Expert Review of Wisconsin's Landfill Organic Stability Rule
Investigators: Colorado State University
Wisconsin’s landfill organic stability rule (OSR) requires owners and operators of municipal solid waste landfills to “incorporate landfill organic stability strategies into the plans of operation for their facilities” (WDNR 2006). The rule has been in place for more than five years and the Principal Investigators (PIs) recently completed an independent review and report on the manner in which the rule is working. Overall, the PIs concluded that the rule is working well and that all ten landfills that were visited are meeting criteria outlined in the OSR.
A general perspective shared by the landfill owners and operators interviewed is that the goals of the OSR currently coincide with the industry goals. The OSR provides a performance check on landfill operations, promotes increased gas generation and waste settlement, and provides a disposal alternative for commercial liquid, which can be added to sites with an active Research, Development, and Demonstration (RD&D) permit. Most of the sites surveyed had an RD&D permit and disposal of commercial liquids represented a source of revenue and a means to increase waste moisture content and enhance organic waste decomposition.
The following recommendations were provided to the Wisconsin Department of Natural Resources (WDNR) to ensure that the OSR continues to achieve the desired objectives while remaining easy to implement and practical.
- WDNR should encourage US EPA to modify RCRA Subtitle D by incorporating the provisions in the current RD&D rule.
- WDNR should develop guidelines regarding biochemical compatibility of liquid waste sources.
- WDNR should clarify existing requirements for early and aggressive gas collection as part of organic stability plans and ensure that these requirements are followed for landfills adding liquid wastes.
- WDNR should promote means to make beneficial use of landfill gas attractive.
- WDNR should consider modification to the gas generation benchmarks in the OSR and development of a standardized gas analysis procedure.
- WDNR should consider metrics for cessation of gas collection as part of the OSR.
- WDNR should recognize that the OSR can affect publicly- and privately-owned landfills differently.
- WDNR should recognize that gas generation alone does not address post-closure care and more comprehensive criteria are needed to address functional stability.
- WDNR should consider a statewide life cycle analysis (LCA) to assess the effects of more aggressive organic waste diversion.
The objectives of this proposal are to (1) further develop the gas generation analysis and develop a uniform methodology for assessment of progress towards compliance with organic stability and (2) convert the report into an article suitable for publication in a journal with a focus on environmental policy. These objectives will allow recommendations to be developed on desirable changes to the OSR other related DNR rules, and/or national policy that ultimately will guide operational, construction, or design practices by MSW landfill owners and operators. Publication of the results in a journal will allow for dissemination of key findings related to organic waste stabilization to the global solid waste community.
As per stipulations in the OSR, landfill owners were required to analyze their gas collection data and assess whether the following benchmarks will be met in ≤ 40 yr post-closure (WDNR 2006): (i) monthly average gas (CH4 + CO2) production rate ≤ 5% of average maximum monthly gas production rate observed during the life of the facility, or ≤ 7.5ft3-gas/yd3-waste/yr; and (ii) cumulative gas (CH4 + CO2) yield ≥ 75% of projected total gas production. Meeting these benchmarks coincides with achieving organic stability as outlined by the WDNR. The PIs observed during the course of the evaluation that every owner was making this assessment using a different methodology. The first deliverable from this project will be a spreadsheet model that builds off the U.S. EPA LandGEM model (USEPA 2005) that owners can use to assess OSR compliance following a uniform methodology. The spreadsheet will be developed in Microsoft Excel and gas generation data from at least two of the landfills will be evaluated to ensure that the spreadsheet is useful and practical.
The analysis completed for the WDNR has nation-wide implications and dissemination of this information is important for the benefit of regulators and policy makers in other states that may be considering similar regulations. A central finding of the report was the importance of the RD&D rule, which allowed the goals of the OSR and landfill owners to largely overlap. A critical analysis of the rule could influence other states to allow for the addition of commercial liquids to landfills that would benefit both the state’s industry and landfill owners.