Fractured Rock

Remediation

Remediation of fractured bedrock is complicated by difficulty in characterizing the flow system, the potential for small aperture fractures that restrict flow, dead end fractures that become contaminant sinks, and for some rock systems, primary porosity that allows diffusion into the rock matrix. All of these factors are influenced by the geology of the site. Previously because of these complexities, some sites with bedrock contamination defaulted to a pump and treat containment strategy that does not rely on detailed knowledge of contaminant location. A recognition of the uncertainty in a fractured rock site conceptual site model (CSM) is crucial (See Site Characterization page), and an adaptive site management approach (ITRC, 2011; 2017a) is well suited for these sites. Extensive and well-designed pilot testing can be an important part of the feedback loop in remedy selection.

Innovations of in situ remediation techniques have expanded the options for addressing fractured rock contamination. Interstate Technology Regulatory Council (ITRC) guidance, Characterization and Remediation of Fractured Rock (2017b), provides an overview of remedial design and technologies for cleanup of contaminated fractured rock sites. These include physical removal, containment, and chemical and biological technologies. Table 6-4. Remediation Technology Screening Matrix of the guidance provides a useful tool for screening of applicable technologies, based on site geology. The Federal Remediation Technologies Roundtable (FRTR) has also developed a technology screening matrix (2019) that isn't specifically focused on fractured rock, but provides a searchable database of chemical/biological, in situ, and ex situ technologies. In addition, Suthersan et al. (2017) provide a general review of remediation technologies. Sites where these technologies are used must be characterized thoroughly as they rely on direct contact with the dissolved contaminants (with the exception of thermal treatment). A clear understanding of the CSM is necessary to facilitate appropriate selection of treatment technologies.

In addition to geological characteristics, the chemical properties of the contaminant(s) will help determine remedy selection at fractured rock sites. Many of the chemicals found at fractured rock sites are present as non-aqueous phase liquids (NAPL), which can result in persistent dissolved phase contamination. Effective selection and use of the technologies discussed below requires an understanding of the chemical properties of the specific site contaminants.¹

New modeling tools are available to evaluate the prospects of remediation in contaminated fractured rock aquifers. For example, REMChlor-MD (Falta et al, 2018), a free publicly available model developed for the Department of Defense's Environmental Security Technology Certification Program (ESTCP), can provide information on matrix diffusion and the potential for rebounding. Note that the model assumes a simplified fractured rock setting with parallel fractures and thus cannot directly evaluate the prospects of remediation where both vertical and horizontal fractures form blocks in the aquifer.

The technologies listed below have been grouped into physical removal, containment, and chemical and biological technologies. A more detailed discussion of each can be found in Section 6.4.2.1 of the ITRC guidance document as well as the case studies in Section 11 (ITRC, 2017b).

Physical Removal

Physical removal techniques remove/recover contaminants from the bedrock. They may include:

• Excavation
• Air Sparging
• Non-Aqueous Phase Liquids (NAPL) Recovery
• Soil Vapor Extraction (SVE) and Multiphase Extraction
• Surfactant/Cosolvent Flushing
• Thermal Remediation Methods

Excavation, air sparging, and NAPL recovery are remedial techniques that have traditionally been employed in both unconsolidated and fractured bedrock environments. They can be applied with varying degrees of effectiveness depending upon site-specific conditions. A brief overview of each can be found in Section 6.4.2.1 of the ITRC guidance document (2017b).

SVE and multiphase extraction involve placing recovery wells into the subsurface and applying a vacuum. This technology generally is used in the vadose zone; however, some fractured bedrock sites have used dual-phase extraction wells that have long screens and draw water as well as unsaturated zone vapors to an aboveground treatment system. SVE is also used in conjunction with thermal technologies (discussed below) to capture any volatile contaminants

Surfactant/cosolvent flushing generally is used for addressing NAPL source zones. Because of the difficulty in fully delineating source zones and controlling mobilization of cosolvents/surfactants and remobilization of contaminants, ITRC (2003) recommends against the use of in situ flushing in fractured rock.

