|Side-by-side testing of different screens was performed at Alden Research Laboratory in Worcester, Mass. All photos courtesy of EPRI|
By Sharryn Dotson, associate editor
Though the Clean Water Act Section 316(b) rule was not finalized as scheduled on Jan. 14, there are still steps that plant owners and manufacturers can take to prepare for the rule’s passage.
Section 316(b) of the Clean Water Act requires that the location, design, construction and capacity of cooling water intake structures reflect the best technology available for minimizing adverse environmental impact, according to the U.S. Environmental Protection Agency (EPA)’s website. Due to the government shutdown in October, the EPA was unable to finalize the rule by November 4 as originally agreed. Plant owners have eight years from when the rule is finalized to be in compliance with the impingement requirement. How long it will take to comply with the entrainment requirement will be determined by how long the project takes to complete.
The rule focuses on two parts: impingement and entrainment. The Electric Power Research Institute (EPRI) is currently evaluating and developing technologies that will help lower the amount of fish and their larvae or eggs getting impinged by or entrained in the cooling water intake systems. Douglas Dixon, technical executive and program manager EPRI’s fish protection program, says the organization’s research into the rule focuses on four areas: technology, biological sampling methods, cost-benefit analyses and thermal discharge.
“One of the key things we have found through our research is that the ways to reduce the impact on marine life are site-specific,” Dixon said. “What you can do at one plant would not be applicable at another.”
Some of those site-specific factors include plant location, species of fish involved, how the plant operates, the debris that it has to filter, the hydraulics of the location and the temperature of the water.
Dixon said research has shown that closed-loop cooling is as close to a broad technological fix of reducing fish and shellfish impacts as any available technology, but it has its own shortcomings and is not a workable solution for many power plants.
“Problem is that while it works, EPRI has done research to document that it would be expensive and highly disruptive of our electric power system and the ecological benefits would be debatable.”
EPRI’s national closed-cycle cooling analysis estimated $100 billion to retrofit 450 power plants four years ago. Those costs are now estimated to be at least $50 million per plant. The system could cost $2 billion or more per plant, particularly for nuclear facilities, Dixon said.
Other technologies include a velocity cap that can only be used by plants located near deep water, such as plants along the Great Lakes, the Pacific coast, the New England coast and in southern Florida. “By moving it offshore, you also have a reduction in the loss of entrainable life like eggs and larvae,” Dixon said. “It has a high performance, but its limited to certain plants.”
Other technologies being researched are variable speed water pumps, fine mesh traveling screens and fish return systems that work similarly to a water slide at an amusement park.
|Bilfinger Technologies contributed its fine-mesh pilot screen for testing at the Alden Lab. It is not available commercially in the U.S.|
Many companies are working with EPRI to prepare for the rule, Dixon said. “There is going to be a high demand for technological support, but the needed expertise may not be available,” Dixon said. “They’re starting to get their contracts together, requests for proposals, educating their own staff about how to comply with the rule.”
Some states are being proactive with their permit requirements, and some have already established what they consider to be the best available technology. The state of California, for example, is requiring Pacific Gas & Electric to look into converting its intake system to closed-loop cooling at the Diablo Canyon nuclear power plant, according to Jason Eichenberger, PE, ENV SP, a senior civil engineer with Burns & McDonnell. Some utilities are leaning toward a fish handling system on the intake screen or traveling screens.
“We are working on one project where they have permit requirements to install wedge wire screens,” Eichenberger said. “We’re putting together a compliance plan for submittal to the state agency and we’re currently proceeding down the path to do the design based on the proposed rule.”
A wedge wire screen is a cylindrical screen that is placed in the river in front of the intake structure, Eichenberger said. It’s a passive screen that gives enough surface area so you’re in compliance with the impingement criteria. Cooling towers could bring a facility into compliance with the entrainment criteria, but they are costly and can impact plant performance by raising back pressures and creating other issues.”
Consulting companies and EPC firms are advising clients to begin lining up suppliers before there is a rush on the projects, and Burns & McDonnell is preparing cost-analysis studies so clients have an idea of how much such a future compliance project could cost. “Clients have been calling and asking how much is it going to cost to retrofit their intake system, Eichenberger said. “With impingement, compliance strategies are relatively clear. With entrainment, that is not the case. It may come down to the state level and what is required on a site-specific basis.”
Jack Tramontano, environmental group manager and program manager for Section 316(b) with URS Corp., said waiting for the rule to be finalized has put everyone in a holding pattern.
“It’s been kind of a frustrating process because of the numerous delays,” he said. “Also, the Notices of Data Availability (NODA) published in June 2012 indicates that EPA is considering some significant changes to the draft rule. It’s difficult for facilities to plan ahead with all of the uncertainty.”
|A close up of a fine mesh screen undergoing testing. Photo courtesy of EPRI|
He echoes that many plant owners are concerned about the costs of retrofitting or modifying their cooling water intake systems.
“Finding ways of complying with minor upgrades to current intake technology is one way to avoid a lot of capital costs,” Tramontano said. “Otherwise, because there is so much uncertainty, most are in a wait-and-see attitude right now.”
That uncertainty has added up to a lot of unanswered questions on how to comply with the rule, including whether closed-cycle cooling will be considered best technology available or if additional fish protection will be necessary.
“Larger plants that have been designed with closed-cycle cooling may still have to install modified Ristroph screen with fish returns for impingement compliance, according to draft regulations,” Tramontano said. “Those who thought that with closed-cycle cooling that they were okay or thought that they wouldn’t have to apply new technologies may now have to apply them. However, EPA may be creating alternatives for facilities with very low impingement levels or mortality rates which should be applicable to facilities with cooling towers. This approach will require impingement sampling, but could allow the facility to avoid a costly intake system upgrade.”
The finalized rule could include a streamlined, or pre-approved, approach based on modified Ristroph-type traveling screens for impingement, a credit for protective measures already in place, allowing local permitting agencies to determine through screen velocity compliance, modifying the compliance schedule for impingement and entrainment and modifying monitoring requirements, Tramontano said. “We have heard from secondhand sources that EPA has adopted many of these changes in the final rule.”
Tramontano said that he is advising clients to collect and organize historic studies and other information on their plant’s cooling water intake systems. “Many of the people we work with in the industry, who have the institutional knowledge of 316(b) at the facility are reaching retirement age or have already retired.” He suggests that companies do a gap analysis of the information needed to comply with the rule and know where that information is before that institutional knowledge is lost.
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