While the Wanganui plant produces solely milk powder, the Miraka company near Taupo produces powder and long-life milk.
Earlier this year the Waikato Times asked OCD chairman Laurie Margrain if the company - the country's second biggest behind Fonterra - had any expansion plans.
"We're very clear what our options are, and we'll make a decision at what we think is at a prudent time," Mr Margrain told the paper.
He said the company could expand at its existing sites or build new. Apart from the Wanganui plant, OCD has milk powder plants at Waharoa near Matamata and Awarua near Invercargill.
The company is building a multimillion-dollar expansion at its Southland factory to make room for a new dryer, understood to double production at the plant. It has three plants with a combined capacity of handling about 900 million litres of milk annually and exports to 50 countries.
OCD is a private company, majority-owned by New Zealand food group Talley's. It was formed in 2001 to take advantage of opportunities within the dairy industry following the passing of the Dairy Industry Restructuring Act (DIRA).
Its strategy has been to site its factories in the major dairying areas of New Zealand and it is now supplied by more than 500 dairy farmers.