"Bioreactor Landfills: Long-term Liability Issues," Geosynthetic Institute

Conference on Hot Topics in Geosynthetics
Geosynthetic Institute
December 2000


This paper explores the long-term liability issues that may be associated with bioreactor landfills, including the statutory and common law theories under which an owner or operator of a bioreactor landfill may be subject to liability. Post-closure care liability as well as potential CERCLA and toxic tort claims are concerns for owners and operators of landfills and are of concern for owners and operators of bioreactor landfills, as well. Post-closure care liability should be reduced in the case of a bioreactor landfill. CERCLA and toxic tort liability will depend upon the long-term success of the technology.


The purpose of landfill design and operating standards developed by federal and state agencies has been protection of human health and the environment. For example, in the so-called Subtitle D regulations promulgated by the United States Environmental Protection Agency ("EPA") in 1988, the agency declared that:

The purpose of this part is to establish minimum national criteria under the Resource Conservation and Recovery Act (RCRA or the Act), as amended, for all municipal solid waste landfill (MSWLF) units and under the Clean Water Act, as amended, for municipal solid waste landfills that are used to dispose of sewage sludge. These minimum national criteria ensure the protection of human health and the environment.[i]

The prevailing approach to achieve this objective for landfills is entombment, encapsulation and isolation of the waste. Design criteria include minimizing the liquid entering the facility to preclude leachate from exiting the facility since leachate is viewed as a significant potential source of environmental contamination. To the extent such a design prevents the escape of pollution from the facility, cleanup and third-party liability that may occur due to the pollution should be minimized.

By limiting or eliminating moisture from the landfilled waste, however, such standards also impede decomposition of the waste, thus leaving the waste largely unchanged until some future time when the encapsulation system may fail. Modified design and operating standards are being studied to evaluate the risks and benefits of controlled management of liquid in a landfill to enhance degradation of the waste. Accelerated decomposition of the waste should increase the volume of waste that can be accepted in the landfill, contribute to the landfill's stability, and increase the potential for utilization of landfill gas for energy production. Such a modified facility is termed a bioreactor landfill. Bioreactor landfills are being evaluated from a technical perspective to determine the desirability of widespread routine implementation of bioreactor technology. In addition to technical considerations, the liability implications associated with the bioreactor landfill approach also require scrutiny. This paper will explore considerations relating to long-term liability that may impact decisionmaking regarding the acceptance of bioreactor landfills.

Liability concerns have become heightened over the last twenty years, due not only to the widespread increase in environmental regulation and enhanced public expectations regarding environmental quality, but also due to enactment of the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA" or "Superfund")[ii] and its state counterparts. CERCLA introduced a fundamental expansion of liability by legislating liability without regard to fault and unlimited by the passage of time for environmental response costs and natural resources damages resulting from the release of contaminants. The new CERCLA liability coincided with a dramatic increase in toxic tort claims by private, third-party plaintiffs seeking recovery for personal injury and property damage alleged to have been caused by environmental contaminants. A related type of liability concern arises out of the regulatory mandate of post-closure care for landfills. Post-closure care generally involves maintenance of the closed landfill, including monitoring, usually for a period of 30 years after closure.[iii] The post-closure care mandate is imposed on the permittee who must fund the post-closure obligation during the operating life of the landfill.

This paper will not discuss general permitting or regulatory issues relating to bioreactor landfill design or routine operation, but will focus instead on long-term liability issues including CERCLA, toxic tort and post-closure issues. A discussion of the legal framework for these issues will first be presented, followed by a discussion of the impact of these theories on the potential bioreactor risk scenario.


Long-term liability concerns are presently framed by CERCLA which in 1980 introduced a concept of strict liability for cleanup of environmental contamination. The concept was new and startling because it imposed liability for conduct which may have been legal at the time it occurred, and it imposed liability on persons who complied with all existing legal requirements in effect at the time of their activity. The structure of the legislation is designed to provide funding for cleanup when there has been a release or a threat of a release of a hazardous substance from a facility. Hazardous substances include a broad array of wastes, substances, and materials without regard to volume. The potential liability is imposed on defined categories of persons including, among others, those who owned or operated a facility at the time of disposal of a hazardous substance at the facility, persons who arranged for disposal of the hazardous substance at the facility, and present owners and operators of the facility.[iv] CERCLA severely modified traditional defenses to liability for harm arising out of prior conduct. No longer can one defend against liability on the grounds that the conduct resulting in the liability was reasonable or lawful at the time it was performed. Also, no longer can one assume that after the passage of a specified period of time the risk of liability will be gone.

