USGS and University at Buffalo scientists injecting tracers to study diffusion.
A Field Method to Quantify Chlorinated Solvent Diffusion, Sorption, Abiotic and Biotic Degradation in Low-Permeability Zones
Completed
By New Jersey Water Science Center
January 21, 2022
A Borehole Test for Chlorinated Solvent Diffusion and Degradation Rates in Sedimentary Rock
A Borehole Test for Chlorinated Solvent Diffusion and Degradation Rates in Sedimentary Rock
A Finite-Difference Algorithm used to Simulate Radial Diffusion, Adsorption, and Reactions of Chlorinated Ethenes in Porous Media
A Finite-Difference Algorithm used to Simulate Radial Diffusion, Adsorption, and Reactions of Chlorinated Ethenes in Porous Media
Strategic Environmental Research and Development Program project ER-2533
In chlorinated-solvent-contaminated fractured-sedimentary-rock aquifers, low-permeability (low-K) strata typically act as long-term or secondary sources of contamination to mobile groundwater in the high-permeability fractures. The fate of dissolved trichloroethene (TCE) in the low-K matrix is controlled by abiotic degradation, sorption, and diffusion in the matrix, and biodegradation reactions that occur principally in the fractures.
The U.S. Geological Survey and the University at Buffalo, with the support of the Strategic Environmental Research and Development Program (SERDP), the Toxic Substances Hydrology Program, and the U.S. Navy, are developing a field method capable of concurrently characterizing site-specific diffusion, sorption, and degradation of chlorinated volatile organic contaminants (CVOCs) in low-K zones.
Research Progress
Prototype Development and Testing
Sources/Usage: Public Domain. View Media Details
At a well-characterized fractured-rock site, diffusive tracer tests were conducted in low-K intervals of open boreholes, open to un-fractured rock, isolated using a straddle-packer apparatus. CVOCs in the borehole fluid were initially removed by gas stripping, and concentrations gradually increased during diffusion out of the rock matrix. Conversely, tracers added to the borehole fluid gradually diffused into the rock matrix, and their concentrations in the borehole fluid decreased. Degradation reactions also contributed to decreases in parent compound concentrations and increases in product concentrations. Downhole components of the apparatus included Viton-clad straddle packers and closed-loop stainless steel tubing for fluid sampling. Bench-scale testing identified tubing inlet and outlet configurations that improved tracer mixing efficiency. Fluid samples from the isolated interval were collected using a peristaltic pump, and the volume of each sample was replaced with CVOC- and tracer-free borehole fluid to minimize pressure changes due to sampling. Prototypes were field-tested for approximately three months in 6-inch open boreholes at the former Naval Air Warfare Center, West Trenton, N.J., where TCE migrated from land surface into underlying fractured mudstones of the Newark Basin, and where hydraulic containment by pump-and-treat remediation, as well as natural attenuation by biodegradation, has been ongoing since the mid-1990s.
More information
Project ER-2533 at SERDP: Background, Objectives, Technical Approach, and Benefits.
Research Team
- Richelle M. Allen-King, Principal Investigator (PI), University at Buffalo (SUNY)
- Rebecca L. Kiekhaefer, M.S., University at Buffalo
- Daniel J. Goode
- Michelle M. Lorah
- Allen M. Shapiro
- Alex Fiore
- Karl B. Haase
- Claire R. Tiedeman (Emeritus)
- Paul A. Hsieh (Emeritus)
- Thomas E. Imbrigiotta (Emeritus)
Contaminant Fate and Transport Studies in Fractured Sedimentary Rock Aquifers at the former Naval Air Warfare Center (NAWC), West Trenton, N.J.
Contaminants associated with industrial, airport, and other activities are present in groundwater in fractured-rock aquifers, posing long-term hazards to drinking-water supplies and ecosystems. The heterogeneous character of fractured rock challenges our understanding, monitoring, and remediation of such sites.
Below are multimedia items associated with this project.
Tracer Addition
USGS and University at Buffalo scientists injecting tracers to study diffusion.
Strategic Environmental Research and Development Program project ER-2533
In chlorinated-solvent-contaminated fractured-sedimentary-rock aquifers, low-permeability (low-K) strata typically act as long-term or secondary sources of contamination to mobile groundwater in the high-permeability fractures. The fate of dissolved trichloroethene (TCE) in the low-K matrix is controlled by abiotic degradation, sorption, and diffusion in the matrix, and biodegradation reactions that occur principally in the fractures.
The U.S. Geological Survey and the University at Buffalo, with the support of the Strategic Environmental Research and Development Program (SERDP), the Toxic Substances Hydrology Program, and the U.S. Navy, are developing a field method capable of concurrently characterizing site-specific diffusion, sorption, and degradation of chlorinated volatile organic contaminants (CVOCs) in low-K zones.
Research Progress
Prototype Development and Testing
Sources/Usage: Public Domain. View Media Details
At a well-characterized fractured-rock site, diffusive tracer tests were conducted in low-K intervals of open boreholes, open to un-fractured rock, isolated using a straddle-packer apparatus. CVOCs in the borehole fluid were initially removed by gas stripping, and concentrations gradually increased during diffusion out of the rock matrix. Conversely, tracers added to the borehole fluid gradually diffused into the rock matrix, and their concentrations in the borehole fluid decreased. Degradation reactions also contributed to decreases in parent compound concentrations and increases in product concentrations. Downhole components of the apparatus included Viton-clad straddle packers and closed-loop stainless steel tubing for fluid sampling. Bench-scale testing identified tubing inlet and outlet configurations that improved tracer mixing efficiency. Fluid samples from the isolated interval were collected using a peristaltic pump, and the volume of each sample was replaced with CVOC- and tracer-free borehole fluid to minimize pressure changes due to sampling. Prototypes were field-tested for approximately three months in 6-inch open boreholes at the former Naval Air Warfare Center, West Trenton, N.J., where TCE migrated from land surface into underlying fractured mudstones of the Newark Basin, and where hydraulic containment by pump-and-treat remediation, as well as natural attenuation by biodegradation, has been ongoing since the mid-1990s.
More information
Project ER-2533 at SERDP: Background, Objectives, Technical Approach, and Benefits.
Research Team
- Richelle M. Allen-King, Principal Investigator (PI), University at Buffalo (SUNY)
- Rebecca L. Kiekhaefer, M.S., University at Buffalo
- Daniel J. Goode
- Michelle M. Lorah
- Allen M. Shapiro
- Alex Fiore
- Karl B. Haase
- Claire R. Tiedeman (Emeritus)
- Paul A. Hsieh (Emeritus)
- Thomas E. Imbrigiotta (Emeritus)
Contaminant Fate and Transport Studies in Fractured Sedimentary Rock Aquifers at the former Naval Air Warfare Center (NAWC), West Trenton, N.J.
Contaminants associated with industrial, airport, and other activities are present in groundwater in fractured-rock aquifers, posing long-term hazards to drinking-water supplies and ecosystems. The heterogeneous character of fractured rock challenges our understanding, monitoring, and remediation of such sites.
Below are multimedia items associated with this project.
Tracer Addition
USGS and University at Buffalo scientists injecting tracers to study diffusion.
USGS and University at Buffalo scientists injecting tracers to study diffusion.