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Ms Mary Meays Page 4 March 2, 1994 Site 2 A release of petroleum products to soil and ground water from a 500-gallon underground fuel 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 lateral occurrence of TPH and BTEX in soils was limited to the area immediately northeast of the former tank location and the vertical occurrence was primarily limited to the 5-to-7 5-foot bgs depth interval Based on data obtained during the investigations, the volume of soils containing TPH as gasoline in excess of 100 ppm at Site 2 was estimated to be approximately 500 to 700 cubic yards 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-IA is upgradient of the former tank location Tidal fluctuations as a result of the proximity of the Stockton Deep Water Channel do influence the ground water gradient at the site, but the ground water flow direction has been generally consistent REMEDIATION PREPARATION_WORK The selected soil remedial alternative, as described in the Final Remediation Plan approved by the County in September 1993, included excavation and aeration of the affected soil Preparation for the remediation included subcontractor selection, selection of rental equipment suppliers, and selection of the aeration treatment area In addition, the following permits and permission were obtained to proceed with the soil remediation • San Joaquin County Unified Air Pollution Control District permit for uncontrolled aeration, and • A grading permit from the City of Stockton SOIL EXCAVATION DETAILS The soil excavation activities were conducted by ERM and Sunriver Engineering & Construction, Inc (Sunrxver) of Brentwood, California and were conducted between 4 October 1993 and 25 October 1993 Prior to initiating excavation activities, a utility search was performed at both Sites 1 and 2 and underground utility locations were outlined with spray paint To expedite the excavation process, a mobile laboratory was used to perform onsite soil sample analyses A state-certified mobile laboratory, Transglobal Environmental Geochemistry (TEG) of Sacramento, California, was used to analyze confirmation soil samples for the chemicals of concern (TPH as . gasoline and BTEX) Visual and olfactory evidence of the presence of gasoline