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ZZ5 In-situ Groundwater Sampling <br /> Groundwater from the three offsite borings will be collected at the saturated zone by hydropunch or <br /> equivalent technology. The HydroPunch will be driven a minimum of two feet into saturated soil as <br /> identified by the driller and site geologist, and a groundwater sample taken. The groundwater <br /> samples will be analyzed for VOCs by EPA Method 8260 and general water quality parameters. <br /> Some of the general water quality parameters will be measured in the field using a water quality <br /> meter, other water quality parameters will be analyzed in the laboratory. <br /> After collection,the groundwater samples will be labeled and the bottles wrapped in bubble wrap, <br /> then placed into a pre-cooled ice chest for shipment. All samples will be documented in the field <br /> and transported to the laboratory in accordance with EPA Chain-of-Custody protocol. <br /> All hydropunch groundwater samples will follow CHSL Specification Section 02670 <br /> (Appendix A). <br /> 2.2.6 Vadose Zone Soil Gas Sampling <br /> All soil borings will be sampled for soil gas at three depth intervals (approximately 20 ft, 40 ft <br /> and 65 feet bgs). These samples will be colleted in separate vessels provided by a state certified <br /> laboratory under chain of custody. <br /> A portable gas analyzer will be used to monitor methane, oxygen, and carbon dioxide <br /> concentrations within boring prior to soil gas sampling. The gas analyzer is equipped with an <br /> internal vacuum pump designed to extract gas samples. The gas analyzer will be used to <br /> evacuate (purge) ambient air from the monitoring points and monitor the concentration of <br /> methane, carbon dioxide, and oxygen in the boring prior to collecting samples for laboratory <br /> analysis. Purged gases were monitored for indications of parameter stabilization prior to the <br /> collection of gas samples, similar to parameter stabilization monitoring during routine <br /> groundwater sampling procedures. <br /> The soil gas samples will be collected into negative-pressure stainless steel Summa canisters or <br /> tedlar bags. After purging, each gas sample collected into the sample vessel using tubing <br /> lowered down into the interior boring. The valve on the sample vessel will be slowly opened, <br /> drawing a representative gas sample into the vessel by pressure equalization. The vacuum within <br /> the vessel will not be allowed to completely equalize to atmospheric pressure in order to ensure <br /> the integrity of the sample during shipment to the laboratory. A vacuum reading will be <br /> recorded before and after each sample is collected and annotated on the Chain-of-Custody <br /> documents. After sampling procedures are completed, the vessels will be placed into protective <br /> Corral Hollow EMP WP.DOC 2.5 February 28,2007 <br />