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09 January 2017 0 AGE Project No. 00-0769 Page 7 of 9 grade with concrete or native material. The EHD will be notified for grout inspection at least 48 hours prior to conducting grouting procedures. 3.2. SOIL-VAPOR WELL INSTALLATION AGE proposes to advance a total of two (2) pilot soil borings to 6.5 feet bsg for installation of depth discrete soil-vapor wells to evaluate the potential threat of vapor intrusion at the site. Proposed soil borings will be advanced using a 4-inch diameter hand auger. For installation of soil-vapor wells, %-inch diameter, 2-inch long polyethylene soil vapor implants and nine feet of 1/4-inch Teflon®tubing will be lowered to the base of the borings; three feet of tubing will remain outside the boreholes for vapor sample collection. However, before installing the vapor implant and tubing, approximately six inches of#2/12 sand will be placed at the bottom of the boreholes for the vapor implants to be placed on. Once the six inches of sand, tubing and vapor implants are in place, the filter pack of #2/12 sand will continue to be added from the bottom of the boreholes to approximately six inches above the base of the vapor implants. Following placement of the filter pack, approximately 12 inches of dry granulated bentonite will be placed atop the filter packs. The remaining annular space will be filled to the ground surface with a cement grout. The grout mixture will consist of Type 1/II Portland neat cement with approximately 3-5% bentonite content. A flush mounted well box will then be installed over the wells. Approximately, 3 feet of extra tubing will be run above ground for soil-vapor sample collection. A well construction diagram illustrating the proposed design is included as Figure 5. Once soil-vapor wells are installed, a minimum of 48-hours equalization time will be observed prior to sampling the wells. 3.3. SOIL-VAPOR SAMPLING Soil-vapor samples will be collected from the vapor wells using Summa canisters. For this method, one 6-liter Summa canister will be utilized for purging and each soil-vapor sample will be collected in a 1-liter Summa canister. The sampling and purge canisters will be connected together with a dedicated and serialized sampling inlet manifold. The sampling inlet manifold will consist of a vapor-tight valve; a particulate filter; a calibrated 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 vapor sampling locations. The purge canister will be attached to the end of the sampling manifold while the sample canisters will be attached to the tee-fitting between the tubing and purge container. Advancer/GcoEm'i ronmcntal Inc.