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' Supplemental Investigation Report,Problem Assessment Report and Work Plan CJ_eanup and Abatement Order No 5-00-707 EAI project No 1232 gasoline USTs, and one boring (Boring 5) was located in the west corner of the Wards site to determine background soil conditions Borings 1 and 2, located at the southwest and southeast ' corners of the USTs, respectively, were drilled to a depth of 20 feet bgs Bonngs 3 and 4 encountered auger refusal at 12 feet bgs, i e , the slab on which the USTs had been located was apparently encountered Detectable concentrations of TPH ranging from 8 to 38 m were encountered in three of the g g PF soil samples tested (see Table 1) The detectable concentrations were all present in soil samples obtained from Borings 3 and 4 Total lead concentrations ranging from 6 to 36 ppm were present in all of the samples tested (see ADS, 1988) In March 1991, EAI drilled and sampled two borings (Borings B-5 and B-6) at the Wards (see Figure 3) Borings B-5 and B-6 were terminated at a depth of approximately 31 5 and 51 5 feet bgs, respectively Ground water was not encountered during drilling No total petroleum ' hydrocarbons as gasoline (TPH-G), benzene, xylenes or ethylbenzene were detected in any of the samples collected from Boring B-5 (see Table 1) Toluene (ranging from 0 01 to 0 14 ppm) was the only aromatic hydrocarbon encountered in the samples obtained from Boring B-5 Elevated concentrations of TPH-G, toluene, xylenes, and ethylbenzene were detected in seven of the ten soil samples obtained at depths from six to 50 feet bgs in Boring B-6 (see Table 1) A solvent odor was noted during drilling of this boring No organic lead was detected in any of the samples tested, and the TPH-G concentration in the sample collected at 50 feet bgs was 7 3 ppm The concentrations of total and soluble lead detected were well below the standards contained in Title 22, California Code of Regulations (see EAI, 1991) Wards suspected that a broken sewer line may be the source of contamination in Boring B-6 On June 9, 1991, Pacific Pipeline Survey (PPS) was retained by Wards to investigate the existence of a possible break in the sanitary sewer manhole, associated 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 3) 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), 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 Boring SB-1 at a depth of 3 5 and 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 sail samples associated with the sewer l,ne However, minor concentrations of BTXE, bromoform, carbon disulfide, chloroform, tetrachloroethane, trichloroethene, 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane and 1,1,2- trichloroethane were detected to the soil samples (see EAI, 1991A) BS 1232P IRW_WP 4- ENWRONMENTAt A[IOIT, INC.®