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Proiect Number 2098RV45 <br /> November 30 2017 <br /> 4.0 SOIL GAS SAMPLING PROCEDURE <br /> The following sections detail the methods and procedures that will be followed to <br /> collect soil gas samples during the proposed site investigation. <br /> 4.1 Field Activities <br /> Prior to installation of temporary soil-gas probe points, all necessary permits and <br /> utility clearance(s) will be obtained. All work will be performed or supervised by a <br /> California-licensed Professional Geologist, in accordance with the Business and <br /> Professions Code, Chapters 7 and 12.5, and the California Code of Regulations, Title <br /> 16, Chapters 5 and 29. E2C will make raw data available to California Regional Water <br /> Quality Control Board - Central Valley Region (CRWQCB) staff, as requested. E2C will <br /> accommodate adjustments, or modifications to the sampling program, mandated by <br /> evaluation of the data set or unforeseen site conditions, if required by the Regional <br /> Water Quality Control Board (CRWQCB) staff. Investigative-derived wastes (IDWs) will <br /> be handled and disposed in accordance with federal, state and local requirements. <br /> To expedite the completion of field activities and to avoid potential project delays, <br /> contingencies have been proposed as follows. Soil samples will also be collected for <br /> analysis of physical properties and placed on hold pending the results of soil vapor <br /> samples. <br /> The CRWQCB field staff will be informed of any problems, unforeseen site conditions, <br /> or deviations from the workplan. When it becomes necessary to implement <br /> modifications to the approved workplan, the CRWQCB will be notified and a verbal <br /> approval will be obtained before implementing changes. <br /> 4.2 Temporary Soil-Gas Vapor Monitoring Well Installation <br /> Soil borings will be advanced using direct-push drilling techniques with dual-cased <br /> drilling rods to collect soil samples for VOC analysis and lithologic description, <br /> maintain a cased boring between sample retrieval runs to minimize the potential for <br /> cross-contamination between sample intervals, and to facilitate the installation of <br /> temporary soil gas probes. <br /> Following completion of soil boring advancement, temporary soil gas probes will be <br /> installed at approximate depths of 5 and/or 15 feet bgs to facilitate the collection of <br /> soil gas samples. Soil gas probes will be constructed using nominal 1/4-inch diameter <br /> Teflon tubing connected to a porous polyethylene soil gas sample probe, which will be <br /> set within approximately 1 foot of #3 sand placed around the sample probes from <br /> approximately 4.5 to 5.5 feet bgs (for the 5-foot probes; deeper probes will be <br /> constructed similarly with adjusted depths and backfilled with granular bentonite <br /> hydrated with potable water in 1-foot approximate lifts between probe depths). <br /> Approximately 1 foot of dry bentonite will be placed above the sand pack of each <br /> probe. The remainder of the boring annular space will be backfilled with granular <br /> bentonite hydrated with potable water in 1-foot approximate lifts to create a seal. <br /> E2C or GSI field personnel will prepare detailed VP well installation boring logs, which <br /> will document the date and time of the installation activity, the depth of each VP well, <br /> the screen type and interval; material utilized, and surface completion details. VP <br /> E2C Remediation 10 <br />