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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. The wells will be surged and purged by the driller, following the placement of the sand pack and prior to the installation of the well seals. Periodic surging and purging will continue until the amount of suspended sediment in the groundwater decreases and stabilizes and/or until at least five well volumes have been removed. Overlying the sand pack, two feet of hydrated bentonite chips will be placed within the annular space between the borehole and the well casing. Over the hydrated bentonite, a surface seal of 20:1 cement:bentonite grout mixture will be installed. The tops of the wells will be secured with water-tight locking caps and traffic-rated, flush-mount street boxes. 2.2.2 Soil Sampling and Analysis During drilling, undisturbed soil samples will be collected at 5-foot intervals using a modified California split-spoon sampler, lined with two-inch diameter by six-inch long brass sample sleeves. A field geologist will log each of the undisturbed 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). Unless field observations dictate otherwise,four soil samples per soil boring will be submitted for laboratory analysis. To further evaluate the lateral extent of impacted vadose zone soil, the soil 4 samples collected at 15 and 25 feet from each soil boring will be submitted for analysis. In addition the soil sample collected from the capillary fringe at approximately 80 feet bgs and from the bottom of the soil boring at approximately 90 feet bgs will be submitted for laboratory analysis. If any other soil samples exhibit evidence of impact(e.g., petroleum odor, discoloration or PID reading), they may also be submitted for analysis. Field observations and sample selection will be reviewed with the PHS/EHID inspector, prior to sample submittal to the lab. Each soil sample will be sealed with Teflon*film and plastic end caps, labeled, packaged in an iced cooler and transported with chain-of-custody documentation to a state of California-certified hazardous waste testing laboratory for analysis. Each of the soil samples will be analyzed on a standard turn-around time for TPH-as-gasoline, BTEX, MTBE, DIPS, ETRE, TAME, TBA and 1,2- DCA by EPA Method 8260B. 9