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4 During drilling, soil samples were collected for analysis of benzene, toluene and xylene (BTX), and total petroleum hydrocarbons (TPH). Two soil samples, one from 40 feet in MW- 3 and one from 40 feet in MW-4 showed detectable levels of BTX and TPH. Geologic logs of MW-2 through MW-4 indicated no gasoline odor to a depth of 40 feet. Below 40 feet to the total depth of each borehole (approximately 60 feet), gasoline odor was present. The geologic log of MW-I indicates gasoline odor noted to roughly 25 feet and no odor detected from 25 to 58 feet. Groundwater samples were taken from each of the four wells and analyzed for BTX and TPH. Groundwater from monitoring wells MW-3 and MW-4 had detectable levels of BTX and TPH. Groundwater from MW-I and MW-2 had very low to nondetectable levels of BTX and TPH. Analytical results are shown in Table 1. Brown and Caldwell (BC) was retained by GLDM in late I985 to conduct a second site investigation at the site. On February 11, 1986, five boreholes, GL-1 through GL-5, were drilled at the site to identify the vertical and lateral extent of hydrocarbon contamination (Figure 2). The locations of the boreholes were selected on the basis of. (1) location of the former underground storage tanks and pump islands, (2) information gained from data review and preliminary stages of the field work, (3) recommendation of a County representative based on her recollection of where the tanks and pump islands were formerly located. Undisturbed soil samples were obtained from specific depths during the drilling of the boreholes and analyzed for TPH and BTX. Analytical results are shown in Table 2. Hydrocarbons were present in boreholes GI-2, GI-3, and in low levels in borehole GLS. The four existing:noniloring wells (Figure 2) were purged and sampled during BC's I986 �.. site investigation. The analytical results of the groundwater samples are shown in Table 1. Table I also shows BTX and TPH results from groundwater samples collected by JHK. On July 9, 1986, BC installed an additional monitoring well at the site (MW-5). The monitoring well was drilled to a depth of approximately 60 feet and completed with 30 feet of 2-inch-inside-diameter 0.020 slotted PVC casing and 30 feet of 2-inch-inside diwileter blank PVC casing. During drilling, a soil sample was collected at a depth of 44 feet for analysis of BTX and TPH. The analyticzl results are shown in Table 2. A groundwater sample was collected from MW-5 on July 9, 1986 and analyzed for BTX and TPH. Analytical results are shown in Table 1. Hydrocarbons were present in both the soil and groundwater of MW-5. Sometime in 1987 the site was renovated,and a building was constructed over monitoring well MW-2. Access to the well remains, but modifications to the building will have to be made (i.e., a trap door over the well) before the sampling can be accomplished. On November 20, 1989, the Regional Board notified GLDM by letter that GLDM must complete an investigation to determine the full extent of contamination resulting from the possible release of hydrocarbons at the GLDM site. As part of this investigation, Geweke retained BC to prepare a work plan for completing a problem assessment report. The work plan is to include the installation of monitoring wells to define the full extent of groundwater contamination at the site.