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Workplan for Additional Assessment and Feasibility Testing 4 <br /> 7-Eleven, Inc Store No 17334 4501 North Pershing Avenue Stockton CA October 17,2001 <br /> Well Construction/Development(GauginalSampling <br /> The groundwater monitoring wells will be constructed with 2-inch diameter Schedule 40 poly-vinyl-chloride j <br /> (PVC) casings with flush threads and 0.020-inch-slot well screen from 5-25 feet below grade. Sand filter <br /> packing will be placed around the well screen to a maximum height of 2 feet above the top of the screen. <br /> The filter packs will be sealed with 2 feet of bentonite (hydrated in place to prevent bridging) overlain by <br /> neat cement to surface grade. The wellheads will be protected at the surface by locking, expandable caps <br /> and traffic-rated street boxes(with watertight bolted lid)set in concrete. <br /> Following installation,the monitoring wells will be developed by hand bailing to remove fine-grained <br /> sediments from the well and filter pack. Water from the development process will be containerized and <br /> temporarily stored on site in DOT-.approved 55-gallon drums. <br /> The top of casing of the wells will be professionally surveyed relative to a mean sea level datum, and <br /> gauged and sampled during the next quarterly monitoring event following drilling. <br /> Groundwater samples from each new well will be analyzed by a State-certified analytical laboratory for <br /> BTEX and TPH-G by EPA methods 8020/8015 modified, and the oxygenates:TBA,MTBE, DIPE, ETBE, <br /> TAME by EPA Method 8260. <br /> Schedule/Report <br /> i <br /> Drilling will commence within 6 months of receipt of written approval of this workplan, pending permit <br /> approval. Report preparation will be completed within.6-8 weeks of well installation <br /> i <br /> WORKPLAN FOR,PROPOSED INITIAL FEASIBILITY TESTING <br /> Soil Vapor Extraction Testing <br /> Soil vapor extraction (SVE) can be used to remove the soil source of the dissolved hydrocarbon plume and <br /> supply additional oxygen to the subsurface to enhance intrinsic biodegradation,with the anticipated goal of <br /> reduction of dissolved gasoline constituents. <br /> Compared with other gasoline constituents, MTBE is both more hydrophilic and adsorbs much less. These <br /> properties result in decreased extraction potential in moist soils,but increased vapor mobility in dry soils, <br /> Given the site's current active status, and the relative low cost of vapor extraction as a remediation <br /> technique,it is considered prudent to test the site for venting capability. <br /> i <br /> 17334SAW.DOC <br /> r <br />