Examination of existing case law
Few facilities regulated by federal and state hazardous waste laws consider the Resource Conservation and Recovery Act (RCRA) mixed-sewage exclusion a potential tool to assist 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. For qualifying facilities, this little-known RCRA regulation provides an exemption from the definition of "solid waste" that could allow certain industrial wastewaters to not be treated or managed as hazardous waste. In other words, in instances where a mixture of domestic sewage and other wastes pass through a sewer system to a publicly owned treatment works, such materials may escape regulation as hazardous waste.
Explanation of RCRA mixed-sewage exclusion
The first step in determining whether something is a hazardous waste as defined by RCRA is to determine whether the material is a "solid waste" as defined by 40 Code of Federal Regulations (CFR) 261.4. If the material is found to be solid waste, then it must be determined whether the material meets any of the criteria set forth in 40 CFR 261.3 that would cause it to be classified as hazardous waste. These criteria outline several hazardous waste categories, including various lists and several tests for characteristics such as ignitability, corrosivity and toxicity. 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.
The mixed-sewage exclusion is set forth in 40 CFR 261.4. It provides as follows:
a) Materials which are not solid wastes. The following materials are not solid wastes for the purpose of this part:
A) Domestic sewage; and
B) Any mixture of domestic sewage and other waste that passes through a sewer system to a publicly owned treatment work for treatment. "Domestic sewage" means untreated sanitary wastes that pass through a sewer system.
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.
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 publicly owned treatment works (POTW) discharges, EPA characterized the mixed-sewage exclusion as follows:
The regulation exclusion applies to domestic sewage as well as mixtures of domestic sewage and other wastes that pass through a sewer system to a POTW 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.
"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 (CWA), 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," said Gary Deitrich, an EPA official, during Congressional testimony on RCRA reauthorization in 1982.
EPA explained further that such an exclusion was necessary because, without it, POTWs would frequently receive wastes that could be classified as hazardous wastes under RCRA. As a result, POTWs would be required to meet extensive RCRA requirements set forth at 40 CFR Part 264 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. (53 Federal Register 47632, Nov. 23, 1988). This decision marked the inception of local POTW pre-treatment ordinances pursuant to the federal CWA (33 U.S.C. Section 1251, et seq).
Rather than relying upon RCRA hazardous waste regulations to regulate discharges to POTWs, EPA has established specific discharge limitations for POTW users. POTW pre-treatment ordinances are usually the source of such discharge limitations. For example, EPA has prohibited the sewer discharge of wastes which are explosive. 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 that 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." Regardless of whether a specific waste's characteristics 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.
Thus, the mixed-sewage exclusion is not only sound public policy that protects POTWs from potentially devastating financial burdens, but it also protects POTWs from threats to public health and the environment. This protection exists in the other non-hazardous waste environmental laws, which are more than adequate to protect the public from discharges to sewage systems, and in the fact that many POTWs render such discharges completely harmless as part of their normal function.
Impacts on facility operations
Some government agencies have argued that the exemption should be available only to industries that pre-treat their waste prior to disposal into a sewer. By EPA's explicit directive, the RCRA mixed-sewage exemption is not limited only to wastes that have been pretreated prior to discharge. If lawmakers had intended to incorporate such a significant limitation in the exemption, then the words of the law presumably would reflect that intent clearly, and EPA would have taken the position that such waste must be pretreated. In fact, the plain wording of the regulation expresses the true intent behind it - that pre-treatment is not required. That intent is confirmed by EPA's 1986 Report to Congress on the Discharge of Hazardous Wastes to Publicly Owned Treatment Works (The Domestic Sewage Study). In Section 6.1.2 of that report, EPA explains as follows:
It should be noted that the exemption is not explicitly conditioned on compliance with other environmental controls (e.g. CWA, pretreatment standards) but on the basis that a waste which is not defined as a RCRA solid waste cannot be a hazardous waste.
The report further states that:
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 DSE 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, CWA pretreatment requirements directly counter this result by mandating treatment to achieve limits.
(Report to Congress, Supra, Section 18.104.22.168) (Emphasis added.)
These passages demonstrate not only that EPA expected and intended the exemption to apply to wastes that are untreated, but also that EPA intended for enforcement of CWA pretreatment requirements to fill any perceived regulatory void created by the RCRA exemption.
The logical flaw in imposing a "pre-treatment" condition upon the exemption, is that waste cleaned to the CWA's stringent standards before entering the sewer would not exhibit any hazardous characteristics that would cause it to be regulated under RCRA. Since 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 government agencies have also argued that the mixed-sewage exemption does not apply until some unknown point within the sewer system when a "mixture" occurs. This argument also directly contradicts EPA's interpretation of the exemption.
