MONITOR TOWNSHIP, MICH. — Michigan Sugar Co., a grower-owned cooperative, plans to invest more than $13 million in its flagship processing plant in Bay County. The cooperative intends to upgrade the beet slicing station and juice machines at the plant. The cooperative said new equipment is expected to give the beets a more consistent cut, improve the amount of sugar extracted and boost efficiency. Michigan Sugar Co. operates four facilities and three warehouse terminals in Michigan and Ohio and has 940 year-round employees. The cooperative, which is the third largest beet sugar processor in the United States, annually produces nearly 1 billion lbs of sugar under the Pioneer and Big Chief brand names.