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20 June 2002 AGE-NC Project No. 01-0827 Page 2 of 6 The Modesto, Riverbank, Turlock Lake Formations and overlying recent alluvium are the principal sources of domestic ground water in the 11,500-square-mile San Joaquin Valley Ground Water Basin (Basin 5-22). This basin is drained primarily by the San Joaquin River. The closest surface water feature to the site is Mormon Slough located approximately 500 feet west of the site. 2.2. PRFVIOLS INVESTIGATIONS During redevelopment construction on the southeastern portion of the site, a former accelerant fuel line used for fire training was discovered. The product line was uncovered, removed and soil was sampled and analyzed for petroleum hydrocarbons. In addition, a former UST location was discovered at the eastern end of the pipeline during the pipeline removal; this location was re- excavated and a soil sample was collected and analyzed. Laboratory analysis of soil samples detected concentrations of total petroleum hydrocarbons as diesel and motor oil (TPH--d and TPH-mo) at 2,300 milligrams/kilogram (mg/kg) and 4,000 mg!kg, respectively. and total lead at 245 mg/kg in one soil sample collected at a depth of four feet below surface grade(bsg)from the south-western most fuel dispersion device(burn-area). In addition,TPH- d and/or TPH-mo were detected in several of the remaining soil samples at low concentrations. 2.3. SIT>✓ HYDROGEOLOGIC CONDITIONS Based upon ground water monitoring well information obtained from the site(100 feet northwest of the southern UST area),groundwater flow direction is northeasterly to eastetnly and currently occurs at a depth of approximately 20 feet bsg within ground water wells. Ground water occurs in a generally sandy layer extending fi-om approximately 20 feet bsg to 30 feet bsg. Based on cross sections on file with the EHD, the sedimentary units are thought to be relatively horizontal and continuous over the area. 3.0. SCOPE OF WORK The objectives of this uivestigation are to determine if ground water is impacted at the site, determine the feasibility of soil excavation and if necessary, aide in determining suitable locations for any necessary ground water monitoring wells To achieve these objectives, the propose scope of work includes advancing four soil probe borings to collect soil and grab ground water samples The proposed scope of work will include the following tasks: • Permitting and pre-field work activities; • Sample and analysis with laboratory reporting; Advwiced(_1eoEnvironmental.Inc.