SITE INFORMATION AND CORRESPONDENCE

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Former TAOC Pump Station - 2 - 24 February 2004 880 Beechnut Tracy, San Joaquin Co. According to the reports, residual petroleum hydrocarbons are present in surficial soils throughout the site to approximately 20-feet below ground surface. The majority of the sampling and analysis has been conducted in the upper 20-feet (maximum depth of historical borings). The historical results reported non-detect for TPH as oil and grease at one foot for several locations to 41,500 mg/kg at a depth of 6.5 feet in the northeast portion of the site where measurable floating product is found in monitoring wells. Generally the historical data indicates that from depths of 11-20 feet, TPH concentrations range between non-detect and approximately 1,000 mg/kg or less. Similarly, concentrations of PAHs were detected in the soil at various locations and depths with the majority of the results generally coincident with the high TPH values. With one exception (xylene at 790 mg/kg), BTEX compounds were not detected, but the analyses were conducted at elevated detection limits. Soil Stockpiles Existing stockpiles are approximately three to five feet high and range from one to two-feet across to greater than 100-feet by 200-feet in size. Historical analytical results indicate that TPH constituents are present in all of the piles sampled with concentrations ranging from less than 100 mg/kg to 24,000 mg/kg. Concentrations of PAH compounds are also present at virtually all locations sampled. With the exception of some samples reporting results slightly above the minimum laboratory detection limits, BTEX compounds were not detected. Groundwater Depth to groundwater is approximately 12 to 15-feet with a north-northwest gradient. Originally, there were six onsite and three offsite groundwater monitoring wells. Four of the onsite wells were destroyed in the mid to late 1980's. Three of the onsite wells sampled in 1985, contained concentrations of petroleum hydrocarbons (<200 pg/L, 4,300 µg/L, and 135,000 µg2), PAHs, and BTEX compounds. The fourth onsite well (Well D), located at the southeast corner(upgradient) of the site, and sampled twice in 1986, did not contain petroleum hydrocarbons, PAHs or BTEX compounds (historically, petroleum hydrocarbon compounds have not been detected in soil and groundwater in the southeast portion of the site). MTBE was not detected in any of the wells sampled through 1997, and subsequent samples have not been analyzed for MTBE. The two remaining onsite wells (REW-2 & 3; two-inch wells) have been monitored sporadically between 1988 and 2003. These wells have contained floating product since installation in November 1988. Removal of floating product from the wells was started by Geomatrix in October 2001. During the most recent monitoring event in September 2003, the wells contained 2.0 and 4.5-feet of floating product. Offsite, there are three existing monitoring wells - one upgradient (REW-1, south) and two downgradient ("E and F", north-northwest). Samples collected from the downgradient wells did not contain TPH-g, motor oil, BTEX, or PAH compounds. However, TPH-d was reported at 1,000 pg/L and 99 pg/L, respectively in October 1996 and ND in two separate monitoring events in 1997. BTEX compounds were also ND. For samples analyzed between 1997 and 2001, test results were ND for the PAH