(Revised 10/09)

Objective:

Vapor intrusion (VI) is an emerging problem involving the entry of vapors into inhabited structures from underlying contaminated soils or groundwater. Presently, there are no commercially available sensor products adapted to or proven for VI application. The overall objective of this project is to take existing and emerging technology and build and demonstrate sensor packages for VI applications. Specific project objectives include screening available advanced sensor technologies, selecting the most promising technology for VI, and building and demonstrating sensor packages for the following VI applications: (1) portable “sniffer” unit for near real-time compound-specific determination for contaminant source assessment and (2) fixed “smoke detector” unit for compound-specific exposure concentrations interfaced with remote communications. The focus of this project is measuring trichloroethene (TCE), which is a volatile organic compound (VOC) of VI concern at Department of Defense (DoD) facilities.

Technology Description:

This project is being conducted in three phases. Phase I involves the screening of existing and emerging vapor detection technologies to determine the most promising technologies for VI applications. Phase II involves prototype construction and testing of the portable and fixed units. Extensive field demonstration of the portable and fixed prototypes will be conducted at Hill Air Force Base in Utah during Phase III.

Interim Results:

The SPIRON micro-gas chromatograph (micro-GC; Dr. Ted Zellers, University of Michigan) sensor technology was selected in Phase I. The SPIRON micro-GC has the sensitivity and selectivity needed for the detection of low levels of TCE in indoor air. Key components of the micro-GC include the micro-preconcentrator/focuser (micro-PCF), micro-column, and gold nanoparticle chemiresistor array detector. The key components are fabricated using Micro-Electro-Mechanical Systems (MEMS) nanotechnology. The SPIRON micro-GC has been configured with a high-volume sampler prior to the micro-PCF to permit sufficiently rapid sampling of adequate volumes of air for the sensitivity and sampling time requirements needed in VI applications.

Laboratory testing of the SPIRON micro-GC has shown that TCE can be chromatographically separated from a number of common compounds found in indoor air, including methyl ethyl ketone, benzene, toluene, tetrachloroethene, ethylbenzene, and m-xylene. A TCE limit of detection (LOD) of 0.15 parts per billion (ppb) has been shown for the C8 sensor in the chemiresistor array detector. Water vapor interferes with the detection of TCE, and several means of addressing this concern are being examined, including a brief dry-air purge prior to injection of the sampled compounds by the micro-PCF onto the separation micro-column. Several means of lowering the TCE LOD for the micro-GC are also being pursued, including increasing the sampling efficiency of the high-volume sampler, improving the micro-PCF design for sharper injections, improving the micro-column design for higher resolution, and increasing sensitivity of the chemiresistor array detector. Work is beginning on the fabrication of four field prototypes, two for the portable application and two for the fixed-location application. The TCE LOD goals are 0.06 and 0.03 ppb, respectively, for the portable and fixed units.

Expected Benefits:

Estimated DoD cost savings of the proposed innovative high-tech sensor-based evaluation and monitoring approach, if commercialized, are estimated at approximately $80 million over the next 5 years. In addition, DoD would benefit from a more comprehensive approach to VI monitoring and site assessment. Application of the proposed high-tech sensor-based approach would result in substantially more data per dollar spent, which would enable more thorough evaluation and the likelihood that a larger percentage of potential VI residences would be eliminated for further consideration as a result of no demonstrable VI or an in-home source. It is anticipated that the proposed technology could be deployed at numerous DoD sites to evaluate and monitor thousands of residences and other inhabited structures. Application of these advanced sensors to private sector VI problems is anticipated to be substantial. (Anticipated Project Completion – 2011)

Principal Investigator:

Mr. Jim Reisinger
Integrated Science & Technology, Inc.
1349 Old Highway 41, Suite 225
Marietta, GA 30060
Telephone: (770) 425-3080
Fax: (770) 425-0295
E-mail: istatlanta@aol.com

DoD Liaison:

Dr. Sam Brock
AFCEE/TDE
3300 Sidney Brooks
Brooks City-Base, TX 78235
Telephone: (210) 536-3253
Fax: (210) 536-5989
E-mail: samuel.brock@brooks.af.mil