CERCLA provided for the development of the National Priorities List ("NPL"),[v] a list of the most seriously contaminated sites which should be given cleanup priority. Landfills were prominent among entries on the original NPL.[vi] The legislation has generated seemingly endless controversies regarding appropriate cleanup criteria, remediation technologies and responsible parties, and the related liability has been very costly. This experience has culminated in cautious evaluation of landfill technology to avoid a repeat of the agonizing CERCLA experience.

Toxic Torts

So-called toxic torts are claims by third parties for personal injury or property damage arising out of negligence, nuisance, trespass or other tort theories. Toxic tort cases have been filed in connection with a number of CERCLA (and other) sites. An important distinction between a CERCLA claim and a toxic tort claim is the following: in a CERCLA claim, the government or another party is seeking to recover response costs or natural resources damages from a person defined as a "covered person" under CERCLA. In general, these costs relate to the cleanup of the facility or to damage to natural resources considered the property of the citizenry as a whole (rather than the property of individuals; e.g. fish, birds, streambeds, etc.). Toxic tort claims seek to recover damages for specific injuries to specific persons and/or property. For example, a toxic tort claim may seek damages for cancer alleged to have been caused by exposure to a contaminant. Specific toxic tort theories are described in greater detail below.

Negligence is likely the most commonly asserted primary toxic tort claim. Negligence arises from conduct which "falls below the standard established by law for protection of others against unreasonable risk of harm."[vii] To prevail on a theory of negligence, the plaintiff must show that the defendant had a duty to meet a certain standard of conduct, the defendant breached that duty, the plaintiff was injured, and the conduct was the proximate cause of the injury that resulted in the damages suffered by the plaintiff.[viii]

Nuisance is another theory commonly asserted in toxic tort claims. Nuisance provides a remedy for the intentional or negligent acts of a defendant that interfere with the plaintiff's reasonable use and enjoyment of his property.[ix] Air and water pollution, odor and noise have all been alleged as nuisances. Landfill leachate has been ruled to be a nuisance.[x]

Trespass is a theory allowing recovery for damages for intentional,[xi] mistaken,[xii] reckless or negligent,[xiii] or abnormally dangerous[xiv] activity causing the entry by a person or thing on the land of another, thus interfering with the other's possessory interest in the land. This includes intrusions "upon, beneath, and above surface of earth."[xv] Landfill leachate has been ruled to have been a trespass onto neighboring property.[xvi]

Finally, in the case of certain ultrahazardous or inherently dangerous activities (e.g., blasting), the defendant may be held liable even in the absence of negligence. If the plaintiff conducts an ultrahazardous or dangerous activity, he may be liable for the harm it causes despite the fact he was not at fault and he acted reasonably. The definition of ultrahazardous activities has expanded in some jurisdictions to include release of contamination from a landfill.[xvii] Whether an activity is ultrahazardous will be determined on a case-by-case basis by the trier of fact based on state law. Hence, what is considered ultrahazardous will vary from state to state.

Toxic tort claims are subject to a statute of limitations specified by state law. The statutes of limitations for such torts are often short (two to three years), but application of the statute in particular states and in particular fact situations may be problematic. In a state where a date of discovery rule prevails, the statute of limitations will not begin to run until the plaintiff reasonably discovers, or should have discovered, the injury.

Toxic tort claims have recently been curtailed by legislative controls in a number of states. Among other things, statutes have attempted to limit plaintiff's recoveries. Also, recent court decisions involving the quality of evidence necessary to establish liability have made it more difficult for plaintiffs to prevail in the toxic tort cases.[xviii] Although the threat of toxic tort claims may not be as threatening as it once was, where toxic tort plaintiffs prevail, the recoveries can be enormous.

