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Mr. M. Scott Mansholt—Chtvfon Environmental Management Corporation`� Page 3 Pombo Property—Soil and Groundwater Investigation Work Plan July 31,2003 WORK PLAN The proposed scope of work consists of the three tasks described below: Task 1 —Soil Borings SAIC will delineate the lateral extent of TPHd in downgradient from boring GMX-32, where it was previously detected in a grab groundwater sample. This will be accomplished by advancing two soil borings, northwest and northeast of GMX-32,using a Geoprobeor equivalent hydraulic sampling equipment. Proposed sampling locations will be on Fruitwood Circle, approximately 150 ft northeast of GMX-32, and on Laurelgrove Lane, approximately 185 ft northwest of GMX-32. Maximum depths of borings will be approximately 15 ft. The proposed locations, as well as selected previous soil boring locations discussed in this Work Plan, are shown on Figure 3. Preparatory to the field investigation, encroachment permits and boring permits will be in place with the local authorities. SAIC will have a health and safety plan in place, contact Underground Service Alert (USA), and contract with a private subcontractor to perform an underground utility clearance at each boring location. Soil samples will be collected in accordance with the ChevronTexaco Quality Assurance/Quality Control Sample Collection Guidelines, Chevron Old Valley Pipeline Sites, California (Geomatrix Consultants, August 2001). A continuous-core sampling device will be used if geologic conditions permit. Soil borings will be advanced until the base of visually affected soils or approximately two feet below the water table. The soil lithologies will be logged by an SAIC field geologist, under the supervision of a California-Registered Geologist in accordance with the Unified Soil Classification System (USCS) as presented in ASTM 2488-90. All soil cores will be field screened visually and by using a photo-ionization detector(PID) to monitor the presence of petroleum hydrocarbons in soil. Based on the field determination, up to two soil samples per boring will be submitted for chemical analyses. One sample will be collected from the zone of observed petroleum impacts, and another at the bottom of the boring, below visibly impacted soils. If the soil samples do not appear to be affected with petroleum hydrocarbons, SAIC will submit one sample collected just above the presumed water table for analysis. Soil and groundwater samples will be labeled, sealed in a plastic bag, and placed in an ice-filled cooler for transport to the laboratory. The soil samples will be submitted to Friedman & Bruya of Seattle, Washington, a California-certified laboratory(ELAP #1727), under SAIC chain of custody protocol, for the following chemical analyses: