Objective:
At both the state and federal regulatory level, concern over the groundwater-to-indoor air pathway has increased dramatically over the past several years. However, due to a limited understanding of the physical mechanisms of vapor intrusion, simple criteria for identifying potentially problematic sites are not available. This project will establish intensive monitoring networks at three sites representing a range of soil, groundwater, and building conditions to characterize the chemical and physical mechanisms and site parameters controlling the transport of volatile organic compounds (VOC) from groundwater into overlying structures via soil vapor diffusion. Specific objectives include: (1) formulate reliable procedural guidelines for measurement of vapor intrusion; (2) characterize site parameters related to vapor migration potential; (3) develop screening criteria to eliminate sites with limited potential for vapor intrusion impacts; and (4) provide well-characterized test sites for use in future vapor intrusion studies.
Technology Description:
Through detailed field investigation, the key deficiencies in understanding vapor intrusion processes will be addressed. Chemical concentration data will be collected using multi-level groundwater monitoring wells, multi-level soil gas points, sub-slab points, and indoor air samples. The physical characteristics of the sites will be analyzed and tracer gas analysis will be utilized to understand indoor air exchange rates. Site data collection will facilitate an improved understanding of vapor intrusion processes related to the water-soil gas interface, unsaturated soil column, and indoor air background.
Expected Benefits:
The vapor intrusion pathway has been subjected to increased regulatory scrutiny in recent years due to the discovery of a limited number of sites with apparent vapor intrusion impacts. Prior to the discovery of these sites, the vapor intrusion pathway was typically given only cursory consideration during the investigation of corrective action sites, and the pathway was rarely a driver in the implementation of response actions. However, U.S. Environmental Protection Agency guidance is likely to require a detailed field investigation of vapor intrusion at a majority of corrective action sites. Under the recently released regulatory guidance, the Department of Defense will be required to commit significant resources to field investigations of vapor intrusion. If an improved understanding of vapor intrusion processes enables the development of screening criteria that eliminate the need for a field investigation at 50% of the sites in question, the potential cost savings would be $18 million. (Anticipated Project Completion - 2007)
Principal Investigator: Dr. Thomas McHugh
Groundwater Services, Inc.
2211 Norfolk, Suite 1000
Houston, TX 77098-4044
Telephone: (713) 522-6300
Fax: (713) 522-8010
E-mail: temchugh@gsi-net.com
DoD Liaison: Dr. Ivette O'Brien
HQ AFCEE/ ERS
3300 Sidney Brooks
Brooks City-Base, TX 78235-5112
Telephone: (210) 536-4329
Fax: (210) 536-4330
E-mail: Ivette.OBrien@brooks.af.mil |
