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S E C 0 R Soil and Groundwater Assessment Work Plan 7-Eleven Store #32262 fi August 12, 2003 Page 2 equipped with 8-inch diameter hollow stem augers to a total depth of approximately 17 feet below ground surface (bgs)to accommodate installation of a monitoring well Borings MW-1 and MW-5 will be continuously cored from 5 to 17 feet bgs to identify any high permeability sand beds at the site Sod samples will be collected from MW-2, MW-3, and MW-4 every 5 feet using a split spoon sampler lined with 2-inch diameter by 6-inch-long brass sample tunes Down hole drilling equipment will be steam cleaned before drilling each borehole, and sampling equipment will be cleaned between each sampling interval Each soil sample will be screened for hydrocarbon vapors using a portable photaonization detector (PID) Soils encountered during drilling will be logged using the Unified Soil Classification System by a SECOR field geologist, working under the supervision of a California registered geologist All soil generated through drilling will be placed in Department-of-Transportation (DOT) approved 55- gallon drums on site pending characterization and disposal Water generated by steam cleaning will be contained in a steam-clean trailer and temporarily stored on site in DOT approved 55-gallon drums All soil samples collected using 2-inch diameter by 6-inch-long brass sample tubes will be sealed with Teflon® sheeting and plastic caps, then labeled and placed on ice in an insulated container for delivery to Kiff Analytical located in Davis, California Soil samples collected at 5, 10, and 15 feet • bgs will be analyzed for benzene, toluene, ethylbenzene and xylenes (BTEX), total petroleum hydrocarbons-as-gasoline (TPHg), and methyl-tert butyl ether (MtBE) di-isopropyl ether (DIPE), tert- amyl-methyl ether (TAME), ethyl-t-butyl ether (ETBE), and tert-butyl alcohol (TBA) using Environmental Protection Agency(EPA) Method 8260B Well Installation and Well Development Each monitoring well will be constructed using 2-inch diameter polyvinyl chloride (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 slurry 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 2 Following installation the well will be developed by surging and bailing using a surge block and bailer to remove fine-grained sediments from the 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 the well during development All water generated during the development activities will be stored in DOT approved 55-gallon drums pending disposal Following installation, the new well will be professionally surveyed to establish horizontal position in relation to pertinent site features and elevation with respect to mean sea level GROUNDWATER MONITORING AND SAMPLING Groundwater monitoring and sampling will be conducted to evaluate the groundwater quality by collecting representative samples Prior to sampling, depth to water in the groundwater monitor well will be taken and subjective analyses performed Each well will be sampled by purging �6 A