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Advocacy Alert 17-02



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To: Members & Affiliates
From: National Office
Date: January 19, 2017
Subject: Proposed National Emission Standards for Publicly Owned Treatment Works
Reference: AA 17-02


EPA published its proposed amendments to the National Emission Standards for Hazardous Air Pollutants: Publicly Owned Treatment Works (“POTW NESHAP”) in the December 27 Federal Register. EPA has also posted a fact sheet about the rule’s requirements and the risk and technology review that was conducted for POTWs. The POTW NESHAP applies to any POTW with a design capacity greater than 5 million gallons per day (MGD) that is also a major source of hazardous air pollutants (HAP) and/or treats wastewater for an industrial user to enable that industrial user to comply with its applicable NESHAP.

This Advocacy Alert provides background information on the POTW NESHAP and a summary of the proposed requirements for the POTWs that are subject to the rule. Although the rule currently applies to a small number of POTWs, some of the proposed changes could broaden the applicability of the rule. In addition, more POTWs could become subject to the rule in the future if their HAP emissions increase or if the method for estimating HAP emissions is changed by their regulatory agency. NACWA will submit comments on the proposal by the February 27 deadline, and requests that all of its members evaluate the potential for this rule to impact them and send input to This e-mail address is being protected from spambots. You need JavaScript enabled to view it by February 15.


NACWA worked with EPA on the original POTW NESHAP for seven years prior to its publication in 1999. The NESHAP was amended in 2002, but EPA neglected to conduct a residual risk and technology review for the NESHAP within eight years as required by the Clean Air Act (CAA). Under these reviews, EPA must assess the remaining health risks to determine whether the maximum achievable control technology (MACT) standards protect public health and the environment. EPA must determine if the standards require changes to protect public health and to account for improvements in air pollution controls and/or prevention. Because this CAA requirement was not met for the POTW NESHAP and 33 other NESHAP, the Sierra Club brought a lawsuit against EPA. A 2013 consent decree required EPA to publish the results of the POTW NESHAP risk and technology review by December 2016.

NACWA’s Air Quality workgroup has had several conversations with EPA throughout the Agency’s process of preparing and conducting the risk and technology review, which included an information collection request (ICR) for seven POTWs – the current group of POTWs subject to the rule. EPA also held a conference call with the Workgroup on January 11 to outline the proposed rule and answer questions about it.

Results of the Risk and Technology Review

To conduct the residual risk review, EPA assessed the human health risk from exposure to both actual and allowable toxic air emissions from POTWs. EPA determined that cancer risks are well below the acceptable level and the likelihood of adverse non-cancer health effects is minimal. EPA also conducted an environmental risk screening assessment and concluded that no adverse environmental effects result from POTW HAP emissions. These risk assessments therefore indicate that no additional controls are necessary.

EPA’s technology review considered add-on control technologies, other treatment units, work practices, procedures, and process changes or pollution prevention alternatives, including pretreatment programs. The 2002 POTW NESHAP identified pretreatment programs and add-on controls, such as covers, as the two primary control options at POTWs, and EPA’s technology review verified that these are still the primary options. Pretreatment remains an effective control option for HAP by limiting the the concentrations of HAP in the wastewater, thereby limiting the potential for air emissions from both the collection system and the treatment facility.

Requirements of Proposed Rule

A POTW will be subject to the proposed POTW NESHAP if it has a design capacity of at least 5 MGD, receives wastewater from industrial users, and is either a major source of HAP emissions or treats an industrial user’s wastewater to comply with requirements of another NESHAP. The proposed rule language, in certain sections, includes reference to industrial and commercial discharges. NACWA is seeking clarification on whether this was an intentional expansion of the applicability or if EPA has simply misused the word ‘commercial’ in these instances. EPA has identified six facilities from four different utilities (Gulf Coast Waste Disposal Authority, Hopewell Regional Wastewater Treatment Facility, New York DEP, and Milwaukee Metropolitan Sewerage District) that will be subject to the rule, although there could be additional facilities that have not been identified yet.

In the 2002 POTW NESHAP, POTWs were divided into two categories: industrial and non-industrial. In the proposed NESHAP, EPA has changed its terminology and defined two categories of POTWs subject to the POTW NESHAP as follows:

  • Group 1 – POTWs that accept wastewater from an industrial user that complies with its NESHAP by using the treatment and control located at the POTW. Group 1 POTWs need not be a major source of HAP to be subject to the POTW NESHAP.