Thermal remediation involves the introduction of heat into the subsurface to volatilize, remobilize, and/or destroy organic contaminants. The remobilized volatile organics are captured through SVE and dissolved compounds are captured by extraction wells. Three methods can be used to introduce the heat:

• Steam-enhanced extraction (SEE): With SEE, the bedrock formation is injected with steam. This method is most applicable to sites with high secondary porosity and large fractures.
• Electrical resistive heating (ERH): ERH passes an electrical current through the subsurface, and the resistance effect produces heat. Since the resistivity depends on moisture content to work, its upper operating temperature is 100�C, the temperature at which water boils.
• Thermal conduction heating (TCH): TCH uses heater wells to raise subsurface temperatures and is capable of reaching much higher temperatures than either SEE or ERH.

Containment

Containment strategies (ITRC, 2017) prevent or reduce contaminant migration and are employed to protect downgradient receptors. They do little to reduce contaminant mass in a source area. Until more innovative approaches were developed, pump and treat was commonly used at fractured bedrock sites. Technologies include pump and treat and permeable reactive barriers.

Pump and treat can be used to achieve hydraulic control. The hydraulic transmissivity of the aquifer can be increased by hydraulic fracturing or controlled blasting; however, care must be taken not to create preferential flow paths that the pumping system does not capture (Henkes et al., 2007). Fractured bedrock aquifers with dead-end fractures and any primary porosity will be subject to diffusion and back-diffusion processes. This will extend the time needed to remediate the site. Pump and treat may be combined with newer, more innovative technologies either sequentially or concurrently to better achieve remedial goals. Pump and treat can be an effective interim action at fractured rock sites, allowing protection of downgradient receptors while characterization to support other remedies is carried out.

Permeable reactive barriers (PRBs) are another form of containment. Reactive material is emplaced within the aquifer between the source area and any downgradient receptors. While in unconsolidated settings, PRBs are often emplaced by trenching; however, this option is not practical for most fractured rock sites. Thereby PRBs can only be constructed by injecting remediation amendments into the subsurface. As groundwater flows through the reactive zone, contamination is removed by chemical or biological processes. Zero valent iron (ZVI) is a commonly reactive medium to address chlorinated volatile organic compounds (CVOCs). In fractured bedrock, ZVI slurry can be injected into fracture zones; however, achieving a continuous wall across all fractures can be challenging given the uncertainty of fracture flow pathways and network.

Activated carbon (AC) is a material that immobilizes contaminants of concern via adsorption. AC can be delivered to the subsurface via grid injection to address well-defined source areas or hot spots, in transects to create a permeable reactive barrier or treatment zone to provide containment of a plume, high pressure injection of tight formations and soil mixing or trenching. AC can be used alone or combined with chemical or biological technologies (U.S. EPA, 2018). When AC is combined with chemical or biological technologies, the contained contaminants are degraded/removed via chemical/biological processes.

Chemical and Biological Technologies

Unlike removal or containment, chemical and biological strategies degrade or transform contaminants into less or non-toxic end products. The technologies typically introduce additives to the subsurface to create oxidizing or reducing environments, which facilitates transformation or destruction of the contaminant of concern or enhances development of bacteria capable of degrading the contaminants. As with other remedies, a strong understanding of the hydrogeology, geochemistry and/or site microbial processes is necessary to select the appropriate remedy or combination of remedies. Common in situ chemical and biological remedies include:

• In Situ Chemical Oxidation (ISCO)
• In Situ Chemical Reduction (ISCR)
• In Situ Bioremediation (ISB)

ISCO involves the injection or infiltration of chemical oxidants into bedrock fractures where they react (or oxidize) contaminants. Common oxidants include Fenton's reagent, hydrogen peroxide, sodium and potassium permanganate, sodium persulfate, and ozone.

