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a a*� ' �:da - $p - - - f [during arterly Ground-Water Monitoring June 30, 1484 acon Station No. 3-492, Manteca, California AGS 56102-3 r� in a sample of ground water collected from monitoring well MW-1 the September 1988 monitoring, Applied GeoSystems commended that subjective analyses of ground water and removal ofloating product be performed on a monthly basis (Applied GeoSystems, Report No. 86102-3, January 31, 1989) . Floating product was observed during monthly subjective inspections of ground-water samples collected from well MW-1 in September, October, November, and December 1988; the maximum thickness of floating product observed was approximately 0.25-inch. No floating product or other subjective evidence of contamination to has been observed in samples collected from wells MW-2 and MW-3. A geologist from Applied GeoSystems was present at the site on December 20, 1988; January 25, 1989; February 22, 1989; and March 2, 1989; to measure the depth to water and perform subjective inspections of samples collected from wells Mw-1, MW--2, and MW-3. The depth to ground water was measured to the nearest 0.01--foot with a Solinst water-level indicator. Samples of ground water for subjective analysis were then collected from the air-water interface in each well by lowering approximately half the length of a clean Teflon bailer through the interface. The bailer was retrieved and the water sample examined for i-W~0 floating product, sheen, or other subjective evidence of hydrocarbon contamination. No floating product, product sheen, or emulsion were observed in the samples. Results of these and previous subjective analyses are summarized in Table 1. On March 2, 1989, ground-water samples were collected from the £y monitoring wells for laboratory analysis. Prior to sample collection, a minimum of 54 gallons (approximately 3 well volumes) of ground water was purged from each ground-water monitoring well using an electric submersible pump; that volume was sufficient to allow the pH, conductivity, and temperature to stabilize. The purge water from the wells was temporarily stored 04 onsite in labeled 55-gallon 17-E steel drums approved for that use by the Depar-ment of Transportation, pending removal by Beacon to .their refinery for treatment. After the wells were pallowed to recover to static levels, groune-water samples were collected by lowering a clean Teflon bailer through the air-water interface. The bailer was retrieved and the samples were ,y transferred to laboratory-cleaned, 40-milliliter glass vials which contained concentrated hydrochloric acid as a preservative. The vials were completely filled to eliminate headspace.. A Chain of Custody Record was initiated by the field geologist and -- ---- _-accompanied -the -sam les.--to--the-anal ytical---laboratory:--A--copy - - -- -- � of------ 3 that record is attached to this letter report. 2 f - - i � Fig