Waste Management Program
Landfill Stability Overview
Issue Statement
Current landfill designs and practices do not provide for degradation of landfilled organic wastes within a defined and reasonable timeframe. Undegraded organic wastes can potentially cause future environmental or economic impacts if the landfill gas and leachate collection and containment systems (cap and/or liner) fail at some time in the future. Potential economic burdens and environmental risks associated with these undegraded wastes will be largely borne by future generations. Better landfill designs and organic management practices should be identified and implemented to provide for organic waste degradation within a reasonable timeframe.
"Reasonable timeframe" means within the lifetime of the people who generate the waste.
"Economic burdens" means costs to manage gas and leachate, to maintain the slopes and cover, to perform environmental monitoring, and to control access.
"Environmental risks" includes potential contamination of groundwater and surface water, air quality degradation, greenhouse gas impacts, explosive gas generation, and/or land instability.
Background
Current waste management practices depend heavily on secure containment and long-term storage of waste materials. The state of engineering practice has developed environmentally secure facilities for an unknown but finite period. Engineered systems have worked well for the last 30 years, and laboratory projections of membrane liner components indicate these could last for several hundred years. Engineering and scientific knowledge of landfill environmental controls with aging is limited and the potential impacts of these facilities on human health and the environment are not well-defined. The waste management community has not until recently focused on management strategies that would enhance the degradation rate of wastes and reduce the potential of the wastes being disposed of now to create adverse environmental or economic impacts in the future.
Wastes contained in modern Subtitle D landfills include significant proportions of organic wastes. These materials degrade within the landfill environment at varying rates depending on material and environmental characteristics. The degradation of organic wastes within modern landfills produces methane and other organic and inorganic gasses, leachate containing harmful organic and inorganic compounds, and settlement within the waste mass. Failure to adequately manage these products of organic matter degradation imposes an economic burden and an environmental risk on future generations. By managing organics properly over the short term, we place the responsibility for costs and risks on the generation that created the wastes.
Management of organic materials to reduce their adverse impacts can take place either outside the landfill or within the landfill environment. Diverting organics from the landfill provides an opportunity for treatment and recovery, and some countries are now beginning to implement changes accordingly. Treatment of organic wastes within the landfill structure involves changing landfill design and operation approaches. In both cases, materials and/or energy can be recovered from the organics.
As landfill facilities grow larger and more complex, the need to find waste disposal methods that reduce the impacts of organic matter degradation becomes more important. Larger landfills are generally believed to be more difficult to repair, and present more significant potential costs and risks. As a first step toward addressing these issues, the Wisconsin Department of Natural Resources has proposed requiring that landfills in the state prepare and implement landfill stability plans beginning in 2007, and has formed a Landfill Stability Workgroup to assist in developing the technical details of the proposed stability plan requirement.
Scope of Workgroup Effort
The Landfill Stability Workgroup is working to identify strategies for stabilizing organic wastes within and outside landfills, thereby reducing their potential long-term adverse impacts. The workgroup's efforts are focused on developing a framework for landfill stability plans that will lead to tangible improvements in the management of organic wastes. Other problem components of the municipal waste stream, such as heavy metals, plastics, and household hazardous wastes, may adversely affect landfill stability in a broader sense, or represent a waste of resources, and may be reduced indirectly as a result of the workgroup's efforts, but are not the principal target of the group's work, although they may warrant future attention.
Among the issues the workgroup is addressing are:
- measurement of organic stability or the potential for landfilled organic material to cause environmental threats;
- applicability of the proposed landfill stability plan requirement (all landfills; new landfills only; expansions; facilities other than landfills?);
- scheduling of proposed stability plan requirements and subsequent evaluation;
- performance standards in evaluating plans' implementation; and
- expected content of plans.
General Workplan
The workgroup expects to complete its work products by January, 2006 in order to provide facility operators with guidance and potentially, rule language that will better define the expected contents of the landfill stability plans.
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