Ensuring that oxidant is dispersed and well mixed within all contaminated fractures can be challenging. One ESTCP project concluded "Chemical oxidation was shown to be ineffective for treating DNAPL sources in bedrock fractures in both the single fracture and fracture network experiments. This ineffectiveness was due to decreases in the effective DNAPL-water interfacial area (as measured using interfacial tracers) that were likely caused by oxidation reaction byproducts." (Schaefer et al, 2011). Because the oxidants remain active for a relatively short period, bedrock with back-diffusion issues will require multiple oxidant applications. For example, Fenton's reagent remains active in the subsurface for minutes to hours, persulfate for hours to weeks, depending upon the activating agent, and permanganate for greater than three months (Huling and Pivetz 2006). Back diffusion can persist for decades or centuries.

ISCR involves injecting a reducing agent into the groundwater. The most widely used reducing agent is ZVI in either a water slurry or an oil emulsion slurry. As with oxidation, achieving effective contact of the iron with the contaminants can be challenging, especially in fractures with small apertures. Because ZVI is relatively long lived (years), it can be used to address back diffusion.

ISB involves biostimulation or bioaugmentation of the groundwater. Biostimulation involves injecting amendments (e.g., organic substrates, electron donors, or nutrients) to encourage the growth of microorganisms that can degrade organic compounds Bioaugmentation involves injecting the specific microorganisms that can degrade the contaminants of concern. These microbes may directly use the contaminants as an energy source leading to the degradation of the compound to potentially less toxic products or they may cometabolize the compounds as they produce enzymes to catalyze the degradation of its growth substrate (e.g., vegetable oil or equivalent organic).

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References:

Falta, R.W., S.K. Farhat, C.J. Newell, and K. Lynch, 2018. REMChlor-MD Software Tool: A Practical Approach for Modeling Matrix Diffusion Effects in REMChlor ESTCP Project ER-201426.

Federal Remediation Technologies Roundtable (FRTR), 2019. Technology Screening Matrix.

Golaski, S. 2020. Personal communication. South Carolina Department of Health and Environmental Conservation, August 13.

Henkes, M., S. Grossi, D. Britton, et. al. 2007. Blast Fracturing: Installation and Evaluation of a Fractured Bedrock Zone within Granitic Bedrock at Edwards AFB. NGWA/U.S. EPA Fractured Rock Conference: State of the Science and Measuring Success in Remediation, 24-26 September, Portland, Maine, pp. 298-311.

Huling, S. G. and B. Pivetz. 2006. In-Situ Chemical Oxidation—ENGINEERING ISSUE. EPA/600/R-06/072, 59 pp

Interstate Technology and Regulatory Council (ITRC), 2017a. Remediation Management of Complex Sites. Web-based document. Rmcs-1.

Interstate Technology and Regulatory Council (ITRC), 2017a. Characterization and Remediation of Fractured Rock. Web-based document FracRx-1.

Interstate Technology and Regulatory Council (ITRC), 2011. Integrated DNAPL Site Strategy.

Interstate Technology and Regulatory Council (ITRC), 2003. Technical and Regulatory Guidance for Surfactant/Cosolvent Flushing of DNAPL Source Zones. DNAPL-3, 140 pp.

Schaefer, C., J. McCray, K. Christensen, P. Altman, P. Clement and J. Torlapati. 2011. DNAPL Dissolution in Bedrock Fractures and Fracture Networks, ESTP Project ER-1554.

Suthersan, S., Horst, J., Schnobrich, M., Welty, N. and McDonough, J., 2017. Remediation Engineering Design Concepts, 2nd Edition. CRC Press, Boca Rotan, 627 pp.

U.S. EPA, 2018. Remedial Technology Fact Sheet - Activated Carbon-Based Technology for In Situ Remediation EPA 542-F-18-001, 9 pp.

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Resources

Unlocking the Secrets of Fractured Bedrock Injection
Brab, B. | SMART Remediation, 13 February, virtual, 18 slides, 2021

An Adaptive Management Approach for Groundwater Remediation in Deep Fractured Rock
Favara, P., P. Zorba, K. Brown, R. Dean, J. Hartley, P. Lawson, and D. Patterson.
DCHWS 2021 Design and Construction at Hazardous Waste Sites Virtual Symposium, 29-30 March and 1 April, Virtual, 20 slides, 2021

Quantification of Toluene Phytoextraction Rates and Microbial Biodegradation Functional Profiles at a Fractured Bedrock Phytoremediation Site
BenIsrael, M., P. Wanner, J. Fernandes, J.G.Burken, R. Aravena, B.L. Parker, E.A. Haack, D.T. Tsao, and K.E. Dunfield.
Science of The Total Environment 707:135890(2020)

Technology Screening Matrix
Federal Remediation Technologies Roundtable (FRTR), 2019.