Post-Closure Care

During its operating years, a landfill will be liable for compliance with its permit conditions as well as with regulatory standards. The 1988 Subtitle D regulations[xix] promulgated by EPA set forth minimal national criteria for landfills and are generally grounded in the encapsulation concept. State solid waste management regulation generally incorporates these standards and, in some cases, more stringent state requirements.

In addition to ongoing operating requirements, Subtitle D imposes a requirement for care and continuing management of a landfill for a time after it has stopped accepting waste and has been appropriately closed. These post-closure care requirements are currently governed by the minimum standards set forth in Subtitle D at 40 C.F.R. § 258.61, which require that post-closure care extend for a period of 30 years after closure. This post-closure care period can be reduced or lengthened if appropriate pursuant to 40 C.F.R. § 258.61(b). During the post-closure care period, the owner or operator (permittee) of the landfill will retain responsibility for maintenance of the closure design, gas and leachate control, and monitoring. During the operating life of a landfill, estimated post-closure care requirements will be funded in advance from operating revenues.

The 30-year standard timeframe for post-closure care was based on a projection that landfill conditions would stabilize within this period. There was little, if any, post-closure experience to back this estimate for landfills engineered in accord with currently accepted design criteria. As a result, there is uncertainty about whether it will be appropriate to stop post-closure maintenance and/or monitoring even after 30 years, thus creating the prospect that such requirements may be even further extended.

Once the permitting (including post-closure) requirements expire, the landfill may be freed for other uses or sold subject to marketplace and other (i.e., zoning) restrictions. However, CERCLA-type liability concerns remain. If a facility is sold and the owner and operator of the landfill are no longer associated with it, under current law, the owner and operator at the time of disposal of the hazardous substance in the landfill would be liable for cleanup even in the event a release occurs after expiration of the post-closure period and transfer of the facility to a new owner. Contractual releases and indemnities may provide some protection from assertion of future liability by the buyer. However, the government and third parties are not bound by such private contractual terms. Therefore, if a new owner should breach the cap or destroy other protective features of the landfill or closure design resulting in the release of hazardous substances requiring expenditure of cleanup costs, the owner and operator of the landfill at the time of disposal of the waste in the facility will continue to be liable under current law. The new owner will not be relieved of liability, but this fact may provide little comfort if the new owner cannot pay for the cleanup costs.

The existence of permitting and post-closure requirements does not shield a landfill owner or operator from enforcement of general environmental standards governing air, water, groundwater and soil contamination. States and the EPA have various authorities that can be used for enforcement of such standards in the event a landfill threatens human health or the environment. The major federal environmental statutes permit the government to respond to avoid an imminent hazard.[xx] State law generally provides authority to enforce against violations of state environmental quality standards. At both the federal and state levels, enforcement authority often includes power to issue orders to prevent further contamination or to stop the on-going contamination.

The Bioreactor Landfill

Bioreactor landfill technology may effect some changes in the long-term landfill liability scenario. These changes are largely grounded in the impacts of more rapid waste decomposition. A bioreactor landfill is projected to achieve a condition of stability within some 5 to 10 years after closure, rather than the 30 years presently assumed for conventional landfills. Bioreactor landfill projections also estimate significant and more complete decomposition of waste accompanied by a more concentrated period of methane gas production. The degradation of waste is expected to reduce the toxicity of various organic substances that may be present in the mound. If these projections are correct, the period in which a bioreactor landfill may be unstable and the period in which methane gas is produced should be significantly curtailed. If toxicity of the materials in the waste is also reduced, the potential for contamination is likewise lessened. However, a greater amount of leachate will be involved in the bioreactor system thus increasing the risk of contamination should there be a liner failure.

The first and most obvious impact of the quicker road to decomposition and stability of the bioreactor landfill is the potential for reduction of the post-closure care period. To the extent the post-closure care period can be reduced, there should be an accompanying reduction of post-closure care costs. To realize the benefit of this reduction, the permitting state must agree to a reduced post-closure care period. Subtitle D would permit a state to reduce the post-closure period subject to a finding that the owner or operator of the landfill has demonstrated that the reduced period is sufficient to protect human health and the environment.[xxi] If a reduction of the post-closure period is approved, new estimates for the costs of post-closure care can be developed, and the financial assurance for the post-closure care adjusted accordingly. If the post-closure care period is reduced, one would assume that the landfill would be freed from the regulatory requirements at an earlier date permitting a change in use or sale sooner. As would be the case with a standard Subtitle D facility, any change in use or sale of the facility would continue to be subject to marketplace and other requirements such as zoning limitations. In sum, the shortening of the post-closure care period should provide a concrete reduction in post-closure care liability.

