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v <br />A WCalifornia Agional Water Quality %-;ontrol Board <br />Winston H. Hickox <br />Secretaryfor <br />Environmental <br />Protection <br />16 September 1999 <br />Mr. Werner Sicvol <br />Central Valley Region <br />Steven T. Butler, Chair <br />Sacramento Main Office <br />Internet Address: http://www.swrcb.ca.gov/—rwgcb5 <br />3443 Routier Road, Suite A, Sacramento, California 95827 3003 <br />Phone (916) 255-3000 • FAX (916) <br />BP Oil Company <br />200 Public Square 7-I <br />t;fevelana,'kinio 44;x,1L3i3" <br />Gray Davis <br />Governor <br />REMEDIAL ALTERNATIVE EVALUATION, <br />BP OIL COMPANY/APPLIED AEROSPACE <br />STRUCTURES CORPORATION, STOCKTON, SAN JOAQUIN COUNTY <br />I have reviewed the 10 June 1999 Quarterly Monitoring Report No. 2 for 1999 (QMR), 23 June 1999 <br />Numerical Modeling Study, Fate and Transport of VOCs in Groundwater, and 21 July 1999 Remedial <br />Alternatives Evaluation for the BP Oil Company/Applied Aerospace Structures Corporation (BP) site <br />in Stockton. The QMR presents results of the April 1999 groundwater monitoring event; the numerical <br />modeling evaluates the capture zone the existing groundwater extraction and treatment system <br />(GWETS) and provides the estimate of future migration of contaminants; and the remedial alternatives <br />evaluation determines the technical and economic feasibility comments on these doremediating cument are prewater to sented <br />beneficial <br />use protective levels using different technologies. My <br />below. <br />Quarterly Monitoring Report <br />My sole comment on the QMR pertains to the detection limit of 1.0 1kg/1 used in the analysis of volatile <br />organic compounds (VOCs) being detected at the site. This detection limit is too high. The Board's <br />contract laboratory call ucl.evc a d lection limit ranging from 0.3 µg/1 through 0.5 µg/1 using U.S. EPA <br />able to detect to that level, which should be used in <br />Method 8021B so your laboratory also should be <br />your next sampling round. <br />Numerical Modeling Study <br />The report shows that operating the existing GWETS at six gallons per minute would not capture the <br />entire plume and result in offsite migration of VOCs, primarily 1, 1 -dichloroethene (1,1-DCE), with <br />concentrations of up to 50 µg/1. The modeling also showed that adding three extraction wells in the <br />downgradient section of the plume would capture the entire plume and shorten the cleanup time. <br />Table 1 below provides the water quality objectives (WQOs) for the constituents of concern (COCs). <br />Migration of contaminants exceeding those WQOs is not acceptable. Therefore, BP should expand the <br />GWETS to capture the entire groundwater plume. <br />California Environmental Protection Agency <br />ct1 Recycled Paper <br />