Current and former owners and operators of a cement plant have come to an agreement with federal and state environmental regulators over what federal officials call "chronic air pollution violations" at the facility.

Cemex, the former owner of the plant, agreed in a proposed consent decree to pay a civil penalty of nearly US$1.36m to federal authorities and the Michigan Department of Environmental Quality, according to the office of United States Attorney in Grand Rapids.

The current owners of the plant, St. Barbara Cement Inc. and subsidiary St. Mary’s Cement Inc., must install a baghouse filtering system estimated to cost more than US$11m. The defendants must also spend at least US$6.2m to install an indirect firing system for the factory’s kiln, which is expected to reduce emissions of particulate matter, sulfur dioxide, and nitrogen oxide.

The Charlevoix plant operated since the 1960s as Medusa Cement Co., before selling to Southdown Inc. in 1998. Cemex then purchased the company in 2000, and it was sold again in 2005 to Votorantim which is the main shareholder in St. Mary’s Cement of Canada.