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Geosyntec® <br /> consultants <br /> Samples will be selected to represent each distinct geologic layer. The number of samples to be <br /> collected will be determined by the geologist after inspection of the soil core and consideration <br /> of the degree of heterogeneity in the geologic materials. <br /> 2.5 Soil Gas Probe Installation <br /> Each soil gas probe will consist of 1/4-inch diameter Nylaflow® or Teflon® tubing connected <br /> with a compression fitting to a 1/4-inch-diameter stainless steel sampling point. Probes will be <br /> installed inside the borehole and a sand filter pack will be placed in the annulus to a height of 6 <br /> inches above the top of the screen. Granular bentonite will be placed in two lifts of 3 inches <br /> above the filter pack and hydrated with a small amount of distilled water after each lift. A thick <br /> slurry of powdered bentonite and water will be added to seal the remainder of the borehole <br /> annulus to ground surface. The top of the probe will be fitted with a compression-fit brass or <br /> stainless steel ball valve to maintain an air-tight seal between installation and sampling. <br /> Permanent probes will be completed with a traffic rated flush mount protective casing. <br /> 3 DOCUMENTATION <br /> Field documentation will include the following information: <br /> • name and number of project; <br /> • name of field personnel; <br /> • date and time of sampling event; <br /> • list of the primary activities performed; <br /> • identification of probes drilled and installed; <br /> • relevant information (weather, attendees, equipment problems, departures from <br /> standard procedures and the reasons and responses) observed throughout the day; <br /> • field instrument information and calibration data (includes time and reading for <br /> each instrument calibration check; and <br /> • volume of probe dead space volume for each soil gas probe. <br /> 2 2020 <br />