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Coalition to Oppose Attacks on Recycling In America


Technical Reasons to Oppose Repeal of
Bans on Disposal of Yard Trimmings

Revised January 5, 2002

* The Coalition to Oppose Attacks on Recycling in America was organized by the Grassroots Recycling Network. Organizational partners include Friends of the Earth, Sierra Club Illinois Chapter, Natural Resources Defense Council, U.S. Composting Council, Institute for Local Self-Reliance, Peoria Area Green Party, Peoria Environmental Action, Eco-Cycle (Boulder CO), Ecology Center (Ann Arbor MI), and St. Paul Neighborhood Coalition (St. Paul MN). Coalition Coordinator is Peter Anderson (608-231-1100;


Yard Trimming Composting Is Vital to America's Recycling Goals
Technical Claims In Support of Repeal Are Premature

Technical Claims In Support of Repeal Are Invalid

Illinois is one of 22 states reported by BioCycle magazine to have a ban on the disposal of yard trimmings in landfills. The City of Peoria owns a landfill that is operated by Waste Management Inc. They recently proposed to repeal that ban for five years in order, they claim, to study how the yard trimmings would degrade when leachate in the landfill is recirculated.

Yard Trimming Composting Is Vital to America's Recycling Goals. Bans on the disposal of yard trimmings in landfills have made it possible to essentially double the overall diversion rate in many communities and are vital to achieving America's recycling goals. Repealing those bans, then, would cripple the Nation's recycling effort.

Technical Claims In Support of Repeal Are Premature. Technical claims made by Waste Management Inc. in support of the proposal to repeal the Illinois ban for an ostensible test in Peoria are that returning yard trimmings to the landfill would increase methane production for electricity generation and that this could be done without consuming precious landfill space because, in a 'bioreactor' landfill (an experimental wet-cell landfill design in which external liquids are added), all of the additional material will immediately decompose. The claims are premature because: (i) the waste hierarchy that prioritizes reduction, reuse, recycling and composting over landfilling; (ii) the unproven and experimental nature of bioreactors; (iii) the preferred alternative of expanded composting; and (iv) the obvious fact that the proposal is not just a test.

Technical Claims In Support of Repeal Are Invalid. Even if those claims were not premature, they are incorrect because: (i) most of the substantial additional methane produced from the yard trimmings will be released uncontrolled into the atmosphere; and (ii) most of the yard trimmings will not disappear.

Yard Trimming Composting Is
Vital to America's Recycling Goals

The vital importance of source separation of yard trimmings and yard trimmings programs to the Nation's integrated waste management policy can be seen by examining how waste is currently managed in America.

According to the Environmental Protection Agency's Characterization of MSW in the United States, in 1998 21.1% of the household waste generation was recycled and 5.7% was diverted due to due to composting at central facilities , for a 27.8% total diversion rate. That is to say, using EPA's methodology, 13.1 million tons (5.7%) of yard trimmings otherwise destined for landfills was successfully diverted in 1998.

However, the true proportion of yard-trimming diversion efforts is substantially higher, especially in jurisdictions with centralized yard trimmings composting or mulching programs or similar ad hoc practices such as ceasing to collect grass clippings at all. Because of the difficulty measuring volumes of grass clippings that are simply left on the lawn or are home composted, rather than sent to central compost facilities where measurements can be made, those diverted tonnages are acknowledged to be uncounted in this and similar sorts of studies.

But, most waste composition studies from the field prior to yard trimmings diversion efforts indicated that yard trimmings were 15%-30% of total generation, depending largely upon how temperate was the region's climate. Those states that subsequently instituted yard trimmings programs or practices are presumably achieving diversion rates close to those levels. In much of the South and Southwest, that would increase yard diversion as much six times those suggested by the EPA estimates.

Repealing yard-trimming bans, then, could dramatically reduce recovery rates. In states with yard trimmings bans, communities with centralized composting and aggressive promotion of on-site management practices are diverting 15%-30% of their total discards, with a mid-point of 22.5% to approximate average climatic conditions. That is to say, the amount being composted, mulched or source-reduced in communities with bans or ad hoc programs is approximately equal to the 21.1% national recycling rate reported by EPA for all materials other than yard trimmings. While we do not know the exact proportion of yard trimmings that would potentially be subject to landfill management, the magnitude of this stream suggests that repealing yard trimmings bans could cripple the Nation's recycling effort.

