David Shea
Principle Engineer, Sanborn Head
David Shea, P.E. has 30 years of experience as an environmental and site remediation engineer. He is a Principal Engineer with Sanborn, Head & Associates in Concord, New Hampshire, where he is responsible for leading vapor intrusion and environmental remediation projects throughout the US and abroad. He has a broad range and depth of experience in environmental site assessment and cleanup measures for groundwater, soil, and soil vapor contaminants. Dave has specialized expertise in vapor intrusion assessment and mitigation for residential, commercial, and industrial buildings, including some of the largest vapor intrusion sites in the world. He leads strategy development and provides technical expertise private and public sector clients, including navigating projects through federal, state, and local regulatory programs. He holds a B.S. in Civil Engineering from Princeton University and a M.S. in Civil Engineering from M.I.T. He is a licensed professional engineer in 16 states.
HVAC Systems for VI Mitigation: Performance and Reliability Considerations
For commercial and industrial buildings subject to vapor intrusion (VI) of subsurface volatile organic compounds (VOCs), the heating, ventilating, and air conditioning (HVAC) system may be an option for VI prevention or mitigation. The HVAC system could be appropriate as a VI engineering control when other typical mitigation options, such as sub-slab depressurization (SSD), are technically infeasible or costly. A key to the effective use of and reliance on HVAC systems for VI prevention, in addition to adequate design capacity, is the recognition that as a mechanical system, certain operating parameters are critical. HVAC systems can either improve or exacerbate an indoor air quality issue due to VI. Therefore, a thorough understanding of the factors that can influence HVAC system performance must be achieved and controlled over the long term. Performance can be compromised by unintended changes in operating conditions (e.g. air exchange, pressure), or modifications arising from changes in building use and/or occupancy. As with any mechanical system, unintended changes in operations can be caused by equipment malfunction, inadequate maintenance, or other factors that affect building air flow and pressure. Even if an HVAC system is not the primary means of VI mitigation, it should be considered in all VI assessments because it is so fundamental to indoor air quality, which is the ultimate concern of VI mitigation. The presentation will include the results of a recent study to evaluate the consistency and reliability of HVAC systems to maintain acceptable indoor air quality in several buildings that would otherwise be affected by VI.