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Work Plan, PFAS Site Inspection <br />Naval Computer and Telecommunications Station Stockton, California Technical Approach <br /> 3-6 DCN: TRBW-0202-5183-0010 <br />minutes, appropriate notation will be recorded in the field log and the sample will be collected. <br />Purge water removed from the wells will be containerized, handled, and disposed of as IDW. <br />Standard operating procedures for groundwater sampling are provided in SOP -009 (Attachment 1 <br />in Appendix A). <br />Groundwater samples will be collected from the newly installed temporary direct push borings and <br />select existing permanent monitoring wells as described in Worksheet #17 and identified in <br />Worksheet #18 of the SAP. To minimize cross-contamination from equipment and construction <br />material containing Teflon, special precautions need to be taken when preparing for groundwater <br />sampling. No Teflon-containing equipment will be used during sampling activities. <br />After completion of purging at each well, monitoring wells will be sampled using low-flow <br />sampling techniques. The objective of low-flow sampling is to minimize stress to the groundwater <br />system by decreasing drawdown caused by pumping. Pumping at a low-flow rate effectively <br />isolates the screened interval from the overlying (stagnant) casing water, thereby sampling water <br />from the screened interval only. Typically, flow rates of 0.1 to 0.5 liter (L) per minute are used <br />during low-slow sampling. <br />After collection, the samples will be placed in a cooler, chilled with ice, and shipped under chain - <br />of-custody protocol to SGS Laboratories for analysis of PFAS compounds. <br />3.4.4 Sediment Sample Collection <br />Sediment samples will be collected using a clamshell sampler or a hand auger, whichever is <br />appropriate for the consistency of the sediment and based on field conditions. Once retrieved, <br />sediment samples will be collected by hand using vinyl gloves and packed with no head space into <br />laboratory-provided glass jars, sealed, labeled, and stored pending transport to the laboratory. <br />Sediment samples will be logged on the Soil Sample Collection Field Sheet (Attachment 1 in <br />Appendix A). After collection, the samples will be placed in a cooler, chilled with ice, and shipped <br />under chain-of-custody protocol to SGS Laboratories for PFAS analysis. Approximately 25% of <br />sediment samples will be analyzed for TOC. <br />3.5 Surveying <br />Soil borings, sediment samples, and temporary monitoring wells will be surveyed by a California- <br />licensed professional land surveyor to measure horizontal and vertical positioning. The survey will <br />be accurate to 0.01 foot vertically above msl and will be surveyed to the State Plane Coordinate <br />System, North American Vertical Datum of 1988 relative to msl and 0.1 foot horizontally and shall <br />be referenced to the State Plane Coordinate System, North American Datum (NAD) of 1983. The <br />survey will also report all horizontal data in CA State Plane NAD 1927 (f eet) and elevations as <br />National Geodetic Vertical Datum 1929 (feet msl).