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20 January 2015 • • <br /> AGE Project No. 15-3317 <br /> Page 3 of 4 <br /> advance soil borings using a hydraulic hammer to drive sampling tools to specified <br /> depths. <br /> 3.1.1. Soil Vapor Sample Collection <br /> Soil vapor samples will be collected from each boring at depths of approximately one <br /> foot (subslab) bag and at a depth of approximately four feet bsg using a 3-inch long, <br /> stainless steel disposable vapor point. Single use, '%-inch diameter disposable <br /> polyethylene tubing will be attached to the vapor point and installed in each boring. <br /> Following installation of each vapor point, a #3 sand will added from the bottom of the <br /> boring to a depth of 6-inches above the total depth; thereafter, bentonite chips will be <br /> installed in each boring to surface grade, and hydrated. Approximately 20 minutes <br /> equilibrium time will be allowed at the soil-vapor boring location prior to purging and <br /> sample collection. Additionally, each soil-vapor boring location will be isolated from <br /> ambient air by enclosing the borehole, tubing and Tedlar bag in a plastic shroud. As a <br /> method to monitor for ambient air cross contamination, isopropyl alcohol (IPA) as a <br /> liquid will be placed in a stainless steel bowl within the plastic shroud and allowed to <br /> volatilize into the air enclosed within the plastic shroud surrounding the borehole, tubing <br /> and Tedlar bag. <br /> Each sampling point will be purged for approximately one to two minutes (approximately <br /> three sample volumes) prior to obtaining a sample in 1-liter Tedlar bags. Following <br /> purging procedures, a sample will be collected using a peristaltic pump, or equivalent <br /> pump, calibrated to 200 milliliters per minute. After sample collection, each Tedlar bag <br /> will be labeled and stored in a dry container. <br /> Soils encountered in the borings will be visually classified by an AGE geologist in <br /> accordance with the Unified Soil Classification System (USCS). Additionally, soil vapor <br /> samples will be field screened for the presence of volatile organic compounds using an <br /> organic vapor meter (OVM), equipped with a photo-ionization detector (PID). CVM <br /> readings will be recorded on a log for each boring. <br /> Following sample collection, each vapor sample will be labeled with the boring location, <br /> depth, time, date, and sampler's initials. Appropriately sealed and labeled samples will <br /> be placed in a dry container and transported under chain of custody to a CDPH-certified <br /> laboratory for analysis for the constituents listed in Section 2.3. <br /> 3.1.3. Boring Abandonment <br /> All soil borings will be permanently sealed to prevent vertical migration of potential <br /> contaminants. The soil boring will be abandoned by backfilling with cement grout from <br /> the total depth to surface grade utilizing tremie procedures, if necessary. The top three <br /> to six inches of the boring abandonments will be completed flush to surface grade with <br /> Advanced GeoEnvironmen[al,Inc. <br />