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Si/ATE OF CALIFORNIA <br /> 1. 1 GEORGE DEUKMEJIAN,Governor <br /> ;�tALIFORNIA REGIONAL WATER QUALITY CONTROL OARD— <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTfER ROAD <br /> SACRAMENTO,CA 95827-3098 <br /> 25 May 1989 <br /> MAY 3 0 1989 <br /> San Joaquin Local Health District PERi�41!T1SER\/1,- r­ <br /> Stockton, CA 95201 ! <br /> WORK PLAN FOR '-'-- STATION 434, --- KETTLEMAN LANE, LODI, SAN JOAQUIN COUNTY ' <br /> We reviewed the 10 March 1989 work plan and supplied our comments to ARCO in a � <br /> 27 March 1989 letter. Brown and Caldwell Engineering submitted a 25 April <br /> 1989 response to our letter. Our comments on this latest submittal by Brown <br /> and ^a'"==. . are as . v/ /v~s ' <br /> Soil Characterization Work � <br /> | <br /> i <br /> -' The --'-_.. of ^..~-~..~.~~ ~~ . . _... / <br /> be defined. Brown and Caldwell believes that additional borings west <br /> and northof B-2 are not "necessary f r soil characterization purposes" . <br /> They have not explained their reasoning. There is a zone of highly <br /> contaminated soil (hazardous waste levels) immediately above the -ground <br /> water surface that has not been delineated. We agree that it may have <br /> been transported there .on ground water or the capillary fringe, but the <br /> source of the contamination was the leaking product line at the ARCO <br /> station. We recommend that ARCO havOheir consultant accurately <br /> delineate the lateral and vert /cu/ distribution of the contaminants in � <br /> the soil . <br /> 3we have no objection to Brown and Cu/ V6p0p <br /> ) <br /> meter r---.'g- _ _- .. .._ continuous_ core samples.Proposed Modification to the Soil Characterization Work . <br /> � <br /> 1 We have no objectionst . ng installed in | <br /> ' <br /> the boreholes proposed to delineate soil contaminati0O. Our only r <br /> concernis that Brown and Caldwell reen these wells from 7 � <br /> to 45 feet below grade, and have suppl�ied no rationale for selecting � <br /> this interval . Discreet screened intervals place at zones of | <br /> contamination would facilitate a more cient and cost effective soil <br /> remediation' Ideally, we recommend that analytical results of soil <br /> samples be Used to identify the zones �of contamination and the screened ' <br /> intervals should be designed accordingly, but the continuous core ' <br /> � <br /> samples may make it possible to desig the screen interval of each well <br /> based On field data. They plan to use field evidence to select the � <br /> boreholes for vapor recovery well ins allations. We suggest that this ' <br /> field evidence also be used to select the best screen interval (s) for . <br /> each well . ' <br />