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MA% AWAKA June 30, 1992 AC Unocal Station No. 5981, Stockton, California ground-Water Monitoring Well Development Before developing the wells, static water levels are measured using a Solinst water-level meter. Following initial water-levels measurements, the water in the wells is 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 thickness of floating product detected is recorded to the nearest 1/8-inch The monitoring wells are developed using a 4-inch-diameter FVC surge block alternately raised and lowered through the water column in each well. Development is performed to remove the fine-grained sediment from the monitoring well. round-Water Sampling The static water level in each well is measured to the nearest 0 01-foot with a Solinst water- level aterlevel sounder cleaned with industrial soap and water before use in each well. A clean bailer is used to obtain a sample from the surface of the water in each well The sample is retrieved and inspected for floating product, sheen, emulsion, color, and clarity The thickness of floating product detected is recorded to the nearest 1/8-inch. Wells that do not contain floating product will be purged using a 3 5-inch-diameter stainless- steel electric submersible pump The pump, cables, and hoses will be cleaned with industrial soap and water before use in each well The wells will be purged until withdrawal is of sufficient duration to result in a stabilized pH, temperature, and electrical conductivity of the water measured using portable meters calibrated to a standard buffer and conductivity standard. If the well was dewatered, the water level is allowed to recover to at least 80 percent of the initial water level. Before collecting each ground-water sample, a Teflon bailer is cleaned with industrial soap and rinsed with tap water and deiomzed water, and the sampler changes latex gloves The appropriate preservative (concentrated sulfuric, nitric,or hydrochloric acid) is added to each sample bottle as required for the preservation of the sample before laboratory analysis A sample of the formation water then is collected from the surface of the water in each of the wells using the Teflon bailer The water samples are sealed in laboratory-cleaned, 40- milliliter glass vials with Teflon-lined lids so that no air bubbles are present. The samples are then labeled and promptly placed in iced storage Chain of Custody Records are initiated by the field geologist and accompanied the samples to the analytical laboratories A field log of well evacuation procedures and parameter monitoring is maintained. • 33052-7 38032-7