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A filter pack of Monterey#3 graded and washed sand will be placed through the hollow-stem augers as they are slowly retrieved and until the sand pack reaches approximately two feet above the top of the screened interval. Overlying the sand pack, two feet of bentonite chips will be placed within the annular space between the borehole and the well casing. Over the hydrated bentonite, a surface seal of neat cement grout will be installed with a tremie pipe. The top of the well will also be secured with a water-tight locking cap and an above-grade stove pipe monument. 2.3.3 Soil Sampling, Well Development and Wellhead Elevation Survey During the drilling of the soil borings for both monitoring wells, soil samples will be collected at 5- foot intervals using a modified California split-spoon sampler lined with brass or stainless steel sleeves. A field geologist will log all soil samples for hydrogeologic and lithologic characteristics according to the Unified Soil Classification System and screen each sample for any organic vapors using a photoionization detector(PID). Given that the extent of impacted soil has been defined, no additional soil samples will be collected for laboratory analysis. Both of the wells will be developed by the driller, following the placement of the sand packs and prior to the installation of the well seals. Well development will include surging with a surge block and periodic purging with a bailer. Surging and purging will continue until at least five well volumes have been removed and/or after groundwater temperature, pH and electrical conductivity have stabilized. A licensed land surveyor will survey each of the newly-installed wellheads. The surveyor will measure the elevation of the tops of well casings to the nearest 0.01 foot, referenced to the wellhead elevations of the existing monitoring wells. The locations of the wells and other site features will also be surveyed. 2.3.5 Groundwater Monitoring, Sampling and Analysis ,.. Once the seals in the new wells have had sufficient time to set (at least 72 hours), the wells will be monitored and sampled. After the initial monitoring and sampling, the wells will be incorporated into the on-going quarterly groundwater monitoring and sampling program at the site. �,. During each monitoring and sampling event, depth-to-groundwater and free product thickness (if necessary) will be monitored in each well using a water level indicator capable of measurements to within 0.01 foot. 9