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Apoendix C Soil Vapor Sampling Well Installation and Sampling Field Protocol Purging is conducted at a rate of 100 to 200 milliliters per minute (ml/min). The purge volume exhibiting the highest concentration is the volume of vapor purged from each SVS well prior to sampling. During sampling, a leak test is performed at each SVS wellhead valve and fitting to check for leaks in the sampling manifold and bentonite seal. An agency approved leak detection compound (such as 1,1-difluoroethane) is applied around the wellhead, or gauze strips soaked in isopropyl alcohol are applied to the down -hole side of the wellhead valve, and a shroud is placed over the system downstream of the sampling container. The soil vapor sample is collected in the sample container while the shroud is in place. Sampling is conducted at approximately the same rate of purging, at 100 to 200 ml/min. Soil vapor samples are submitted under chain -of -custody protocol for the specified laboratory analyses. At a minimum, weather conditions (temperature, barometric pressure and precipitation), the sampling flow rate, the purge volume, the leak detection chemical, the sample canister identification number, the method of sample collection, and the vacuum of the sampling canister at the start and end of sample collection (if applicable) are recorded on a log for each SVS well purged and sampled. Decontamination Procedures If soil samples are collected, Cardno ERI or the contracted driller decontaminates the soil sampling equipment between each sampling interval using a non -phosphate solution, followed by a minimum of two tap water rinses. De -ionized water may be used for the final rinse. Downhole drilling equipment is steam -cleaned or triple -rinsed prior to advancing each borehole. Waste Treatment and Disposal Soil cuttings generated from the well installation are stored on site in labeled, Department of Transportation - approved, 55 -gallon drums or other appropriate storage container. The soil is removed from the site and transported under manifest to a client- and regulatory -approved facility for recycling or disposal. Decontamination water is stored on site in labeled, regulatory -approved storage containers, and is subsequently transported under manifest to a client- and regulatory -approved facility for disposal or treated with a permitted mobile or fixed -base carbon treatment system. 2