Adding the RCRA Mixed Sewage Exclusion to Your Compliance Arsenal

Joseph F. Madonia and E. Lynn Grayson

Editors' Summary: Unlike other regulatory provisions of RCRA, the mixed sewage exclusion has been largely ignored by legal and technical scholars. Industry may be overlooking a potentially attractive opportunity, however, because the exclusion exempts certain industrial wastewaters from the definition of "solid waste," thereby excluding those wastes from hazardous waste regulation under RCRA. This Article examines the mixed sewage exclusion and its implications for operating facilities. After looking at the exclusion's regulatory language, the authors discuss interpretations of the regulation under existing case law. The authors then address public policy considerations supporting the exclusion and examine the exclusion's regulatory history. The Article also responds to arguments that seek to limit the exclusion's scope. The authors conclude that despite unclear regulatory interpretations by some governmental entities, the mixed sewage exclusion is a viable compliance option for certain operations.

Joseph F. Madonia is a partner in the Environmental Law Department of Wildman Harrold Allen & Dixon in Chicago, Illinois. E. Lynn Grayson is a partner in the Environmental Law Department of Jenner & Block in Chicago, Illinois.

[29 ELR 10199]

Few facilities regulated by federal and state hazardous waste laws recognize the Resource Conservation and Recovery Act's (RCRA's)¹ mixed sewage exclusion as a potential tool for assisting them in their compliance efforts. Unlike other more studied elements of the RCRA regulatory maze, the mixed sewage exclusion historically has been largely ignored by legal and technical scholars. Industry may be overlooking a potentially attractive opportunity, however, because for qualifying facilities, this little known RCRA regulation provides an exemption from the definition of "solid waste" such that certain industrial wastewaters might not need to be treated or managed as hazardous waste. In instances where a mixture of domestic sewage and other waste passes through a sewer system to a publicly owned treatment works (POTW), such materials may escape regulation as hazardous waste.

This Article will discuss the mixed sewage exclusion including applicable policy and regulatory history promulgated by the U.S. Environmental Protection Agency (EPA). In addition, the authors will examine existing case law and discuss implications of the exclusion for operating facilities. The authors will conclude that despite unclear regulatory interpretations by some governmental entities, the exclusion is a viable compliance option for certain operations.

Explanation of the RCRA Mixed Sewage Exclusion

The first step in determining whether something is a "hazardous waste" under RCRA is to determine whether the material is a "solid waste" as defined by 40 C.F.R. § 261.4. If the material is a solid waste, then it must be determined whether the material meets any of the criteria for listed and characteristic wastes under 40 C.F.R. § 261.3. If the waste satisfies the criteria either because it is a listed waste or because it has the characteristic of a hazardous waste such as ignitability, corrosivity, or toxicity, the waste is deemed to be hazardous. Even if waste meets one of those criteria, however, it is not a hazardous waste if it is exempted from the definition of solid waste. One such exemption is the mixed sewage exclusion.

Regulatory Definition

The mixed sewage exclusion provides that "domestic sewage … and … any mixture of domestic sewage and other wastes that passes through a sewer system to a publicly-owned treatment works for treatment" is not a solid waste.² "'Domestic sewage' means untreated sanitary wastes that pass through a sewer system."³ The plain wording of this exemption indicates that "other waste" that mixes with domestic sewage in a sewer system is not a solid waste and, therefore, cannot be a hazardous waste, regardless of its characteristics. Industrial wastewater is a classic example of such "other waste."

Examination of Existing Case Law

The Fourth Circuit held in United States v. Dee⁴ that to fall within the scope of the exclusion, wastes from an industrial [29 ELR 10200] facility must mix with sanitary wastes from residences before entering a POTW. Although the Fourth Circuit did not reach the issue of the mixed sewage exclusion's scope, it cited with approval the general standard set forth in Comite Pro Rescate de la Salud v. Puerto Rico Aqueduct & Sewer Authority.⁵

The Comite case involved an environmental suit filed under RCRA's citizen suit provision⁶ against the owners of several factories located within a large industrial park. The plaintiffs alleged, among other things, that the factory owners violated RCRA hazardous waste disposal prohibitions by discharging certain solid wastes into a sewer system without meeting various recordkeeping and permitting requirements. Plaintiffs also sought injunctive relief to stop the sewer discharges. The district court dismissed all of the RCRA claims, holding that because industrial wastes in the sewer system mixed with untreated sanitary wastes, the factories' discharges fell within the scope of the mixed sewage exclusion.⁷ The plaintiffs chose not to appeal the majority of the district court's decision, opting instead to appeal the holding only as it applied to their request for injunctive relief.

