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• FIELD METHODS • Ground-Water Sam lin • The static water level in each well was measured to the nearest 0 01 foot with an electronic water-level sounder cleaned with a laboratory-grade, non-phosphatic detergent and deiomzed 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 casing volumes of ground water were purged from the wells using an 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 pH buffer and conductivity standards The wells recovered to more than 90 percent of the static water level before samples were collected At Unocal's request, the purged water was removed from the site, transported to Gibson Oil & Refining Company, Inc in Redwood • City, California, and recycled Before collecting each ground-water sample, the geologist cleaned the Teflon bailer with a laboratory-grade, non-phosphatic detergent and rinsed it with tap water and distilled water Appropriate preservatives were added to the sample containers A sample of the formation water then was collected from the surface of the water in each of the wells with the Teflon bailer and slowly transferred to sample containers Reporting Results of Analyses Hydrocarbon constituents in ground-water samples are reported by the laboratory in units of parts per billion (ppb) The maximum contaminant levels listed in Title 22 of the California Code of Regulations for benzene, ethylbenzene, and total xylene isomers in drinking water are 10, 680, and 1,750 ppb, respectively The action level established by the California Department of Health Services for toluene is 100 ppb We report groundwater chemical data in units of ppb to conform with the laboratory reports Sample Labeling and Handling Water samples for hydrocarbon analysis were preserved in new 40-milliliter glass vials that contained concentrated hydrochloric acid as a preservative The water samples were sealed with Teflon-lined lids to eliminate air bubbles The sample containers were labeled in the field with the site identification, monitoring well number and depth, and date and promptly placed in iced storage for transport to the laboratory The geologist initiated Chain of Custody Records in the field that accompanied the samples to a laboratory certified by the State of California for the analyses requested Samples were transported promptly to the •� laboratory Mbbou 38012-14 •