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t <br /> E-Z SERVE <br /> MANAGEMENT COMPANY 4 <br /> APR 14 1881 <br /> ENV] ��E�)�Ira,) AL �EALTH <br /> April 5, 1993 <br /> Ms. Laurie Cotulla <br /> Program Manager <br /> San Joaquin County <br /> Public Health Services <br /> P.O. Box 2009 <br /> Stockton, California 93276 <br /> Re: Work Plan to Install Additional Monitoring Wells <br /> E-Z Serve #100966 <br /> 253 ' Waterloo Road <br /> Stockton, California <br /> Dear Ms. Cotulla: <br /> The objective of this Work Plan is to outline a scope of work to <br /> • install additional monitoring wells intended to assess the extent <br /> of dissolved petroleum hydrocarbons in groundwater adjacent to the <br /> subject site, located at 2537 Waterloo Road, Stockton California. <br /> Previous work has included the advancement of 8 soil borings and <br /> the installation of five monitoring wells. Three soil borings were <br /> advanced by Nanchant Environmental and the results are described in <br /> the report dated November 22 , 1991. Five monitoring wells were <br /> constructed by Tank Protect Engineering and are described in a <br /> report dated September 3 , 1992 . <br /> The results of the laboratory analysis of soil samples collected <br /> during well installation indicate the presence of petroleum <br /> constituents at low to moderate concentrations in borings labels <br /> MW-1, MW-3 and MW-4 . Groundwater is present at approximately 83 <br /> feet below grade. The direction of groundwater flow is toward the <br /> south at a gradient of approximately O. 00o4 foot per foot. <br /> Groundwater samples collected from each monitoring well contain <br /> dissolved benzene at concentrations ranging from nondetect to 86 <br /> ppb. The initial sampling event indicates the sample collected <br /> from the upgradient groundwater monitoring well (MW-3) contained <br /> the highest dissolved benzene concentration. <br /> The fourth quarter 1992 monitoring report indicates an increase in <br /> dissolved benzene concentrations over the site. Well MW-1 has <br /> indicated the highest levels with the December sampling event <br /> resulting in 8600 ppb. <br /> 2550 NORTH LOOP WEST,SUITE 600 <br /> P O BOX 922021 • HOUSTON, TEXAS 77292-2021 <br /> (713)684-4300 „! <br />