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� `� AfIM1CK�IfAAfA Mr. Charles Leubner 9 July 1997 Page 2 Two soil borings are proposed at this site to evaluate the vertical and lateral extent of petroleum hydrocarbons remaining in the soil. Because the excavation was backfilled with pea gravel, the deeper boring (B-1) will be located outside of the backfilled tank excavation. Soil boring B-1, located next to the tank excavation(see Figure 2), will be sampled to a maximum depth of 35 feet to evaluate the vertical extent of hydrocarbon migration. If groundwater is encountered above this depth, the boring will be terminated at the groundwater surface and a water sample will be collected with a hydropunch-type sampler. Three soil samples will be collected for laboratory analysis - one from the 15-foot depth, one from the 35-foot depth (or the deepest sample collected), and one other sample that is the Iikeliest to contain high concentrations of hydrocarbons based on field observations such as staining, odors or field screening for the presence of elevated organic vapors using a portable organic vapor analyzer. A second boring (B-2) will be driven approximately 10 feet from the excavation to a maximum depth of 25 feet to evaluate the lateral of hydrocarbons (see Figure 2). At a minimum samples collected from depths of 15 and 20 feet below the ground surface will be selected for laboratory analysis. If indications of petroleum hydrocarbons are present at other depths, additional samples may also be analyzed to better evaluate the lateral extent of petroleum hydrocarbons as diesel. Diesel Tank Remote Fill Line Soil samples were collected during the removal of the diesel tank at a depth of approximately 3 feet at 20-foot intervals along the remote fill line. One of the samples (Sample No. 045) was found to contain TEPH at a concentration of 5,000 mg/Kg. One deeper soil boring (B-3) and two shallower soil borings (B-4 and B-5) are proposed to evaluate the vertical and lateral extent of hydrocarbons in this area (see Figure 2). The deeper boring will be driven to a depth of 10 feet and the shallower borings to a depth of 5 feet. The shallower soil borings will be driven 5 feet and 7 feet from the location where Sample No. 045 was collected. Since the closest samples in the former pipe trench did not contain detectable TEPH concentrations and the backfill along the remote fill would be the preferential pathway for migration of leaked product, borings placed 5 feet from the location of Sample No. 045 in native soil should be adequate for evaluating the lateral extent of hydrocarbons through native soil. Two samples from the 10-foot boring (the 5-foot and 10-foot samples) and one sample for the 5- foot soil borings will be analyzed for petroleum hydrocarbons as diesel.