Conventional Landfill Covers

The Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) are applicable Federal law governing landfill remediation. RCRA is the controlling federal law for both municipal solid waste and hazardous waste landfills. RCRA enforcement authority is delegated to the states as each state adapts equal or more stringent regulations than those contained in federal rules and regulations. Most states' regulations closely follow the RCRA regulations. The remediation of old landfills is generally addressed under CERCLA. However, RCRA is considered as a primary source of technical requirements for CERCLA.

RCRA divides landfills into two categories:

• Landfills where hazardous wastes are disposed in accordance with RCRA §264-Subtitle C Hazardous Wastes; and
  
  
• Landfills where only municipal wastes are disposed in accordance with RCRA §258-Subtitle D Municipal Solid Waste.

When RCRA was implemented, barrier-type covers using multiple low permeability layers were considered the most permanent and protective landfill cover options. While the regulations allow for some design flexibility, both municipal and hazardous waste covers described in RCRA have specific permeability requirements reflecting this prejudice. Additional detail is available in AFCEE reference documents and the EPA references shown below.

The Evapotranspiration (ET) Landfill Cover

Federal and state regulations have long dictated not only the application of a landfill cover as a remedial alternative, but also its actual technical design. Given the prescriptive nature of both RCRA and many state regulations, the intimate association among CERCLA, RCRA, and state regulations has historically been an impediment to the selection and installation of alternative landfill covers. However, the same association may also be interpreted as providing latitude to install alternative covers under the CERCLA process because of the flexibility in selecting ARARs. EPA, DOD, and the states are fully aware of this dichotomy. They have expended considerable effort in defining and supporting the role of innovative technologies in remediation programs.

There is a specific option for alternative cover designs for Subtitle D landfills that allows the director of an approved state to allow an alternative final cover design that includes an infiltration layer that achieves an equivalent reduction in infiltration (§258.60[b][1]). In addition, there are regulatory directives that support the use of innovative technology. Additional detail is available in AFCEE reference documents.

The EPA's Alternative Landfill Cover Assessment Project (ACAP) is actively investigating alternative covers and some vegetative covers have been built. See the section on Interest Groups for the reference to the ACAP effort.

As a result of development effort by the AFCEE and others, there is increasing interest in the use of the ET landfill cover concept. The Interstate Technology Regulatory Council (ITRC) includes regulators from 40 states; they sponsored a landfill summit to discuss the ET landfill cover. The AFCEE sponsored development of the white paper that was the focus of that meeting; the title is "Alternative Landfill Covers". The ITRC has developed technical regulatory guidance on alternative landfill covers, "Technical and Regulatory Guidance for Design, Installation, and Monitoring of Alternative Final Landfill Covers". The document was published in December 2003 and is available for download on the ITRC web site.

To cover specific ET landfill covers that have been built in the US, in March 2003 the ITRC published "Technology Overview Using Case Studies of Alternative Landfill Technologies and Associated Regulatory Topics." The document presents examples of flexibility used in regulatory frameworks for approving alternative landfill cover designs, current research information about the use of alternative covers, and examples of approved designs and constructed covers. This document is also available for download on the ITRC web site."

EPA Rules and Regulations:

        RCRA Subtitle C (Hazardous Wastes) 40 CFR 264.310 Closure and Post-Closure Care

        RCRA Subtitle D (Municipal Solid Waste) 40 CFR 258, Subpart F - Closure and Post-Closure Care

(Both may be found on the EPA Solid Waste site)

Landfill reference documents containing technical details and other assistance for ET landfill cover selection, evaluation, design and use, available from AFCEE:

• "Landfill Covers for Use at Air Force Installations" (AFCEE, Feb. 1999);
• "Survey of Air Force Landfills, Their Characteristics, and Remediation Strategies" (AFCEE, July 1999);
• An Access database (zip file) containing the survey results above
• "Decision Tool for Landfill Remediation" (AFCEE, August 1999);
• "Landfill Remediation Project Managers Handbook" (AFCEE, Dec. 1999).
• Golf Courses on Air Force Landfills (AFCEE, September 2000)
• Vegetated Landfill Covers and Phytostabilization-The Potential for Evapotranspiration-Based Remediation at Air Force Bases (AFCEE, May 2001)
• Alternative Landfill Covers [prepared for the ITRC's Alternative Landfill Covers summit] (AFCEE, July 2001)
• Downey, D. and J. Hicks. 2003. "Impact of Landfill Closure Designs on Long-Term Natural Attenuation of Chlorinated Hydrocarbons". Proc. 2003 AFCEE Technology Transfer Workshop" 25 Feb. 03, San Antonio, Texas
• Hauser, V. L. 2003. Alternative Landfill Remediation - Ready for Air Force Use. Proceedings, 2003 AFCEE Technology Transfer Workshop, 25 February 03
• "Protocol for Controlling Contaminated Groundwater by Phytostabilization (980 KB) (AFCEE, Dec. 2001)
• Evaluating Evapotranspiration (ET) Landfill Cover Performance Using Hydrologic Models (1,159 KB) (AFCEE, Jan. 2004)

References

• Reinhart, D. R., and T. G. Townsend. 1998. Landfill Bioreactor Design & Operation. Lewis Publishers, Boca Raton, FL.
• Hauser, V. L., B. L. Weand, and M. D. Gill. 2001. Natural Covers for Landfills and buried Waste. Am. Society of Civil Engineers, J. Environmental Engineering, vol. 127, no. 9: 768-775
• ESTCP. 2002. Impact of Landfill Closure Designs on Long-Term Natural Attenuation of Chlorinated Hydrocarbons. Prepared by Parsons Engineering for Environmental Security Technology Certification Program, Arlington, VA, Final, March 2002. (available at: http://www.estcp.org/index.cfm)