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Mr Ron Rowe February 24, 1999 Page 2 of 6 generally slopes gently to the west The elevation is approximately thirty-two feet above mean sea level (USGS 7 5 minute topographic quadrangle, Lodi South) The nearest surface water body is an unnamed canal located approximately 30 feet south of the site The Mokolumne Aqueduct is located approximately 2,000 feet west of the site and the Calaveras River is located 7,000 feet to the south SITE BACKGROUND On January 28, 1998, three 8,000-gallon gasoline underground storage tanks (USTs), dispenser pumps, and associated piping were removed from the property Obvious contamination was noted during UST removal operations and soil samples collected from beneath the removed USTs and pump island revealed significant levels of petroleum hydrocarbon constituents The excavation measured approximately 25' x 30' x 15' deep As an interim abatement measure, the excavation was lined with�66, _ and the soil was returned to the hole Because of the high levels of`c tamination and the proximity to a water supply well on the property, the San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) required that the vertical limits of contamination be evaluated, and the domestic well be sampled and its integrity determined On September 23, 1998, Jim Thorpe Oil, Inc excavated approximately 166 cubic yards of impacted soil The soil was transported directly to Forward Inc landfill for disposal A strong petroleum odor and some visible discoloration were noted in the upper portion of the removed soil As soil removal continued, the bottom of the excavation be clean up, and the west and south wal appeared to have only occasional areas of inor contamination However, t e north and east walls still showed evidence of discoloration The removal of the contaminated soil was supervised by William J Hunter, RG, of Wm J Hunter & Associates On September 23 & 24, 1998, approximately 369 cubic yards of clean fill dirt and 54 cubic yards of gravel base was brought in to fill the excavation The soil was compacted as required by San Joaquin County SUPPLY WELL INVESTIGATION On November 4, 1998 a Ground Zero technician measured the groundwater level in the water supply well located at the site The depth to groundwater was measured using an electronic water level probe through a '/2-inch di meter access port on the well faceplate Groundwater was encountered at a depth f 63 84 eet from the top of the casing The estimated depth of the well, based on measuring with a 300-foot probe, s 261 fee he technician was unable to groundzeltulehurgltnitrpt doc 4 1