ARCHIVED REPORTS XR0006987 - Laserfiche WebLink

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I f Lleration Lontnuis LStimatLLl using the depth-to-watet measuremLiAs collected on December 31 1997 indicated that grOundwatcr Ilam It thL site rtias t?CllerallV LcinsrstLnt with the estimated flow on Septernber 19 1997 Oil March 27 1008 t ondor personnel were, otr ,rte to conduct quarterly groundwater monitoring Laboratory analyses of urnundwatei Samples LullLLted from thL tine monttoi wells Indicated that BTF'X, TPH-G and the selected gasolrnL oxri;enatcs/additives were not detected at or above. the laboratory reported detection limits in ' the, sample LOIIcLl d lioln MW-1 I-thanol tertiarv-biitanoi I)IPI ETBE and TAME were not detected at or above the. [aboratoir reported deteLtlon limits in any of the gIOLrndwatLr Samples Detection limits for the analysis of thL s,tntp[Ls L011ceted from MW-2 and MW-3 were raised however due to relatively high concentrations ail MY131 in the samples LolleLtcd Itoni those wells (as described below) Benrene and IPH-G ' were not dLtLLted Lit or above raised detection Ilmlts and low concentrations of 1 I X constituents were detected in the, sample L011eLted tron-i MW-2 MTBF was detected at 110,000 ftg/l in the MW-2 sample B I I X and I Pll-(j were not detected at or above ihL laboratory reportL,d detection limits in the sample collected trom til W-3 MTBE was detected at 1900 }Lg=il in the MW-3 sample I PH-6 and BIF X constituents were detected rn 111L sample LOIILLtLd from \4 ti' -4 M I H1 was not detected at of above the laboratory reported detection hrnit m the MW-4 Isample No float rnti pi()duct sheen, or petroleum itvdrocarbon odor was noted in the monitor wells laboratory analytical results of the groundwater samples for the First quarter 1998, monitoring evL.nt were generally consistent with historical quarterly groundwater analytical data MTBE concentrations in samples from MW-2 however, increased by more than two orders of magnitude during the three sampling events conducted at the site ' 6roundwatet elevation measurements collected at the site monitor wells on 'March 27 1998, indicated that the average depth from the ground surtaeL to groundwater was approximately S feet rhe average depth to water at the site increased by approximately I toot between Decernbei 31 1997 and March 27, 1998 Groundwater elevation contours Lstirnated using the depth-to-water measurements collected on March 27 1998 Indicated that groundwater giadtent at the site was generally consistent with the estimated gradient on September 18 1997, and December 31 1997 IIn a telephone conversation on ;March 23 1998 Mr Ronald Rowe of the San Joaquin County Public Health Services/Fnvironmental Health Department (PHS/E:HD) indicated that based on his review of the report dated I December 1 1 1997 (referenced above) he was requesting that quarterly groundwater monitoring continue at the site Furthermore he requested that a work plan be prepared for conducting quarterly surface water sampling and additional investigation of tile gasoline oKygL.nate/additive plume to the east of monitor well MW-2 C ondor SLrb,,cgLrently prepared the Wnrk flail lIcldilional ,sod and Oroundwutrr lnvvngation / .Sur face Water %amphng dated May 27 1998 In a tweed nntL dated June 1 1998 Mr Rowe approved the work plan with the stipulation that a work plan addendum be prepared desei ibing installation of additional borings to those proposed I in thL Wolk plan and grab sampling Of thL I lLrman & Helen's Maima drinking water source C ondor subsequently prepaied the Work Plan Addendum dated July 9 1998 In a tax dated July 27, 1998, Mr Ron Rowe appioved the work plan addendum adding that both the facility pre-treated drinking water and the post- treatment water should be sampled and analyzed by appropriate methods On June 26 1998, a Condor representative was on site to conduct quarterly groundwater monitoring Laboratory analyses of groundwater samples collected from the site monitor wells indicated that BTEX, I PH-G and the selected gasoline o\),enates/additn es \rcre not detected at or above the laboratory reported detection limits in the sample collected frorn MW-1 Ethanol, tertiary-butanol, DIPS, and LTBE; were not detected at or above the laboratory tepoited detection limits in any of the groundwater samples TAME, was detected in the samples collected from MW-2 and MW-3 MTBE: was detected in the samples collected from MW-2, MW-3 and MW-4 BI EX and TPH-(j wete not detected at or above raised laboratory detection limits in the samples collected from MW-2 and MW-3 Relatively low concentrations of benzene, ethyl benzene, total xylenes, and FPH-G were detected rrt the sample collected fiom MW-4 Toluene was not detected at or above a raised laboratory detection