In response to updated U.S. Environmental Protection Agency regulations, entrainment studies are under way at Basin Electric Power Cooperative’s coal-fired Leland Olds Station, located near Stanton, N.D.
Entrainment is where organisms that live in the water are brought through the traveling screens located in front of the water intake, circulated through the facility’s condenser and returned to the water body, Basin Electric noted in a Sept. 11 statement.
Leland Olds Station is made up of Unit 1 (222 MW) and Unit 2 (447 MW), and it burns North Dakota lignite.
“We’ve hired consultants that on a bi-weekly basis sample the waters that are withdrawn from the Missouri River and pass through the water intake screens. The fish larvae and eggs are collected and individual species will be counted and identified in the laboratory,” said Cris Miller, Basin Electric senior environmental project specialist. “Between April 2015 and October 2016, 26 surveys are being conducted to determine the magnitude of impacts on marine life in the Missouri River.”
Section 316(b) of the Clean Water Act requires the EPA to issue regulations on the design and operation of intake structures in order to minimize impacts to organisms that are present in the water body. The rule was first enacted into law in 1972; however, it has been litigated numerous times by both industry and environmental groups. The 2014 version of the rule requires additional biological studies at the Leland Olds Station beyond previously required studies.
Entrainment and impingement studies at Leland Olds Station will characterize the facility’s impact to organisms that reside in the Missouri River. The results of the studies will assist regulatory agencies with determining what technologies are required to achieve adequate protection when considering both costs and benefits.
“The intake screens have three-eighth-inch openings. The entrainment study determines the quantity and speciation of the various eggs and larvae that pass through the screens in the cooling water flow,” Miller said. “As a simplifying assumption, EPA assumes that any organism present in the once-through circulating water is mortally impaired. However, it appears that in reality, a significant portion survives.”
According to Miller, a 2006 study determined de minimis levels of fish impinged at Leland Olds Station, though EPA never made a final determination due to the rule being remanded in 2007.
Leland Olds Station utilizes once-through cooling, which means water is withdrawn from the Missouri River, pumped through the plant’s condensers to cool steam back to liquid, and then discharged back to the Missouri River. Leland Olds is the only Basin Electric facility that uses once-through cooling. Miller, however, said that both the Antelope Valley Station, located at Beulah, N.D., and the Laramie River Station, located at Wheatland, Wyoming, are required to respond in a more limited fashion to the requirements in the current version of the 316(b) rule due to their withdrawal of water from a surface water body in excess of two million gallons per day.