Cox-Colvin Presented on Soil-Gas Prospecting at AIPG Meeting

I presented a talk in September 2011 at the American Institute of Professional Geologists (AIPG) National Meeting in Bloomingdale, Illinois titled "The Use of Innovative Soil-Gas Sampling Methods to Locate VOC Sources". The presentation, which discussed how Cox-Colvin used the Vapor Pin to collect soil gas from beneath the floor of a large industrial facility to locate sources of volatile organic compound (VOC) contamination, was very well received. The use of the Vapor Pin, combined with collecting soil gas into disposable, evacuated glass vials, allowed us to collect approximately 240 samples over the entire building footprint in one week, using only hand-held equipment.

As we've seen at other sites, VOC contamination at this site was not located beneath former degreasing operations or storage tanks. Instead, using aerial photos and historic maps to reconstruct the building's history, we found that the contamination was located where loading docks and back doors used to be prior to building expansion. Before the Clean Water Act in 1977, it was accepted practice to dump used solvents on the ground - commonly through the nearest door. By now it's unlikely that any present employees remember dumping of waste, or would be comfortable discussing it if they did. But by sampling subslab soil gas in a grid over the entire building, and tying the analytical results to the building expansion history, we located an unsuspected source of VOCs and determined that it probably resulted from spillage or dumping prior to 1952. Better yet, the sample points were installed, sampled, and plugged each day at minimal cost and without interrupting plant operations. And when we're done locating sources, the soil-gas data will be useful for assessing vapor intrusion.