Morton A. Barlaz^1, * and Alix Rooker¹ and Peter Kjledsen²

1North Carolina State University, ²Technical University of Denmark

*Correspondng Author: Dept. of Civil Engineering, Raleigh, NC, 27695-7908, barlaz@unity.ncsu.edu

Current regulations specify termination of the post-closure monitoring period 30 years after closure. While emissions are likely to continue well beyond 30 years, the EPA lacks the scientific basis to define an appropriate endpoint for post-closure monitoring. In addition, the increased use of leachate recirculation to enhance MSW decomposition is introducing new issues including a potential reduction in the time required for post-closure monitoring.

For the past year, we have been evaluating the types of criteria that could be used to define the end of the post-closure monitoring period for Subtitle D landfills. This evaluation has included reviews of data on the composition of leachate from well decomposed refuse, the quantities of water that might be expected years after installation of the final cover, long term gas management as well as landfill stability. In addition, input has been solicited from representatives of the landfill industry, consulting engineers, state regulators and the research community.

In this presentation, the results of the project will be discussed. This will include summaries of data on the presence of both organic matter and metals in leachate from well decomposed refuse and data on long term leachate quantity. Data on leachate composition and quantity were then used to evaluate the significance of a potential release of leachate to surface water. If it can be shown that a release of leachate to surface water will not result in an adverse environmental impact, then such a release could be considered to be acceptable in making a decision to terminate post-closure monitoring. Finally, strategies for long term gas management will be discussed.