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June 21, 1993 ARCO Service Station No. 4548, Stockton, California Working To Restore Nature • brass sleeves with aluminum foil, plastic caps, and aluminized duct tape. The respective sample containers were labeled in the field with the job number, sample location and depth, and date, and promptly placed in iced storage for transport to the laboratory. Chain of Custody Records were initiated in the field by the geologist or technician and accompanied the samples to a laboratory certified by the State of California to perform the analyses requested. Qround-Water MonitoringWe ]2MIopment Before developing the wells, static water levels were measured using a Solinst water-level meter. Following initial water-levels measurements, the water in the wells were examined for subjective evidence of hydrocarbons by lowering about half the length of a Teflon bailer past the air-water interface. The sample is retrieved and inspected for floating product, sheen, emulsion, color, and clarity. The new well was developed using a 4-inch-diameter PVC surge block alternately raised and lowered through the water column. Development is performed to remove the fine-grained sediment from the monitoring well. Ground-Water Sampling •. The static water level in each well was measured to the nearest 0.01 foot with a Solinst electric water-level sounder cleaned with a laboratory-grade, non-phosphatic detergent and deionized water before use in each well. A clean bailer was used to obtain a sample from the surface of the water in the well for subjective analysis of hydrocarbons. The sample was retrieved and visually examined for floating product, sheen, color, and clarity. Approximately 3 well volumes of ground water were purged from the wells using a stainless- steel electrical submersible pump. The pump, cables, and hoses were cleaned with a laboratory-grade, non-phosphatic detergent and water before use in each well. The wells were purged until withdrawal was of sufficient duration to result in stabilized pH, temperature, and electrical conductivity of the water, as measured by portable meters calibrated to a standard buffer and conductivity standard. The wells recovered to more than 90 percent of the static water level within 5 minutes of turning off the pump. The ground water purged from the wells was temporarily stored in 17-E, steel, 55-gallon liquid waste drums approved for this use by the Department of Transportation. ,• Hydrochloric acid (or other appropriate chemical) was added to the sample vials as a .preservative. A sample of the formation water then was collected from the surface of the water in each of the wells with disposable clean Teflon bailer and slowly transferred to laboratory-cleaned sample containers. - • 0331ccar 30004-8 0