Other sources of long-term liability that apply to Subtitle D facilities are little changed in the bioreactor scenario, assuming the bioreactor landfill is engineered so that liners and caps do not fail and leachate and gas do not escape to the environment. The concern, of course, is that such systems may fail or a subsequent owner or user of the facility may destroy the systems, thus permitting escape of contaminants into the environment. This concern would be the same for Subtitle D landfills. Without legislative change, CERCLA and toxic tort liability, together with the possibility of enforcement action for violation of environmental quality standards, remain a concern for both types of landfills. These liability concerns can be addressed by a variety of mechanisms.

First, technical confidence in the integrity of the design is critical to potential liability. As long as no contaminants escape from the facility, liability is unlikely. However, the greater the uncertainty involved in the long-term performance of the technical design criteria, the more prominent will be the concern regarding liability risk.

Legislative and regulatory change may also have an impact on the potential for long-term liability, but the likelihood for such change is also highly dependent on the fickle political system. The sooner such change is enacted, the greater comfort such reforms will provide to financial institutions, regulators and others involved in the development of this new technology. Tort reform legislation continues to be prominent on the current political agenda, and will continue to soften the threat of toxic tort liability. However, although recent trends have included measures to slow such litigation, plaintiffs' interests continue to mount vigorous opposition to such reforms, and the trend to curtail such litigation could be quickly reversed.

Proposals for a "permit shield" could also be useful.[xxii] This concept would shield a permittee from liability arising out of the landfill so long as a valid and effective permit had been granted and the permittee was in full compliance with all of its terms. Should such protection be authorized, permitting agencies may exercise further caution to assure that the permit terms are adequately protective. Further, regulatory agencies have been reluctant to have any design approval they issue be deemed a performance guarantee.

Recently, efforts have been made to exempt certain parties from CERCLA liability. These efforts have focused on recyclers, banks, municipalities and small business. Although legislation to narrow the scope of CERCLA liability has been proposed for years in the interests of such parties, only recyclers have significantly benefitted.[xxiii] From the standpoint of public policy, a practical reality must be confronted. If any group of CERCLA parties is exempted from liability, the amount that would otherwise have been paid by the exempted parties must be assumed either by non-exempt parties or by the government. Hence, providing an exemption from CERCLA has significant funding implications and may also require a budget enhancement to assure continued cleanup, a politically unpopular position in recent times.

Through its Project XL, EPA may permit bioreactor landfills to operate as a form of experimental technology.[xxiv] It is important to note that such projects must be governed by Project XL agreements that purport to waive certain regulatory requirements that would otherwise apply to the project. However, such agreements also contain specific provisions reserving the government's enforcement rights in the event any violations of environmental quality standards result from the project.[xxv] While participation in Project XL does not single out participants for enforcement, it also does not shield participants from enforcement.[xxvi] Participation in Project XL can be a mitigating factor in enforcement responses related to violations discovered as a result of such participation. Further, the agency may in its discretion refrain from enforcing against violations where warranted to advance the purpose of the project.[xxvii]


With the exception of the potential for reduction in post-closure care requirements and the costs related thereto, bioreactor landfills reduce the potential for long-term liability only insofar as the technology delivers on its promises. To date, there has been no trend toward significant relaxation of environmental quality standards, nor is one expected. Long-term liability concerns will be resolved with most assurance by the proven success of the technology.



Restatement (Second) of Torts (1965).


Herman, Steve (1995), "OECA's Operating Principles for Project XL Participants," Office of Enforcement and Compliance Assurance.


Public Health Service Act, 42 United States Code § 300i.

Resource Conservation and Recovery Act, 42 United States Code § 6973.

Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. 9601 et seq.

