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5 • • 14 August 2003 AGE-NC Project No. 01-0865 Page 2 of 6 3.1. PERMITTING AND PRE-FIELD WORK PREPARATIONS Applicable site assessment permits will be obtained from the San Joaquin County Environmental Health Department(EHD).hi addition,an update to the health and safety plan presently on-file will be prepared in accordance with Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities (National Institute for Occupational Safety and Health Administration, U.S. Coast Guard and U.S. Environmental Protection Agency, 1985). Prior to mobilization, each probe boring location will be clearly marked and a utility clearance obtained through Underground Service Alert. 3.2. DRILLING AND SOIL SAMPLE COLLECTION AND ANALYSIS AGE proposes to advance four vertical soil probe borings at the site,using a van-mounted Geoprobe 5400 direct-push probing unit equipped with 1.25-inch probing rods,to further assess the impact to soil and ground water from the former UST area.Proposed probe boring locations are illustrated in Figure 2. Based on soil contamination encountered in the area of well MW-6 down-gradient of the former USTs,AGE proposes soil probe borings in the following locations: • Approximately 10 to 12 feet northwest of MW-6 and a minimum of five feet from the foot of the retaining wall. This is to further delineate vertical soil and shallow ground water contamination directly down gradient of the former USTs and up gradient of MW-6. • Approximately 45 to 50 feet east of MW-6 on the eastern side of the AST enclosure to further delineate vertical soil and shallow ground water contamination down gradient of the AST enclosure between MW-6 and MW-7. This boring's location may be modified due to existing trees and undulating surface topography in the immediate area. • Approximately 20 to 25 feet northeast of MW-6 on the western side of the ASTs, near the tank filling station and immediately north of the product piping from the ASTs to the dispensers. This boring will further delineate vertical and lateral soil and shallow ground water contamination adjacent to the AST enclosure. • Approximately 22 to 24 feet northwest of MW-5,this soil boring is to further determine the lateral extent of contamination in the northern portion of the property up-gradient of MW-5. Soil boring MW-5 had moderate methyl tertiary butyl ether(MTBE)concentrations detected in the soil, 1.0 mg/kg in sample MW54 and 0.017 mg/kg in sample MW-5-14; and the groundwater samples at MW-5 have had elevated amounts of MTBE and total petroleum hydrocarbons quantified as gasoline(TPH-g)the last three quarters. Advanced GeoEnvironmental,Inc.