  • Group 2 – POTWs that do not meet the definition of a Group 1 POTW. Group 2 POTWs treat wastewater that is not specifically regulated by another NESHAP or that is from an industrial user that complies with its NESHAP requirements prior to discharging to the POTW collection system. Group 2 POTWs must also be major sources of HAP to be subject to the POTW NESHAP.

The proposed NESHAP clarifies that HAP emissions from collection systems should be included when determining if a POTW is major source of HAP. This has been a concern for NACWA in the past and raises important questions as to what portions of the collection system should be included in any estimates since the POTW may not own the entire system.

The major proposed requirements for existing POTWs, and the differences between these requirements and the 2002 POTW NESHAP, are as follows:

  • Group 1 and Group 2 POTWs must demonstrate that the HAP fraction emitted from all emission points up to secondary treatment does not exceed 0.08 on a 12-month rolling average. Any combination of pretreatment, wastewater plant modifications, or control devices may be used to meet this performance standard. Group 2 POTWs were not subject to emission limits in the 2002 POTW NESHAP.

  • Group 1 and Group 2 POTWs must develop and implement a pretreatment program. While the 2002 POTW NESHAP listed a pretreatment program as one of the criteria for applicability, EPA is proposing that pretreatment programs be a NESHAP requirement instead.

  • Group 1 POTWs must meet all requirements for each appropriate NESHAP for the wastewater from each industrial user. In the 2002 POTW NESHAP, only requirements of the most stringent NESHAP had to be met by the POTW.

The major proposed requirements for new POTWs are as follows:

  • Group 1 and Group 2 POTWs must install covers on the emission points up to secondary treatment. All covered units except the primary clarifiers must have the air in the headspace below the cover ducted to a control device.

  • Alternatively, Group 1 and Group 2 POTWs can demonstrate for all emission points up to secondary treatment that the HAP fraction emitted does not exceed 0.014 on a rolling 12-month average.

The startup, shutdown, and malfunction (SSM) exemptions that were contained in the 2002 POTW NESHAP have been eliminated from the proposed rule, along with associated recordkeeping and other requirements associated with the SSM exemption. EPA explained in the proposed rule that eliminating these exemptions is “consistent with the court decision in Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008), which vacated two provisions that exempted sources from the requirement to comply with otherwise applicable CAA section 112(d) emission standards during periods of SSM.”

Member Input Requested

NACWA is asking its members, whether or not their facilities currently meet the applicability requirements of the POTW NESHAP, to provide input on the proposed rule. NACWA is particularly interested in hearing from POTWs that were not subject to the 2002 POTW NESHAP, but think they may be subject to the revised NESHAP. NACWA would also like to know if POTWs already include the collection system in their estimates of HAP emissions, or if EPA’s clarification that collection systems should be included will cause more POTWs to be classified as major sources of HAP emissions.

EPA also requested comments on many aspects of the rule, including the following:

  • Additional control measures that could be used to reduce the risk from this source category.

  • A potential additional requirement that POTWs specifically evaluate the volatile organic HAP for each industrial user, because organic HAP that volatilize readily are most likely to result in air emissions in the collection system and treatment plant.

  • Requiring POTWs to develop local limits for volatile organic HAP to reduce emissions from the collection system and treatment plant.

  • Specific controls or operational practices that can be required to address emissions from collection systems.

  • Ways to harmonize the pretreatment programs as a means to meet both CAA and Clean Water Act (CWA) requirements.

  • Whether an alternative to the 0.08 HAP fraction emitted standard should be provided. The first alternative would be either covering the primary clarifier, or covering and control of all primary treatment units (except primary clarifiers, which would only require covering). The second alternative would keep the requirements for existing sources consistent with those for new sources, namely to cover and control their primary treatment units or to meet the HAP fraction standard.

NACWA is interested in the input of its members on these and other requests for comment from EPA, as well as comments on the applicability and requirements of the proposed NESHAP. Please send comments and input to This e-mail address is being protected from spambots. You need JavaScript enabled to view it by February 15. NACWA members are also encouraged to submit their own comments to EPA by the February 27 deadline.



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