Emissions, Policy & Regulations, Water Treatment

316(b) Technical Challenges

Issue 11 and Volume 118.

By Douglas A Dixon and David E. Bailey, Electric Power Research Institute

Editor’s note: This is the second of a two-part series on the U.S. Environmental Protection Agency’s 316(b) rule, which will affect more than 500 power plants in the U.S.

A turnkey installation of a refurbished thru-flow traveling water screen at a coal-fired power plant
A turnkey installation of a refurbished thru-flow traveling water screen at a coal-fired power plant. The screen was removed from the well and shipped to Atlas Manufacturing for a complete restoration and returned and installed with a new screen warranty applied. Photo courtesy: Atlas Manufacturing Company Inc.

There are numerous technical and schedule challenges associated with implementation of 316(b). The following are a few of those challenges, particularly those on the immediate horizon:

  • Many facilities with actual intake flows > 125 MGD will need to begin entrainment characterization studies in 2015. Collecting and identifying early life stages of fish and shellfish are technically challenging. Demand for qualified consulting services may exceed existing capacity. The rule also requires identification of species “to the lowest taxon possible.” (e.g. the lowest plant or animal classification grouping) It is unclear how that will be implemented since it is not uncommon to see as many as 50% of entrainment samples characterized as “unidentified.” The new method of DNA bar-coding can identify species to the lowest taxon possible, however the technique is new, relatively expensive and those with the requisite skills are limited. It is unclear if EPA considered DNA bar-coding relative to identifying eggs and larvae to “the lowest taxon” possible.
  • Two streamlined approaches (compliance alternative 5 using modified traveling water screens and 6 using an integrated system of technologies) require conducting a 2-year optimization study with sampling occurring at least monthly. The rule is suggestive of possible approaches for optimizing traveling water screens and fish return systems, however approaches for optimizing an integrated system of technologies are absent. Implicit in the idea of optimization studies is the notion that impingement is chronic, however impingement characterization studies have consistently demonstrated that impingement is episodic, occurring at irregular intervals. For many months of the year impingement can be zero. When it does occur it is typically dominated by fragile species (e.g., Gizzard Shad, Alewife, Bay Anchovy) and numbers of non-fragile species can be very low (maybe 5, 10 or 25 fish per day of a certain species). It would be difficult to detect significant differences in an operational parameter (e.g., screen rotation speed, pressure wash) with very small sample sizes. Water quality (e.g., temperature, suspended solids, dissolved oxygen) and the health of fish may also factor into the optimization assessment. While not mentioned in the rule, conversations with EPA have indicated that they do not see any problem in addressing this issue by using hatchery fish in an experimental design that could serve as a proxy for actual field monitoring. The challenge for applicants will be to develop a creative experimental design, such as using hatchery fish, and Directors will need to be understanding and flexible in their review and acceptance of optimization studies and results in order to get meaningful assessments. In addition to these experimental challenges, traveling water screen and fish return system components will be costly and/or difficult to change post installation.
  • While EPA “relaxed” the implementation schedule from the one in the proposed rule and tied information submittals to the NPDES permit cycle, completion of all the requisite studies, particularly for those facilities also in-scope for entrainment compliance, will be extremely challenging and taxing of the qualified existing in-house staff and available consulting services.
  • Economic social cost analysis (the “r10” study for entrainment compliance) is a complex issue and those with the requisite skills to complete the studies are very limited. Compliance costs to industry are not social costs. Social costs include the cost of environmental impacts caused by a potential BTA (e.g., noise, air pollution, habitat loss, salt drift, increased carbon emissions, and water consumption associated with closed cycle re-circulating systems) and the increased cost of electricity to the consumer as a result of the compliance cost. Downtime associated with a potential retrofit of a closed cycle system and its impact on energy reliability is an additional complexity that will challenge benefit analysis. It is also unclear how non-use benefits will be assessed or quantified. EPA did not use its “willingness-to-pay” (WTP) survey results to support quantifying the rule’s benefits, however EPA intends to consult with its Science Advisory Board on how the results can be used in the future. It is possible the WTP results could return in some form in the future. The rule also does not require the Director to require a facility owner or operator to conduct or submit a stated preference survey to assess benefits. Whether such a study is conducted is left to their discretion, and it remains to be seen how this would be used.
  • EPA’s requirement for peer review of the three entrainment-related “r” studies (r10 through r12) was included to reduce the report review burden on Directors. The requirements or qualified peer-reviewers should probably include an understanding of how power plants operate, how fish and shellfish eggs and larvae are spatially and temporally distributed and develop, how fish protection technologies work and perform, and how economic benefits are calculated. The pool of potential reviewers who possess this knowledge and can also be an independent and un-biased is not large.
  • Most of the industry is expected to select the streamlined fish protection-modified traveling water screen compliance option (i.e., option 5) for impingement control. The fine-mesh form of these screens may also be the predominant technology identified as BTA for entrainment control where Directors determine control of entrainment mortality is required. EPA estimates that 93 percent of the electric power industry and 73 percent of the manufacturing industry in-scope of the rule currently use traveling water screens. EPA further estimates that 29 percent of the industry will select this streamlined compliance approach. When installed and optimized (a challenging study in itself), these screens will need to be operated continuously and monitored carefully for debris clogging – basically a significantly heightened level of O&M. Practical industry experience indicates that these modified screens can be effectively maintained, including fine mesh (there are two U.S. nuclear plants with fine mesh ≤ 1.0 mm operating since the late 1980s and another 10 to 12 fossil plants with screen mesh ≤ 2.0 mm). Fine mesh screens are also common in Europe. There are still concerns about the long-term viability of these screens when operated continuously as well as concerns about the debris handling ability of fine mesh. While a challenge for developing new O&M best practices, practical experience suggests the challenge can be met.
  • While the EPA dropped requirements to protect entrapped fish, they still require they be counted as mortality as part of Compliance Options 5, 6 and 7. It is unclear how someone can count entrapped fish. While they may not be able to escape, entrapped fish and shellfish can lead a sustainable life for many years including spawning. Theoretically, tag and release studies, acoustic cameras, sonic devices, remotely operated cameras and scuba divers can be used to estimate the size of entrapped fish and shellfish populations, but it would be very difficult to use these methods in some intake configurations such as the header pipe for velocity caps. An absolute count can also be made by using rotenone to kill and count entrapped populations. While this method seems counter-productive, the EPA already considers entrapped fish as 100 percent mortality.

