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Mr Kyle Christie Project 20805-144 004 July 26, 1996 Page 4 Soil Interval (ft-bgs) Estimated TPHG Mass Gallons TPHG 2 to 6 ft 355 pounds 57 5 gallons 6 to 14 ft 10 pounds 16 gallons 14 to 20 ft 368 pounds 59 6 gallons 20 to 35 ft 16 pounds 0 3 gallons Totals 735 pounds 119 gallons conversion factor I ixm d gasoline = 6 17 ga4ons_ , f'T_ STRATIGRAPHIC CONTROLS ON TPHG DISTRIBUTION Four general stratigraphic intervals are present at depths of 1 foot to the total depth explored of approximately 64 5 feet bgs The upper 8 to 10 feet of soil generally consists of sand to silty sand grading laterally to silts in the area immediately north of the former UST complex The silt unit is encountered at 1 foot bgs, extending to depths of 16 to 18 feet bgs At 10 to approximately 20 feet bgs interbedded sand, silty sand, and silt are encountered Below approximately 20 feet bgs to approximately 55 feet bgs, fine to coarse grained sands are interbedded with silty sand and silt The silts appear to have greater lateral and vertical extent at depths of 20 to approximately 33 feet bgs Below 55 feet bgs, silt and clay are encountered Site stratigraphy is depicted on geologic cross-sections A-A' and B-B' The former UST complex is underlain by fine to medium grained sand and locally, in the vicinity of well VW-6, by a thin silt layer The fine to medium grained sand extends vertically to a depth of approximately 22 to 27 feet bgs The former product piping trenches and the dispenser locations are underlain by silty sand to depths of approximately 8 to 10 feet bgs and silt from approximately 8 to 10 feet bgs to greater than 20 feet bgs DISCUSSION Based on the detected petroleum hydrocarbon concentrations, the vertical extent of the . impacts appears to be restricted to the vicinity of the former UST complex and the piping trenches Exploratory borings drilled in the vicinity of the former UST complex 3AC1K\08051440 DOC-961dms 1