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AdvancedGeo <br />Environmental <br />'Ogg <br />13 June 2018 <br />AGE Project No. 18-4433 <br />Page 4 of 4 <br />SOIL-VAPOR SAMPLING <br />Soil-vapor samples will be collected from nested (dual-completed) soil-vapor points. For <br />installation of the dual soil-vapor points, a temporary/disposable vapor-tip and %-inch <br />Teflon tubing will be lowered to the base of the borings at approximately 15 feet bsg; two <br />feet of tubing will remain outside the boreholes for vapor sample collection. Once the <br />tubing and vapor-tip are in place, a filter pack of #3 sand will be placed from the bottom <br />of the boreholes to one-foot above the vapor tips. Following placement of the filter pack, <br />one-foot of dry bentonite crumbles will be placed atop the filter packs. Thereafter, <br />bentonite chips will be placed and hydrated to approximately 5 feet bsg. Once the 15-foot <br />soil-vapor point is set, an additional temporary/disposable vapor-tip and %-inch Teflon <br />tubing will be lowered to the base of the borings at approximately 5 feet bsg; two feet of <br />tubing will remain outside the borehole. Once the tubing and vapor-tip are in place, a filter <br />pack of #3 sand will be placed from the bottom of the boreholes to one-foot above the <br />vapor tip. Following placement of the filter pack, dry bentonite crumbles will be place atop <br />the filter pack. Thereafter, bentonite chips will be placed and hydrated to near surface <br />grade to seal the vapor well from ambient air intrusion. <br />Following soil-vapor point installations, a minimum of one-hour stabilization period will be <br />observed prior to sample collection at each of the vapor point locations. A one-liter <br />Summa canister and a 6-liter purge canister will be connected together with a dedicated <br />and serialized sampling inlet manifold. The sampling inlet manifold will consist of an <br />air/vapor-tight valve; a particulate filter; a calibrated flow restrictor calibrated to 200 <br />milliliters per minute (ml/min), a stainless steel tee-fitting, two vacuum gauges at either <br />end of the controller and connections for both purge and sampling canisters (manifold <br />assembly). The manifold assembly will be attached to the %-inch Teflon® tubing from the <br />vapor sampling locations. The purge canister will be attached to the end of the sampling <br />manifold while the sample canisters will be attached to the tee-fitting between the tubing <br />and purge container. <br />Leak tests will be performed on each soil-vapor sampling assembly by attaching and <br />securing the sample and purge canisters to the manifold and opening the valve on the <br />purge canister and the manifold. The leak test will be performed for approximately 3 to 5 <br />minutes on each assembly. <br />Upon achieving a successful leak test, the purge canister valve will be opened for a <br />calculated period of time to allow for three volumes of air to be purged. The purge canister <br />vacuum gauge will be monitored to ensure a proper decrease of vacuum ensuring flow <br />and purging. The purge volume will be determined by calculating the internal volume of <br />the tubing and open borehole area. <br />Upon achieving the targeted purge volume, the purge canister valve will be closed and <br />the sample canister valve will be opened. The initial pressure and time will be recorded. <br />Upon reaching at least -5 in Hg or less, the sample canister valve will be closed and final