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Quarterly Report - Second Quarter 2002 • CALIFORNIA FUELS CARDLOCK STATION I2402 Pacific Avenue, Stockton, California I10. INTRODUCTION At the request of Mr David Atwater,Advanced GeoEnvironmental, Inc (AGE) has prepared this quarterly report of ground water monitoring and soil remediation activities for 2402 Pacific Avenue, Stockton, Cahtornia The objectives of the site activities were to monitor dissolved petroleum I hydrocarbon concentrations in ground water,to assess ground water flow direction and gradient and to monitor the progress and effectiveness of soil vapor extraction (SVE) and in-situ air spargmg (IAS) remediation at the site The site setting is illustrated on Figure 1 Site structures and Imonitoring well locations are depicted on Figure 2 This report has been prepared in accordance with guidelines issued by the California Regional Water ' Quality Control Board(RWQCB)- Central Valley Region for investigation of underground storage tank(UST)sites A summary ofprevious investigations at the site was included in the AGE-prepared Corrective Action Plan-May 1998, dated 05 May 1998 Analytical data acquired to date is included Iin this report • 2.0. GROUND WATER MONITORING AND SAMPLING PROCEDURES On 19 June 2002, ground water monitoring was performed at the site on wells MW-1 through MW-13 and air sparge wells AW-1A, AW-1B, AW-2A and AW-2B (AW-IA through AW-213), ground water samples were collected from the above wells on 20 June 2002 except for well MW-13 I which was damaged due to casing separation,AGE has submitted a letter to the San Joaquin County Environmental Health Department (SJCEHD), dated 25 June 2002, detailing the damage Ground water monitoring procedures for the site were outlined in Work Plan Addendum, dated 16 May 2000 I and conform to ground water monitoring guidelines issued by the SJCEHD As built construction details of all monitoring wells are summarized in Table 1 ' 2 1 WELL MONITORING AND EVACUATION PROCEDURES The depth to ground water was measured at each well from the tops of the well casings to the nearest 0 01-toot, utilizing a Solinst water level meter Ground water elevation at the site was calculated by subtracting the measured depth to ground water from the surveyed well casing elevations (Table 1) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) After water levels were measured, approximately 6 to 15 gallons of ground water (a minimum of three casing-water volumes per well) were evacuated (purged) from the wells utilizing either a polyethylene disposable bailer or a Watera-Hydro-Lift IT pump,approximately 1 Y2 gallons of ground water were removed from well MW-11 before being purged "dry" Temperature, pH and