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rN <br /> Quarterly Monitoring Report dune 1, 1989 <br /> Former UNOCAL Station No. 2859, Stockton, California AGS 38012-2 <br /> The sample containers; were then labeled and quickly placed in <br /> iced storage. A Chain of custody Record was initiated by the <br /> geologist in the field and accompanied the samples to the <br /> � analytical laboratory. A copy of this record is attached to this <br /> letter report. <br /> The ground-water samples were analyzed for total petroleum <br /> hydrocarbons (TPH) as gasoline using modified Environmental <br /> Protection Agency (EPA) Method 8015 and benzene, toluene, <br /> ' ethylbenzene, and total xylene isomers (BTEX) by EPA Method 602 <br /> at Applied GeoSystems' laboratory in Fremont, California <br /> (Hazardous Waste Testing Laboratory No. 153) . The results of <br /> these and previous analyses are summarized in Table 3. <br /> The r6sults of the analyses indicate that 1) TPH as gasoline and <br /> BTEX remain nondetectable in ground water from well MW-1; 2) <br /> concentrations of TPH as gasoline, and BTEX have decreased in <br /> ground water from well MW-2, and 3) hydrocarbon concentrations in <br /> ground water from well MW-3 remain essentially unchanged and <br /> slightly above recommended maximums established by the California <br /> Department of Health Services (DHS) for drinking water with <br /> respect to benzene. Water from well t1W-2 exceeds DHS recommended <br /> action levels for benzene, toluene, ethylbenzene, and total <br /> xylene isomers. <br /> Because well MW-2 is located near the property line in the <br /> downgradient direction of ground-water flow, it is likely that <br /> hydrocarbon-contaminated ground water has migrated offsite. <br /> Applied GeoSystems recommends installing two additional offsite <br /> monitoring wells to delineate further the extent of hydrocarbon <br /> contamination. <br /> ,f <br /> 3 <br /> Apclled GeoSystems <br />