Oakbrook Terrace, IL – April 29, 2013 ‐‐ On April 26th the three companies that own Big Stone Plant ‐ Otter Tail Power Company, Montana Dakota Utilities Co., and NorthWestern Energy ‐ held a groundbreaking ceremony for the plant’s air quality control system (AQCS). Graycor Industrial Constructors is the general contractor for this major AQCS project. "We commemorate this $405 million project that will help us balance our commitment to environmental stewardship with cost effective service for our customers," Mark, Rolfes, project manager, said in his welcoming remarks.

Chuck MacFarlane, President and CEO of Otter Tail Power Company, which operates Big Stone Plant on behalf of the other owners, noted that the plant began commercial operations 38 years ago, on May 1, 1975. "It was built for a cost of $150 million. And it was built to comply in every way with the environmental standards of the day. Since 1975 it has kept pace with increasingly stringent regulations," said MacFarlane, "and with regularly upgraded technologies it is more efficient now than it was when it was built."

MacFarlane said that today’s ceremony marked the launch of a three‐year construction project to install new air‐quality control equipment that will reduce emissions even further to comply with new Environmental Protection Agency and state requirements. "The primary components of the AQCS are the selective catalytic reduction system, a dry scrubber, and baghouse," he said, adding that this equipment "will reduce emissions of nitrogen oxides, sulfur dioxide, and mercury by 80 to 90 percent at a cost more than 30 percent less than alternatives." MacFarlane concluded his remarks by thanking plant employees, supportive communities and policymakers, and the state of South Dakota, among others. He acknowledged distinguished guests including South Dakota Governor Dennis Daugaard and the mayors of neighboring Milbank, Big Stone City, and Ortonville.

"Installing an air‐quality control system is just another step in providing a responsible power source for our customers," said Frank Morehouse, President and CEO of Montana‐Dakota Utilities Co. "I am excited to kick off this project that not only will give the local economy a huge boost over the next few years but serve our customers for many years to come." Bob Rowe, President and CEO of NorthWestern Energy echoed Morehouse’s comments. "This project is possible because of our excellent operating partnership with Montana‐Dakota and Otter Tail. It demonstrates the commitment that we all have to this facility, the community, the environment, and especially our customers," he said. "Big Stone has served our customers for almost 40 years and, with this upgrade in technology, it will be ready to serve for many more years."

About Graycor Industrial Constructors Inc.
Graycor Industrial Constructors Inc. is a leading provider of construction services to clients in the power, process, and metals industries throughout North America. To learn more about Graycor Industrial Constructors, visit www.graycor.com.

About the Graycor Companies The Graycor Companies provide industrial and commercial construction services as well as industrial maintenance technologies, throughout North America and to select clients worldwide. As an industry leader, Graycor commits to safe work environments, demands project excellence and rewards passion for performance. Established in 1921, Graycor functions under four major operating units – Graycor Industrial Constructors Inc., Graycor Construction Company Inc., Graycor Blasting Company Inc., and Graycor International. For more information on the Graycor Companies, visit www.graycor.com or call 630‐684‐7110.