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PROPOSED PRELIMINARY SITE INVESTIGATION OVERVIEW The proposed preliminary site investigation consists of borehole soil sampling within, and just outside of, the property boundaries at the Thornton Gas Dehydrator Station. The work will consist of coring and sampling the subsurface soils at approximately 15 locations in the immediate vicinity of the site to assess the presence or absence of petroleum hydrocarbons. Soil sampling will be performed from the ground surface to approximately 15 feet (or refusal); however, the borings will not be advanced below first encountered groundwater. The data and results derived from this study will be compiled and presented in a summary report. PERSONNEL AND PROCEDURES All environmental work described in this workplan will be supervised by a PG&E California Registered Geologist. An experienced field geologist will log the exploratory borings, collect subsurface soil samples, and coordinate delivery of the samples to a State of California-certified analytical laboratory. The PG&E Registered Geologist will oversee the exploratory program during all phases of work, conduct site visits during field activities, review the data, and participate in report preparation and other agency submittals. The assessment procedures (e.g., permitting, sampling protocol, chain of custody, Health and Safety Plan, etc.) will follow the San Joaquin County and LUFT manual guidelines. SOIL CORING AND SAMPLING PROCEDURES Borehole Advancement Prior to conducting any subsurface soil sampling procedures at the site,the location of underground utilities will be checked and marked by reviewing available blueprints of the site. PG&E locating crews will be utilized to locate all underground gas supply lines. The soil borings will be advanced at the approximate locations shown on Figure 2 using a hand-operated soil coring device (JMC's Environmentalist Subsoil Probe-ESP). The ESP collects 1-inch diameter soil samples, up to 3 feet long, to a maximum depth of 15 feet (depending on soil conditions). Each soil core collected by the ESP is encased in a plastic liner. The core liners are driven into the soil by a 12.5-pound sliding drop hammer that advances the core barrel and fills the plastic liner. Once the probe is driven 3 feet, the core barrel is extracted from the subsurface using a foot-operated jack that allows rapid retrieval. By repeating this process,the subsurface soils are sampled in 3-foot intervals to the total depth of the borehole. After each soil sample has been collected, the sample liner ends will be covered with aluminum foil, sealed with vinyl caps, and secured to the tube with plastic adhesive tape. Each sample tube will be labeled using cca/9-23-92/8809a/JAWP 12 5