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' • P however, upon request, Walsh can take the appropriate measures to responsibly dispose of the soil Soil samples will be selected for laboratory analysis based on OVM readings and proximity to the groundwater surface The samples will be listed on a Chain of Custody record and transported directly to the laboratory for analysis Selected samples will be analyzed for TPHg using Environmental Protection Agency (EPA) method 8015 (modified), and for BTEX using EPA method 8020 by Matrix Environmental Laboratories of Rancho Cordova, California, a state-certified environmental laboratory for these analyses Monitoring Well Construction Monitoring wells will be constructed in the borings using flush-pointed, 2-in or 4-in inner diameter, Schedule 40 polyvinyl chloride (PVC) casing No chemical cements, glues, or solvents will be used in well construction The screened portion of each well will consist of factory-perforated casing with 0 020-in-wide slots The well screen will be set through the augers and will extend from the total depth of the borings to approximately b to 8 ft above the groundwater surface at the time the well is installed This construction allows sampling near the air/water interface in the formation during seasonal fluctuations of groundwater elevations The base of each well will be fitted with a threaded PVC plug, and the top of each well will be fitted with a watertight locking cap The annular space of each well will be packed with sorted #3 Monterey sand to a point approximately even with the tops of the perforated casing A 1- to 2-ft thick plug consisting of bentonite pellets/chips will be placed above the sand in each well to prevent cement from entering the sand pack The remaining annular space will be backfilled with a mixture of neat cement and powdered bentonite (<5%) to grade A traffic-rated, cast-iron utility box with a metal apron will be placed over each wellhead and set in concrete flush to slightly above the surrounding grade Utility boxes such as these have a watertight seal to protect against surface-water infiltration and a cover fixed by countersunk bolts A locking well cap will be installed on each well head This design discourages vandalism and reduces the possibility of accidental or unauthorized disturbances of the well Groundwater Sampling Following the completion of monitoring well construction, each well will be surged with a vented surge block and groundwater in each well will be subjectively inspected by lowering a clean bailer to the groundwater surface and retrieving a groundwater sample The water will be examined for floating product, sheen, or odor If floating product is detected, the well will not be developed or sampled If the well does not show floating product, it will be developed by extensive pumping until three to five well volumes of groundwater are purged from the well, and stable field readings of pH, specific conductivity, and temperature are obtained The existing monitoring well MW i will not be sampled -.r 9/14193 5 1685-030 scw &Associates, Inc Environmental scientists and Engineers