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CLOSURE REQUEST 5-31-94 of Health Services, State of California certified laboratory and analyzed using EPA methods 8015 and 602 . C) Groundwater sampling methodology Prior to sampling each well, WEGE personnel obtains two measurements : the depth to ground water and the product thickness using a depth to water-product interface probe . If no product is present in a given well, a ground water sample is collected, as described below, using a fresh bailer Before collecting the ground water sample, WEGE personnel purge the well . This is accomplished by removing ground water from the well until the water quality parameters (temperature, pH, and conductivity) stabilize. Water produced by the purging process, at least three well volumes, is collected in a 55 gallon DOT steel drum, labeled and left at the site Upon receipt of well chemical results, this water was then pumped to the sewer clean out after permission was obtained from Mr Larry Williams of the City of Stockton Sewer Dept . This purged water is currently being transferred to the ongoing ground water treatment system at former Regal Station 603 , 6425 Pacific Avenue, Stockton, California for tank sparging remediation and disposal under that sites Wastewater Discharge Permit The well is allowed to recover after purging, and a ground water sample is collected and divided among three to four 40-m1 vials and one liter amber bottle that have teflon seals with the lids . The bottles supplied by a chemical supply company and/or the certified laboratory are furnished pre-cleaned to meet EPA standards. Since the sampling that occurred on December 7, 1992 all sample containers contain 0 . 5 ml of HC1 as a preservative . All previous samplings, the containers were preservative free, but were analyzed within a one week time frame . The vials containing the sample are labeled as to station, well, time, and sampler, and documented on the chain-of-custody sheet . They are then placed into an: ice chest and cooled to 4 C with ace . The samples are then chain of custody transported directly to the laboratory performing the analysis by the sampler or via a courier that day for normal turn-around analysis QUALITY CONTROL AND ASSURANCE IN THE COLLECTION OF SOIL AND GROUND WATER SAMPLES Western Geo-Engineers follows the approved EPA and California guidelines to assure quality control in the collection of soil and ground water samples : Collection of Soil Samples o Augers and drilling equipment are steam cleaned prior to use o Equipment entering the borehole is lightly lubricated with olive oil and/or Mazola corn oil only. o Sampling equipment is cleaned between sampling intervals pagell