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U 15 March 2005 AGE-NC Project No. 04-1168 Page 4 of 9 3.2. MONITORING WELL PILOT BORINGS AND SOIL SAMPLING AGE proposes to use a truck-mounted,hollow stem drill rig equipped with 8-inch diameter hollow- stem augers to advance three pilot soil borings to approximately 70 feet bsg to install ground water monitoring wells(MW-1 through MW-3);the wells are required in order to further assess petroleum hydrocarbon-impacted soil and ground water beneath the site. The total depth of each pilot boring may vary according to hydrogeologic/geologic information, depth to ground water during drilling and drilling conditions. Based on known contamination encountered at the site to date and nearby ground water flow directions towards the northwest and west, AGE proposes to advance the pilot borings in the following locations (Figure 2): • One boring near boring B2 at the northeast corner of the former UST excavation to assess the petroleum hydrocarbon-impacted soil and ground water; • One boring approximately 40 feet northwest of the first boring(near 132)to assess the down- gradient extent of impacted soil and groundwater; and • One boring approximately 30 to 40 feet south-southwest of the first boring (near 132) to assess the down-.gradient extent of impacted soil and ground water. 3.2.1. Soil Sample Collection and Analyses As the borings are advanced,soil samples will be collected at 5-foot intervals beginning at 5 feet bsg and extending to the total soil boring depth.Field procedures for advancement of the soil boring and collection of soil and groundwater samples are presented in Section 4.L. Selected soil samples will be analyzed by a State of California Department of Health Services (DHS)-certified laboratory for the following constituents: • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015M; and • Benzene,toluene, ethyl benzene and xylene (BTEX),and the fuel additives methyl tertiary- butyl ether(MTBE),tertiary butanol(TBA),di-isopropyl ether(DIPE),ethyl tert-butyl ether (ETBE),tert-amyl methyl ether(TAME),ethylene dibromide(EDB)and 1,2-dichloroethane (1,2-DCA) in accordance with EPA Method 8260B. Laboratory reports for the soil analyses,testing methods,laboratory quality assurance/quality control (QA/QC) reports, and sample chain of custody documentation will be presented in a report with findings and recommendations. Advanced GeoEnvironmental,Inc.