Aquatic Biology Project

Burns & McDonnell is performing a comprehensive demonstration study to show that a power generation facility using once-through cooling in its steam condenser complies with current regulations.

As part of the comprehensive demonstration study, Burns & McDonnell is performing a two-year study to quantify the fish and shellfish community that would be vulnerable to entrainment and impingement. Organisms that could be entrained are those small enough to fit through the intake screens, such as the larval stages of fish and mussels. Juvenile and adult fish could become trapped on the screens. Larval fish are sampled using a 0.5-m diameter, 500-mm mesh plankton net at four stations along a transect across the Mississippi River.

Burns & McDonnell scientists are collecting replicate samples at the surface, mid-depth, and bottom levels at each station. A flow meter mounted in the net provides data for determining the amount of water passing through. Morning and evening samples are collected weekly from May through September.

In February 2002, the U.S. Environmental Protection Agency finalized new regulations implementing Section 316(b) of the Clean Water Act for facilities with new cooling water intake structures. The purpose of Section 316(b) is to minimize the impacts to fish and shellfish from entrainment and impingement by cooling water intake structures. New facilities are required to reduce impacts to the level obtainable by a cooled-loop cooling system (i.e., cooling towers) in a water withdrawal rate of less than 0.5 feet/second. Facilities that propose to use other cooling technologies are required to conduct a Comprehensive Demonstration Study to demonstrate that they will achieve the same reduction in entrainment and impingement.

Our client plans to replace a 50-MW, coal-fired generation station in Cassville, Wis., with a new 280-MW, coal-fired facility. Space and topography will prevent the use of cooling towers.

Burns & McDonnell scientists are using several methods to collect fish. A drag seine is used to collect smaller fish. A boat-mounted electrofisher is used to collect larger fish. Hoopnets are set in offshore areas too deep to be seined or electrofished. The fish collected by electrofishing and hoopnet techniques are identified, measured, and returned to the river.

In the first year of the study, mussels were collected by scuba divers. Quadrates, 50 by 50 centimeters, were excavated at 3-meter intervals located upstream and downstream. The mussels were identified, measured, and returned to the river. The collected data were used to create a map of mussel distribution in the new cooling water intake area.

Other data collected in the first year of the study included bathymetric cross-sections and substrate composition of the river in the vicinity of the power plant.