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P Site Background ln£ormation Eckert Cold Storage,Manteca,CA January 10,2003 Page 2 of 2 . i n; ,depth to water measurements indicate the groundwater gradient was generally towards the west on June f 26, 2002. The groundwater gradient estimated with MW-3;MW-4, and MW-6 was 0.0011 ft./ft. towards the northwest. Historical groundwater data collected by WHF indicates a highly variable gradient-at the site. Upon review of historical groundwater gradient information provided by WHF, Condor agrees that the general historical groundwater gradient is predominantly towards the northwest at the site. The highly" k` variable gradient at the site may be related to domestic/supply well pumping both on-and off-site. In addition, when the water table slope has been very flat,iiand 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. 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 Quarterly sampling of Total Petroleum Hydrocarbons quantified as Diesel (TPH-D) was discontinued during the third quarter 2002. Condor.documented approval b.y the SJCEHD regarding discontinuation of + TPH-D as a quarterly monitored analyte in a letter to Mr. Knoll dated September 26, 2002. SJCEHD approval was based on historical data indicating that the presence of TPH-D in site groundwater has been sporadic, very low in concentration, and likely the result of weathered gasoline rather than from the -� possible presence of diesel in the source area. Condor conducted the third quarter 2002 groundwater monitoring event at the site on September 30, 2002. Groundwater samples were collected and submitted for laboratory analyses from monitor wells, MW-1, MW-3, MW-4, MW-5, MW-6, MW-7, MW-8, and domestic well DW-l. No separate phase 4 petroleum was noted in the groundwater recovered from the kells,but a strong petroleum odor was noted I in MW-i, MW-3, and MW-8 and a very slight "earthy" odor was noted in MW-7. A slight sheen was observed in the groundwater purged from MW-1. The groundwater samples collected from the monitor wells and the domestic well were analyzed for BTEX, THP-G; and selected gasoline oxygenates/additives including MTBE by Argon Laboratories of Ceres, California. Laboratory analytical results for the September 30, 2002, monitoring event were generally consistent with historical laboratory analytical results. ds The average groundwater elevation was approximately 1.71 feet lower on September 30, 2002 than the previous sampling event conducted on June 26, 2002. The groundwater elevation contours estimated with the depth to water measurements indicated the groundwater gradient was generally towards the west on # September 30, 2002. The groundwater gradient estimated using MW-4, MW-6, and MW-7 was 0.0013 ft./ft. towards the northwest, and was generally consistent with historical groundwater gradients estimated for the site.. i On October 10 and 11, 2002, Condor conducted the additional groundwater investigation activities described by the PAWP at the Eckert Cold Storage facility. using direct push boring methods [Cone- Penetrometer (CPT) and Hydropunch] in order to satisfy SJCEHD requirements to further investigate the lateral and vertical extent of groundwater contamination at the site. Condor supervised the installation of ten shallow direct push (hydropunch) borings and two deep direct push (CPT) boring pairs (four CPT borings total). Condor prepared a Problem Assessment Report (PAR) dated November 25, .2002, describing the results of the additional groundwater investigation. Qj�"