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� v o A S S O C I A T E S I N C collected from wells MW-5, MW-6, and MW-7 The highest concentration of MTBE was detected at 97,300 ug/l in the water sample collected from well MW-7 Benzene was detected at 7 24 ugll only in the water sample collected from well MW-7 THPd was detected in the water samples collected from wells MW-3 through MW-7 with the highest concentration detected in the water sample collected from well MW-7 Underground Storage Tank System Repair and Removal The King Island Resort property previously contained three underground storage tanks (USTs) The tanks consisted of one 2,000-gallon gasoline, one 6,000-gallon gasoline, and one 4,000-gallon gasoline and diesel tank The 2,000-gallon UST was removed in 1991 and the 4,000- and 6,000-gallon USTs were removed in 1999 The USTs were replaced with one split aboveground storage tank (AST) containing premium gasoline and regular gasoline On August 19, 1989, diesel fuel was discovered leaking from a product line between the buildings and the castside of the levee The diesel fuel line was purged, capped, and removed New diesel and gasoline fuel lines were installed and placed aboveground Approximately 40 cubic yards of petroleum affected peat were excavated and removed by Falcon Energy, and replaced with sandy loam backfill In July 1991, RESNA personnel witnessed the removal of the 2,000-gallon regular gasoline UST and the associated product line No holes were observed in the UST Soil samples were collected beneath the UST and product line and contained only toluene at 0 045 mg/kg In March 1999, Pile Construction removed one 6,000-gallon and one 4,000-gallon UST According to the Pile Construction Underground Tank Removal Sampling Results for King Island Resort, 11530 West Eight Mile Road, Stockton, California, both USTs contained gasoline, but the 4,000-gallon UST previously contained diesel Four soil samples were collected from the former location of the USTs and these samples contained low concentrations of TPHd and MTBE Fuel pipelines connected the USTs to dispensers located adjacent to the river and near the boat dock Three soil samples were collected from the former product line trench located on the levee that separates the store from the river MTBE, TPHg, toluene, ethylbenzene, and total xylenes were detected in the two soil samples located on the eastern portion of the levee In June 1999, Pile Construction installed one split aboveground storage tank(AST) containing diesel and gasoline along with the double-walled product lines connecting the AST to the fuel dispensers located on the dock According to Westrec Properties, the fuel lines have an electronic monitoring system and no fuel release alarms have occurred to date Groundwater Monitoring Groundwater monitoring and sampling has been performed at the site since April 1991 Groundwater elevation data is included in Table 1 The hydraulic gradient has been consistently towards the east- northeast with a magnitude between 0 05 and 0 08 feet per foot The groundwater surface is highest near the river and slopes downward with distance from the river The depth to first groundwater water beneath the site is relatively shallow The depth to groundwater in the wells furthest away from the levee . separating the site from the adjacent waterway has been less than I foot bgs Depth to groundwater has been the greatest in MW-7, between 8 and 11 feet bgs, which was installed on the levee w\625141reportslstatusreport doc 3