If the news stories were correct, Waste Management Inc. would appear to be claiming that the widely accepted benefits of reduction and diversion that would be lost under the Company's proposal are somehow offset for two reasons. One is that returning yard trimmings to the landfill would increase methane production for electricity generation. The other is that this could be done without consuming precious landfill space because, in a bioreactor landfill, all of the additional material, Waste Management Inc. is reported to contend, will immediately decompose.

Any such claims are manifestly premature, and several major hurdles would need to be overcome before those contentions can even be up for consideration. Without in any way conceding otherwise, we would put forward the following observations in passing.

Technical Claims In Support of Repeal Are Premature

Among the major issues that need to be resolved before the Company's reported claims can be considered are: (i) the waste hierarchy; (ii) the unproven nature of bioreactors; (iii) the preferred composting alternative; and (iv) the proposal is not just a test.

Waste Hierarchy Prioritizes Reduction. EPA states in its Agenda for Action that it "has ranked the most environmentally sound strategies for MSW. Source reduction (including reuse) is the most preferred method, followed by recycling and composting, and, lastly, disposal in combustion facilities and landfills."

In our view, any change to the well-established waste hierarchy that places landfilling above composting would have to follow a rigorous factual showing that is vetted by all stakeholders and then reviewed and concurred in by EPA. Such a radical reversal of a decade's accepted practices ought not be done unilaterally without any factual showing or peer review process to support it.

'Bioreactors' are Unproven and Experimental. Apart from a few ongoing and incomplete experiments, 'bioreactors' (landfills in which external liquid is added to speed decomposition) are not accepted practice. In fact, the controlling federal landfill rules set forth in 40 CFR §258.58(a) prohibit the liquid additions that are required for bioreactors to work, because current regulations are predicated on designs intended to keep the site as dry as possible in order to minimize difficult-to-manage, biologically active conditions. WMI is reported to be currently in the midst of performing some of the tests of bioreactors, but they are not complete and most certainly have not been passed on by any independent scientific institution or regulatory body.

EPA has indicated that as much as five years will be required to reach a final decision on whether to approve or disapprove bioreactors based on that and other data, inasmuch as that new approach would completely upend the entire basis for the existing Subtitle D rules, which has guided waste disposal policy for the last decade. Also, the distinct possibility of new risks and challenges are significant whenever the level of bioactivity is deliberately increased.

There are numerous alternative and competing bioreactor designs that are experimental, controversial and unproven. Some concepts, such as Waste Management's consideration of using highly dangerous pathogenic sludge as the source of makeup water, appear particularly unacceptable to the public. It would, therefore, seem to be highly imprudent to jettison yard trimming composting programs, which are one of the Nation's most successful recovery efforts, for a chimera.

True, almost everyone in the waste management community now recognizes that the "dry tomb" designs embedded in those Subtitle D rules are fatally flawed. According to EPA themselves, the entire physical system of barriers, liquid and gas removal systems and monitoring equipment has a lifetime measured in decades, while the waste load remains actively a threat to the environment for thousands of years.

The EPA's admissions mean that, at best, we have only postponed the occurrence of pollution, not prevented it, and done so to the worst possible time after all of the responsible parties have left the scene. Even respected leaders from within the landfill community itself such as SWANA's John Skinner have publicly recognized these problems.

Expanded Composting is Preferable to Bioreactors. But saying the current designs are flawed is a very different thing from concluding that there is any consensus that bioreactors will be the next generation landfill for the 21st century. Not only do many of the reviewers in the EPA and state environmental agencies harbor very serious concerns about whether the technology in its current design parameters, which emphasizes cost over safety, can protect the environment, but in addition the rest of the developed world is moving in the opposite direction from adding more problem-causing organic material to landfills.

Beyond the fact that no one has ever proposed to actually reverse a decade's advance in America's recycling efforts, the greater movement has been in the opposite direction toward barring all compostable waste from landfills. For either decomposition in "dry tomb" landfills, or current designs for bioreactors, keep landfills biologically active and a threat far longer than the sites can be cared for.

Contrary to advertised claims, measures intended to accelerate decomposition in a bioreactor can only be partially successful due to numerous operational constraints. It may be true that current bioreactor designs used by Waste Management will, but to an unknown degree, partially reduce the proportion of organic material that keeps the landfill biologically active and a threat to the environment after the site is closed. But, those designs will most certainly not eliminate them and may not even come close to doing so.

Moreover, the price of accelerating decomposition in the ground is that our ability to isolate the hazardous waste load from the environment becomes that much more difficult. Recirculation, biosolid additions and heightened bioactivity mean, for example, that rapid and uneven subsidence places greater stresses on the essential barrier and gas removal systems, and accelerated biofouling clogs the mission-critical leachate collection systems. These create a whole new set of risks that threaten to release hazardous substances more directly into the environment than do current designs, and when cost considerations drive design, as they manifestly do with most of the current bioreactors, those new risks are more likely than not to override all other considerations.

