The venture will be 51 percent owned by Bunge, 29 percent by Itochu and 20 percent by STX.
"The venture plans to build a grain export elevator facility with an annual capacity of more than 8 million tonnes of grains by 2011," STX Pan Ocean said in a statement.
The project, which will include a shuttle train unloading system and capability to unload barges from the Columbia river, will be the first export terminal built in the United States in more than two decades, Bunge said in a separate statement.
STX, which carries over 20 million tonnes of grain annually, is seeking to bolster its grains shipping business with its first agribusiness investment.
South Korea, which depends heavily on imports of almost all grains, is the world's No.3 corn importer and buys more than 90 percent of its corn requirement from the United States.