Generating and Manufacturing facilities using modified traveling water screens to meet cooling water intake compliance are required to complete a two-year Impingement Technology Performance Optimization Study in an effort to optimize the screens operation to minimize fish mortality.

The U.S. Environmental Protection Agency (EPA) requires Impingement Technology Performance Optimization Studies (or optimization studies) under the Clean Water Act (CWA) § 316(b) regulations (Rule). This applies to all existing facilities that withdraw water from waters of the United States as a design flow of greater than 2 million gallons per day and using 25% of the water for cooling. The Rule requires applicable facilities to use the best technology available (BTA) to reduce impingement mortality of fish at these cooling water intake structures. 

It is anticipated that most facilities will select Compliance Alternative 5 which identifies fish-friendly modified traveling water screens (MTWS) defined at § 125.92(s) as BTA for reducing impingement mortality at water intakes. 

The Verdantas Flow Labs (Flow Labs) Team is currently assisting clients with the selection of an appropriate MTWS vendor and developing engineering specifications which include the key civil, mechanical, electrical, and instrumentation aspects to ensure a successful MTWS installation. As part of this process, our experienced engineers are supporting the modeling, design, and construction of fish return systems necessary for a fish-friendly MTWS installation. The Flow Labs team has conducted numerous laboratory and field studies to assess mortality associated with fish collection and fish return systems, making us the true industry leaders in the design of fish-friendly MTWS and fish return system installations.

Once installed, an optimization study must be performed to determine the optimal configuration and operating conditions of the MTWS so that it is consistently protective of fish and other aquatic organisms. We have been at the forefront in helping clients and industry leaders understand the requirements and process of optimization studies. The Flow Labs team is currently contracted to support optimization studies at the Ameren Labadie Energy Center on the Missouri River and the Con Edison East River Generating Station on the East River in New York City. 

Our expert staff developed study plans for the projects, incorporating key elements required by the Rule. We are also drawing from our staff's knowledge and experience gained through the successful completion of one of the first optimization studies in the country on the Upper Mississippi at Dairyland Power’s John P. Madgett Generating Station.  Some of these factors include screen rotation speed, spray wash pressure, screen rotation operation (continuous and near-continuous) and transfer efficiency (i.e., the proportion of fish captured by the fish buckets that are transferred to the fish return trough).

The Flow Labs team has been responsible for all aspects of these optimization studies for our clients, including project management, development of the study plan, construction and installation of the fish collection and holding systems, conducting monthly sampling throughout the two-year optimization period, developing sampling reports, and leading the presentations given to permit Directors. 

The objective of an optimization study is to meet the Rule requirements in reducing fish impingement mortality, while also maintaining flexibility in the operation and maintenance of the cooling water intake for the facility.