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I 02 May 2002 ' AGE-NC Project No 98-0452 S Page 2 of 4 ' 3.0. PROCEDURES ' Quarterly ground water monitoring was performed on 29 March 2002 Field work was performed m accordance with the Central Valley Regional Water Quality Control Board(CVRWQCB)and San Joaquin County Environmental Health Department (EHD) guidelines for investigations of ' underground storage tank (UST) sites and sampling ground water monitoring wells, respectively 3 1 MONITORING WELL PURGE PROCEDURES On 29 March 2002, a Sohnst water level meter was used to measure the depth to groundwater in the three wells relative to the tops of the well casings (well heads) The ground water elevations and gradient were determined from this data (Table 1) rAfter recording water level measurements, a dedicated disposable plastic bailer was used to purge each monitoring well of standing water Approximately 7 to 10 gallons of water were removed from each well(approximately 3 casing-water volumes) Ground water temperature, pH and conductivity were measured at regular intervals during the purge process using an Oakton water analyzer Field data sheets are included in Appendix A Purged water was stored on site in labeled, 55-gallon DOT- lie OT- 1• approved drurns Domestic well DW-1 was purged by opening the purge valve and allowing the holding tank to be emptied Following complete discharge of the holding tank the pump was allowed to operate for at least one minute and a sample was collected from the sampling port located on the supply line between the well head and the holding tank 3 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Following purging and allowing a minimum of 80% recovery of initial water volume in the wells, I water samples were collected from each purged well using new disposable plastic bailers Additionally, a water sample was collected from domestic well DW-1 Each water sample was transferred into laboratory-supplied 40-m1 VOA vials containing 0 5 ml 18% hydrochloric acid as I a sample preservative After collection, the samples were properly labeled, placed in a chilled container and transported under cham-of-custody to McCambell Analytical Laboratories, Inc and were analyzed for • TPH-g and TPH-d in accordance with EPA Method 8015 Modified, and • Oxygenated fuel additives-MTBE,tertiary butyl alcohol(TBA), di-isopropyl ether(DIPE), ethyl tertiary butyl ether(ETBE), and tertiary amyl methyl ether(TAME)in accordance with . EPA Method 8260 Modified IAdvanced GeoEnvironmental,Inc