SITE INFORMATION AND CORRESPONDENCE_FILE 1

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ENVIRONMENTAR` IALTH DEPARTMENT SAN JOAQUIN COUNTY Unit Supervisors Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. 304 East Weber Avenue, Third Floor { Director Mike Huggins,R.E.H.S.,R.D.I. Al Olsen,R.E.H.S. Stockton, California 95202-2708• Douglas W.Wilson,R.E.H.S. • �q. �P Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. � FOR� Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. DAN KOCH AND FRED BERTETTA MAR 2 1 2003 OLYMPIAN GALT PROPERTIES 260 MICHELE COURT SOUTH SAN FRANCISCO CA 94080-6297 RE: JIMCO TRUCK PLAZA SITE CODE: 1604 22502 S. Highway 99 Ripon, California San Joaquin County Environmental Health Department(EHD) has reviewed Free-Phase Petroleum Remediation Work Plan dated 18 February 2003 and prepared by Advanced GeoEnvironmental, Inc. (AGE) on your behalf. EHD agrees with the recommendation to recover free-product from well MW-6 using a passive skimmer deployed in the well and twice monthly extracting free-product from the well using a vacuum extraction truck. During a telephone conversation between William Little, Project Geologist of AGE, and Nuel Henderson, Jr., RG, of EHD, on 21 February 2003, Mr. Little informed Mr. Henderson that free-product is also present in MW-1 at this site. Although free-product in MW-1 was not addressed in the above referenced work plan, the same procedures used to remove free-product in MW-6 must also be applied to remove free-product in MW-l. A site conceptual model (SCM) should be prepared to explain the sudden increases of gasoline concentrations in MW-1,MW-2, MW-6, MW-7, and MW-8; diesel concentrations in MW-2, and MW-6; and methyl-tertiary butyl ether(MTBE) concentratons in MW-1 and MW-8, during the September 2002 groundwater sampling event. The SCM may include the following: 1. Local and regional maps showing location of sources, man-made conduits, extent of contamination(i.e., an interpretive drawing-not merely a plot of laboratory results), direction and rate of groundwater flow, and locations of receptors. "Receptors" include, but are not limited to, all supply wells within 2,000 feet of the source area; 2. Cross-sections showing subsurface geologic features, depth of groundwater, man- made conduits, monitoring well construction, and an interpretive drawing of the vertical extent of soil contamination; 3. Plots of key chemical concentrations vs. time (e.g., plots should be shown for monitoring wells that demonstrate significant trends in contaminant concentrations);