Work will begin in October on a massive upgrade to Clearwater Paper's Lewiston site, the Lewiston Tribune reports. The Lewiston-Clarkston Valley's largest employer announced this week that it is moving forward with a $160 million project to build a new chip pulp digester. They received an air permit last week from the Idaho Department of Environmental Quality. The upgrade is expected to reduce the cost of producing paperboard in Lewiston. Currently production costs are the fifth-highest for such operations in North America. A Clearwater spokesman says the project is expected to be completed by September 2017. The upgrade should also reduce the odor from the mill.