Thus, in 1999, the European Commission began the phase out of all organics in landfills, requiring that "biodegradable municipal waste going to landfills must be reduced to 35% of the total amount (by weight) of biodegradable municipal waste produced in 1995." In North America, increasing numbers of communities are testing or rolling out programs to divert the entire organic stream, not just yard trimmings, for composting among them are programs in San Francisco, St. Paul and Nova Scotia.

This constructive path would eliminate the major problem that compromises landfill safety today, and which bioreactors fail to achieve. Banning all organics - and not just yard-trimmings - would also eliminate the 61% of current landfill volumes that comprise the organic fraction that keeps the waste loads active. That would:

  • Make landfills substantially easier to manage safety,
  • Avoid the need to wrestle with the entire constellation of complex, unresolved issues of how to design a facility to safely accelerate decomposition and cope with the resulting hyper-biologically active conditions deep underground; and
  • Delay the time when new sites must be found.

The Proposal is Not Just a Test. Regardless of whether one attaches a label to legislation permitting the landfilling of yard trimmings as just a test, the well-known fact is that households and businesses do not change their diversion habits back and forth overnight. Because the instrumentality to affect source separation is dispersed among millions of homes and stores, a major education program must accompany any change that is considered. For these reasons, recycling coordinators do not make temporary changes in what items are included only to reverse those changes later. Any so-called test such as this would, patently, constitute a permanent change.

The fact that the proposal is for five years and asks to repeal the current source separation program for that length of time would seem to make this clear for another reason. While decomposition of wet yard trimmings could take slightly more than five years from waste emplacement in the first year, there is no technical justification to continue adding new loads of grass and leaves for the succeeding four years that follow the first as well. Rather, the obvious thing to have done is just to track what happens to the first year's load.

Furthermore, again, since one does not change program parameters like separate yard collection back and forth, a load of yard trimmings for that first year could better be purchased from supplies of source-separated material and added back to the landfill in measured amounts, thereby producing more accurate data.

Technical Claims In Support of Repeal Are Invalid

Lastly, we have been unable to find the kind of supporting study design that one would normally associate with a serious proposal to gather technically valid field data. But, the sketchy claims reported in the newspaper are invalid on their face. As detailed below, (i) most of the additional methane produced from the yard trimmings will be released uncontrolled into the atmosphere; and (ii) most of the yard trimmings will not disappear.

Most Methane Production is Not Captured. The Company claims that land disposal of yard trimmings in bioreactors is a positive thing because grass and leaves will enable the landfill to generate more methane. Presumably the contention is meant to imply that virtually all of that additional methane will be captured and utilized for energy production. However, gas collection systems intended to capture methane produced in landfills have limited efficiency. When this is recognized, the fallacy of adding more organics to produce more methane - when a significant part of that additional methane will escape into the atmosphere - becomes self apparent.

For, in fact, the bioreactor designs utilized by Waste Management will not capture all or even the major part of the additional greenhouse gases produced from decomposing yard trimmings. Even in more easily managed dry tomb landfills, gas extraction systems will capture only 10%-50% overall, if the Swedish Environmental Research Institute's study is to be believed (EPA admits that its substantially higher values are arbitrary assumptions without empirical basis).

The yard trimmings component of all organics discarded in bioreactors will fare far worse for the following reasons. Even in those relatively stable "dry tomb" sites, the necessary piping cannot be installed for 5-10 years after waste emplacement due to the inherent limitations of the geometry of the waste load. Yet, the decay curve for the yard component of the waste stream when wetted has a half-life of 2.8 years, according to ECON of Norway, and the grass part of that is substantially less (and the leaves that contain lignin, substantially more). That is to say, almost all of the grass clippings will have already decomposed, and the landfill gases it produces that are not oxidized or sequestered will have been emitted uncontrolled into the atmosphere before the extraction systems are even installed.

In bioreactors, the situation is more confusing because there is no single standard design to evaluate, but it is no more satisfying. For accelerated decomposition will lead to conditions that are far more difficult to manage than in "dry tombs." As an example, accelerating decomposition of heterogeneous waste loads will lead to very rapid and uneven subsidence that precludes the use of rigid horizontal piping that would snap. The flexible horizontal piping commonly used in bioreactors will, instead, tend to sag in places. At those dips, the liquids that are being recirculated will pool preventing the passage of gas for collection.

