System Maintenance Drainage system maintenance shall include quarterly inspection of the extended detention basin,sediment forebay,and basin inlet.Inspection shall look for evidence of erosion of slopes inside and outside the basin,failure of berm,lack of stabilizing vegetation,erosion at the inlet or outlet,erosion downstream of the outlet or blockage of the outlet culvert or flow paths.Evidence of any erosion will be addressed immediately to correct the situation by reconstruction,placement of crushed stone or other additional stabilization.During the inspections, trash, debris and other foreign materials will be collected or picked up and disposed of properly. i LI06354WocsVopodslENF_Exparld9c;t Wens ri,B_Dra4ragedoo Appendix B 1 Mowing of the detention basin slopes shall be conducted on an annual basis in the fall to prevent the establishment of woody plant species. Trash Removal The parking lot and the adjacent wetland resource areas will be inspected for litter and trash on a weekly basis.Perimeter trash will be removed as observed, with a major litter pick occurring at least every month.Trash cans will be provided at the building entrances. No disposal of trash,landscaping debris,or sediment collected from the stormwater management system shall be disposed of in wetland resource areas or buffer zone. Snow Removal Snow removal will be undertaken as the weather dictates. Snow removed from parking areas will be stored within the Snow Storage areas as indicated on the Site Plan. Materials to be used for snow and ice control will be stored within the designated Maintenance Storage area as shown on the Site Plan. Materials used for onsite snow and ice control will not contain rock salt(sodium chloride).The attached site plan illustrates the suitable locations of the snow storage areas on site. Invasive Species Control The detention basins will be inspected at least once a year in late summer for invasive and unwanted plant species. This inspection will occur prior to the scheduled annual mowing.If invasive plants are found they will be uprooted and removed from the area. Invasive plants will be removed from these areas throughout the year as they are observed.Invasive plants will include Purple Loosestrife(Lythrum salicaria),Reed Canary Grass(Phalaris arundinacea),and Common Reed(Phragmites australis), Reporting and Documentation A site maintenance log will be kept, This log will record the dates of completion of maintenance task,the person or company who completed the task,and any 1-�08354WOcsArepD"eNF�-expar,aeaapper�Y_a oroma9e.do Appendix B o i observations of malfunctions in components of the stormwater management system.A sample of the Maintenance log follows this narrative. L.M354VOCsVepoRslENF_Expw4odV4*ondz_e_oreteaye.aoo Appendix B y Vanasse Hangen Bnustlin,inc. tl 1 i i i L:\08354\docs\reports\Drainage\08354—Drainage Report-03-09.doc i Vanasse Hangen Brustlin,Inc. 1 Appendix F: Hydraulic Calculations L:\08354\docs\reports\Drainage\08354—Drainage Report-03-09.doc 26 5tarmwater Management Plan