Effluent Guidelines

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Centralized Waste Treatment

Alternate Approach for Establishing Limitations and Standards for Mixed Wastes for the Centralized Waste Treatment Industry

EPA's 1999 proposal would establish limitations and standards for three subcategories of CWT facilities: facilities treating either metal, oil, or organic wastes and wastewater. Section VII of the proposal details this subcategorization scheme. The proposal also discusses EPA's consideration of a mixed waste subcategory, but did not include rule language that incorporated mixed waste subcategory limitations. As detailed in the proposal, mixed waste subcategory limitations would be used for facilities which treat wastes in more than one subcategory, and would be established by combining pollutant limitations from all three subcategories, selecting the most stringent value where they overlap.

EPA's consideration of this option was in response to comments to the 1995 proposal and the 1996 Notice of Data Availability. The primary reason industry suggested the development of a mixed waste subcategory was to simplify implementation for mixed subcategory facilities. As detailed in the proposal, EPA's primary reason for not proposing this option was its concern that facilities which accept wastes in multiple subcategories do not have treatment in place to provide effective treatment of all waste receipts. While these facilities meet their permit limitations, compliance may be due to co-dilution of dissimilar wastes rather than treatment. The "mixed waste subcategory" limitations described above would not prevent ineffective treatment and could actually encourage it.

While EPA did not propose rule language for the mixed waste subcategory, EPA solicited comments on ways to develop a "mixed waste subcategory" which ensures treatment rather than dilution. The vast majority of commenters to the 1999 proposal supported the establishment of a mixed waste subcategory for this rule, and reiterated their concerns about implementing the three subcategory scheme at multiple facilities. One commenter suggested a way to provide for a mixed waste subcategory while ensuring adequate wastewater treatment. This commenter suggested that EPA follow the approach taken by categorical regulations for the Pesticide Formulating, Packaging and Repackaging (PFPR) category (40 CFR Part 455). Under this approach, mixed subcategory facilities would have the option of 1) monitoring for compliance with the appropriate subcategory limitations after each treatment step or 2) monitoring for compliance with the mixed waste subcategory limitations at a combined discharge point and certifying that an equivalent treatment system is installed and properly designed, maintained, and operated. This option would eliminate the use of the combined waste stream formula or building block approach in calculating limits or standards for mixed subcategory CWT facilities. The commenter suggested that an equivalent treatment system could be defined as a wastewater treatment system that is demonstrated in literature, treatability tests or self-monitoring data to remove a similar level of pollutants as the applicable appropriate pollution control technology for treatment of the unmixed waste streams selected as the basis for the limitations and standards.

EPA is considering adopting a modified version of this approach for several reasons. First, EPA agrees with commenters that developing appropriate limitations for mixed waste facilities presents many challenges and that the use of a mixed waste subcategory would make implementation of the rule vastly simpler. Second, the limits applied to mixed waste treaters would be a compilation of the most stringent limitation from the proposed subcategories. Third, the limits under the mixed waste subcategory would be similar to the limits calculated via the application of the combined waste stream formula or building block approach. Fourth, the equivalent treatment certification requirement would appear to address EPA's concerns that the waste receive adequate treatment.

Implementation for Facilities in Multiple Subcategories

EPA estimates that many facilities in the CWT industry accept wastes in two or more of the individual subcategories EPA has proposed for regulation. In other words, the facilities actively accept a variety of waste types. This situation is different from the case in which metal-bearing waste streams may include low-level organics or that oily wastes may include low level metals due to the origin of the waste stream accepted for treatment.

Multiple subcategory facilities, under the approach being considered, could comply with this rule in one of two ways: 1) facilities might elect to comply with the limitations or standards for each applicable subcategory directly following treatment (before commingling with different subcategory wastes); or 2) facilities that demonstrate achievement of equivalent treatment might elect to comply with one of four sets of limitations⁽¹⁾ for the mixed waste subcategory. Each of these options is discussed further below.

