Vapor Intrusion: Spatial Variation

Cox-Colvin's October 2012 Focus on the Environment newsletter discussed variability in airborne vapor concentration over time and its relation to Vapor Intrusion (VI). However, at least in soil gas, temporal variation may be less of a problem than spatial variation.
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Cox-Colvin Presentations at Ohio Brownfield Conference on Thursday, May 24

Thursday, May 24th, will be a busy day for Cox-Colvin at the 2012 Ohio Brownfield Conference at the Columbus Convention Center.  At 10:10 am in Room E170, Mort Schmidt will be talking about "Rapid Sub-Slab Soil Gas Sampling for Finding Sources".  In the same room at 1:55 pm, George Colvin will be discussing "Use of an Alternate Regulatory Mechanism and Results-Based Approaches for Site Cleanup".   Also, visit Cox-Colvin at Booth 18!

Vapor Pin Included in Michigan Vapor Intrusion Guidance

Cox-Colvin & Associates, Inc., in cooperation with the Michigan DEQ, completed a comparative study of sub-slab soil-gas sampling equipment to evaluate the Vapor Pin as an acceptable technology for vapor intrusion studies. The study demonstrated that samples collected through the Vapor Pin were consistent with those collected by other means. As a result, a SOP on the use of the Vapor Pin has been included as Appendix D.7 of Michigan DEQ's January 2012 Draft Vapor Intrusion Guidance - "Sample Collection and Evaluation of the Vapor Intrusion to the Indoor Air Pathway When the Generic Criteria Do Not Apply". (See p. 167 of the pdf for the Vapor Pin SOP).

Cox-Colvin is participating in a similar study in California in late April, in cooperation with H&P Mobile Geochemistry, Inc. Results of the Michigan and California studies are being submitted as a presentation topic at the October 2012 AWMA Conference in Denver, CO.

Click here for more information on the Vapor Pin.

EPA Releases Vapor Intrusion FAQs

EPA recently posted Vapor Intrusion FAQs (frequently asked questions) on its Vapor Intrusion (VI) website. This 56-page document is much more than the average fact sheet, and provides a preview of what the much anticipated final VI guidance is likely to look like. Read More>>

Short-listing Vapor Intrusion Constituents: Not Always A Good Idea

Many Vapor Intrusion guidance documents encourage analyzing a short list of comhttp://www.blogger.com/img/blank.gifpounds in indoor air -- for example, instructing the lab to report only the compounds detected in subsurface samples during previous related investigations. But be careful! As vapor intrusion assessment moves toward indoor air sampling, analyzing only for a short list of compounds could come back to bite you.
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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.