ARCHIVED REPORTS XR0001742 - Laserfiche WebLink

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Quarterly Ground-Water Monitoring December 1, 1988 --- Beacon Station No. 1-502, Lodi, California AGS 86091--6 After initial water levels were measured, samples of ground water from the air-fluid ir.terface were collected for subjective analysis by lowering approximately half the length of a clean Teflon bailer past the interface. The bailer was then retrieved and the water sample examined for floating product, sheen, and other subjective evidence of hydrocarbon contamination. No floating product, product sheen, or emulsion was noted in samples from the monitoring wells. Results of these and previous subjective analyses are summarized in Table 1. The monitoring wells were purged prior to sampling with an electric submersible pump. Monitoring wells MW-1, MW--2, MW-3, and MW-5 are 4-inch-diameter wells, and 44 to 66 gallons of ground water were removed from each. Well MW-4 is 2-inch- diameter well, and 29 gallons of ground water were removed from it. The purge water was temporarily stored onsite in 55-gallon Department of Transportation drums, pending removal to Beacon's refinery in Hanford, California, and subsequent treatment in a wastewater separator. After purging, ground-water samples were collected from the wells by lowering the bottom of a clean Teflon bailer to a point, approximatL.ly 3 feet below the air-water interface. The bailer was then retrieved and the sample transferred to laboratory-cleaned, 40-milliliter glass vials. Concentrated hydrochloric acid was added as a preservative. A Chain of Custody Record was initiated by the field geologist and accompanied the samples to Applied GeoSystems' analytical laboratory in Fremont, California. A copy of that record is attached to this letter report. The samples were analyzed for total Petroleum hydrocarbons by Environmental Protection Agency (EPA) Method 8015 (modified for gasoline) and the volatile hydrocarbon constituents benzene, ethylbenzene, toluene, and total xylene isomers by EPA Method 602 . Applied GeoSystems' laboratory is certified by the State of California for tl•.ese analyses. Copies of the laboratory Analysis Reports are attached to this letter report. The results of the laboratory analyses, which are summarized in Table 2, indicate that the benzene concentration in ground-water samples collected from monitoring wells MW-1, MW-2 , and MW-4 exceeded the maximum level for drinking water recommended by the California Department of Health Services (DHS) . In general, the concentrations of toluene, ethylbenzene, and total xylene isomers in the samples from wells MW-1 and MW-2 have increased in comparison to the previous analyses but remained below the maximum levels for drinking water recommended by the DHS. The concentrations of the volatile hydrocarbon constituents in 2