Eric Lovenduski (New York) will present on March 24 and his session is entitled "A Vacuum Field's Sunset: An Anecdotal Summary of Mitigation System Shut Down in New York" at the Vapor Intrusion Session II.
This presentation presents the process by which a responsible party (RP) pursued shut-down of a subslab depressurization (SSD) system at a commercial building in upstate New York (NY). In 2010, an SSD system was installed in a 50,000 square foot former electronics research and development facility in NY for the purpose of vapor intrusion mitigation related to sub-surface volatile organic compound (VOC) contamination.
Regulatory guidance related to SSD system shut down does not exist in NY State. Consequently, at the time of SSD system commissioning, the RP and authors coordinated with NY state regulators (the Agencies) to create a pathway towards shut-down based on empirical evidence. The shut-down plan was documented in the Agency approved Site Management Plan.
Sub-slab soil gas samples were collected annually for the first three years of system operation, during which time sub-slab VOC concentrations decayed to below the Agency’s mitigation criteria. As such, a proposal for temporary SSD system shut-down was submitted and approved by the Agencies in September 2014. During temporary SSD system shut-down, indoor air was continuously monitored using passive air samplers. Additionally, sub-slab soil gas samples were collected at both three months (December 2014) and nine months (June 2015) after temporary system shut-down to evaluate VOC concentration rebound. To date, sub-slab soil gas concentrations remain below the Agency’s mitigation criteria. As such, an approval request for permanent SSD system shut-down is being prepared for submittal to the Agencies.
Success of the mitigation system shut-down has depended on open communication between the RP, consultant, and the Agencies from the onset of mitigation system installation. This open communiation has resulted in all parties having a voice in the shut-down process. The Agencies have confidence that they are fulfilling their obligation to ensure protectiveness of public health and the environment, and the RP has observed progress towards closure while maintaining their concern for stewardship of the environment.