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GRANITE CONSTRUCTION COMPANY • WKA No 2088 06 October 12, 1994 Page 3 Samples obtained during removal, of the waste oil tank revealed low levels of Total Petroleum hydrocarbons as motor oil in soils beneath the UST Angle borings completed subsequent to the UST removal revealed no significant levels of TPH as motor oil in the soils beneath the waste oil UST A sample obtained from beneath the former dispenser island at the time of removal, revealed elevated diesel and gasoline contamination in soils at a depth of six feet below site grade Following a soil boring investigation, approximately 700 cubic yards of diesel contaminated soil was removed from beneath the former dispenser island Thirteen samples obtained from the bottom and sidewalls of the excavation revealed only trace concentrations of diesel and motor oil along the northerly and easterly sidewalls of the excavation The excavation was backfilled by Granite Construction Company using clean fill, following authorization from San Joaquin County Environmental Health Department (SJCEHD) The soil removed from the excavation was moved to another on-site location for treatment EIevated concentrations of diesel and gasoline were also reported beneath the diesel and gasoline tanks following removal Subsequent to removal, a soil boring and ground water investigation was conducted in the vicinity of the four former diesel and gasoline USTs (Plate 3) Eleven soil borings and six monitoring wells were completed in this area between March 13 and September 22, 1993 Review of four sets of quarterly data since October of 1993, has revealed a northwesterly flow direction beneath the site Based on this information, SJCEHD has required the installation of two additional monitoring wells to better evaluate the ground water and one additional soil boring to evaluate the southwesterly extent of soil contamination in the vicinity of the former USTs INK WALLACE KUHL Rir>c1cd�ulk> Er ASSOCIATES INC