Assessment of Groundwater Quality and Remediation in Karst Aquifers: A Review (Abstract)
Kalhor, K., R. Ghasemizadeh, L. Rajic, and A. Alshawabkeh.
Groundwater for Sustainable Development 8:104-121(2019)

A Practical Approach for Modeling Matrix Diffusion Effects in REMChlor
Falta, R.W., S.K. Farhat, C.J. Newell, and K. Lynch.
ESTCP Project ER-201426, 2018

Remedial Technology Fact Sheet - Activated Carbon-Based Technology for In Situ Remediation
U.S. EPA, EPA 542-F-18-001, 9 pp, 2018

Characterization and Remediation of Fractured Rock
Interstate Technology and Regulatory Council (ITRC), Web-based document FracRx-1, 2017

Remediation Engineering Design Concepts, 2nd Edition
Suthersan, S., J. Horst, M. Schnobrich, N. Welty, and J. McDonough, CRC Press, Boca Rotan, 627 pp, 2017

Remediation Management of Complex Sites
Interstate Technology and Regulatory Council (ITRC), Web-based document Rmcs-1, 2017

Performance and Costs for In-Situ Remediation at 235 Sites
McGuire, T., D. Adamson, C. Newell, and P. Kulkarni, ESTCP Project ER-201120, 144 pp, 2016

Characterization, Modeling, Monitoring, and Remediation of Fractured Rock
National Research Council. National Academies Press, Washington, DC. ISBN: 978-0-309-37372-2, 176 pp, 2020

DNAPL Dissolution in Bedrock Fractures and Fracture Networks
Schaefer, C., J. McCray, K. Christensen, P.Altman, P. Clement, and J. Torlapati, ESTP Project ER-1554, 146 pp, 2011

Integrated DNAPL Site Strategy
Interstate Technology and Regulatory Council (ITRC), 2011

Blast Fracturing: Installation and Evaluation of a Fractured Bedrock Zone within Granitic Bedrock at Edwards AFB
Henkes, M., S. Grossi, D. Britton, and P. Hallman.
NGWA/U.S. EPA Fractured Rock Conference: State of the Science and Measuring Success in Remediation, 24-26 September, Portland, Maine:298-311(2007)

Developing Remedial Strategies in a Mixed Porous Medium/Fractured Rock System: Lemberger Site, Whitelaw, Wisconsin
Wedekind, J.E., K.R. Bradbury, P.M. Chase, M.B. Gotkowitz, E. Gredell, K.D. Krause, and J.M. Rice.
NGWA/U.S. EPA Fractured Rock Conference: State of the Science and Measuring Success in Remediation, 24-26 September, Portland, Maine:389-402(2007)

In-Situ Chemical Oxidation—ENGINEERING ISSUE
Huling, S.G. and B. Pivetz., EPA/600/R-06/072, 59 pp, 2006

The Economics of Remediating NAPLs in Fractured Aquifers
Hardisty, P.E. and E. Ozdemiroglu.
Proceedings of the National Ground Water Association Cost of Clean-Up Conference, 12 pp, 2005

Microfracture Surface Characterizations: Implications for In Situ Remedial Methods in Fractured Rock
Eighmy, T., J.C.M. Spear, J. Case, H. Marbet, J. Casas, W. Bothner, J. Coulburn, L.S. Tisa, M. Majko, E. Sullivan, M. Mills, K. Newman, and N.E. Kinner, EPA 600-R-05-121, 99 pp, 2005

