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Mr.Ron Rowe November 24, 1997 Page 5 Methodology and Procedures Before initiation of field activities,SECOR will update the existing Site-specific Health and Safety Plan(HASP) to address the proposed scope of work and obtain well construction permits from the SJCEHD. The proposed drilling locations will be cleared with respect to underground utilities and other obstructions using a professional utility locator and Underground Service Alert(USA)will be notified at least 48-hour in advance of field activities. The San Joaquin County Environmental Health Division Well Construction Permit application is attached as Appendix D with a check for$89. At each CPT location,an initial CPT hole will be advanced using an electronic piezocone tip. The piezocone tip will measure cone bearing,sleeve friction and dynamic pore pressure at 5 centimeter intervals. At selected depth intervals, pore water pressure measurements will be monitored over time to determine relative hydraulic conductivity and hydrostatic head in the formation adjacent to the tip. A second CPT hole will be advanced adjacent to the first for the purpose of collecting groundwater samples from water-bearing horizons identified in exploratory boring and initial CPT boring. Depth discrete groundwater samples will be collected using a Hydropunch sampling tool. Groundwater samples will be analyzed for TPHg, BTEX, and MTBE by EPA Methods 8015(modified)and 8020,respectively by a state-certified laboratory on an overnight 05-hour)rush basis. Proposed CPT sounding locations are depicted on Figure 2. An initial CPT sounding(CPT-1)will be advanced adjacent to the MW-7 well cluster within the former UST excavation. This CPT sounding will provide the following information, (1) allow correlation between soil types logged by physical examination in exploratory boring MW-7 and soil types interpreted by CPT, and (2)assess the vertical extent of petroleum hydrocarbon- affected groundwater beneath the former UTs. It is anticipated that three depth discrete groundwater samples will be collected from CPT-1. One sample from approximately 80 to 85 feet bgs to confirm the results from well MW-7-D and two samples from deeper water-bearing zones beneath 85 feet bgs. The total depth of CPT-I will be based on the depth limitations of the CPT rig(estimated to be approximately 125 feet lags). At a minimum,two additional soundings will be advanced inside the building in the anticipated down-gradient direction from well cluster MW-7 and CPT-I (CPT-2 and CPT-3). The required depth of these CPT soundings will be based upon the groundwater analytical results from CPT-1. It is anticipated that a trdnimum of four discrete groundwater samples will be collected from these two CPT soundings. Pending the results of groundwater samples from CPT-2 and CPT-3, up to three additional CPT soundings will be advanced further downgradient(CPT-4,CPT-5,and CPT-6). Fuel Fingerprinting Groundwater samples will be collected from two water-bearing zones at the Site to help identify the source(s)of dissolved phase petroleum hydrocarbons present beneath the Site. The constituent composition of each sample (fuel fingerprinting) will be assessed. The first sample will be collected from vapor extraction well VE-1 (if groundwater is located in the well;if not,well MW-1 will be sampled), which is screened from 15 to 35 feet bgs and is located within the former UST excavation. Well MW-1 is located north of the former UST excavation and is screened from 26 to 46 feet bgs. The second sample will be collected from well MW-7-D,which is screened from 80 to 85 feet bgs and is located with the former UST excavation. The samples will be collected after purging a minimum of three well volumes from each well and allowing the well to recover to 80%of the initial water level. The samples will be delivered to Global Geochemistry Corporation (GCC) in Canoga Park, California,with completed chain-of-custody records. The samples will be extracted with methylene chloride by f\ GCC,with the extracts fractionated by column chromatography and the separated fractions analyzed using gas chromatography and mass spectrometry (GC/MS). The resulting chromatograms will be used to assess the constituent compositions in each of the samples. H ASFFR\STOC KTONI W K P2.RAT