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'TATE OF CALIFORNIA — ENVIRONMENTAL -RC "ION AGENCY PETE WILSON. Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION — <br /> 3443 ROUTIER ROAD, SUITE A E�lV1ROH `iF�TL,L HEALTH m <br /> rr�� IT 5ERViCE <br /> SACRAMENTO, CA 95827-3098 P*.f`��� g <br /> PHONE: (916) 255-3000 <br /> FAX: (916) 255-3015 03 juy[ -I PM 2• l4 <br /> 3 June 1993 <br /> Mr. Nathan Esformes <br /> Triple E Produce Corporation <br /> P.O. Box 239 <br /> Tracy, CA 95378 <br /> GROUND WATER REMEDIATION, TRIPLE E PRODUI'E; TRACY; CAN _04QblN COVI rTY <br /> I am writing in response to a 13 May 1993 letter from Robert Dixon of AGRO <br /> Environmental Services regarding the Triple E Produce facility at 8690 West <br /> Linne Road in Tracy. Mr. Dixon' s letter erroneously stated that " . a site <br /> specific cleanup level for chloroform will be based on a risk assessment . . . " <br /> To clarify the Board' s position I refer you to my 4 May 1993 letter to <br /> Mr. Robert Cabral . In that letter I stated the initial cleanup goal for <br /> chloroform at the Triple E Produce facility is 4.5 ug/l and "if some time <br /> after remediation has begun and it is determined that such a level is no <br /> longer technologically or economically feasible to achieve, then the cleanup <br /> goal will be reevaluated. " No mention was made about a risk assessment, nor <br /> was a risk assessment ever discussed between Board staff and Mr. Dixon or any <br /> other consultants for Triple E. It is not the Board's policy to determine <br /> ground water cleanup levels based solely on risk assessments. <br /> Another point needing clarification is Mr. Dixon's statement "Although the <br /> Board generally considers the lateral extent of contamination to be defined by <br /> nondetectable levels of the contaminant, it is our understanding that addi- <br /> tional investigation of this northern boundary will not be required. " I <br /> stated during our 7 May 1993 meeting that if the chloroform concentrations in <br /> MW-7, the most downgradient well , fall below 4.5 ug/l then it would not be <br /> renuired to inctall an additional "'v,,i-&or4 _ Wc; i to datet'iiilfi8 the ldierdII <br /> extent of contamination in the downgradient direction. Mr. Dixon stated in <br /> his letter the chloroform level in MW-7 is about 9.0 ug/l . This is twice the <br /> initial cleanup goal . Looking at the overall trend in chloroform concen- <br /> trations in both MW-7 and other monitoring wells in which chloroform is <br /> present, it is not certain if chloroform concentrations will decrease in MW-7. <br /> Since the initial sampling in October 1992, MW-7 has shown a very slight <br /> increase in chloroform concentrations from 8.7 to 10 ug/l in the latest April <br /> 1993 sampling. <br /> Chloroform concentrations in MW-4A and MW-6 have fluctuated significantly. <br /> MW-4A has had chloroform concentrations ranging from 48 to 1 ,900 ug/l with no <br /> consistent decrease or increase in concentrations. MW-6 has had chloroform <br /> concentrations ranging from 14 to 94 ug/l until the latest sample event in <br /> April 1993 in which the concentration rose significantly to 200 ug/i . Since <br /> MW-6 is the well most directly upgradient of MW-7, it is likely that chloro- <br />