Maryland Electric Utility Must Pay Millions For Wastewater Violation

Wastewater discharge violations at the two largest coal-fired power plants in Maryland will cost electric utility company NRG Energy a significant chunk of change.

According to the state, the Attorney General has entered into a Consent Decree on behalf of the Maryland Department of Environment with NGR for nitrogen exceedances at the Chalk Point and Dickerson electric generating stations. As part of the consent decree, NRG will pay a $1 million penalty and will implement $1 million worth of supplemental environmental projects designed to produce lasting nitrogen load reductions to the Patuxent and Potomac River sheds.

“Power plants have a responsibility to keep Maryland's rivers, skies, and lands clean for all," said Secretary of the Environment Ben Grumbles, in a press release. “This strong enforcement action includes a stiff penalty, improved technology at the plants to prevent nitrogen pollution, and significant investments in projects to protect the health of our priceless Potomac and Patuxent rivers.”

The nitrogen exceedances may be due to the electrical company installing the wrong type of wastewater treatment technology, reports Power Magazine.

The plants were using flue gas desulfurization (FGD) scrubbers, as required by the state’s 2007-enacted Healthy Air Act, and employed sequencing batch reactors (SBRs) to treat FGD wastewater and water from gypsum collection systems at the plants.

“The technology was well established at the time for treatment of municipal sewage, but it had rarely been used to treat power plant waste streams. It essentially uses bacteria, in the form of a sludge bed, that are suspended and cycled between aerobic and anoxic conditions in order to remove nutrients in the wastewater, including nitrogen and phosphorous,” reports Power Magazine.

The consent decree alleges that at both the Chalk Point and Dickerson plants the microbes used to remove nutrients in the wastewater died, causing an exceedance in annual limits for total nitrogen over the last six years.

GenOn, a subsidiary of NGR that operates the two plants, claims that the wastewater difficulties were complicated by the extended dispatch-based shutdown periods stemming from changes in power consumption, cheap natural gas, and the increased cost of operating the control devices on the coal-fired units, reports Power Magazine.

The company alerted state regulators of its operational difficulties, asking in 2010 for both plants’ discharge permits to be reopened for a revision of the annual nitrogen-loading limit. The state did not officially act on the request.

GenON also says it has implemented a number of measures to improve the wastewater treatment plants, including modifying capabilities for pH adjustment of the clarifier effluent and using a new strain of microbes that can better tolerate the high chloride levels associated with the FGD waste stream.

Due to the consent decree the company plants to install and operate ammonia, nitrate, and oxygen uptake measurement instruments in the SBR vessels at both plants’ wastewater systems. It will also install and operate membrane ultra-filtration technology at both plants. The consent decree requires NRG to submit project proposals to the Maryland Department of Environment for its review and approval.