a. Comply with Limitations or Standards for Subcategory A, B, and/or C

In implementing a rule for multiple subcategory facilities in this manner, the permit writer or pretreatment authority would need to ensure that the CWT facility has an optimal waste management program. First, the control authority should verify that the CWT facility is identifying and segregating waste streams appropriately since segregation of similar waste streams is the first step in obtaining optimal mass removals of pollutants from industrial wastes. Next, the control authority should verify that the CWT facility is employing treatment technologies designed to treat all off-site waste receipts effectively. Finally, the control authority should establish compliance monitoring for each applicable subcategory directly following treatment of each subcategory's waste steam. As a further point of clarification, permit writers should not allow CWT facilities to commingle waste streams from different subcategories prior to monitoring for compliance with each subcategory's limitations or standards.

b. Comply with Limitations or Standards for a Mixed Waste Subcategory

First, facilities which wished to be subject to this option would submit information to support a determination by their permit writer that their treatment train includes all applicable equivalent treatment systems. EPA's current thinking is that this initial demonstration should include, at a minimum, the applicable CWT subcategories (i.e., metals, oils, organics) of wastes treated at the facility, a listing and descriptions of the treatment technologies and operating conditions used to treat wastes in each subcategory, and the basis for concluding that the treatment provided achieves equivalent removals to that obtained employing BAT technology for the applicable subcategories. For example, a facility which accepts metals subcategory and oils subcategory wastewaters could show that their treatment train includes oil/water separation, two stage chemical precipitation, and dissolved air flotation operated in a similar manner to that evaluated by EPA. Because these are the proposed BAT treatment technologies, these should provide equivalent treatment. However, at this time, unlike the approach adopted in the PFPR regulation, EPA is not considering defining "equivalent treatment" as either specific treatment technologies or the technology bases. Rather, the approach under review would define equivalent treatment as suggested by the commenter and described above. This approach would leave the decision as to whether a particular treatment train is "equivalent treatment" to the permit writer. The requesting facility must provide the permit writer with enough information and/or data to make the equivalent treatment determination. As is the case with information submitted with a permit application or an industrial user's report, a responsible corporate officer as defined in 40 CFR 403.12(l) or 40 CFR 122.22 must certify to the accuracy of any material submitted to support the "equivalent treatment" determination. If the control authority determines that equivalent treatment is demonstrated, then the control authority will issue discharge requirements based on one of the four subsets of limitations promulgated for the mixed waste subcategory.

Next, EPA would expect, under this approach, that the facility would submit a semiannual statement which indicates that the treatment technologies are being utilized in the manner set forth in their original demonstration or a justification to allow modification of the practices listed in its initial demonstration. If the information contained in the initial statement were still accurate, a facility would simply notify the permitting authority of this, and the letter would constitute the periodic statement. However, if the facility had modified its treatment system in any way, it would need to notify EPA or the permitting authority of the changed circumstances.

Finally, the facility would be required to maintain on-site compliance paperwork. The on-site compliance paperwork should include information from the initial demonstration and periodic statements, but must also include: (1) the supporting documentation for any modifications that have been made to the treatment system; (2) a method for demonstrating that the treatment system is well operated and maintained; and (3) a discussion of the rationale for choosing the method of demonstration. Proper operation and maintenance of a system include a qualified person to operate the system, use of correct treatment chemicals in appropriate quantities, and operation of the system within the stated design parameters. For example, a facility may operate dissolved air flotation. The method for demonstrating the dissolved air flotation system is well operated can be as simple as maintaining records on the temperature and pH, the chemicals added (including quantity), the duration of treatment, recycle ratio, and physical characteristics of the wastewater before and after dissolved air flotation. Alternatively, the facility could monitor for selected parameters for the purpose of demonstrating effective treatment. This could include any pollutant or a combination of pollutants.

Control authorities, at or any time after entering into an individual control mechanism, or permitting authorities, at or any time after issuing, reissuing, or modifying the NPDES permit, could inspect the CWT facility to confirm that the listed practices are being employed, that the treatment system is well operated and maintained and that the necessary paperwork provides sufficient justification for any modifications.

¹ Depending on the types of wastes treated at the facilities, there would be different mixed waste limitations and standards. For example, if the facility treated oily wastes and metals wastes, the applicable mixed waste limitations would reflect the most stringent limitations from both the metals subcategory and the oily waste subcategory. If the facility treated metals wastes and organic wastes, the applicable mixed waste limitations would be based on the most stringent limitations for pollutants regulated in the metals and organic subcategories.