June 6, 2019

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Chase Holton Coauthored a Paper on Volatile Organic Chemical Emission Flux in Groundwater Monitoring and Remediation Journal

Chase Holton, Ph.D., P.E. (Colorado) coauthored a paper entitled "Influence of Fluctuating Groundwater Table on Volatile Organic Chemical Emission Flux at a Dissolved Chlorinated‐Solvent Plume Site" published in the journal Groundwater Monitoring and Remediation (GWMR) on pages 43-52 in Volume 39, Issue 2 on March 5, 2018.

Chase's coauthors were Yuanming Guo, Hong Luo, Paul Dahlen, and Paul C. Johnson.

Chase has over eight years of experience in environmental research and consulting, with expertise and experience in several areas, including vapor intrusion, site characterization, and soil and groundwater remediation.

Chase has identified and addressed soil and groundwater contamination at numerous sites across the U.S. and Canada under the Resource Conservation and Recovery Act (RCRA), Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), Underground Storage Tanks (UST) Regulations, Voluntary Cleanup and other regulatory programs, including chlorinated solvents, petroleum compounds, pesticides, and per- and polyfluoroalkyl substances (PFAS).

Groundwater Monitoring and Remediation is a resource for researchers and practitioners in the field, with application oriented, fully peer-reviewed papers together with insightful articles from the practitioner's perspective. Each issue features information on treatment technology as well as EPA updates, news briefs, industry announcements, equipment news, professional services, annual directories, and buyer's guides.


Groundwater elevation fluctuation has been recognized as one mechanism causing temporal indoor air volatile organic chemical (VOC) impacts in vapor intrusion risk assessment guidance. For dissolved VOC sources, groundwater table fluctuation shortens/lengthens the transport pathway, and delivers dissolved contaminants to soils that are alternating between water saturated and variably saturated conditions, thereby enhancing volatilization potential. To date, this mechanism has not been assessed with field data, but enhanced VOC emission flux has been observed in lab‐scale and modeling studies. This work evaluates the impact of groundwater elevation changes on VOC emission flux from a dissolved VOC plume into a house, supplemented with modeling results for cyclic groundwater elevation changes. Indoor air concentrations, air exchange rates and depth to groundwater (DTW) were collected at the study house during an 86‐day constant building under‐pressurization test. These data were used to calculate changes in trichloroethylene (TCE) emission flux to indoor air, during a period when DTW varied daily and seasonally from about 3.1 to 3.4 m below the building foundation (BF). Overall, TCE flux to indoor air varied by about 50% of the average, without any clear correlation to changes in DTW or its change rate. To complement the field study, TCE surface emission fluxes were simulated using a one‐dimensional model (HYDRUS 1‐D) for conditions similar to the field site. Simulation results showed time‐averaged surface TCE fluxes for cyclic water table elevations were greater than for stationary water table conditions at an equivalent time‐averaged water‐table position. The magnitudes of temporal TCE emission flux changes were generally less than 50% of the time‐averaged flux, consistent with the field site observations. Simulation results also suggested that TCE emission flux changes due to groundwater fluctuation are likely to be significant at sites with shallow groundwater (e.g., < 0.5 m BF) and permeable soil types (e.g., sand).

More Information

Learn more about the article: https://onlinelibrary.wiley.com/doi/abs/10.1111/gwmr.12322
Learn more about the journal: https://onlinelibrary.wiley.com/journal/17456592
For consultation regarding pressure cycling for evaluating vapor intrusion, contact Chase Holton at This email address is being protected from spambots. You need JavaScript enabled to view it..
Learn more about Chase at: https://www.linkedin.com/in/chase-holton-59617559/