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z Mr. Kyle Christie Project 20805-146.006 August 5, 1996 Page 6 Approximately 360 cubic yards of soil excavated from the former UST locations were stockpiled (SP-1) for use as backfill material. EMCON sampled the stockpile at a frequency of four samples per 80 cubic yards and submitted samples SP-1-1 through SP-1-4 for profile analysis. This material was subsequently used to backfill the former UST cavity at depths of 5 feet to 12 feet bgs. SOIL OVEREXCAVATION Based on the vertical extent of petroleum hydrocarbon impacts observed at the site, a remediation program, consisting of excavating petroleum hydrocarbon-impacted soils above 4 feet bgs, was implemented. The area in the vicinity of the former piping and dispenser islands was excavated on February 13, 1996 (see Figure 4). During overexcavation activities an additional (third) set of fiberglass product piping was discovered in the northwestern corner of the overexcavation area. ACES removed the asphalt and excavated backfill to expose the third set of piping. The piping set consisted of three 2-inch-diameter fiberglass pipes. The pipes were similar in material and appearance to the piping removed concurrent with UST removal on February 7, 1996. The third set of piping extended approximately 31 feet to the west of the most recent dispenser locations and made a 90 degree turn to the north. The three pipes were capped at a distance of 12 to 13 feet north of the 90 degree turn. An additional 19 feet of piping extended north of the capped pipe ends. The piping terminated in a series of "T" and 90 degree elbows in a configuration consistent with a dispenser island. Concrete footings and utility conduits provided additional evidence of a former dispenser location. The extent of the piping is shown on Figures 3 and 4. The capped piping contained gasoline. Approximately 5 gallons of product were recovered and contained in a 55-gallon drum. The gasoline consisted of light pink gasoline recovered from the center pipe and 1 gallon of gold gasoline recovered from the right and left pipes. ACES disposed of the gasoline. The piping trench area was overexcavated to remove petroleum hydrocarbon-impacted soils to depths ranging from 4 to 7 feet bgs. EMCON collected soil samples at three locations following overexcavation: the eastern end of the piping at 7 feet bgs (P-4), underlying the 90 degree turn in the piping at 5.5 feet bgs (P-5), and underlying the former dispenser location at 7 feet bgs (P-6). Sample locations are shown on Figure 3. SA(--\N:\P3(rD80S080514b0.G1)s-9-5\c jb:3