Steam Enhanced Remediation Research for DNAPL in Fractured Rock, Loring Air Force Base, Limestone, Maine
Davis, E., N. Akladiss, R. Hoey, B. Brandon, M. Nalipinski, S. Carroll, G. Heron, K. Novakowsk, and K. Udell. EPA/540/R-05/010, 211 pp, 2005

Technical and Regulatory Guidance for Surfactant/Cosolvent Flushing of DNAPL Source Zones
Interstate Technology and Regulatory Council (ITRC), Report No. DNAPL-3, 140 pp, 2003

Chlorinated Solvents in Fractured Sedimentary Rock: Naval Air Warfare Center (NAWC) Research Site, West Trenton, NJ

USGS website providing the science and tools to understand the actual versus perceived health risks due to anthropogenic chemical contaminants that have persisted for decades in fractured-rock aquifers, and to provide the science needed to economically and effectively minimize exposure and actual health risks.

Contamination in Fractured Rock Aquifers

USGS webpage listing research papers, fact sheets, and publications addressing contaminated fractured rock aquifers.

New Paradigm for Fractured Rock Cleanup

USGS webpage discussing a comparative analysis of hydraulic tests conducted in a variety of rock environments to test for hydraulic responses at fractured rock sites.

Improving Bioaugmentation Strategies for Remediating Contaminated Fractured Rocks

USGS website that summarizes a groundwater bioaugmentation field experiment that demonstrates the effectiveness and potential weaknesses of bioaugmentation and provides guidance for improved design of bioaugmentation in fractured-rock aquifers.

Physical Removal Resources

White Paper on Thermal Remediation Technologies for Treatment of Chlorinated Solvents: Santa Susana Field Laboratory, Simi Valley, California
California Department of Toxic Substances Control, 69 pp, 2018

Assessment of a Large Scale In-Situ Thermal Treatment Project Performed at a Chlorinated Solvent Site in the UK
Baldock, J., L. Chesher, D. Reid, A.-M. Sexton, A. Thomas, S. Tillotson, R. Niven, K. Johnson, and J. Dablow.
AquaConsoil 2013, 16-19 April 2013, Barcelona. Paper 1954, 7 pp, 2013

Dense Non Aqueous Phase Liquid (DNAPL) Removal from Fractured Rock Using Thermal Conductive Heating (TCH)
Lebron, C.A., D. Phelan, G. Heron, J. LaChance, S.G. Nielsen, B. Kueper, D. Rodriguez, A. Wemp, D. Baston, P. Lacombe, and F.H. Chapelle.
Contract Report CR-NAVFAC ESC-EV-1202, ESTCP Project ER-200715, 427 pp, Aug 2012

Thermal Conductive Heating in Fractured Bedrock: Screening Calculations to Assess the Effect of Groundwater InfluxAbstract
Bastona, D.P. and B.H. Kueper.
Advances in Water Resources 32(2)231-238(2009)

Use of Thermal Conduction Heating for the Remediation of DNAPL in Fractured Bedrock
Heron, G., R.S. Baker, J.M. Bierschenk, and J.C. LaChance.
Remediation of Chlorinated and Recalcitrant Compounds: Proceedings of the Sixth International Conference, May 19-22, 2008. Battelle Press, Columbus, OH. 8 pp, 2008

Assessing the Influence of Ground Water Inflow on Thermal Conductive Heating in Fractured Rock
Baston, D., G. Heron, and B.H. Kueper
Fractured Rock Conference: State of the Science and Measuring Success in Remediation, September 24-26, 2007, Portland, Maine. 116-130(2007)

Steam Enhanced Remediation Research for DNAPL in Fractured Rock, Loring Air Force Base, Limestone, Maine
Davis, E., N. Akladiss, R. Hoey, B. Brandon, M. Nalipinski, S. Carroll, G. Heron, K. Novakowski, and K. Udell.
EPA 540-R-05-010, 211 pp, 2005

Technical and Regulatory Guidance for Surfactant/Cosolvent Flushing of DNAPL Source Zones.
ITRC, 140 pp, 2003

Containment Resources

Mitigation of Chlorinated Solvent Groundwater Plumes with Colloidal Activated Carbon
Haupt, S.J., Master's Thesis, University of Rhode Island, Paper 1510, 131 pp, 2019

