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' The new EDF monitor well data was used in the First Quarter 2002 Groundwater Monitoring Report. Groundwater elevation contours estimated with the depth to water measurements on that date and new 1 monitor well survey data indicated that the groundwater gradient was generally towards the northwest. Laboratory results indicated petroleum hydrocarbon concentrations detected in MW-1 generally increased with respect to the previous sampling event conducted on December 17, 2001. BTEX concentrations detected from MW-3 and MW-5 generally decreased with respect to the previous sampling event, while the concentrations of oxygenates/additives generally increased. BTEX constituents were not detected at or above the laboratory reported detection limits in MW-4. This was the first time that some or all of the BTEX constituents were not detected in MW-4 since the June 2000 monitoring event; however, concentrations of TPH-G and 1,2-dichloroethane (1,2-DCA) in the sample from MW4 were consistent with previous monitoring events. Petroleum hydrocarbons were not detected at or above the laboratory reported detection limits in the samples collected from MW-6 and MW-7. Petroleum hydrocarbon concentrations detected in the sample collected from MW-8 generally decreased with respect to the previous sampling event. ' Condor conducted the second quarter 2002 groundwater monitoring event at the site on June 26, 2002. Groundwater samples were collected and submitted for laboratory analysis from monitor wells, MW-1, ' MW-3, MW-4, MW-5, MW-6, MW-7, and MW-8. No sheen or separate phase petroleum was noted in the wells; however, a strong petroleum odor was noted in MW-1 and moderate petroleum odors were noted in monitor wells MW-3 and MW-8. The groundwater samples collected from the monitor wells were analyzed for BTEX, THP-G, and selected gasoline oxygenates/additives including MTBE by a ' California certified laboratory. Laboratory analytical results for the June 26, 2002, monitoring event were generally consistent with historical laboratory analytical results. The average groundwater elevation was approximately 2.2 feet lower on June 26, 2002 than the previous sampling event conducted on February 27, 2002. The groundwater elevation contours estimated with the depth to water measurements indicated the groundwater gradient was generally towards the west on June 26, 2002. The estimated groundwater gradient direction and magnitude using monitor wells MW-3, MW-4, and MW-6 was 0.0011 ft./ft. ' towards the northwest. Historical groundwater data collected by VHF indicated a highly variable gradient at the site. Review by Condor of historical groundwater gradient information provided by WHF indicated that there are potential inconsistencies in the data and possibly components of the interpretation of those data, especially related to MW-5 measurements. However, Condor agreed that the general historical groundwater gradient is predominantly towards the northwest at the site. The highly variable gradient at the site may be related to domestic/supply well pumping both on and off site. At times, the water table slope has been very flat (very gentle groundwater gradient); consequently, any slight variability in ' groundwater measurements and the tolerance for error for the water level measurement devices can result in apparent groundwater elevation contours that are not particularly coherent. Therefore, when the water table at the site is relatively flat, it may be more representative to depict the groundwater gradient with a ' three-point construction using groundwater elevation data from three site monitor wells that circumscribe the site, allowing triangulation of the contaminant plume, including the contaminant source area. 1 At the direction of the SJCEHD, Condor prepared and submitted a Problem Assessment Work Plan _ (PAWP) for the site, dated May 31, 2002. Mr. Harlin Knoll of the SJCEHD approved the PAWP in a letter dated July 11, 2002. Condor subsequently prepared a UST Fund cost pre-approval request dated ' July 29, 2002, for the scope of work described by the PAWP. i 1 i