SITE INFORMATION AND CORRESPONDENCE

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PUBLIC HEAL'T'H SEIM�� SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION Karen Furst, M.D., M.P.H., Health Officer off.. to GipoAN 304 East Weber Avenue,Third Floor • Stockton, CA 95202 209/468-3420 DEC 3 12001 PAUL SUPPLE GARY SCANNAVINO ARCO PRODUCTS COMPANY SCANNAVINO PROPERTIES P O BOX 6549 5463 E CHEROKEE LANE MORAGA CA 94570 STOCKTON CA 95215 RE: ARCO Station #595 SITE CODE: 0707 6100 N. Hwy. 99 Stockton CA 95209 - San Joaquin County Environmental Health Department (SJC/EHD) has reviewed the "Site Assessment Report" dated December 11, 2001 that was submitted by SECOR International Incorporated (SECOR) on your behalf and has the following comments. The report documents site fieldwork that took place in July 2001, to continue the investigation of the vertical and lateral extent of the petroleum hydrocarbon and fuel oxygenate contamination at this site. The work performed was proposed in the "Work Plan for Additional Site Assessment" dated November 30, 2000, that was submitted to SJC/EHD by SECOR. Three additional shallow groundwater-monitoring wells (MW-5, MW-6 and MW-7) and two continuously cored soil borings (PS13-1 and PSB-2)were installed. Selected soil samples from the monitoring well borings were submitted for laboratory analysis. Though not proposed in the work plan, selected soil samples from PSB-1 and PSB-2 were also submitted for laboratory analysis. Discrete water samples were collected from PSB-1 and PSB-2 at different depths. The new monitoring wells were sampled at the routine quarterly monitoring event in August 2001. Analytical results from the soil samples were similar to previous site investigation results, indicating that little petroleum hydrocarbon or fuel oxygenate contamination to soil exists at this site. Analytical results from the depth discrete water samples collected from PSB- 1 and PSB-2 indicate that the vertical extent of the petroleum hydrocarbon contaminant plume has been defined, but the vertical extent of the methyl tertiary butyl ether (MtBE) and 1,2-dichloroethane contaminant plume has not been defined. Analytical results from the groundwater monitoring and sampling event indicate that the lateral extent of the shallow contaminant plume has not been fully defined. In addition, a 500-foot door-to-door well survey was completed; three additional water supply wells were located nearby the site. Construction details are not available for these wells. The report recommends that the owners of these wells be contacted, and that sampling of these wells should be added to the routine quarterly groundwater monitoring and sampling events conducted by ARCO. SJC/EHD agrees with this recommendation. A Division of San Joaquin County Health Cate Services