COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

AdvancedGeo Environmental -Ogg 11 January 2019 AGE Project No. 19-4606 Page 5 of 6 0.75 feet of dry granular bentonite will be placed to a depth of 4.5 feet bsg. Thereafter, neat cement will be used to seal each location to prevent ambient air intrusion during sampling. An as built well diagram is included in Figure 2. Soil-vapor samples will be collected after allowing a minimum of two-hours equalization time following installation of the soil-vapor wells. Prior to soil-vapor sample collection, three calculated volumes of air will be purged utilizing a 6-liter purge canister and manifold, calibrated to 200 milliliters per minute (ml/mm). One-liter Summa® sampling canisters will be used to collect soil-vapor samples for TO-15 analysis. Sampling and purge canisters will be connected together with a dedicated and serialized sampling inlet manifold. The sampling inlet manifold consists of a vapor-tight valve; a particulate filter; a flow restrictor calibrated to 200 milliliters per minute (ml/min); a stainless-steel tee-fitting; two vacuum gauges at either end of the flow controller and connections for both purge and sampling canisters (manifold assembly). The manifold assembly will be attached to the %-inch Teflon® tubing from the soil-vapor well. The purge canister will be attached to the end of the stainless-steel sampling manifold while the sample canisters will be attached to the tee-fitting between the %-inch Teflon® tubing and purge container. Teflon® tape will be placed on the threads of each open fitting of the manifold assembly prior to attaching the %-inch Teflon® tubing and sampling and purge canisters (Figure 3). Each canister's initial vacuum will be measured and recorded between -26 and -30 inches of mercury (in hg). Shut-in tests will be performed on each assembly by attaching and securing the sample and purge canisters to the manifold and opening the valves on the purge canister and the manifold. The shut-in test is performed for approximately 10 minutes on each assembly. Each soil-vapor well location will be isolated from ambient air by enclosing the borehole, tubing and manifold/canister assembly in a 100-liter shroud. Isopropyl alcohol (IPA) will be emitted into the shroud surrounding the well borehole, tubing and manifold/canister assembly and acts as a tracer gas to evaluate if leaks in the sampling apparatus have allowed infiltration of ambient air. Upon achieving a successful leak test, the purge canister valve will be opened for a period to allow the three calculated volumes of air to be purged. The purge vacuum gauge will be monitored to ensure a proper decrease of vacuum purged. Upon achieving the targeted purge volume, the purge canister valve will be closed, and the sample canister valve opened. The initial pressure and time is recorded. Upon reaching at least -5 in Hg or less, the sample canister valve will be closed, and final pressure and time recorded. The sampling port on the sampling canister will be capped with a brass end-cap.