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PROPOSED SITE INVESTIGATION OVERVIEW The proposed site investigation consists of borehole soil sampling and groundwater assessment within the property boundaries of the Lathrop Gas Dehydrator Station and in the property located immediately east of the site. The work will consist of drilling and soil sampling 6 to 9 exploratory soil borings, installing a groundwater monitoring well in one of the boreholes located adjacent to the reboiler unit, and collecting groundwater grab samples from each of the borings (see Figure 2 for the location of the proposed exploratory borings and monitoring well). In addition, if the groundwater level in each borehole stabilizes within a 24-hour period, an attempt will be made to determine the groundwater flow direction and gradient prior to borehole abandonment. Lastly, a survey of all water wells located within a Ih-mile radius of the site will be performed. The data and results derived from this study will be compiled and presented in a summary report. These data and results will be evaluated to determine if additional site investigation activities (e.g., soil borings and/or groundwater monitoring wells) are needed. PERSONNEL AND PROCEDURES All environmental work described in this work plan will be performed under the direction of a PG&E California Registered Geologist. A qualified field geologist will log the exploratory borings and the monitoring well, collect subsurface soil and groundwater samples, and coordinate delivery of the samples to a State of California-certified analytical laboratory. The 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 and LUFT manual guidelines. UNDERGROUND UTILITIES Prior to conducting any drilling activities at the site, the location of underground utilities will be checked by reviewing available blueprints of the site. PG&E crews will be utilized to locate all underground gas supply lines. In addition, a soil probe and/or magnetic locator will be used at proposed drilling locations where the presence of underground utilities remain unknown. The upper 3 to 5 feet of each borehole will be advanced using a hand auger or similar device. SOIL AND IN-SITU GROUNDWATER SAMPLING Six primary soil borings will be advanced in the area adjacent to the reboiler unit to facilitate the collection of soil and groundwater samples. The purpose of the sampling will be to further define the lateral and vertical extent of petroleum hydrocarbons in the subsurface soils and groundwater. One exploratory boring located near the reboiler unit will be used for the installation of a groundwater monitoring well. Should the cca/9-30-92/8913a/JAWP13 7