The First Circuit vacated, holding that the mixed sewage exclusion did not bar plaintiffs' suit for injunctive relief.⁸ The First Circuit stressed, however, that its opinion was the direct result of the peculiar facts of the Comite case and suggested that it might have ruled otherwise had the sewersystem at issue been configured differently. In fact, the First Circuit remanded the case to the district court for further proceedings to determine whether the discharges actually fell within the exclusion in light of changed circumstances that occurred during the pendency of the case. The court explained:

The record suggests there may have been a significant factual change since the plaintiffs filed the original complaint in this case. As we said at the outset, the [industrial] Park's sewer pipe runs from the Park to a public sewer line. Before December 1987, that public line ran to a … (POTW) which did not receive sewage from residences. Since December 1987, however, the Park's sewage has been treated at another POTW which also receives sewage from residences outside the Park. Thus defendants' sewage now appears to mix with "domestic sewage" in the public line.⁹

The POTW at issue in the Comite case was unusual in that it served only the industrial park. The sewage system leading to that POTW did not connect with any private houses.¹⁰ This was a critical fact, because the First Circuit reasoned that in order for industrial waste to mix with domestic sewage, the sewer lines must connect industrial facilities and domestic sources (i.e., homes).¹¹ Because there was no such mixture in the Comite case, at least during the pre-1987 period, the court held that the exclusion was inapplicable to the pre-1987 discharges.¹² The court rejected the factory owners' claim that the mixture of sanitary wastes and industrial wastes, both of which originate within the same industrial park, was sufficient to exempt the discharges from the definition of solid waste.¹³

Of course, any facility considering the use of the mixed sewage exclusion must also determine whether it is subject to more stringent state hazardous waste laws. Maryland, for example, is a state to which EPA has delegated the authority to administer the RCRA program, but it has not adopted the mixed sewage exclusion.¹⁴

Evaluation of EPA Policy and Regulatory History

Compelling public policy considerations support the mixed sewage exclusion. In the preamble to 1988 federal regulations relating to POTW discharges, EPA characterized the mixed sewage exclusion as follows:

The regulatory exclusion applies to domestic sewage as well as mixtures of domestic sewage and other wastes that pass through a sewer system to aPOTW (see 40 CFR 261.4(a)(1)). The exclusion thus covers industrial wastes discharged to POTW sewers which contain domestic sewage, even if these wastes would be considered hazardous if disposed of by other means.¹⁵

As one EPA official put it:

If [a hazardous waste] is discharged into the sewer system by a pipe and that sewer system is connected to a treatment works which is regulated or would be regulated under the Clean Water Act, that is exempted from our RCRA regulations. If you back up with a truck and put it in the sewer system, that is covered by our regulations.¹⁶

EPA further explained that such an exclusion was necessary because without it, POTWs would frequently receive wastes that could be classified as hazardous under RCRA. As a result, POTWs would be required to meet extensive RCRA requirements for treating, storing, and disposing of hazardous wastes. Recognizing that such overwhelming regulatory burdens could be unfair and financially devastating for POTWs, EPA opted to regulate any potential public health risks associated with discharges to POTWs outside of the RCRA hazardous waste context.¹⁷ This decision marked the inception of local POTW pretreatment ordinances under the Federal Water Pollution Control Act (FWPCA).¹⁸

Rather than relying on RCRA hazardous waste regulations to regulate discharges to POTWs, EPA established [29 ELR 10201] specific discharge limitations for POTW users. POTW pretreatment ordinances usually are the source of such discharge limitations. For example, EPA prohibited the sewer discharge of explosive wastes.¹⁹ The obvious rationale for prohibiting explosive discharges is the danger those discharges would create for POTW workers.

An important part of the rationale that led EPA to adopt the mixed sewage exclusion was its belief that "materials exhibiting these [hazardous waste] characteristics often lose their hazardous qualities when they are mixed with domestic sewage or treated at a POTW. The fact that a particular substance exhibits a RCRA hazardous waste characteristic does not necessarily indicate the likelihood of pass through or interference [with POTWs]."²⁰ Regardless of whether the characteristics of a specific waste could create a danger once it reached the POTW, however, EPA concluded that any such dangers could be more than adequately addressed through a POTW ordinance prohibiting dangerous discharges, without recourse to hazardous waste regulations under RCRA. Thus, the mixed sewage exclusion is not only sound public policy that protects POTWs from potentially devastating financial burdens, it also anticipates that other regulations are adequate to protect public health and the environment. This protection exists in the other nonhazardous waste environmental laws such as the FWPCA and POTW ordinances that are more than adequate to protect the public from discharges to sewage systems. The existence of such protections is evidenced by the fact that many POTWs render such discharges completely harmless and as part of their normal function.

