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STATE OF CALIFORNIA _ <br /> t GEORGE DE UKMEJIAN G <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTIER ROAD <br /> �� <br /> SACRAMENTO, CA 95827-3098 <br /> s9 <br /> NOV 2 8 1989 <br /> ENVIRONMENTAL HEALT4�j <br /> PERM IT/SERV,C;'D <br /> 27 November 1989 <br /> Mr. James C. Wang <br /> Diamond Properties, Inc. <br /> 2546 Derby Drive <br /> San Ramon, CA 94583 <br /> DIAMOND PROPERTIES SITE, 825 WEST 11TH STREET, TRACY, INTERIM MONITORING <br /> REPORT <br /> We have reviewed the 31 October 1989 Interim Monitoring Report prepared:by <br /> your consultant Geological Technics, Inc. , for this site. The report includes <br /> the results of a soil gas survey, and one additional round of sampling the <br /> three on-site monitoring wells. <br /> The ground water analytical results confirm that high levels of hydrocarbon <br /> contamination are present in ground water in the vicinity of the former <br /> underground storage tanks. Hydrocarbons were also detected in soil vapor <br /> samples obtained upgradient from the former underground storage tanks. Based <br /> on these soil vapor readings, you have proposed installation of one additional <br /> upgradient monitoring well . This well is intended to identify whether the <br /> contaminants originated from an off-site source. <br /> We have Dreviouslv commented on the 11 .January 1989 Site Tnvestigatinr RepOr+ <br /> prepared by Brown & Caldwell Consulting Engineers. In our letter, dated 20 <br /> September 1989, we noted that hydrocarbon contamination has been detected in <br /> soil and ground water beneath your site, and we requested that you submit a <br /> work plan for additional investigation to determine the extent of this <br /> contamination. The proposal to install only one upgradient well cannot be <br /> approved because one additional well will not adequately define the extent of <br /> the contamination. <br /> Because high levels of hydrocarbon contamination were detected in both soil <br /> and ground water obtained near the former on-site underground storage tanks, <br /> it is unlikely that this contamination originated solely from an off-site <br /> source. Furthermore, information from soil vapor surveys does not provide <br /> direct evidence of ground water conditions. We again request that you submit <br /> a work plan for identifying the extent of soil and ground water contamination <br /> resulting from discharges at your site. If you do not comply with this <br /> request by submitting an appropriate work plan, we may initiate formal <br />