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3 Work Plan for Additional Site InvestigationMarch 29,1997 The Southland Corporation,4501 North PershingAvenue,Stockton,CA All soil generated through drilling will be placed in Department of Transportation (DOT)-approved 55-gallon drums pending characterization and disposal. Water generated by steam cleaning will be contained and temporarily stored on site in DOT-approved 55-gallon drums pending characterization and disposal. TASK 3: WELL CONSTRUCTION/DEVELOPMENT/GAUGING/SAMPLING A groundwater monitoring well will be constructed in each boring of 2-inch Schedule 40 poly-vinyl-chloride (PVC) casing with flush threads and 0.020-inch-slot well screen. The well screen in monitoring wells MW- 1, MW-2, MW-3, and MW-4 will be installed from approximately 13 to 33 feet BGS. The screen in monitoring well MW-1A will be installed from approximately 38 to 40 feet BGS. A sand filter will be placed around each well screen to a maximum height of 1 foot above the top of the screen. The wells will be sealed with 2 feet of hydrated bentonite,followed by a neat-cement grout to grade containing a mixture of 95 pounds of Portland Type 1/II cement to 5 gallons of clean water. The wellhead will be protected at the surface by a Igcking, expandable cap and traffic-rated street box (with watertight bolted lid) set in concrete. These wells will be used to characterize and delineate the extent of dissolved petroleum hydrocarbons. Well MW-1A will be used to characterize dissolved petroleum hydrocarbons beneath the existing water table. Following installation, each monitoring well will be developed using a surge block and hand bailing to remove fine-grained sediments from the well and filter pack. Water from the development process will be temporarily stored on site in DOT-approved 55-gallon drums. The top of casing of the wells will be professionally surveyed relative to a mean sea level datum. At least 48 hours after development, static liquid levels in all monitoring wells will be gauged using an ORS Environmental Equipment INTERFACE PROBE TI Well Monitoring System,which consists of a dual optical sensor and electrical conductivity probe that distinguishes between water and petroleum products. The survey data will be used along with the depth-to-water measurements to calculate water elevation in the monitoring wells, and estimate local groundwater flow direction and gradient. Following monitoring,4 well casing volumes of water will be removed from each well prior to sampling of groundwater. A log will be maintained that includes measurements of pH, temperature, and conductivity of purged water. Once measurements have stabilized, groundwater samples will be collected from each well. Collected groundwater samples will be analyzed by a State-certified analytical laboratory for BTEX, MTBE, and TPH-G by EPA methods 8020/8015 modified. i 0496WKP LTR FLUOR DANIEL GTI