Investigation and Validation of Multiple Lines of Evidence to Assess Vapor Intrusion at Selected Air Force sites

Tetra Tech, Inc. (Tetra Tech) has been contracted by the United States Air Force (USAF), HSW/PKAH to conduct an investigation of multiple lines of evidence (MLE) used in assessing risk associated with the vapor intrusion (VI) pathway. To that end, research is being conducted at four Air Force instal ..... More

Summary of Indoor Air Modeling and Calculation of Risk-based Groundwater Goals Protective of Indoor Workers at Middle River Complex, Maryland

Risk-based goals (RBGs) for groundwater were derived to be protective of onsite workers inhaling indoor air in Buildings A, B, and C of Block I of the Middle River Complex. The RBGs were calculated using modeling of vapor intrusion into the buildings using two modeling approaches: the Johnson and Et ..... More

Modeling and Mathematical Analysis of PCE Attenuation Between Floors of Multistory Dwellings

The purpose of this project is to examine how volatile organic compounds (VOCs), such as tetrachloroethene (PCE), that migrate into multi-story apartments with concrete floors from subsurface sources may attenuate between floors. Ultimately the attenuation factors between floors may be important in ..... More

Development and Testing of Air Exchange Rate Methods to Improve Cost Effectiveness While Maintaining Accuracy

Background. One of the important factors that determine whether vapors that intrude into buildings will adversely impact human health is the magnitude of the air exchange rates (AERs) for those building. AERs are defined as the flow rate of air through a building divided by its volume. For buildings ..... More

U.S. Coast Guard Alameda Housing, Alameda, California

For the U.S. Coast Guard, Tetra Tech evaluated the potential for adverse health effects to personnel and families in housing situated over soil and groundwater with VOC contamination. Potential vapor intrusion exposure to VOCs was assessed using the USEPA recommended Johnson and Ettinger indoor air ..... More

Vapor Intrusion Risk Assessment, Proposed Residential Development, San Dimas, California

Tetra Tech performed a vapor intrusion human health risk assessment for a six acre former commercial property that was associated with a former dry cleaner and had a former gas station located in close proximity. The results of a screening level soil gas evaluation of soil gas data collected from fi ..... More

Vapor Intrusion Risk Assessment, Historical Manufacturing Site, Huntington Beach, California

Tetra Tech conducted a human health risk assessment for potential vapor intrusion exposures to commercial workers for a site that was being reconfigured for commercial use by an internationally known clothing company. Historical manufacturing operations resulted in a release of VOCs to shallow groun ..... More