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16 May 2012 AGE-NC Project No. 12-2113 Page 3 of 5 BORING ADVANCEMENT Borings proposed inside the buildings will be advanced utilizing a Bosch 11223 EVS Hammer Drill equipped with 5/a-inch AMS Gas Vapor Probe rods. Borings proposed outside the buildings will be advanced using a truck-mounted PowerProbe 9600 direct-push probing unit equipped with 1.25-inch probing rods. The probe advances borings using a hydraulic hammer to drive soil and ground water sampling tools to specified depths. SOIL-VAPOR SAMPLE COLLECTION AND ANALYSIS Soil vapor samples will be obtained at depths of approximately five feet bsg in borings inside the buildings, and at 5 feet and 15 feet bsg in borings outside the buildings at 1350 Scotts Avenue and 1400 Scotts Avenue. Soil vapor samples inside the buildings will be collected using an AMS Gas Vapor Retract- a-Tip sampling assembly. A retractable vapor point will be placed into a point holder at the bottom of an assembly of%-inch diameter hollow rods. The vapor sampling assembly will then be advanced to the specified depth and retracted approximately 1/2-inch in order to disengage the point and expose a column of strata from which soil-vapor will be extracted. Soil vapor samples outside the buildings will be collected using a Geoprobe soil-vapor assembly. An expendable vapor point will be placed into a point holder at the bottom of an assembly of 1.25-inch diameter hollow drive rods. The assembly will then be advanced to the specified depth and retracted approximately six to twelve inches in order to disengage the expendable point and expose a column of strata from which soil vapor can be extracted. For all soil-vapor sampling, a single use, '/4-inch diameter disposable polyethylene tubing is then attached to a tubing adapter equipped with an O-ring to ensure a vacuum-tight seal. The adapter assembly is then lowered through the center of the rods to the specified depth and secured by threading into the expendable vapor point holder. A stabilization time of 20 minutes will follow boring placement. Above ground, the surface around the soil vapor sampler will be sealed with a bentonite sealant to prevent ambient air intrusion. The end of the polyethylene tubing is attached by a two-way inlet port to a Tedlar bag placed inside an SKC Vac-U-Chamber (lung box) vacuum chamber.A vacuum pump attached to a purge port of the vacuum chamber is then used to purge the exposed soil column, through the sampling tubing and inlet port, until approximately three volumes of soil vapor or ambient air is evacuated through the sampling system. The vacuum chamber is then sealed and the vacuum pump is attached to a vacuum outlet port of the chamber. When vacuum is applied to the chamber, a negative Advanced GeoEnvironmental,Inc.