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25 September 1995 <br /> AGE-NC Protect No 95-0125 <br /> Page 2 of 5 <br /> Ground water was sampled on eight occasions between 1987 and 1995 Ground water depth <br />' measurements and field observations was performed - <br /> fraqueat*ms between 1993 and 1994 by representatives of LSD <br /> Petroleum hydrocarbons were detected in ground water only in the vicinity of the former dispensers <br /> Previous sampling events have established an ellipse-shaped ground water plume, extending from <br /> MW-2 at the south to near MW-5 at the north The center of the plume has apparently remained near <br /> MW-6 (GTI report dated 3 March 1992) <br /> Mstoncal ground water depth at the site vanes between 5 and 10 feet below surface grade, flowing <br /> to the northwest <br /> 3.0. PROCEDURES <br /> 3 1 MONITORING WELL PURGE PROCEDURES <br /> On 26 June 1995, the water level in all ten wells was measured relative to the casing top using a <br /> Sohnst water level meter The relative ground water elevation in each well and prevailing hydraulic <br /> gradient were determined from these data Ground water depth data is presented in Table 1 <br /> After depth measurements were collected, a submersible pump was used to remove approximately <br /> 6 or 7 gallons of standing water from each well, except for MW-2, to stabilize temperature, pH and <br /> conductivity Due to a low volume of standing water in MW-2, only two gallons were removed from <br /> this well Stabilization parameters were measured at one-gallon intervals using an ICM Water <br /> Analyzer Purged water was stored on-site in DOT drums Ground water stabilization and field data <br /> sheets are included in Appendix A <br /> 3 2 GROUND WATER SAMPLE COLLECTION <br /> On 26 June 1995, ground water samples were collected from each monitoring well Samples were <br /> retrieved from each well using new disposable plastic bailers Ground water were collected 40-ml <br /> EPA vials and transported in a chilled container under chain-of-custody to McCampbell Analytical, <br /> Inc (MAI) in Pacheco, California <br /> Each sample was analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g) and <br /> volatile aromatics (benzene, toluene, ethyl benzene and xylenes BTE&X) in accordance with EPA <br /> methods 5030/8015m and 602, respectively Laboratory reports and chains-of-custody are presented <br /> in Appendix B <br />