These are some of the known challenges, and many more are likely to develop as compliance is implemented. The challenges will not be limited to power plants and other manufacturers. Permit Directors will be similarly challenged in understanding the application information, managing the peer review results, making BTA decisions, coordinating EPA oversight, plus the additional oversight and recommendations of the Services relative to protecting T&E species – and typically with existing staff and flat budgets.

EPA Guidance and Litigation

EPA does not plan to issue any formal guidance to support the rule’s implementation, however it does plan to respond to “frequently asked questions” (FAQs) and post the responses to its website (see introduction for link). They have also indicated they may have conference calls with Permit Directors and they plan, assuming travel budgets are available and management approval is received, to attend technical conferences to make presentations and engage in attendee dialog. . Many required studies in the rule, such as the de minimus waiver for impingement compliance and the two-year Screen and Technology Integration Optimization studies for compliance options 5 and 6, lack procedural or content information. In lieu of guidance for such key required studies, permit applicants will need to develop approaches on their own and seek approval from their Permit Director.

The window for filing litigation starts following the rule’s official publication in the Federal Register. The rule’s promulgation date is 14 days after it appears in the Register, then litigants have 10 days to file appeals which will go into a lottery for selection of the court that will hear the litigation. Final petitions are due 120 days after promulgation. Environmental groups who oppose the lack of a national uniform BTA standard and a requirement for retrofit of closed cycle re-circulating systems have publically stated their intent to litigate. The rule’s provisions remain in force until litigation is decided, unless a stay is issued. Relative to the 2004 Final Phase II rule for existing facilities, litigation was decided in 2007 and that rule was remanded shortly thereafter and replaced by permit decisions based on Permit Director’s BPJ. That approach is replaced by this EPA regulatory action.


Douglas A. Dixon is a Technical Executive and Program Manager of EPRI’s Fish Protection Research.

David E. Bailey is a Senior Technical Leader managing EPRI’s closed cycle cooling retrofit research and 316(b) compliance support.

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