2009 Issue

27 Figure 3: Air Sampling Canister. Figure 4: Exterior Vapor Mitigation System. Figure 2: Vapor Intrusion Conceptual Model. action levels, the base recommends and installs mitigation systems which prevent the chemicals from coming into the home from the ground. The mitigation systems work by removing vapors from below the home and venting them above the roof using a fan and associated piping. The systems are fairly easy to install and are the same type of systems used to deal with radon problems throughout the country. Figure 4 shows what a typical exterior (the fan is located outside of the home) vapor mitigation system looks like. Alternatively, an interior system can be installed as an option, where the fan and piping are all located within the home, with the fan placed in the attic. About 100 systems have been installed so far around the base and they have proven to be very effective at fixing the problem. Another significant challenge faced by the in- door air sampling program is dealing with chemi- cals in the air from inside sources, rather than from the groundwater. The samples collected don’t distinguish between vapors coming from the ground and those inside the home fromother sources, such as cleaning products. To help com- bat this problem, Hill AFB has recently purchased a portable testing device, which allows them to detect very low levels of specific chemicals in the air. This technology, known as Gas Chromatogra- phy/Mass Spectrometry or GC/MS, is the same technology used in a laboratory and has proven very useful in quickly identifying inside sources of chemicals. The application of this valuable tool has helped to prevent unneeded systems from being installed in residences and has also helped residents to understand where chemicals could be coming from in their homes. The indoor air sampling program is managed by the Hill AFB Environmental Management Division (75 CEV), which is part of the 75th Civil Engineer Group. Hill AFB is being assisted by the communications firmConcordia Communications and the engineering consulting firmMontgomery Watson Harza [MWH]. Jarrod Case holds B. S and M.S. in Environmental Engineering from Utah State University, and is a Professional Engineer. Mr. Case is currently working as a ProjectManagerintheEnvironmentalRestorationBranch at Hill Air Force Base. Kyle Gorder a graduate of Utah State University with Bachelor’s and Master’s degree in Environmental Engineering ,is a Professional Engineer, working as a Project Manager in the Environmental Restoration Branch at Hill Air Force Base.