Tuesday, March 11, 2014


The Clean Water Act Section 316(b) rule was not finalized on Jan. 14 as scheduled. Due to the government shutdown in October, the EPA missed a November 4 deadline, so it was extended to January. EPA will release the final rule "as soon as possible."

Section 316(b) of the Clean Water Act requires that the location, design, construction and capacity of cooling water intake structures reflect the best available technology (BAT) for minimizing adverse environmental impact.

The rule focuses on two parts: impingement and entrainment. 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.

Despite pressure from environmental groups and the courts, the EPA decided not to mandate closed-cycle cooling for entrainment in the draft rule.

The Center supports Wedgewire Screens as BAT

EPRI's national closed-cycle cooling analysis four years ago estimated $100 billion to retrofit 450 power plants. Those retrofit costs are now estimated to be at least $50 million per plant, or $22.5 billion total. The system itself could cost $2 billion or more per plant, particularly for nuclear facilities.

Some states are being proactive in establishing permitting requirements, including 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.

A wedge wire screen is a cylindrical screen that is placed in the water in front of the intake structure. 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.

Larger plants that have been designed with closed-cycle cooling may still have to install modified Ristroph screen with fish returns for impingement compliance.

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 BAT through screen velocity compliance, modifying the compliance schedule for impingement and entrainment and modifying monitoring requirements.

Section 316(b) of the Clean Water Act would affect roughly 670 U.S. power plants. It would require plants that draw more than 2 million gallons a day and use 25 percent of that water for cooling to install the best technology available (BTA) to minimize the mortality of aquatic life. Losses occur when fish and other organisms become trapped (impinged) against water intake structures or sucked (entrained) into cooling systems and exposed to heat, pressure and machinery. The rule requires the best technology to mitigate what it describes as "adverse environmental impact" resulting from entrainment and impingement. The measure would require some power producers to modify cooling water intake structures or construct new cooling towers.

The 316(b) rule was first enacted in 1972 when Congress passed the Federal Water Pollution Control Act Amendments. Since then, the rule has been suspended and rewritten several times in a long and drawn out legal battle between utilities and environmental groups.

The EPA has not performed a single study that shows entrainment and impingement impact fish populations any more than commercial fishing. Adverse impacts have been implicitly or explicitly defined as entrainment and impingement per se, irrespective of whether any adverse changes in populations can be demonstrated or predicted. The 316(b) rule does not provide a definition for "adverse environmental impact."  (Power Engineering, 1/30/2014, Power Engineering, 9/9/2-13)

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