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3.0 SCOPE OF WORK As shown in Figure 3, PEI plans to complete twenty soil vapor borings, twenty shallow soil borings (up to 20 feet), and four (4) deep borings to groundwater (estimated at 45 feet bgs). Borings will be placed proximal to suspect features identified in the geophysical survey. 3.1 Geophysical Survey The geophysical survey is intended to be used as an initial exploratory technique and to direct some of the next phases of the Assessment, depending upon the findings. A geophysical subcontractor will conduct a geophysical survey in accessible areas using electro-magnetic (EM) and ground-penetrating radar (GPR) survey equipment. The survey will be extensive and include significant exterior areas of the property in an effort to evaluate the potential boring locations, locate potential subsurface anomalies (e.g., potential USTs), and locate underground utilities in the potential boring locations. However, due to the size of the property (5 acres) not all areas will be surveyed and some areas will only be briefly surveyed. Interior and exterior concrete slab areas and areas consisting of reinforced concrete, dissimilar paving or subsurface materials, and/or metallic items may limit the results of the survey. 3.2 Soil Vapor Sampling Soil vapor sampling will be conducted to assist in the location of areas of potential environmental concern to better locate soil borings. Soil vapor sampling will be conducted in accordance with the protocols of California EPA-Department of Toxic Substance Control (DTSC), Advisory-Active Soil Gas Investigations, January 28, 2003. Soil vapor sampling probes will be installed at 5 feet bgs (all borings). If areas of impact are discovered (based on mobile laboratory results), additional soil vapor samples may be obtained at deeper intervals (e.g., 15 feet bgs) depending on time and field conditions. Dedicated sample tubing will be nylon or polyethylene. Sample probe tips will be embedded midway within a minimum one-foot section of sand pack, followed by at least one foot of dry granular bentonite. Hydrated granular bentonite will then be placed and depth-measured in the bore hole to the next shallower probe depth and probe placement procedures will be repeated. Tubing is to be marked with probe depth and capped at surface. After installation of the five-foot bgs sample probe and one-foot of dry granular bentonite, the boring will be filled to within six inches of surface with wetted bentonite. After completion of soil vapor probe installation, at least 30-minutes prior to sampling will be allowed for the soil vapor to reach equilibrium. A purge volume test will be conducted in the boring closest to a room that reportedly contained chemicals on the north-central portion of building. The purge volume test will be conducted using one, three and seven purge volumes. The final sample purge volume will be based on the highest concentrations of contaminants of interest (COI, e.g., chlorinated solvents) detected during the purge step test. Isopropanol tracer gas will be used as a leak check compound during soil vapor sample extraction and will be analyzed and reported with the COI. Purge and sample rates will be maintained between 100 to 200 milliliters per minute. Samples will be collected in either a syringe or glass bulb covered Remediation Pilot Study Workplan Pinnacle Environmental,Inc. 248 Industrial Drive,Stockton,CA Page 4