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Mailing Address​​​​​​: MBGS P.O. Box 14044 Lansing, Mi 48901-4044

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MBGS Monthly Meetings

Monthly Meetings take place typically on the second Wednesday of each month from September through
May. The meetings are open to all. The Executive Committee Officers meet prior to the meeting to discuss
Society issues and is open to anyone interested in attending.

Meetings hosted by the Michigan Basin Geological Society have been moved to the Natural Sciences Building, MSU
Campus, for more information contact Peter Rose at The lecture ends usually no later than 9:00.

Next MBGS Meeting

       Michigan Basin Geological Society

MBGS Membership Meeting,  Tuesday March 10, 2020, 7:00 PM

Members are welcome to bring guests

LOCATION: Michigan State University in the Natural Science Building, Room 204 288 Farm Lane, East Lansing, MI 48823

SPEAKER: Stacy Metz and Graham Crockford, TRC, Ann Arbor, Michigan

TOPIC: “Evaluation of the Vapor Intrusion Pathway at a Non-Residential Facility using VaporSafeTM Continuous Air Monitoring results in a Sustainable Solution”


Background/Objectives. TRC has been assisting with site investigation and cleanup at a USEPA Region V RCRA Corrective Action Site. Corrective Action for the Site, as outlined in the Final Decision, is largely complete. However, new remediation goals were established for the Site in 2016 after USEPA published revised trichloroethene (TCE) toxicity values. Because of the new remediation goals, a passive sub-slab ventilation (SSV)
system was installed and short-term indoor air monitoring was completed to demonstrate system effectiveness. Despite favorable indoor air sampling results, USEPA was hesitant lift the occupancy restrictions which would return the 225,000 square foot building to full industrial use. This position was justified by citing historic data variability and the possibility that there may be exceedences of the indoor air criteria for TCE between quarterly
sampling events since recent risk assessment guidance raises concerns with short-term TCE exposures during pregnancy.

Approach/Activities. Due to tight clay soils beneath the majority of the building footprint, active mitigation throughout the 150,000 square foot restricted area would be very costly. However, continuing traditional 8-hr canister indoor air sampling on a quarterly basis, may not have ever fully addressed concerns with short-term data variability. Therefore, TRC recommended using the VaporSafeTM Automated Continuous Real-Time Vapor Intrusion Monitoring and Response System (VaporSafeTM). VaporSafeTM is equipped with a gas chromatograph (GC), which is deployed on-site to provide real-time indoor air results. VaporSafeTM is also equipped to monitor air/vapor pressure measurements concurrent with air sampling. During the initial phase of the project, air samples were collected for direct injection into the GC to provide rapid response, real-time analysis to identify preferential pathways affect indoor air concentrations. Following this initial assessment, a multiplexed, automated system to collect continuous samples from twelve sample locations over a period of several days was set up. Differential outdoor/indoor/sub-slab pressure measurements were also collected over the same time period. Concentration and pressure data were then used as a basis for highly targeted building improvements. After building improvements were completed, the VaporSafeTM system was deployed to document post-mitigation building conditions. Results/Lesson Learned. TRC evaluated the data to better understand the variability of TCE in indoor air as well as the potential effect of preferential pathways and variable pressure on vapor intrusion. Data were used to identify encroachment locations and an indoor air source unrelated to historical operations (brake degreasing in an area of the plant where the current tenants are operating a garage). Additionally, TRC could document 3 how atmospheric pressure, wind speed, and site operations affected indoor air concentrations. These data have allowed TRC to recommend targeted, cost-effective modifications to the existing structure/SSV system to address those areas with lingering vapor intrusion concerns. Ultimately the mitigation and two one-week continuous air monitoring events cost approximately $150,000, followed by an anticipated annual energy use of ~3,000 kW-hr. By contrast active mitigation throughout the entire restricted area likely would have a significantly higher capital cost with annual energy use in excess of 50,000 kW-hr, which constitutes a 94% reduction in energy use, while protecting human health.


Stacy Metz, PE, TRC, Project Manager/Environmental Engineer.
Stacy graduated from Alma College with a Bachelor of Science degree in Environmental Science in 2001. Following Alma College, Stacy worked as a wet chemist in an environmental testing laboratory before attending the University of Wisconsin-Madison where she obtained a Master of Engineering degree in Geological Engineering in 2007. Her graduate research was focused on the in situ treatment of arsenic contaminated groundwater. Stacy has worked as an environmental consultant at TRC since 2007, specializing in environmental characterization and remediation of commercial, landfill and industrial properties. Stacy coleads TRC’s CORE vapor intrusion team. Her work includes environmental site assessments; development of project plans and specifications; project coordination; implementation of field investigation, monitoring, and remediation activities; risk assessment; report writing; and project permitting. Recently, much of Stacy’s work has supported efforts to characterize and mitigate vapor intrusion concerns near historic industrial facilities where chlorinated solvents were released and at the associated downgradient residential and non-residential properties. These efforts include the calculation of site-specific cleanup levels, mitigation system design, and oversight of performance monitoring. 

Graham Crockford, CPG, TRC, ECR Practice Lead.
Graham has over 30 years of experience in the fields of consulting, environmental engineering, geology, and hydrogeology. He currently serves as TRC's Office Practice Leader for the Michigan offices, and leads TRC’s CORE vapor intrusion and sustainable remediation workgroups, and a member of TRC’s PFAS CORE team. He also serves as a Principal Consultant/Program Manager for TRC's solid waste, utility, and manufacturing/industrial clients, and is a program manager for TRC’s Coal Combustion Residual (CCR) program. He also has decades of contaminant investigation and remediation experienced focused recalcitrant solvent contamination, and metals. Graham also provides litigation support services including expert and fact witness. Graham has served on several technical committees providing advocacy and industry perspective during development of solid waste rules in response to RCRA Subtitle D. His education includes a B.S. in Geology from Grand Valley State University and M.S. coursework in geology/hydrogeology at Wayne State University.