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Figure 1 <br />Typical Single and Nested Soil Gas Probe Design <br />Surface-i <br />Gas Tight Fitting <br />Probe Box (optional) <br />Neat-Cement Grout <br />(if permanent) <br />Or <br />Hydrated Bentonite <br />(if temporary) <br />Tubing — <br />(metal, nylon, PEEK, teflone) <br />1 Ft Dry Granular Bentonite <br /> Probe Tip <br />-1 Ft Sand <br />DBT <br />ST <br />DBT <br />-X- <br />ST <br />TL <br />Legend <br />BD = borehole diameter (inches) <br />DBT = dry bentonite thickness (ft) <br />ST = sand pack thickness (ft) <br />TL = tubing length (ft) <br />PEEK = Polyetheretherketone <br />Neat-Cement Grout <br />(if permanent) <br />or <br />Hydrated Bentonite <br />(if temporary) <br />-1 Ft Dry Granular Bentonite <br />Probe Tip <br />-1 Ft Sand DBT <br />-X- <br />ST <br />F -BD <br />ADVISORY - ACTIVE SOIL GAS INVESTIGATIONS <br />included in the project workplan if the project proponent chooses not to use <br />probe support for deep soil gas wells. <br />Neat-Cement Grout means a mixture in the proportion of 94 pounds of Portland cement and not <br />more than 6 gallons of water. Bentonite up to 5 percent by weight of cement (4.7 pounds of <br />bentonite per 94 pounds of Portland cement) may be used to reduce shrinkage. <br />3.2.2 Sampling Tubing <br />Small diameter (1/8 to 1/4 inch) tubing is typically used for probe construction, made of <br />material which will not react or interact with site contaminants. At sites where soil <br />July 2015 11