In the previously discussed EPA report to Congress, EPA unequivocally rejects such reasoning and makes the following statement about the domestic sewage exemption (DSE):
Another basic issue surrounding the DSE is when it takes effect ... the Agency's interpretation is that the exemption beginning when the waste first enters a sewer system that will mix it with sanitary wastes prior to storage or treatment by a POTW emphasis in original citation omitted. Thus, the DSE may actually apply prior to actual mixing with domestic sewage.
(Report to Congress, Supra, Section 22.214.171.124.) (Emphasis added.)
The Federal Register preamble that accompanied the 1980 enactment of the mixed-sewage exemption (45 Fed. Reg. 33097) contains the definitive statement of EPA's interpretation, and demonstrates that EPA specifically considered, and rejected, the 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.
45 Fed. Reg. 33097, May 19, 1980 (Emphasis added.)
EPA's concern for predictability and uniformity in informing regulated industries of the specific scope of RCRA regulations prompted the agency to adopt the following position:
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.
45 Fed. Reg. 33097, May 19, 1980 (Emphasis added.)
Despite the existence of some contrary interpretations of the mixed-sewage exclusion, it remains a viable compliance option for certain facilities seeking to correctly manage wastewater. Reliance upon the exemption, assuming site operations justify its use, eliminates many of the regulatory burdens typically associated with the RCRA program, including storage, recordkeeping and closure responsibilities. The key to successful reliance upon the exclusion requires 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.
Since 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 scope of the hazardous waste regulations. Thus, the mixed-sewage exclusion is not a loophole. It is simply a recognition that in light of the countless regulations that could apply to industrial discharges to a POTW, it is sound public policy to exclude those which would impose an unintended regulatory burden upon the POTWs.
The RCRA mixed-sewage exclusion remains a viable, cost-effective option allowing certain facilities to operate in a legal manner outside the scope of federal and state hazardous waste laws. If applicable, reliance upon the mixed-sewage exclusion results in reduced compliance obligations for industrial wastewater management facilities.
Examination of existing case law
To fall within the scope of the exclusion, wastes from an industrial facility must mix with sanitary wastes from residences prior to entering a POTW, according to the ruling of the 4th Circuit Court of Appeals in United States vs. Dee, 912 F.2d 741 (4th Cir. 1990) (interpreting the federal mixed-sewage exclusion set forth at 40 CFR Section 261.4(a)). Although the 4th Circuit in the Dee case did not reach the issue of the scope of the mixed-sewage exclusion, it cited with approval the general standard set forth by the 1st U.S. Circuit Court of Appeals in Comite Pro Rescate De La Salud vs. Sewer Authority, 888 F.2d 180 (1st Cir. 1989).
The U.S. federal court system consists of district courts located in each state and territory. There is also one court of appeals situated in each of 12 multistate circuits. A decision of a court of appeals is binding upon other courts within that same circuit and may provide guidance for any courts outside the circuit.
The Comite case involved an environmental suit filed by the environmental activist group Comite Pro Rescate de la Salud against factory owners pursuant to the RCRA citizen suit provision. (42 United States Code (USC) Section 6922(a)(1)(b)). The Comite group's main allegation was that the factory owners violated RCRA hazardous waste disposal prohibitions by discharging certain solid wastes into a sewer system without meeting legal requirements.
The Comite group also sought injunctive relief to stop the factory's sewer discharges. The court dismissed all RCRA claims, holding that since industrial wastes in the sewer system mixed with untreated sanitary wastes, the factory's discharges fell within the scope of the mixed-sewage exclusion. (Comite, supra, at 182.) The Comite group chose not to appeal the majority of the court's rulings in this case, opting instead to appeal the holding only as it applied to their request for injunctive relief.
The 1st Circuit Court of Appeals set aside the lower trial court's ruling and held that the mixed-sewage exclusion did not bar the Comite group's suit for injunctive relief to stop the factory's discharges. The court stressed, however, that its opinion was the direct result of the peculiar facts of the Comite case and suggested that it might have ruled differently if the sewer system at issue had been configured differently. In fact, the 1st Circuit sent the case back to the district court for further proceedings to determine whether the discharges did, in fact, fall within the mixed-sewage exclusion in light of changed circumstances which occurred during the pendency of the case. The 1st Circuit explained as follows:
We mention this last point particularly because 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 park's sewer pipe runs from the park to a public sewer line. Before December 1987, that public line ran to a POTW that 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.
The POTW at issue in the Comite case was unusual in that it only served an industrial park. The sewage system leading to that POTW did not connect with any private houses. This was critical, 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.
Since 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. The court rejected the defendants' claim that the mixture of sanitary wastes and industrial wastes, both of which originate within the same industrial facility, was sufficient to exempt the discharges from the definition of solid waste.
Of course, any facility which is considering reliance upon the mixed-sewage exclusion must also determine if it is subject to state hazardous waste laws, which in some cases may be more stringent than RCRA. For example, EPA has delegated to Maryland the authority to administer the RCRA program, but the state has not adopted a more narrow exclusion.
This article originally appeared in the 07/01/1999 issue of Environmental Protection.