US-based Ash Grove Cement Company has applied for a change to its air quality permit for possible modernisation to its Montana cement facility.

The Montana Department of Environmental Quality is accepting public comment on its preliminary decision to grant Ash Grove a change to its existing permit. The modified permit includes possible modernisation of the facility in the form of a new, more energy-efficient kiln and construction of an overland conveyor for transporting raw materials from a quarry.

Cement production and storage capabilities would also expand along with a drop in emissions with a new permit. After an air quality and impact analysis, DEQ determined that modifications to the plant will require the best available control technology to minimise emissions and to comply with the Clean Air Act.

DEQ projects a decrease in emissions of SO2 and other contaminants under the proposed permit, said DEQ environmental engineer Craig Henrikson.