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BAR HOLE SAMPLING for SUBSURFACE GAS DRAFT FEB 10, 1995 Soil gas samples can be collected using the following bar hole probe methodology which has been used successfully by Board staff for screening in soil-gas investigations related to subsurface migration of landfill decomposition gas. 1 . An approximately 1/2-inch diameter metal rod (bar hole punch) is driven into the desired test location to an approximate depth of 3 feet. Note: The use of the bar hole punch is limited to soil types into which the probe may be driven with a reasonable amount of effort and extracted. The bar hole punch will not work in rock formations. 2 . Withdraw the bar probe from the hole and slip a section of 1/2-inch Schedule 40 PVC pipe, 16-18 inches long, over the bar probe and carefully insert the bar punch into the hole. Drive the rod and the PVC pipe into the hole leaving approximately 1-2 inches of the PVC pipe above the ground surface. Note: One end of the PVC pipe should be cut at a 45-degree angle and placed over the bar probe with the beveled tip facing the ground. 3 . Withdraw the bar probe being careful that the PVC pipe stays in place. ' Reinsert the bar probe into the PVC pipe sleeve and reform the hole. 4 . Remove any loose soil around the PCV pipe sleeve and place a thick bentonite slurry around the PVC pipe sleeve in order to reduce the potential for ambient air infiltration or gas leakage around the PVC pipe sleeve. Place a solid rubber stopper in the exposed end of the PVC pipe sleeve. 5 . Sampling the probe is accomplished by removing the stopper and replacing it with a one-hole stopper fitted with a tubing adapter and connected with flexible plastic tubing to the inlet of the gasmeasuringinstrument or use an auxiliary diaphragm pump to fill a tedlar bag to sample from. Proceed with sampling as described in "PROCEDURE FOR GAS MONITORING AT SITE PERIMETER PROBES" TWC:twc caps\h&s\samp105.doc