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[GreenYes] Landfills, Bioreactors and Composting
- Subject: [GreenYes] Landfills, Bioreactors and Composting
- From: "Peter Anderson" <email@example.com>
- Date: Tue, 27 Feb 2001 10:11:48 -0600
In addition to the landfill subsidy issues that I summarized in my last posting, recyclers need to familiarize themselves with the waste industry push to receive regulatory approval for bioreactors as an alternative landfill design to the so-called "dry tomb" approach.
Essentially, this country faces a choice between bioreactors, on the one hand, and greatly expanded recovery efforts in the form of composting, on the other. Yet, to date, this very important choice has been obscured even though the environmental and economic differences between that choice appear likely to be extremely significant.
The three points which follow is a summary of more detailed information the National Recycling Coalition has provided to EPA and can be found at:
CURRENT LANDFILL DESIGNS UNSAFE. The first thing to understand is the so-called dry tomb designs incorporated in the current EPA landfill regulations adopted in 1991 in 40 CFR Part 258, contain a fatal flaw. In fact, the regulations do not, as advertised, eliminate the environmental problems of discarding solid waste containing hazardous constituents and decomposable material that creates acidic leachate and landfill gases.
Rather, as to the constellation of drinking water contamination issues from leachate, the elaborate system of daily cover, top and bottom liners, leachate collection systems and monitoring wells all, according to EPA's own technical experts and as is intuitively obvious, "will ultimately fail." At the same time, according to studies done for the Commission of European Communities, the waste loads in so-called "dry tomb" landfills remain a threat to the environment for hundreds of years, depending upon local rainfall conditions, long after the barriers have malfunctioned.
That is to say, we have not prevented drinking water contamination. Instead, we have only moved the timing of its occurrence, and done so to a point when all of the responsible institutions, and whatever financial assurance originally existed, will have long passed from the scene. In hindsight, it is difficult to construct a worse design strategy for an engineered solution, although, in its time, we would want to fully acknowledge that EPA made great strides in comparison to the open dumps that had existed before. They deserve recognition for what they did achieve in the face of major political cross-currents, notwithstanding the fact that, in hindsight, the product did not stand the test of time.
As to air pollution, the gas recovery systems mandated after 1996 in large landfills only capture just a fraction of the gases generated. Few practitioners would argue that even half of the gas is actually recovered by these systems that are often not even installed for years after emplacement of the waste. These landfill gases, even with current required recovery, are said by EPA to contribute to 4% of the manmade U.S. greenhouse gases each year. Since that is based upon assumptions and pencil calculations, not field data, there is a significant possibility that the true number is substantially greater. Also studies suggest that there may also be carcengenic considerations from landfill gases that warrant further analysis to resolve.
Thus, it must be understood that the base line condition against which bioreactors are considered is one in which current landfill designs make for major adverse environmental impacts. This is not recognized by the general public and decision makers.
BIOREACTORS HAVE THEIR OWN PROBLEMS. Bioreactors are the deliberate introduction and recirculation of liquids in a landfill intended to encourage early decomposition. This model attempts to respond to the problem of grave risks from delaying the onset of decomposition until a future time when remediation is either extremely costly or likely to remain undone. However, recirculation presents its own set of major new environmental problems that may elude solution because cost-effective solutions to one set of new problems tend to create whole new categories of problems.
Theoretically, it certainly could be possible to engineer a solution to these problems. However, there are two factors that, in practice, will tend to make that unlikely (albeit not impossible):
For one thing, there is substantial pressure, as you can read in the many articles on the subject in Waste Age, to artificially constrain the designs so that the overall net costs are not more expensive than the current so-called dry tomb designs. The likely need for pretreatment, including in-vessel bag breaking, shredding and mixing to increase the portion of the waste load that is actually decomposed before closure, as an example, is often rejected on cost, not technical grounds.
For another thing, the bench mark for designs is to achieve that amount of pre-closure decomposition which achieves sufficient airspace recovery and leachate treatment reductions to offset the costs of the additional piping and care. But, this ignores the key base line condition that must be recognized: namely the need to prevent the encasement of decomposable in the ground, because, ultimately, the barriers will fail, water will enter, and leachate and gases will be formed after the responsible parties and remediation systems are gone. Only when this central problem is ignored, and the pretense maintained that landfills are already safe so that any improvement is gravy, can bioreactors be given a casual pass.
This is quite important because the actual decomposition that is encouraged in bioreactors tends to be localized at the core away from the sides to reduce the chance of sidewall failure from seepage and away from the bottom to prevent degradation of the polymer liner. That may alleviate some of the downside concerns over bioreactors making new problems, but it fails to address the fact that we can no longer design landfills in ways that leaves a significant fraction of the organic fraction not decomposed.
THE COMPOST ALTERNATIVE. Since the issue is how to eliminate the inevitable problems whenever one discards organic material primarily food waste and unrecovered paper constituting approximately 50% of the remaining waste stream, the simple and elegant solution would seem to leap to everyone's lips. That is to source separate these items for composting. The fact that the compost alternative has to date received virtually no attention as a possible solution worthy of consideration is a sad commentary on the process suggesting that the waste industry is unduely dominating the regulatory process. And it is one which shows how important it is for the recycling community to become involved in this debate.
We would urge you to become familiar with these issues, and join the NRC in insisting that composting receive equal consideration to problematic bioreactors. You can start by sending your views to EPA at:
RCRA Docket Information Center
Office of Solid Waste (5305W)
U.S. Environmental Protection Agency Headquarters (EPA HQ)
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460
Docket No. F-2000-ALPA-FFFFF
NRC's letter on our webpage noted above can provide you with more information to consider. Although the docket is officially closed, the agency is still considering the issues.
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