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5 li Report, Soil and Groundwater Contamination, February 26, 1990) A water sample was collected the same day in accordance with RESNA's (WaterWork) Groundwater Sampling Protocol (Appendix IIl, Problem Assessment Report, Soil and Groundwater Contamination, February 26, 1990) The sample was analyzed by B C Laboratories for BTEX and TPHd BTEX constituents were not present above method detection limits, however, 150 parts per billion (ppb) TPHd was recorded in the sample The results of the investigation were presented in a report dated February 26, 1990 (WaterWork Problem Assessment Report, Soil and Groundwater Contanunation) On September 14, and 17-21, 1990, the former tank pit area was over-excavated with a backhoe to remove as much contaminated soil as possible Approximately 800 cubic yards of soil were removed from the excavation The final excavation limits were approximately 55' by 35' The lateral extent of the excavation was 10 feet west and east, 8 feet south and 32 feet north of the former tank pit (Figure 2) The vertical extent of excavation was approximately 9 5 feet deep, where groundwater was encountered All observable contaminated soil was removed in the northern, eastern, and western directions High voltage utilities and lighting structures prevented complete excavation of all contaminated soils abo-ve the water table along the southern boundaries of the excavation However, it is clear that the vast majority of the contaminated soil in the unsaturated zone was removed On September 21, 1990, seven confirmation soil samples were collected at the bottom of the pit along the side walls These soil samples were submitted to B C Laboratories for analysis TPHd was not �j present in the soil samples collected from the north wall (SE 1g, SE 10, low levels were present in the soil samples collected from the east and west walls (SE la 8 5' - 5 2 ppm, SE lb 8 5' - 22 ppm, SE I 9 0' - 7 1 ppm and SE 1 e 9 0 - 9 5 ppm, and one sample with significant levels present was collected from the south wall (SE lc 7 5'-2600 ppm) None of the samples contained detectable concentrations of BTEX constituents Soils encountered at the site during over-excavation consisted of lean and fat clays, and sandy clay to poorly graded sand Sixteen composite samples were collected from the excavated material The samples were analyzed under Title 22 requirements for total and soluble metals and for 96 hour static fish bioassay Based on these analyses, the soils were self-certified as non-hazardous and transported to the BJJ Company facility at 2431 East Manposa Road, Stockton, California The soils were stockpiled on 6 mil plastic and subsequently remediated and disposed of in an appropriate manner under approval of San Joaquin County Public Health Services The results of the excavation and sampling program were presented in a report dated November 15, 1990 The pit was subsequently backfilled with clean sandy soil and which was compacted to 94% maximum compaction at optimum moisture A new asphalt road was constructed over the top of the former excavation During the paving of the area, monitoring well MW 1 was damaged and has subsequently been abandoned under permit from San Joaquin County Public Health Services w\967311ssiwkp doe 2 • SMTN n