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detected in anof the soil samples. Oil and Grease was detected at concentrations of 230 m, 140 Y A AA —} ppm, and 50 ppm in the 10.5 ft, 20.5 ft, and 30.5 ft samples, respectively. Soil analytical results from the initial investigation are summarized in Table 1. Low to moderate levels of TPHg and BTEX were reported in the initial groundwater sample collected from the well. Subsequent samples did not contain detectable TPHg or BTEX but did contain low levels of methyl tert-butyl ether (MTBE). The MTBE presumably originates from the massive fuel leak at the adjacent property (601 E. Miner). Groundwater analytical results are summarized in Table 2. 2.3 Conclusions of Previous Investigations The lateral and vertical extent of soil contamination appeared to have been defined during the phase of work completed in May 1995. Soil contamination is laterally concentrated beneath the former USTs and is vertically limited to depths between approximately 15120 and 30135 feet bgs. Contamination consists of moderately high levels ( 8,000 ppm) of weathered gasoline. Benzene is ' not present in detectable concentrations and TEX levels are minimal Based on extensive investigation conducted on an adjacent property (601 E. Miner), groundwater flow in the site vicinity is easterly to northeasterly. During the 1995 investigation, saturated soil was first encountered in monitoring well MWI at a depth of approximately 51 feet. Groundwater stabilized at a depth of approximately 46 feet. However, water levels subsequently rose until by ' 1998 groundwater levels were less than 30 feet bgs. In 1995, residual soil contamination was not in contact with groundwater and a suitable protective buffer existed. By 1998, groundwater had risen to the point at which it may have been in contact with the contaminated soil. Because of this circumstance the current investigation was proposed. 3.0 INVESTIGATIVE PROCEDURES ' In accordance with the approved workplan dated March 22, 1999 for additional subsurface investigation, soil borings were advanced at the site to investigate the potential impact to groundwater from contaminated soil. Work was conducted under the supervision of field ' geologist Sean Garvey, and project manager Gregory Stahl, a California Registered Geologist. On July 21, 1999, Fisch advanced boring HPI to a depth of approximately 5 feet bgs., however due ' to malfunctioning of the rig, work at the site was terminated. Boring HPI was backfilled to the native surface with neat cement grout, and capped with asphalt. ' On July 29, 1999, Fisch advanced borings HPI through IIP3 to a depth of approximately thirty-six feet below ground surface (bgs) by the direct push method. Due to the close proximity of underground piping along the western side of Stanislaus Street the proposed location of boring HP4 ' was investigated with a hand auger. At this location two parallel water mains(one 12' diameter and one 33" diameter) are present. The exact location and depth of the larger water line could not be determined from Cal Water Service. During hand auger advancement, unidentified clay and metal ' datalgroundzclvalleyvw\summary.doc 3