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PHASE VII SU13SURFACE INVESTIGATION San Joaquin County Montgomery Ward Auto Service Center Public Health Services Department 5400 Pacific Avenue Stockton CA Site Code 2163 1 piping, and a clarifier which are located in close proximity to the former location of the ' gasoline USTs According to this investigation, about one foot of the sewer line was broken On September 12, 1991, representatives of Stone Brothers excavated a trench around the suspected broken sewer line to an approximate depth of 2 5 feet bgs (see Figure 2) Two slant ' borings were drilled around the sewer line using a hand auger Commencing near the base of the clay pipe (2 5 feet bgs), slant boring SB-1 was hand augered to a calculated vertical depth of 5 75 feet bgs Two soil samples (SS-1 and SS-2) were collected from slant boring SB-1 at a ' depth of 3 5 and 5 5 bgs, respectively Slant 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 tested (see Table 3 and EAI, 1991A) ' 2 3 3 2 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 PL-1 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) 2.3.4 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 (B-7 (& 5') contained a TPH-G concentration (43 ppm), and only one sample from boring B-10 (B-10 @ 5') contained a detectable concentration of TPH-G (8 ppm) TPH-G concentrations encountered in boring B-9 ranged from 1,220 to 3,490 ppm The total I lead rnnrnn*ro+rnt�� rlatar t'-A Ion IIa..+a l -F--- +1-- f-- l. ..,... A f- C '711 �-. VV11.r,rAlLiµLi VAi�} de Ly . 111 sa.FlV� LVii\rL..LIyLL 1LV111 LI1L,Jl. IVL&L VV11116a 1Q11r V'iu 1100 J J(. LV 13 4 ppm (see Table 4 and EAI, 1992) Further, selected soil samples were also analyzed for carbon chain breakdown (see Table 4) I Project No 1232 - 3 - ENVIRONMENTAL AUDIT, INC