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Ms Mary Meays Page 2 April 13, 1994 confirmed after construction and development of monitoring wells at both sites • indicated that stabilized water levels tended to be higher than initial water levels In general, the ground water potentiometric surface at the site is at a depth of approximately 4 to 6 feet bgs Potentiometric surface maps prepared individually for Sites 1 and 2 between January 1991 and March 1993 have consistently shown ground water flow directions to be toward thesouth-southwest The predominant flow direction appears to be away from the Stockton Deep Water Channel, which lies immediately north of the property line Tidally-induced water level fluctuations in the channel appear to be the cause of slight-to-moderate variations in the ground water flow gradient Ground water wells are a common source of potable water in the Great Valley geomorphic province However, no water supply wells are located within a 2,000- foot radius of the West Weber sites PREVIOUS INVESTIGATIONS A brief summary of the ground water investigation activities previously conducted at Sites 1 and 2 is provided below (for additional details, see the Preliminary Assessment Report prepared by ERM-West in May 1993) For reference, see the attached General Site Plan illustrated in Figure 1 Site 1 1515 West Weber A release of petroleum products to ground water from a 2,000-gallon underground gasoline storage tank formerly located at Site 1 was documented Subsequent investigations conducted at the site defined the extent of the release The extent of total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylene (BTEX) in ground water was limited to a localized area in the vicinity of the former tank, and no significant migration of chemicals in ground water has been observed over time The results of quarterly ground water samples collected from the five site monitoring wells between April 1991 and April 1993 showed a steady decline in the concentrations of TPH as gasoline and benzene in ground water All monitoring wells at Site 1 (except for well MW-5) have been non-detect for these compounds since December 1992 MW-5 is located directly beneath the former tank Site 2 1325 West Weber A release of petroleum products to ground water from a 500-gallon underground gasoline storage tank formerly located at Site 2 was documented The extent of the release was defined during a Phase I and Phase II investigation The extent of TPH and BTEX in ground water at Site 2 was limited to a localized area surrounding monitoring well MW-1A (located lust north of the former tank location) Based . on historic ground water level data, MW-1A is upgradient of the former tank location The remainder of the monitoring wells at Site 2 (MW-2A through MW-