It comes after an earlier expansion completed in March this year.
Barry Callebaut will now add increased molding, liquid chocolate and compound production capacity.
The company produces milk, dark and white chocolate and compound products at the plant, which was established in 2005.
West Coast population growth
Dave Johnson, CEO and president Americas of the Barry Callebaut Group, said: “Population growth in the West Coast is driving an increased chocolate demand,” which had led to the decision to expand.
Barry Callebaut reported 8.8% sales volume growth in its region Americas, in its full-year results published last week.
The chocolate confectionery market in the region declined 3% over the same period (September 2015 to August 2016), according to market analysts Nielsen.
Barry Callebaut's $20m plant upgrade forms part of the group’s annual Capital Expenditure (CAPEX) of roughly $200m.
The project is due for completion by mid-2017.