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' PRASE VI SUBSURFACE INVESTIGATION Site Code 2163 Montgomery Ward Auto Service Center 5400 Pacific Avenue,Stockton CA ' 5 5 bgs, respectively Boring SB-2 was hand augered to an estimated depth of 4 75 feet bgs in the sidewall of the excavation and a soil sample (SS-3) was collected at the termination depth The boring was terminated approximately beneath a second sewer line that extends west of the manhole ' No TPH were detected in any of the three soil samples associated with the sewer line (see Table 3) However, minor concentrations of BTEX, bromoform, carbon disulfide, chloroform, tetrachloroethene, trichloroethene, 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane and 1,1,2- trichloroethane were detected in the soil samples (see EAI, 1991A) ' Product Lines In June 1986, after the gasoline USTs were removed, the underground piping associated with the USTs was rinsed, stubbed back, capped and left in place pursuant to approval from the County ' On September 12 and 13, 1991, 12 slant borings were hand augered to depths of approximately four feet bgs Soil samples PLA to PL-12 were collected along the product lines which extend ' between the former fuel islands and the former USTs locations (see Figure 2) No detectable concentrations of TPH were present in any soil samples tested, except for soil sample PL-7 (see Table 3) TPH (844 ppm), toluene (0 95 ppm) ethylbenzene (0 65 ppm) and xylenes (9 55 ppm) were detected in soil sample PL-7 @ 4-4 5' (see EAI, 1991 A) Phase IV Investigation In July 1992, EAI drilled and sampled four additional borings (Borings B-7 through B-10) Borings B-7 and B-8 were located in the vicinity of the sewer line and former gasoline USTs, and Borings B-9 and B-10 at the former fuel islands (see Figure 2) No TPH-G were detected in the samples collected from Boring B-8 (see Table 4) Only one sample from Boring (B-7 @ 5') contained a TPH-G concentration (43 ppm), and only one sample from Boring B-10 (B-10 @ 5') contained a TPH-G concentration (8 ppm) TPH-G ' concentrations encountered in Boring B-9 ranged from 1,220 to 3,490 ppm The total lead concentrations detected in samples collected from these four borings ranged from 5 72 to 13 4 ppm (see Table 4) (see EAI, 1992) Further, selected soil samples were also analyzed for carbon ' chain breakdown (see Table 4) Phase V Investigation ' In February 1993, three borings (Borings B-11, MW-I and MW-2) were drilled on the Montgomery Ward site Two of the borings (Borings MW-1 and MW-2) were converted into ground water monitoring wells MW-1 and MW-2 (see Figure 2) 1 The analytical testing results of the soil samples obtained from borings drilled as part of this investigation show that TPH-G concentrations ranging from 6 9 to 3,110 ppm were encountered The highest concentrations of TPH-G were detected in samples collected from boring location MW-2 at depths ranging between 20 and 60 feet bgs (see Table 5) Elevated concentrations also were detected in the samples collected from Boring B-11 between 40 and 50 feet bgs TPH-G were detected only in one sample (MW-1 @ 45 feet) collected from Boring MW-1 BTEX were detected in many samples Several chlorinated hydrocarbons not associated with gasoline also were detected at selected Sample locations, e g , tetrachloroethene (PCE), trichloroethane (TCE), I ' Project No 1232 3 ENVIRONMENTAL AUDIT, INC