Evaluating risk mitigation options for new BWON rule enforcement approach

A core concern among facility owners and operations is that even established BWON compliance programmes are now susceptible to the EPA’s new enforcement approach, which includes using advanced optical gas imaging (OGI) technology for vapour leak detection from regulated waste management systems. The OGI technology dramatically improves what was once a cumbersome and intensive process, resulting in greater ease in identifying fugitive emissions, and expanding the enforcement capabilities of the EPA and the US Department of Justice (DOJ).

Recent BWON consent decree settlements require multiple capital projects, large initial fines and compressed implementation timelines backed by punishing stipulated penalties.

For example, recent consent decree settlements finalised between the EPA, DOJ, and three refiners from 2023 to early 2025 illustrate the scope of the new enforcement campaign. The settlements include civil penalties ranging from US$19 million to US$40 million and mandated capital investments ranging up to US$250 million that go well beyond compliance with the rule.

New EPA enforcement approach

Benzene has long been on the EPA’s radar. Multiple EPA air quality rules focus on benzene as a volatile organic compound (VOC) and a hazardous air pollutant (HAP). Benzene is commonly present in process or product streams like gasoline and waste streams. The BWON rule focuses on benzene in waste streams and controlling waste management unit emissions. Benzene emissions from aging waste management units, equipment malfunctions, and unenclosed or partially sealed wastewater treatment units may lead to previously undetected BWON compliance problems.

EPA inspectors are deploying OGI technology to produce real-time images of emissions based on the infrared signatures of VOC vapours. OGI cameras can detect leaks faster than traditional handheld vapour leak detection instruments as specified in the BWON rule.

Using traditional EPA inspection methods, intermittent leaks from infrequent pressure fluctuations inside enclosed units were difficult to detect. EPA inspectors often spent days on-site at operating facilities, visually inspecting and measuring benzene emissions at individual potential leak points using handheld VOC analysers based on flame ionisation or photoionisation technologies. Now, however, OGI cameras can be trained on specific units to detect intermittent leaks from multiple points over time. As a result, more sites are being inspected and more leaks are being detected.

New settlement requirements

The EPA’s new OGI leak detection strategy aligns with its stricter enforcement of the existing BWON standard for no detectable emissions (NDE) from waste management units. Even plants that completed previous consent decree requirements may face the possibility of a new consent decree. The three refineries that have signed BWON consent decree settlements stipulating significant BWON requirements all had previously established BWON compliance programmes.

New BWON consent decrees may require facilities to invest in new benzene strippers or wastewater treatment units, to upgrade monitoring systems or to improve operational practices. Significant increases in capital and operational costs are possible, particularly for older plants. To avoid punishing stipulated penalties and to mitigate other settlement costs, operators may need to meet aggressive timelines for implementing project engineering, wastewater unit replacement, upstream benzene removal unit design and installation, and stringent new leak detection and repair practices.

Wastewater NDE challenges

For facilities that rely on benzene removal in wastewater treatment plants, the new BWON settlements may also result in major capital projects. For example, one common challenge is achieving consistent NDE compliance for BWON wastewater management units. Improving wastewater unit NDE compliance is a top proactive strategy for facilities wanting to minimise the risk of BWON enforcement or reduce settlement compliance costs.

Unfortunately, meeting the EPA’s new NDE expectations is inherently difficult for older wastewater units. Some older and commonly installed separators, tanks, and other unit types were not designed to prevent detectible emissions across the entire operating pressure range.

OGI cameras can detect intermittent vapour leaks from relief valves, overhead vapour collection systems, seam gaskets, and many other potential leak points. Fixing one component may shift leaks to other components. Many older units need detailed NDE assessments to understand the fundamental leak drivers and develop effective NDE solutions, which may include replacing entire units. The EPA has been sceptical about traditional strategies to find individual leaks and fix them, and OGI technology gives the agency a much more efficient way to identify units that do not maintain long-term compliance with the NDE standard.

Benzene strippers and other upstream treatment

New settlement requirements are driving upstream benzene wastewater treatment and removal projects. For example, the EPA has recently required new or improved upstream benzene removal as a means of reducing VOC leaks from downstream wastewater units, especially if some older leak-prone units will not be replaced.

Facilities that previously did not require benzene stripping prior to wastewater treatment may be required to implement benzene stripping or other expensive capital upgrades to enhance removal efficiency, integrate vapour recovery systems or even implement secondary treatment methods to meet stricter benzene removal targets.

Removing benzene from process wastewater upstream of the treatment train has been considered a good practice following EPA’s earlier BWON enforcement campaigns. However, new BWON settlements contain stricter treatment and reliability requirements for strippers and flash columns, meaning that older upstream removal units may not achieve the reliability or removal efficiencies needed to comply. Some facilities with existing benzene strippers may be required to install improved upstream capture or removal technologies.

Unique solutions require multidisciplined approach

Developing the most economical solution will require a comprehensive look at multiple options. Evaluation of components and pathways for benzene removal will certainly be tailored to account for the unique operating profile of each refinery or chemical facility. These will not be plug-and-play solutions. Schedule requirements may not tolerate typical sequential option evaluations and gated engineering studies.

There are multiple ways to combine more upstream treatment options, like benzene strippers or flash columns, with wastewater treatment reconfigurations and individual wastewater unit projects. The multiple options and compressed schedule create challenges for aligning the team strategy and negotiating effectively.

Before meeting with these agencies, company stakeholders should align on a clear plan backed by modelling data, studies, and rigorous analysis. The goal is to deploy capital properly, following an economical plan to resolve compliance concerns with the EPA. Meeting the goal will depend on effective, durable partnerships between internal teams and trusted suppliers.

The process of developing a comprehensive and economical solution will be complex. Process engineering for unit operations and wastewater systems, niche BWON regulatory analysis, project scheduling/estimating, and project execution experience are only a few of the critical disciplines needed. When every decision counts, selecting an experienced, multidisciplined partner with a proven track record may be the first key step toward a successful outcome.

This article was written by Ryan Kirkland, Donald Leigh, and Blake Soyars, courtesy of Burns & McDonnell.

Read the article online at: https://www.hydrocarbonengineering.com/special-reports/07032025/evaluating-risk-mitigation-options-for-new-bwon-rule-enforcement-approach/