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A4OM • Sand will be added for another six inches. • A granular bentonite plug, will be placed directly above the sand pack and continued to the surface as described below per temporary or permanent installment of the vapor well. o If the vapor well is temporary, bentonite will be added to the borehole until the surface is reached or to the bottom of the next sampling interval. o Prior to adding the next sand pack and probe, hydrate bentonite to seal the bottom of the next interval. o If the vapor well is permanent, hydrated neat-cement grout will be added to the borehole until the surface is reached or to the bottom of the next sampling interval. Neat-Cement Grout means a mixture in the proportion of 94 pounds of Portland cement and not more than 6 gallons of water. Bentonite up to 5 percent by weight of cement (4.7 pounds of bentonite per 94 pounds of Portland cement) may be used to reduce shrinkage. • Small diameter (1/8 to 1/4 inch) tubing is typically used for probe construction. At sites where soil moisture is high and/or finer-grained materials are present, larger diameter tubing, up to 3/4-inch, may also be used. Using larger diameter tubing is less susceptible to plugging by high soil moisture and fine-grained materials. The probe tip, probe and probe connectors should all have the same diameter to provide a good seal between the formation and the sampling assembly. The tubing must be made of one of the following materials: metal, nylon, polyetheretherketone (PEEK), teflon which will not react, absorb or interact with site contaminants. It is suggested to use new tubing for new field events or demonstrate that the tubing you are using is contaminant free. • The completed soil vapor probes will be protected from the elements and/or tampering by installing probe housing. Probes that are permanent and/or located in a parking lot, roadway, or easement will be completed at the surface with a traffic-rated well box. • Complete surface ends of tubes with Swagelok® caps, valves, or other equivalent terminations. • Label tubing of probes at the surface to be sure that the sampling depth is easily identifiable. Make sure the identification system remains in place for future re- sampling.