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a. <br /> GEOMATRIX <br /> Boring Methodology <br /> Borings will be advanced using a Cone Penetrometer(CPT)rig and a Hydropunch I1 sampler <br /> used to collect discrete groundwater samples. A description of basic CPT field protocols is <br /> included in Appendix A. <br /> At each location, a standard CPT probe with the capability of measuring resistivity will be <br /> advanced from a minimum depth of 50 feet bgs to a maximum depth of 100 feet bgs. CPT data <br /> will be evaluated to characterize the nature of the subsurface material at each sampling <br /> location. These data will be used to identify areas in the predefined zones that will be capable <br /> of yielding adequate quantities of groundwater samples for the laboratory analysis. <br /> Borings will be advanced to a depth where the TDS levels in the groundwater reach <br /> background levels or to a maximum of 100 feet bgs,whichever is shallower. TDS levels will <br /> be approximated using the resistivity function of the CPT probe. Based on the principle that <br /> resistivity is the reciprocal of conductivity and that conductivity is directional proportional to <br /> TDS,borings will be advanced until the resistivity measurements correspond to a TDS <br /> concentration of approximately 1,000 milligrams per liter. <br /> Discrete Groundwater Sampling <br /> Groundwater samples will be collected utilizing a Hydropunch II or similar groundwater <br /> sampling device advanced by the CPT rig. Discrete groundwater samples will be collected at <br /> depths approximating the water table,the shallow zone, and the intermediate zone by <br /> advancing the sampling device to the desired depth based on CPT lithology and resistivity data. <br /> Groundwater samples will be collected by using a decontaminated Teflon bailer. Groundwater <br /> samples will be placed in containers provided by Agriculture and Priority Pollutants <br /> Laboratory, Inc. (APPL), a California-certified analytical laboratory in Fresno, California. <br /> Samples will be stored under chain-of-custody procedures in an ice-cooled chest until delivery <br /> to the laboratory. The discrete groundwater samples will be analyzed by APPL for the <br /> constituents described in Section 5.1. Groundwater samples will be handled as described in <br /> Appendix A. <br /> 5.1.2 Monitoring Well Sampling <br /> Concurrently with the advancing of the borings, groundwater samples will be collected from <br /> monitoring wells LP-1 through LP-7 and PW1-48. Prior to collecting samples, water levels <br /> will be measured using an electric sounder and at least four casing volumes of groundwater will <br /> be purged from each well using a decontaminated pump. During purging, field water quality <br /> 1:\6000s\6741.000\Archive\6741-13.doc 9 <br />