WORK PLANS - Laserfiche WebLink

Home Browse Search

09 October 2023 AdvancedGeo Project No. 23-7573 CLIENT —ATTORNEY PRIVILEGE An Employee-Owned Company Page 4 of 5 will be purged a total of three purge volumes. The purge volume will be determined by calculating the sum of the internal volume of the Teflon tubing and the volume of the boring trace. Upon achieving the targeted purge volume, the purge syringe will be disconnected, and the sample canister valve will be opened. Each canister's initial vacuum will be measured and recorded between -26 and -30 inches of mercury (in hg). Each soil-vapor well location will be isolated from ambient air by enclosing the borehole, tubing, and manifold/canister assembly. Helium 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 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. The soil-vapor samples will be labeled with sample ID, project name, date, time, and samplers' initials. The soil-vapor samples will be transported under chain-of-custody procedures to an ELAP-certified laboratory for analysis. All soil vapor samples will be analyzed for VOCs by EPA method TO-15 and helium (as tracer gas) by Modified ASTM D-1946. 2.3. SUB-SLAB SOIL-VAPOR POINT INSTALLATION, SAMPLING AND ANALYSIS Sub-slab soil gas probes will be installed by initially drilling a 1'/2-inch diameter pilot hole into the foundation slab for 13/4-inches utilizing a drill and spline bit. Thereafter, a %-inch diameter drill bit will be utilized to completely drill through the foundation slab. Once the slab is penetrated approximately 1- to 2-inches into the underlying soil to form a void, the drill bit will be removed, and the hole cleared using a '/2-inch bottle brush and vacuum. The slab thickness will be measured and a %-inch Vapor Pin®with silicone sleeve will be inserted flush into the %-inch drilled hole using a dead blow hammer to tap into place and form an air-tight seal between the silicone sleeve and the slab. A protective plastic cap will be placed on the Vapor Pin® to prevent vapor loss and allowed to re-equilibrate for approximately 20 minutes prior to sampling. Soil-vapor samples will be collected and analyzed as described in Section 2.2. 2.4. BORING ABANDONMENT All soil borings will be permanently sealed to prevent vertical migration of potential contaminants. Soil borings shall be abandoned by backfilling with cement grout from the total depth to surface grade. The top three to six inches of the boring abandonments will be completed flush to surface grade with concrete or native material.