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Supplemental Investigation Report.,Problem Assessment Report and Work Plan Cleanup and Abatement Order No 5-00-707 _.._., EAI Project No 1232 In June 1999, EAI installed seven nested wells, each containing a 2-inch diameter air sparging well to a depth of 60 feet bgs, and a 3-inch diameter vapor extraction well to a depth of 30 feet ' bgs (see Figure 3) After receiving the permits required to install and operate the remediation System, the system was put into full operation in November 1999, and has been in operation since then removing approximately 8,000 pounds of hydrocarbons to date 2 2 4 Ground Water Monitonn ' Ground water monitoring at the Wards site has been conducted since 1993 Table 4 summarizes the results of the ground water testing, and Table 5 contains ground water elevation data 2.3 Unocal Site The property located at 5606 Pacific Avenue contained a gasoline station between approximately 1955 and 1985 (see Figures 1 and 4) In 1985, the station was closed and the USTs removed In or about 1991, the property was redeveloped into an office complex 2 3 1 Removal of USTs In the first half of 1985, Bassett Construction removed the three USTs (i e , two 10,000-gallon fuel and one waste oil), fuel islands, and UST piping associated with the site (see Figure 4) 2 3 2 Assessment/Remediation In August 1985, J H Kleinfelder and Associates (JHK) drilled one 44 5 foot deep boring on the site in the approximate center of the excavation which contained the fuel tanks (see Figure 4) Three soil samples obtained at depths of 24 feet bgs, 28 feet bgs, and 35 feet bgs were analyzed for TPH and BTEX (see Table 2) Two grab ground water samples collected from the boring contained TPH at concentrations ranging between 6 4 and 7 4 mg/L, benzene between 1 2 and 6 3 mg/L, toluene between 1 7 and 2 0 mg/L, and xylenes between 4 4 and 4 9 mg/L (see JHK, 1985A) In September 1985, JHK completed two 60 foot deep borings (B1 and B2) at the site, which were converted into wells MW-1 and MW-2, respectively (see Figure 4, and JHK, 1985A and 1985B) Ground water was encountered at approximately 43 feet bgs The results of the soil testing are summarized on Table 2, and ground water testing results on Table 4 In April 1986, JHK completed a Phase II site investigation which including drilling three soil borings (two labeled B 1 and one labeled B2) and installing well MW-3 (see Figure 4 and JHK, 1986) The results of the soil testing are summarized on Table 2, and ground water testing results on Table 4 In March 1987, JHK drilled borings B4 and B5, however, EAI was unable to locate any analytical data for soil samples collected from these borings (see JHK, 1987) 1 118123211[RW-WP -6- ENVIRONMENTAL AUDM INC