Published reports in the trade press claiming that bioreactors will have superior gas collection capability over "dry tomb" designs are, upon examination, either based upon self-serving assumptions without empirical data or upon confusion between two completely unrelated concepts.

Certainly, accelerated decomposition will produce a more concentrated flow of methane to supply combustion engines or micro-turbines at the wellhead. But that is solely a measure of the efficiency of electricity production, not whether more of the total quantity of methane from rotting organic matter is captured. Climate change, however, is a function of the proportion of methane that isn't captured - and instead is released to the atmosphere - not of electrical generating efficiency.

Adding yard trimmings back into landfills will substantially increase the quantity of methane generated, and, as shown, a substantial part of the additional methane will be uncontrolled. EPA estimates that each wet ton of yard trimmings discarded in a landfill will produce 420 pounds (on a carbon equivalent basis) of greenhouse gases. Therefore, if the proposal to repeal the yard trimming ban was adopted nationwide, America would generate an additional 2.5 million - 9.9 million metric tons carbon equivalent (MMTCE), of which some part of that will be oxidized and sequestered, but most of that remaining will escape being captured in gas collection systems. This compares to EPA's estimate of 78.9 MMTCE generated from landfilling of municipal waste before the currently diverted yard trimmings are added back.

Of course, when yard trimmings are source separated instead of landfilled, none of these concerns seriously arise. Typical composting is done in aerobic conditions, which do not produce methane, except in trace quantities where aeration is incomplete. When anaerobic bioconversion technologies are utilized, the process is done inside a vessel using an uncontaminated organic stream. Methane production is maximized by maintaining temperatures above 98-104°F (something that require heat additions and that landfills which continuously recirculate liquids cannot achieve), and the process is controlled in-vessel to preclude the release of any of that methane.

The proposal to return yard trimmings to the landfill in order to significantly increase methane production, which has 21 times the global warming capacity as CO2 - the majority of which will be emitted uncontrolled - is a serious climate change issue of major proportions that appears to be glossed over in Waste Management's representations.

Decomposition Only Reduces Quantity Slightly. The Company's reported claim that no landfill capacity will be consumed by the addition of yard trimmings, if true, is based upon two other rather significant misstatements: (i) not all of the yard trimmings, in fact, will be decomposed; and (ii) of the trimmings that do decompose, more than three-quarters of the original weight remains converted into compost material.

(i) Not All Yard Trimmings Is Wetted. It is correct that the part of the yard trimmings that are wetted will decompose rapidly prior to the cell being capped. However, because recirculating liquids near the sides of the landfill would jeopardize the sidewall integrity, and at the bottom would produce heat that will degrade the polymer liner, and because of the various barriers to water flow in the waste load itself (from broken bags, gas pools and heavy compaction), not all of the yard trimmings will be wetted sufficiently for complete decomposition before the cell is capped.

(ii) Decomposition Leaves Significant Residues. Moreover, as to that part of the yard material that is wetted and does decompose, the fact that the trimmings will degrade does not mean that they disappear. In terms of a mass balance analysis, the liquid portion of the grass and leaves are volatized. But, there remain the solid fraction, which is biologically transformed into compost, along with residual bulking agents and whatever material was used to bag the grass and leaves that remain behind. Even under academic assumptions of complete conversion, the compost that remains is approximately 57% of the original volume, according to detailed analyses by Renewable Carbon Management.

Therefore, as a hypothetical example, if one-third of the yard trimmings were not decomposed, and, under real-world field conditions two-thirds (instead of 57%) of the wet weight of the yard trimmings that are degraded remain as residual material, the reduction in the weight of yard trimmings in a bioreactor would only be 22.2%. More than three-quarters of the original weight remains.

On the other hand, were this done in a source-separated compost operation rather than in a landfill, the residual volume then becomes something positive, because compost that has not been contaminated with toxic-laden solid waste can be returned to the soil to restore fertility to our crop and forest land. However, in a landfill where the yard trimmings have been laced with hazardous substances as well as mixed with other incompatible material, its positive value has been destroyed and converted into an environmental hazard that is left in the ground where it threatens future drinking water supplies.

The most fundamental principle of wise waste management practice and environmental stewardship is to minimize, and isolate for treatment, the mixture of the toxic components of our waste stream and those components that have positive value when recovered. Waste Management's reported proposal works diametrically in the opposite direction.

For all of these reasons, the proposal to repeal the yard trimming ban for an ostensible test would undermine America's recycling and composting efforts, and be a threat to the environment. It should be rejected.

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