Impacts on Facility Operations

Some local governmental enforcement agencies have argued that the mixed sewage exclusion should be available only to industries that pretreat their waste before disposing of it into a sewer. By EPA's explicit directive, however, the RCRA mixed sewage exclusion is not limited only to pretreated wastes. If lawmakers had intended to incorporate such a significant limitation in the exclusion, the plain language of the law presumably would have clearly reflected that intent, and EPA would have taken the position that such waste must be pretreated. Yet the plain wording of the regulation does in fact demonstrate the true intent of the exclusion — pretreatment is not required.

EPA confirmed that intent in its 1986 Domestic Sewage Study report.²¹ In that report, EPA explains that "the exemption is not explicitly conditioned on compliance with other environmental controls (e.g. [FWPCA], pretreatment standards) but on the basis that a waste which is not defined as a RCRA solid waste cannot be a hazardous waste."²² The report further states:

If the waste is discharged to a POTW prior to any treatment …, at first entry the hazardous waste is no longer a hazardous waste. The [domestic sewage exemption (DSE)]²³ defines away the regulated status of the discharge, although it may actually retain the characteristics of a hazardous waste…. This appears to give [industrial users] an incentive not to treat wastes prior to discharge to the sewer. However, [FWPCA] pretreatment requirements directly counter this result by mandating treatment to achieve limits.²⁴

These passages demonstrate not only that EPA intended and expected the exemption to apply to untreated wastes, but also that the Agency intended for the enforcement of FWPCA pretreatment requirements to fill any perceived regulatory gaps created by the RCRA exemption.

The fact that the mixed sewage exclusion is intended to exempt certain wastes from regulation under RCRA further counters arguments of those in favor of imposing a pretreatment condition on the mixed sewage exclusion. Waste that is cleaned up to the FWPCA's stringent standards before it enters the sewer would not exhibit any hazardous characteristics that would cause it to be regulated under RCRA. Because the treated, "clean" waste discharged to the sewer would not be a hazardous waste, there would be no reason to "exempt" it from RCRA hazardous waste regulation.

Some governmental agencies have also argued that the mixed sewage exclusion does not apply until some unknown point within the sewer system where the "mixture" occurs. This argument directly contradicts EPA's interpretation of the exemption. In the Domestic Sewage Study report, EPA states:

Another basic issue surrounding the DSE is when it takes effect…. The Agency's interpretation is that the exemption begins when the waste first enters a sewer system that will mix it with sanitary wastes prior to storage or treatment by a POTW. Thus, the DSE may actually apply prior to actual mixing with domestic sewage.²⁵

The Federal Register preamble that accompanied the 1980 enactment of the mixed sewage exclusion contains the definitive statement of EPA's interpretation of the exemption. It demonstrates that EPA specifically considered, and rejected, the "mixture" argument, reasoning that:

Defining the point at which "mixture" occurs may seem to be a relatively straightforward task. Practical problems arise, however, in defining the point at which mixture of sanitary and other wastes occurs in a complex sewer system. Moreover it is particularly difficult to define this point for regulatory purposes in such a way that all parties understand when RCRA obligations begin and end.²⁶

EPA's concern for predictability and uniformity in informing regulated industries of the specific scope of RCRA regulations prompted EPA to adopt the following position:

[29 ELR 10202]

Waste falls within the domestic sewage exemption when it first enters a sewer system that will mix it with sanitary wastes …. EPA recognizes that this interpretation brings various wastes within the exemption before they are actually mixed with sanitary wastes. In light of the fact that the wastes will be mixed prior to treatment and that the mixture will be properly treated by the POTW, EPA believes that the need for administrative clarity in this otherwise complicated regulatory program warrants such an approach.²⁷

Despite contrary interpretations of the mixed sewage exclusion as advocated by some governmental agencies, it remains a viable compliance option for certain facilities seeking to manage wastewaters correctly. Assuming site operations justify its use, the mixed sewage exclusion eliminates many of the regulatory burdens typically associated with the RCRA program including storage, recordkeeping, and closure responsibilities. The key to the successful use of the exclusion requires the precise evaluation of a facility's wastewater flow configuration coupled with a thorough, accurate knowledge of the relevant sewer system and its path to the applicable POTW.

