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Mr. Ron Rowe June 2, 1997 Page 3 3.0 FIELD ACTIVITIES 3.1 Drilling and Soil Sampling SECOR will supervise the installation of two groundwater monitoring wells (MW-2 and MW-3) at the locations shown on Figure 2. The wells will be installed in the anticipated cross-gradient and down-gradient direction from the former USTs to provide additional characterization of the extent of petroleum hydrocarbons in groundwater beneath the Site. The boreholes will be advanced to an approximate depth of 45 feet bgs or 10 feet below first encountered groundwater using a truck-mounted drill rig equipped with 8-inch diameter hollow-stem augers. Relatively undisturbed soil samples will be collected for lithologic description and possible chemical analysis at a minimum of 5-foot intervals using a California-modified split-spoon sampler lined with three 6-inch long brass tubes. A SECOR geologist will describe the soil encountered according to the Unified Soil Classification System (USCS) and will maintain boring logs of these descriptions. Representative soil samples from each sample interval will be screened in the field for the presence of volatile organic compounds (VOCs) using a Photoionization Detector(PID). Screening results will be documented on each boring log. SECOR will select a minimum of two soil samples from each drilling location for chemical analysis,one from the vadose zone and one from directly above the first encountered groundwater. The ends of the brass tubes containing the soil samples will be covered with teflon sheeting, capped with plastic end caps, labeled, sealed in plastic bags, and stored in an ice-filled cooler. The samples selected for chemical analysis will be delivered to a California state-certified analytical laboratory with a completed chain- of-custody documentation. Before use and between advancement of boreholes,drilling equipment will be decontaminated using a steam cleaner. Soil sampling equipment will be washed in a laboratory grade soap and potable water solution and rinsed with potable water before use and between sample intervals. 3.2 Monitoring Well Installation The boreholes will be converted to a groundwater monitoring well upon reaching the desired well completion depth. Wells will be completed with 15 to 20 feet of capped, flush-threaded, 2-inch diameter Schedule 40 PVC 0.020-inch machine-slotted well screen from the base of the borehole and completed with blank casing to ground surface. For each well location, filter sand will be placed in the annular space between the wall of the borehole and casing,to a height of one foot above the screened interval. One foot of bentonite pellets will be placed above the sand and hydrated. A cement grout mixture(5%bentonite)will then be place into the remaining annular space to ground surface. A flush-mounted,protective watertight monument cover will then be grouted slightly above ground surface to complete the well installation. The well will also be fitted with a locking watertight well cap. H AS FFMSTOCKTO N\W PLN.RPT 50090-011-03,001