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09 March 2015 • • AGE Project No. 15-3325 Page 3 of 4 and 10 feet bsg and then retracted to approximately 6 inches at each depth in order to expose the screen from which soil-vapor can be extracted. Single use, '/<-inch disposable polyethylene tubing will be attached through the rods to the sampling point tubing adapter equipped with an O-ring to ensure a vacuum-tight seal. Each sampling point will be purged for a minimum of 2 minutes prior to obtaining a sample in 1-liter Tedlar bags. Once the purging is complete, a sample will be collected using a peristaltic pump and low-flow sampling techniques (200 milliliters per minute). After the sample is collected, the Tedlar bag will be labeled and stored in a dry container. Hydrated bentonite will be placed around the steel probe sampler at ground surface to prevent ambient air intrusion. A minimum of 20 minutes equilibrium time will be allowed at each soil-vapor sampling location prior to purging and sample collection. Each soil- vapor boring location will be isolated from ambient air by enclosing the borehole, tubing, and sample bag in a plastic shroud, which will be weighted at the surface. Isopropyl alcohol (IPA) as a liquid will be placed in a stainless steel bowl within the plastic structure and allowed to volatilize into the air enclosed within the plastic structure surrounding the borehole, tubing and sample bag. Soil-vapors purged through the pump will also be field-screened using an organic vapor meter (OVM) equipped with a photo- ionization detector (PID). Soil-vapor samples will be transported under chain-of-custody procedure to a CDPH- certified laboratory and analyzed for TPH by EPA method 8015M and VOC's by EPA method 82606. 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 GeoEnvironmental,Inc.