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Home My WebLink About2012-01-17 Planning Board Eggleston Environmental January10,2012 NorthAndoverPlanningBoard 1600OsgoodStreet NorthAndover, MA01845 Attn:JudyTymon,TownPlanner NorthAndoverConservationCommission 1600OsgoodStreet NorthAndover, MA01845 Attn:JenniferHughes,ConservationCoordinator RE:StormwaterManagementReview MerrimackCollege,VolpeCenter Expansion DearMs. TymonandMs.Hughes: IhavereceivedandreviewedtheDecember22,2011ResponsetoPeerreviewcomments andrevisedplansandcalculationsfromVHB,Inc.ontheabove-referencedproject.The revisedsubmittalsatisfactorilyaddressesmostofthecommentsinmypreviouslettersof September28,2011andOctober26,2011,howeverIdohavethefollowingcomments: 1.ItisstillnotclearwhethertheworkcalledforintheStormwaterMasterPlan, includingthe2005modifications,hasbeensatisfactorilycompletedandthe footballfielddetentionbasintowhichthisprojectdischargesfunctioningas designed. TheresponseindicatesthataCertificateofCompliancehasnotyetbeen issued,buthaveas-builtplansandanengineer’scertificationbeensubmitted,or cantheAndoverConservationCommissionindicatewhethertheyaresatisfied withthatportionoftheproject? 2.FigureAintheDecember8,2011ResponsepacketsubmittedtotheAndover ConservationCommissionindicatesthattherearetwowetlandareaswithinthe TownofNorthAndoverneartheterminusofthetwodrainlinesthatconveyflow fromtheVolpeCentersitetothefootballfielddetentionbasin.Itisnotclear whetherthesearejurisdictionalwetlandsand,ifso,whytheyhavenotbeen includedintheNOIfiling.Atleastoneofthedrainsisbeingreplacedwitha largercapacitypipesandoutletprotectiondeviceincloseproximitytothe wetlands. 3.FigureA(referencedabove)alsocallsforaportionofthedrainfromexisting catchbasinB3tobereplaced/upsizedandanewriprapaproninstalled,howeverI donotbelievethatwaspreviouslydiscussedaspartofthisproject. 32OldFramingham RdUnit29SudburyMA01776tel508.259.1137fax866.820.7840 VolpeAthleticCenter, TechnicalReview2 January10,2012 4.MaintenanceofthegrassandgravelfilterstripupgradientofRainGarden2 shouldbeincludedintheO&MPlan.Iwouldsuggestusingalargerstoneinthe trenchtokeepitinplace,asitislikelythatsnowfromtheparkinglotwillbe plowedacrossit.Ifthatisthecase,thegrassfilterstripwillalsoneedtobe periodicallyrakedtopreventaccumulatedsolidsfromenteringtheraingarden. 5.Thecompositionofthebioretentionsoilmixfortheraingardensshouldbe specifiedonthedesigndetails. Onceagain,IappreciatetheopportunitytoassisttheNorthAndoverPlanningBoardand ConservationCommissionwiththereviewofthisproject,andhopethatthisinformation issuitableforyourneeds.Pleasefeelfreetocontactmeifyouortheapplicantshaveany questionsregardingtheissuesaddressedherein. Sincerely, EE GGLESTONNVIRONMENTAL LisaD. Eggleston,P.E.