Conclusion

Because it is possible to control sewage discharges and to protect human health and the environment through the use of laws other than RCRA hazardous waste laws, EPA and Congress saw fit to exempt sewage discharges from the hazardous waste regulatory scheme. Thus, the mixed sewage exclusion is not a loophole. It is simply a recognition of the fact that in light of the countless pervasive regulations that could apply to industrial discharges to a POTW, it is sound public policy to exclude those regulations that would impose an unintended and unconscionable regulatory burden on POTWs.

The RCRA mixed sewage exclusion is a viable option that allows certain facilities to manage their industrial wastewaters in an effective and legal manner outside the scope of federal and state hazardous waste laws. When applicable, the mixed sewage exclusion provides such facilities with a powerful tool for reducing their costs and compliance obligations.

1. 42 U.S.C. §§ 6901-6992k, ELR STAT. RCRA §§ 1001-11012.

2. 40 C.F.R. § 261.4(a) (1998) (emphasis added).

3. Id.

4. 912 F.2d 741, 21 ELR 20051 (4th Cir. 1990) (interpreting the federal mixed sewage exclusion set forth at 40 C.F.R. § 261.4(a)).

5. 888 F.2d 180, 20 ELR 20211 (1st Cir. 1989), vacating 693 F. Supp. 1324, 19 ELR 20143 (D.P.R. 1988).

6. 42 U.S.C. § 6922(a)(1)(b), ELR STAT. RCRA § 3002(a)(1)(b).

7. Comite, 693 at 1331-33, 19 ELR at 20146-47.

8. Comite, 888 F.2d at 181-82, 20 ELR at 20212.

9. Id. at 187-88, 20 ELR at 20215.

10. Id. at 182, 20 ELR at 20212.

11. Id. at 184-85, 20 ELR at 20214.

12. Id. at 186, 20 ELR at 20215.

13. Id., see also Lincoln Properties, Ltd. v. Higgins, No. S-91-760 DFL/GGH, 1993 U.S. Dist. LEXIS 1251, 23 ELR 20665 (E.D. Cal. Jan. 18, 1993).

14. See Westfarm Assocs. v. International Fabricare Inst., 846 F. Supp. 422, 24 ELR 20009 (D. Md. 1993), aff'd sub nom. Westfarm Assocs. Ltd. Partnership v. Washington Suburban Sanitary Comm'n, 66 F.3d 669, 25 ELR 21587 (4th Cir. 1995).

15. General Pretreatment Regulations for Existing and New Sources, Proposals to Implement the Recommendations of the Domestic Sewage Study, 53 Fed. Reg. 47632 (Nov. 23, 1988) [hereinafter General Pretreatment Regulations] (emphasis added).

16. Reauthorization of the Resource Conservation and Recovery Act, 97th Cong. 475 (1982) (testimony of Gary Deitrich, Director, Office of Solid Waste).

17. General Pretreatment Regulations, supra note 15, at 47632.

18. 33 U.S.C. §§ 1251-1387, ELR STAT. FWPCA §§ 101-607.

19. General Pretreatment Regulations, supra note 15, at 47632.

20. Id. at 47633.

21. U.S. EPA, REPORT TO CONGRESS ON THE DISCHARGE OF HAZARDOUS WASTES TO PUBLICLY OWNED TREATMENT WORKS (THE DOMESTIC SEWAGE STUDY) (1986) [hereinafter DOMESTIC SEWAGE STUDY].

22. Id. § 6.1.2. (emphasis added).

23. EPA uses the term "domestic sewage exemption" (DSE) when discussing the mixed sewage exclusion. This term is misleading, however, because the DSE includes both the exemption for domestic sewage, 40 C.F.R. § 261.4(a)(1)(i), and the mixed sewage exclusion, id. § 261.4(a)(1)(ii).

24. DOMESTIC SEWAGE STUDY, supra note 21, § 6.2.1.4 (emphasis added).

25. Id. § 6.1.2.2. (citation omitted) (first emphasis in the original, second emphasis added).

26. Hazardous Waste Management System: Identification and Listing of Hazardous Waste, 45 Fed. Reg. 33097 (May 19, 1980) (emphasis added).

27. Id. (emphasis added).