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_ ,yam _ _ <br /> �? - .'�Y:' �-'+y..� 3'SA'�d <br /> "t- .•� ME <br /> a� �. v*•. .,ti �, �� to m...r• a +errs -^ -'evr . <br /> • "`x' -"s+c- 'ra ��+'.Y <br /> f� <br /> 1 <br /> I. <br /> • BROWN AND CALDWELL <br /> fe, � CONSULTING ENGINEERS <br /> July I8, 1989 <br /> Mr. Kyle Christie <br /> ARCO Products Company <br /> 2000 Alameda de las Pulgas <br /> Post Office Box 581I <br /> San Mateo, California 94403 017-3173-54/1 <br /> Subject: First Quarter VSampling Results ARCO Station 2133, <br /> 2908 Benjamin Holt Drive, Stockton, California _ <br /> Dear Mr. Christie: <br /> On May 30 and 31, 1984, Brown and Caldwell collected groundwater samples from 8 selected <br /> monitoring wells at the subject site. The sunples represent the fust quarterly sampling event <br /> of 1989 for the site. <br /> Quatlerly Sampling <br /> Prior to sampling Wells PR-1, BHDA, E-2, 13-5,:E-8, E-10, E-11, and E-12, a diaphragm <br /> "! pump (supplied by Armour Petroleum Services) woa used to purge approximately three well <br /> casing volumes of water from each. Each well was then sampled with a Teflon bailer <br /> equipped with a bottom-emptying valve. The sample was then dMined directly fmia the <br /> bottom valve into two 40-milliliter glass bottles with Teflon-lined septa. <br /> The samples were stored on ice from the time of collection through delivery to Eureka <br /> Laboratorms. All of the samples were analyzed for benzene,ethylbenzene, toluene, and xylene <br /> (BETX) by U.S. Environmental Protection Agency (EPA) Method 602. Results are <br /> summarized in Table 1. The complete laboratory reports are enclosF,d. All,groundwater <br /> produced during well sampling was removed from the site by Armour Petroleum Services. <br /> Constituents in the groundwater sample from Well PR-1 am below detection limits. BETX <br /> constituents are detectable in the samples fmm Wells BHD-2, E-2, E-5, E-8, 'E.10, E-11, and <br /> E-12. In all samples, except PR-I, the benzene concentration exceeds California Department <br /> of Health Services (DHS) Maximum Contaminant Levels (MCLS). <br /> Benzene concentrations in wells E-2, E-5, E-10, and E-11 have increased since the winter <br /> quarter 1989 (February 27, 28, and March 2, 1989). Monitoring well E-10 has shown a <br /> dramatic increase in benzene concentrations since the winter quarter 1989. Bcnzer:e <br /> concentrations in wells E-8 and E-12 have decreased since the winter ouarter 1989. A contour <br /> may of May 30-31, 1989, benzene concentrations it, groundwater are shown on Figure 1. <br /> r <br /> .. - 7P7SSTREET SArF"ENTQCAIrtORNtA95$i4-Y -(S*!u4St2] - �� <br />