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• ��g_g' 02 : 51P Mash pea DPW 508-539-3894 P .03 <br /> WOODARD&CURRAN <br /> Engineering Science s Operations <br /> Mr.Gregory Taylor, P <br /> April', � -7 <br /> Page 2 <br /> nd is relativel shallow, ")a to 40 feet. The Mashpee portion of pond has a. <br /> wakeby portion of the pa Y <br /> =�ciMUM depth of 87 feet. Groundwater measurements along the shore of the pond indicate l�a�v inty <br /> m� P <br /> thep and occurs along the wakeby portion and discharge along much of the Mashpee portion, <br /> Contaminant Distribution, Contaminants are present in both the on-site soils and on--at)d off-site <br /> � <br /> gs otindwater. <br /> On-Site Soils. Site studies indicate that widespread low levels of volatile organic compound (VOC) <br /> contamination existed in JBT site soils. Tetrachloroethylene(also known as PCE)and Trichlorothylene <br /> SCE were the predominant compounds detected. These compounds are constittaents of chlorinated <br /> solver'=ts. The presence of contaminants in the site sails were/are the predominant source Of <br /> contain i nation of the uniderlying groundwater. <br /> s <br /> Groundwater. Groundwater contamination was conifirmed at tthe site in 'M'7. R o_su lts of <br /> . well installation and sampling and analyses o�`monitoHng wells and residential yells <br /> borings/monitoring el P g <br /> over theast 10 gears has resulted in under standing the aerial and vertical distribution of contamination. <br /> p r atte.. February 1997 shows <br /> Attachment 2 - Approxirn <br /> Configuration of dissolved v��s in Groundwater, <br /> relatively narrow plume, in relation to its length, of groundwater contaminated :'�fith dissolved <br /> that a retat � <br /> g <br /> VOCs extends from the JBT site in a southeast direction over 4,500 feet. Pickerel Cove area of wakebv- <br /> n is only 950 feet down.gradient of known contamination. The predominant contaminants <br /> iV1a�.hpee pod � g r <br /> in addition to TCE and PCE, include 1,?-dichloroethane,and 1,1,2-trichloroetha-}e each Of which occt r <br /> at concentrations exceeding x a "'cable drinking water standards. Assutni;gig that contarr:ina-rdon of the <br /> pp <br /> gromidwater commenced coins-idtmt wilth use of the site as a Junkyard in the rnid--1930's:th Y <br /> contaminated <br /> plume of roundwater could extend 6,600 feet ar:nar-e ��am the JBT sit,: (assuming ars <br /> g <br /> p <br /> average on rate of l 1 feet per vear�. This would put the leading edge of the plurn.e.=;ever 700 feet <br /> g p <br /> beyond the west share of the pond. <br /> No. _ na the axis of the groundwater lunie shown in Attachncem No. ?. <br /> Attachment�:o. 3 is a crass <br /> ss-section alc � g p <br /> '~ in data from a September 1992 sampling event, shows that the plume�f dissolved ���;s <br /> This figure, using la <br /> ' P arenti bean <br /> `�sin.ks'" as it mows from the JBT site towards the wakebywlviashpe� pond. This is app. g <br /> updated to reflect the results of the February 1997 sampling effort. However, even without the most <br /> recent data sampling events in March 1994, April 1996,and February 1997 indicate the �CE <br /> r leading edge of the lume (MW-�6A)have increased from 7.8 ppb in 199 to 33 <br /> concerr_rat�ans at she l � g P <br /> Pab In 1997. <br /> The�� a ` •• ' � = the lead i nu edge of•the contaminated groundwater plume e Nt��n s be-•ond the <br /> 5_ date, �r�dcc�tt at4d, <br /> f e�y iou esti-mated leading ec��e of the plume, may be ""sinking��deeper tlzarr pre�riai sl.0 arRtrc=,p . <br /> Previously est �, �. <br /> and the NI -?�7 may not have been in a locaticn that would intercept the plume. <br /> assessment conducted as part of the Phase 11 Comprehensive Assessment <br /> Risk Assessment. The risk � t � ,. tial �rsers of Vroundti=rater as <br /> concluded that the JBT site Poses a signrf cant risk to publ.c h..alth .e. pote� .. <br />