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Additional Site Assessment Report and Work Plan for Additional Subsurface Investigation 5 The Southland 22URoration,Store#19976,1399 N Main St Manteca California June 5 1998 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 temporarily stored on site in DOT-approved 55-gallon drums pending characterization and disposal All waste well be disposed of as non-hazardous at a certified facility by a licensed hauling firm 5.2 Well Installation, Monitoring and Sampling ' A groundwater monitoring well will be constructed In each boring of 2-inch diameter Schedule 40 poly-vinyl- chloride(PVC) casing with flush threads and 0 020-4nch-slot well screen The well screen for each monitoring well will be Installed from approximately 10 to 30 feet BGS The wells maybe Installed to 35 feet BGS If field observations Indicate that petroleum hydrocarbons are present below 30 feet BGS A sand filter pack will be placed around the well screen to a maximum height of 1 foot above the top of the screen ' The well 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 IAA cement to 5 gallons of clean water The wellhead ' will be protected at the surface by a locking, expandable cap and traffic-rated street box(with watertight bolted lid)set in concrete These wells will be used to characterize and delineate the lateral extent of dissolved petroleum hydrocarbons Following installation,each monitoring well will be developed by 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 each well will be professionally surveyed relative to a mean sea level datum At least ' 48 hours after development, liquid levels In all monitoring wells will be monitored to measure static liquid levels Liquid levels will be monitored using an ORS Environmental Equipment INTERFACE PROBE"' 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 groundwater elevations and generate a potentiometric surface map Following monitoring,field Instruments will be used to determine dissolved oxygen levels in the wells Then, each well will be purged pnor to sampling During purging,temperature,pH, and conductivity of the ' purged water will be measured, until measurements have stabilized After stabilization of purge water parameters indicate achievement of formation conditions,the wells will be allowed to recharge to within 80%of static level, and then groundwater samples will be collected from each well Water samples will be ' obtained using dedicated disposable bailers and clean string The samples will be collected Into 40- milliliter glass volatile organic analysis(VOA) vials,filled to zero headspace, acidified to a pH of 2,sealed with Teflon septa and screw-on caps, labeled,and placed on Ice in a cooler for shipment under legal chain- of-custody to a state-certified laboratory for BTEX, MTBE, and TPH-G analysis by modified EPA methods 8020/8015 1997"w rpt FElf4R DANIEL GTI