Technical Report: In Situ Activated Carbon Case Study Review
Nair, D and S, Rosansky., NAVFAC EXWC. 27 pp., 2019

Lessons Learned and Paths to Success with Activated Carbon Injections
Winner, E. and T. Fox.
ASTSWMO Workshop, 70 slides, 2016

Overburden and Bedrock Remediation Using Activated Carbon Based Injectates
Simpson, G.
SMART Remediation, 4 February, Ottawa, Ontario, 22 slides, 2016

Remediation of a Fractured Rock Aquifer Containing Trichloroethylene Dense Nonaqueous Phase Liquid
Orient, J., L. Monaco, K. Davies, and R.A. Sloto.
NGWA/U.S. EPA Fractured Rock Conference: State of the Science and Measuring Success in Remediation, 24-26 September, Portland, Maine:315-327(2007)

Using Major Ions Data to Support the Demonstration of Hydraulic Containment in a Fractured Bedrock Aquifer
Sayko, S.P., W.F. Daniels, and R.J. Passmore.
NGWA/U.S. EPA Fractured Rock Conference: State of the Science and Measuring Success in Remediation, 13-15 September, Portland, Maine:100-114(2004)

Chemical and Biological Resources

ISCO

Rapid Assessment of Remedial Effectiveness and Rebound in Fractured Bedrock
Schaefer, C., D. Lippincott, K. Hatfield, and H. Klammler.ESTCP Project ER-201330, 126 pp, 2017

Final Report: DNAPL Dissolution in Bedrock Fractures and Fracture Networks
Schaefer, C., J. McCray, K. Christensen, P. Altman, P. Clement, and J. Torlapati. SERDP Project ER-1554, 146 pp, 2011

Assessment of TCE Oxidation by KMnO₄ using Stable Carbon and Chlorine Isotopes at a Fractured Bedrock Site
Helsena, J., R. Aravena, M. Zhanga, O. Shouakar-Stasha, and L. Burns.
Fractured Rock Conference: State of the Science and Measuring Success in Remediation, September 24-26, 2007, Portland, Maine. 94-107(2007)

Full-Scale Permanganate Remediation of Chlorinated Ethenes in Fractured Shale: Part 1. Site Characterization and Design and Implementation of Full-Scale Remedy (Abstract)
Goldstein, K., A.R. Vitolins, D. Navon, S.W. Chapman, B.L. Parker, and T.A. Al.
Fractured Rock Conference: State of the Science and Measuring Success in Remediation, September 24-26, 2007, Portland, Maine.

In-Situ Chemical Oxidation
Huling, Scott G. and Bruce E. Pivetz
USEPA, EPA/600/R-06/072, 60 pp, 2006

Fractured Crystalline Bedrock Ground Water Remediation of Dissolved TCE via Sodium Permanganate Solution Injection & Re-circulation.
Simons, W.F. and P.D. Steinberg.
Fractured Rock Conference: State of the Science and Measuring Success in Remediation, September 13-15, 2004, Portland, Maine. 417-424(2004)

Technical and Regulatory Challenges Resulting from VOC Matrix Diffusion in a Fractured Shale Bedrock Aquifer
Vitolins, A.R., K.J. Goldstein, D. Navon, G.A. Anderson, S.P. Wood, B. Parker, and J. Cherry.
Fractured Rock Conference: State of the Science and Measuring Success in Remediation, September 13-15, 2004, Portland, Maine. 115-126(2004)

ISCR

Rapid Source Zone Remediation of TCE in Fractured Bedrock Using High-Flow Injection
Pizarro, D. | DCHWS Design and Construction Spring 2022 Symposium, 30 March-1 April, Philadelphia, PA, 14 slides, 2022

Fracture Emplacement of a Micro-Iron/Carbon Amendment for TCE Reduction in a Bedrock Aquifer
Adventus Group.
7th International Battelle Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey California, May 2010. 23 slides, 2010

