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07 December 2020 <br />Project No. 20-6249 <br />Page 4 of 6 <br />2.3. SOIL AND GROUNDWATER LABORATORY ANALYSIS <br /> <br />Selected soil and groundwater samples will be analyzed by a California ELAP-certified <br />laboratory for the following constituents: <br /> <br /> Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with <br />EPA Method 8015M. <br /> VOCs in accordance with EPA Method 8260B. <br /> <br />Laboratory reports for all analyses, testing methods, laboratory quality assurance/quality <br />control (QA/QC) reports, and sample chain-of-custody documentation will be presented <br />in a report with the findings and recommendations. <br /> <br /> <br />2.4. SOIL VAPOR POINT INSTALLATION, SAMPING AND ANALYSIS <br /> <br />AGI proposes to advance a total of two (2) soil borings utilizing a three-inch diameter <br />hand auger or hand-tooling equipment to install temporary soil vapor points to total depths <br />of 5 feet bsg. Soil-vapor samples will be collected to evaluate the potential threat for vapor <br />intrusion to the site building. The vapor sampling points will be installed adjacent to the <br />site building and near the north and south ends for the former UST area (Figure 2). <br /> <br />At each of the two (2) proposed soil-vapor sampling locations, borings will be advanced <br />to 5 feet bsg. Once the total depth is reached a semi-permanent soil-vapor sampling point <br />will be installed within the boring. The temporary sampling point will consist of 7.5 feet of <br />0.25-inch Teflon tubing and a sampling tip (generally inert ceramic stone). Prior to <br />installing the tubing and sampling stone, #2/12 sand will be poured in the annuals of the <br />boring for the sample tip to rest on. The tubing and sampling tip will then be lowered to a <br />depth of 5 feet bsg and one foot of #2/12 sand will be poured around the tip to create a <br />filter pack. Above the sand, one foot of dry granular bentonite will be placed to a depth of <br />3 feet bsg. Thereafter, hydrated bentonite will be placed from 3 feet bsg to near surface <br />grade to seal each location and prevent ambient air intrusion during sampling. <br /> <br />Soil-vapor samples will be collected after allowing a minimum of two hours equalization <br />time following installation of the soil-vapor points. Prior to soil-vapor sample collection, <br />three calculated volumes of air will be purged utilizing a 6-liter purge canister and <br />manifold, calibrated to 200 milliliters per minute (ml/min). One-liter Summa® sampling <br />canisters will be used to collect soil-vapor samples for TO-15 analysis. <br /> <br />Sampling and purge canisters will be connected together with a dedicated and serialized <br />sampling inlet manifold. The sampling inlet manifold consists of a vapor-tight valve; a <br />particulate filter; a flow restrictor calibrated to 200 milliliters per minute (ml/min); a <br />stainless-steel tee-fitting; two vacuum gauges at either end of the flow controller and <br />connections for both purge and sampling canisters (manifold assembly). The manifold