The Texas-based company that owns a coal-fired power plant in Maryland announced it will retire the facility’s three generating units, which have been in operation for about 60 years.

GenOn Holdings said Units 1, 2, and 3 at its Dickerson Generating Station will be closed due to “unfavorable economic conditions and increased costs associated with environmental compliance.” GenOn in a May 15 news release said that “deactivation of the coal-fired units is subject to a 90-day reliability review period by PJM,” after which the company “

The PJM Interconnection website shows the units’ requested deactivation date as Aug. 13. PJM is the regional transmission organization (RTO) that oversees the movement of wholesale electricity in Maryland, 12 other states, and the District of Columbia. The RTO has experienced the closure of about 30 GW of coal-fired generation over the past several years, according to POWER research, with as much as 80% of that generation replaced by new natural gas-fired units.

PJM lists nearly 6 GW of total generation capacity in its territory as scheduled for closure in the next three years, with about 92% of that coal-fired capacity.

The three coal-fired units at Dickerson together have about 540 MW of generation capacity. The company in a May 19 regulatory filing under the federal Work Adjustment and Retraining Notification Act said as many as 63 workers at the plant could lose their jobs as of Aug. 1 due to the closure. GenOn said it would provide severance packages and healthcare coverage to the impacted employees.

The three units at Dickerson came online in 1959, 1960, and 1962, respectively. GenOn will continue to operate two natural gas-fired units and one oil-fired unit, totaling 312 MW of generation capacity, at the site.

The Dickerson plant, located in Montgomery County on the Potomac River, was built by the Potomac Electric Power Company. That group, better known as Pepco, sold the facility to Southern Co. in late 2000. The plant was included in Southern Co.’s spinoff of Mirant in 2001. Mirant merged into GenOn Energy in 2010; GenOn then merged into NRG Energy in 2012.

The discharge channel at the plant was used as a canoe and kayak training course for the U.S. team that competed in the 1992 Olympic Games in Barcelona, Spain.

The plant completed a $1.1-billion upgrade to its emissions system in late 2009. NRG in 2013 said it planned to decommission the coal-fired units by 2017, due to Maryland’s emissions regulations, but in 2015 said it would delay that action until 2019. NRG in early 2016 then said it would continue to operate the units.

GenOn, which filed for Chapter 11 bankruptcy protection in 2017, also at that time split from NRG and became a standalone company as part of its reorganization. GenOn took back several power plants from NRG.