Development of a Guidance for Natural Attenuation as a Remedial Technology at CCR Facilities
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Geosyntec developed a monitored natural attenuation (MNA) framework for the Electric Power Research Institute (EPRI). This framework was applied at two CCR facilities with different hydrogeologic conditions and unique constituents of interest.

These two facilities have very different hydrogeologic conditions and unique constituents of interest (boron and arsenic), making them very useful for evaluating a single technology. EPRI's goal for the resulting framework was for it to function as a guide for decision-making processes to evaluate the necessary level of justification for MNA, including defining the geochemical processes governing the attenuation and sequestration of the site-specific constituents, hydrogeologic setting, and long-term stability of MNA implementation at these two sites.


Geosyntec began by developing sampling and analysis plans to gather the necessary data needed for a full, four-tiered analysis of MNA at the two CCR facilities, one in the midwest and one in the southeast. While it was determined that the boron site was not a candidate for a full-scale MNA evaluation, we collected additional data at the arsenic-impacted site in accordance with the sampling and analysis plan. We also provided a robust technical assessment and interpretation of the data to determine if MNA is a viable remedial alternative for these CCR facilities.

We then synthesized the results of our evaluation into site-specific case-study reports and developed a framework to evaluate the potential for MNA application at other CCR facilities. Using the two CCR facilities in question, we applied our framework for the long-term evaluation of MNA based upon their constituents of interest, sensitive ecological receptors, etc.


The results of Geosyntec's evaluation determined that MNA was a feasible remedial alternative for implementation at the two test sites. Working with an EPRI member, we successfully negotiated the four-tiered MNA framework for arsenic groundwater exceedances, guiding the stakeholders through the geochemical modeling and bench-scale investigations necessary for a demonstration of arsenic attenuation capacity and attenuation rate.

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Project Summary

  • Location: Multiple
  • Client: Electric Power Research Institute
  • Project Practice Areas: Water & Wastewater, Waste Management, Environmental Management
  • Type of Facility: Coal ash landfills
  • Services Provided: Development of MNA decision framework for application at CCR sites, MNA evaluation for arsenic exceedances, Integrated results of MNA evaluation for arsenic as a case study
  • Type of Work: Technology evaluation
  • Governing Regulation: Federal regulations