SITE INFORMATION AND CORRESPONDENCE

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Chevron Chevron ri 1 5t} Chevron U.S.A.Products Company 2410 Camino Ramon May 13, 1994 San Ramon,CA 94583 Y P0.Box 5004 San Ramon,CA 94583-0804 Marketing Department Ms. Mary Ways Phone 510 842 9500 San Joaquin County Environmental Health Department P.O. Box 2009 Stockton, CA 95201 Re: Former Chevron Station #9-7780. 3246 East Fremont Street. Stockton. CA 9&05 Attached Summary of Site Environmental Activity Attached Tabulation of Site Soil Analytical Results Attached Estimate of Remaining Hydrocarbon Mass Attached Site Map Showing Estimated Areal Extent of Remaining Hydrocarbon Mass Attached Derivation of Remaining Hydrocarbon Mass Dear Ms. Meays: On January 7, 1994 groundwater sampling and monitoring was performed by Chevron's consultant, Groundwater Technology, Inc. (GTI). Results of that monitoring event were compiled in GTI's report dated, February 22, 1994. The report generated by GTI also provides a historical documentation of groundwater sampling at the subject site. A review of the historical groundwater data indicates that significant levels of groundwater contamination occurred only at monitoring wells MW-1, MW-2, and MW-3. Trace levels of dissolved petroleum hydrocarbons were detected at wells EA-1, EA-2, and EA-4. However, EA-1 and EA-4 went dry after two successive.quarters of non-detect results and well EA-2 went dry before confirmatory samples could be obtained. Dissolved petroleum hydrocarbons have never been detected at the five remaining site monitoring wells;EA-3, EA-5, EA-6, MW4, and MW-5. The last detections of hydrocarbon contamination in groundwater beneath the site were measured in February, 1988. Since then groundwater levels have dropped approximately thirty feet. The historical data suggest that there was not an extensive contaminant plume beneath the site. An evaluation of the historic soil analytical results for the site(Attachment 2) indicates the greatest hydrocarbon impact was limited to soils beneath the former UST area. This area is thought to have been the source area which caused groundwater contamination. The lateral and vertical extent of soil contamination in this area has been defined by samples from monitoring wells and borings SB- 1, MW-1 and MW-4. Soil samples collected from other borings and wells beyond the former UST area did not detect petroleum hydrocarbons above method detection limits. The lack of any detectable hydrocarbons outside of the former UST area provide evidence that there are no other potential source areas beneath the site and that no smear zone of residual hydrocarbons remains in soil above the groundwater table. After giving careful consideration to all site environmental information, I feel it is now appropriate to request case closure. To assist in your review of this site for case closure I am providing several attachments of supporting documentation.