Federal Register

48 Federal Register, 40,658, September 8, 1983.

65 Federal Register 54,420, September 8, 2000.


40 Code of Federal Regulations, § 122.5

40 Code of Federal Regulations, Part 258.


Cabrera v. Municipality of Bayamon, 562 F.2d 91 (1st Cir. 1977).

Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

Dingwell v. Town of Litchfield, 496 A.2d 213 (Conn. Ct. App. 1985).

Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137 (1999).

Piccolini v. Simon's Wrecking, 636 F.Supp. 1063 (D. Penn. 1988).

State v. Ventron Corp., No. C-299675 and C-1110-78 (N.J. Sup. Ct. 1979).

Sterling v. Velsicol Chemical Corp., 855 F.2d 1188 (6th Cir. 1988).

United States v. Waste Industries, Inc., C.A., No. 80-40-CIV-7 (N.C. 1981).


Draft USEPA Project XL Final Project Agreement, Bioreactor Pilot Project, Ann Arundel County, Millersville Landfill and Resource Recovery Facility, Section VI.


[i] 40 C.F.R. § 258.1(a).

[ii] 42 U.S.C. § 9601 et seq.

[iii] 40 C.F.R. § 258.61

[iv] 42 U.S.C. § 9607(a).

[v] 42 U.S.C. § 9605.

[vi] 48 Fed. Reg. 40,658 (September 8, 1983).

[vii] Restatement (Second) of Torts, § 282 (1965).

[viii] See, e.g., Sterling v. Velsicol Chemical Corp., 855 F.2d 1188 (6th Cir. 1988).

[ix] Restatement (Second) of Torts, § 822 (1965).

[x] Cabrera v. Municipality of Bayamon, 562 F.2d 91 (1st Cir. 1977); Dingwell v. Town of Litchfield, 496 A.2d 213 (Conn. Ct. App. 1985); Sterling v. Velsicol Chemical Corp., 855 F.2d 1188 (6th Cir. 1988).

[xi] Restatement (Second) of Torts, § 158 (1965).

[xii] Restatement (Second) of Torts, § 164 (1965).

[xiii] Restatement (Second) of Torts, § 165 (1965).

[xiv] Restatement (Second) of Torts, § 166 (1965).

[xv] Restatement (Second) of Torts, § 159 (1965).

[xvi] Piccolini v. Simon's Wrecking, 686 F.Supp. 1063 (D. Penn. 1988).

[xvii] State v. Ventron Corp., No. C-299675 and C-1110-78 (N.J. Sup. Ct. 1979); United States v. Waste Industries, Inc. C.A., No. 80-40-CIV-7 (N.C. 1981).

[xviii] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993); Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137 (1999).

[xix] 40 C.F.R. Part 258.

[xx] See, for example, Resource Conservation and Recovery Act, 42 U.S.C. § 6973; Public Health Service Act, 42 U.S.C. § 300i.

[xxi] 40 C.F.R. § 258.61(b)(1).

[xxii] See, for example, 40 C.F.R. § 122.5 which applies to Clean Water Act NPDES permits and states: . . . , compliance with a permit during its term constitutes compliance, for purposes of enforcement, with sections 301, 302, 306, 307, 318, 403 and 405 (a)—(b) of CWA. However, a permit may be modified, revoked and reissued, or terminated during its term for cause as set forth in §§ 122.62 and 122.64.

[xxiii] Pub. L. 106-113, Title VI, § 6001; 42 U.S.C. § 9627 (1999).

[xxiv] See, for example, 65 Fed. Reg. 54,420 (September 8, 2000), "Project XL Draft Final Project Agreement: Waste Management, Inc. Landfill Bioreactor Systems," Maplewood Recycling and Waste Disposal Facility and King George County Landfill and Recycling Facility.

[xxv] See "Draft USEPA Project XL Final Project Agreement," Bioreactor Pilot Project, Ann Arundel County, Millersville Landfill and Resource Recovery Facility, Section VI.

[xxvi] Memorandum from Steve Herman, Assistant Administrator for Office of Enforcement and Compliance Assurance, OECA's Operating Principles for Project XL Participants, October 2, 1995.

[xxvii] Id.

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