ISB

Microbial Community Response to a Bioaugmentation Test to Degrade Trichloroethylene in a Fractured Rock Aquifer, Trenton, N.J
Underwood, J.C., D.M. Akob, M. Mi Lorah, T.E. Imbrigiotta, R.W. Harvey, and C.R. Tiedeman.
Microbial Ecology 98(7): fiac077(2022)

A Dual Biorecirculation System to Facilitate VOC Mass Reduction and Hydraulic Control in Fractured Bedrock
Bamer, J. | Design and Construction Issues at Hazardous Waste Sites Virtual Meeting, 26-28 October, 24 slides, 2020

Acetylene Fuels TCE Reductive Dechlorination by Defined Dehalococcoides/Pelobacter Consortia (Abstract)
Mao, X., R.S. Oremland, T. Liu, S. Gushgari, A.A. Landers, S.M. Baesman, and L. Alvarez-Cohen.
Environmental Science and Technology 51(4):2366-2372(2017)

Designing, Assessing, and Demonstrating Sustainable Bioaugmentation for Treatment of DNAPL Sources in Fractured Bedrock.
Schaefer et al., ESTCP Project 201210, 72 pp, 2017

Enhanced Dichloroethene Biodegradation in Fractured Rock Under Biostimulated and Bioaugmented Conditions (Abstract)
Bradley, P.M., Journey, C.A., Kirshtein, J.D., Voytek, M.A., Lacombe, P.J., Imbrigiotta, T.E., Chapelle, F.H., Tiedeman, C.J., and Goode, D.J.
Remediation, 22(2):21-32(2012)

Estimated Trichloroethene Transformation Rates Due to Naturally Occurring Biodegradation in a Fractured Rock Aquifer (Abstract)
Chapelle, F.H., Lacombe, P.J., and Bradley, P.M.
Remediation 22(2):7-20(2012)

DNAPL Dissolution in Bedrock Fractures and Fracture Networks
Schaefer, C., J. McCray, K. Christensen, P. Altman, P. Clement, and J. Torlapati.
SERDP Project ER-1554, 146 pp, 2011

Fracture Emplacement of a Micro-Iron/Carbon Amendment for TCE reduction in a Bedrock Aquifer
Adventus Group.
7th International Battelle Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey California, May 2010. 23 slides, 2010

High-Pressure Injection of Dissolved Oxygen for Hydrocarbon Remediation in a Fractured Dolostone Aquifer (Abstract)
Greer, K.D., J.W. Molson, J.F. Barker, N.R. Thomson, and C.R. Donaldson.
Journal of Contaminant Hydrology, 2010

Biodegradation Potential of MTBE in a Fractured Chalk Aquifer Under Aerobic Conditions in Long-Term Uncontaminated and Contaminated Aquifer Microcosms (Abstract)
Shah, N.W., S.F. Thornton, S.H. Bottrell, and M.J. Spence.
Journal of Contaminant Hydrology 103(3-4)119-133(2009)

Flowpath Independent Monitoring of Reductive Dechlorination Potential in a Fractured Rock Aquifer (Abstract)
Bradley, P.M., P.J. Lacombe, T.E. Imbrigiotta, F.H. Chapelle, and D.J. Goode.
Ground Water Monitoring & Remediation 29(4):46-55(2009)

Enhanced Bioremediation Using Whey Powder for a Trichloroethene Plume in a High-Sulfate, Fractured Granitic Aquifer (Abstract)
Mora, R.H, T.W. McBeth, T. MacHarg, J. Gundariahalli, H. Holbrook, P. Schiff.
Remediation18(3):7-30(2008)

Lessons Learned from Bedrock Blast Fracturing and Bioremediation at a Superfund Landfill (Abstract)
Pearson, S.C. B.B. Johnson, N. Walter, R. Galloway, and S. Waldo.
Fractured Rock Conference: State of the Science and Measuring Success in Remediation, September 13-15, 2004, Portland, Maine.

Biodegradation of Chlorinated Ethenes at a Karst Site in Middle Tennessee
Byl, T.D. and S.D. Williams.
U.S. Geological Survey Water-Resources Investigations Report 99-4285, 65 pp, 2000