United Grain Corp. is proposing a $72 million expansion of its Port of Vancouver USA grain terminal that could nearly double the port’s already sizable grain exports.

Port commissioners on Tuesday signed off on demolishing three buildings on the port’s Terminal 2, paving the way for Portland-based United Grain to expand its grain terminal on that site.

Mitsui & Co. Ltd., the Japanese trading house that owns United Grain, said in a news release last month that the project should be complete by summer 2012.

From the Portland Business Journal