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26 February 2015 • AGE Project No. 15-3325 Page 3 of 4 SOIL VAPOR SAMPLE COLLECTION AND ANALYSIS Soil gas samples will be obtained at depth of approximately 7 to 8 feet bsg in each boring. Samples 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 drive rods. The assembly will then be advanced to the specified depth and retracted approximately 6 to 12 inches to disengage the expendable point and expose a column of strata from which soil vapor can be extracted. A single use, %- inch diameter disposable teflon 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 Geoprobe hollow drive 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 teflon 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 pressure is created around the Tedlar bag, which inflates, allowing the soil-vapor sample to enter directly into the bag via the inlet port. When the sample is collected, the negative pressure in the chamber is reduced and the sample bag is sealed, labeled, log on a chain-of-custody form, and place into a dry cooler (room temperature). Subsequently, all of the collected soil-vapor samples will be transported under chain-of-custody procedure to a CDPH-Certified laboratory for analysis of TPH in the gasoline range and VOCs by EPA method 8260. EQUIPMENT DECONTAMINATION Prior to use, all sampling tools used for sample collection will be thoroughly rinsed with clean water after being washed with a solution of Alconox. All probing rods will be cleaned prior to advancement at each probe boring location. BORING ABANDONMENT The probe borings will be permanently sealed to prevent vertical migration of potential contaminants. Each soil boring shall be backfilled to surface grade with neat cement and covered with concrete or asphalt, depending on the surrounding surface material. Advanced GeoEnvironmen[al,Inc.