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. 7-Eleven Store#32262 Work Plan for Additional Site Assessment and Interim Remediation March 19, 2004 Page 6 r delivery to Kiff Analytical in Davis, California Soil samples will be collected following the soil sample plan presented In Table 4 The selected samples will be analyzed for BTEX, TPHg, MtBE, DIPS, TAME, EtBE, and TBA using Environmental Protection Agency (EPA) Method 82606 a Well Installation and Well Development Groundwater Monitoring Wells Each monitoring well will be constructed using 2-Inch diameter PVC blank casing and 0 020-inch-slot well screen set from 7 feet bgs to 17 feet bgs A sand filter pack will be placed within the annulus of the well from the bottom of the boring to approximately one foot above the top of the well screen The annulus of the well will be sealed with two feet of bentonite on top of the sand, and a portland cement/bentonite grout to the surface An 8-Inch-diameter, traffic-rated, watertight street box will be Installed to protect the well from surface traffic Each monitoring well will be Installed at the location depicted on Figure 5 Following Installation, the new wells will be professionally surveyed to establish horizontal position in relation to pertinent site features and elevation with respect to mean sea level Groundwater Extraction Well Extraction well EX-1 will be constructed using 4-inch diameter PVC casing with the screen set from 10 to 25 feet bgs In order to improve well efficiency, a 0 010-Inch Circum Slot casing from Boart Longyear and #2416 sand will be used to complete the well The sand filter pack will be placed within the annulus of the well from the bottom of the boring to approximately one foot above the top of the well screen The annulus of the well will be sealed with two feet of bentonite on top of the sand, and a portland cement/bentonite grout to the surface A 12-inch-diameter, traffic-rated, watertight street box will be Installed to protect the well from surface traffic The extraction well will be Installed at the location depicted on Figure 5 Well Development Following Installation, the monitoring and extraction wells will be developed by surging and bailing using a surge block and bailer to remove fine-grained sediments from each well and sand pack Periodic measurements of pH, conductivity and temperature will be made during development to establish baseline values for groundwater Approximately 10 well casing volumes will be removed from each well during development All water generated during the development activities will be stored In DOT approved 55-gallon drums pending disposal Oxygen Infection Well The oxygen infection well (S-1) will be constructed with 3/4-inch diameter schedule 80 PVC blank casing and a 3-foot long stainless steel sparging diffuser tip The sparge tip will be Installed from 17 to 20 feet bgs (Table 3) A sand filter pack will be placed within the annulus of the well from the bottom of the boring to approximately one foot above the top of the diffuser tip The annulus of the well will be sealed with two feet of bentonite on top of the sand that will be capped with a Portland cement/bentonite grout to the surface The well will be sealed using a locking expansion cap An 8- inch-diameter, traffic-rated, watertight street box will be installed to protect the well from surface traffic 32262 Offsite well install and interim remediation workplan doc SECOR International Incorporated