The mine, operated by the company’s Wilson Creek Energy subsidiary, sells met coal to both domestic and export customers. The new unit, however, is expected to produce coal primarily for sale in the United States.

Through three quarters of 2014, Casselman produced about 200,000 tons of coal, placing it on track to meet or exceed last year’s total of 248,532 tons, according to the U.S. Mine Safety and Health Administration. However, output ticked up in the third quarter to 96,429 tons, up from 70,252 tons in the second quarter.

Eventually, the addition of the second unit should enable Wilson Creek to double Casselman’s annual production to about 500,000 tons, according to COO Keith Dyke.

Earlier this year, Corsa, headquartered in Toronto, purchased PBS Coals from Russia’s OAO Severstal for $60 million. Following the acquisition, Corsa idled one unit at the three-unit Kimberly Run underground met coal mine in Somerset County, Pennsylvania, because its economically mineable reserve had played out.

Dyke said some of the idled unit’s production will be picked up by Casselman. Kimberly Run’s other two units remain in operation.

In a technical report prepared in October on the PBS acquisition, Corsa said PBS controls approximately 123.34 million “measured and indicated in-situ” coal resource tons. Of that total, 86% are measured and 14% are indicated.

The report said PBS controls about 37 million tons of “proven and probable” coal reserves, of which 80% are proven and 20% are probable. Of the total coal reserve, about 2.84 million tons are recoverable through surface mining and 34.16 million tons are recoverable through underground mining.