The U.S. Environmental Protection Agency has approved a revision to the Pennsylvania State Implementation Plan (SIP) that addresses an error in the Best Available Retrofit Technology (BART) requirements for Boiler Number 1 of the coal-fired Cheswick Generating Station in Allegheny County, Pa.
EPA said in a notice to be published in the Jan. 21 Federal Register that it is approving the portion of Pennsylvania’s SIP revision addressing the particulate matter (PM) BART requirements under the regional haze program of the Clean Air Act (CAA).
The Pennsylvania Department of Environmental Protection (PADEP) explained in its March 25, 2014, SIP revision that the PM10 BART emission limit of 361 tons per year (tpy) for Boiler No. 1 at Cheswick included in a December 2010 regional haze SIP submission was found to be incorrect during the public comment period for EPA’s proposed approval of the regional haze SIP. The December 2010 regional haze SIP submittal included the 361 tpy PM10 limit because at the time PADEP was assessing the appropriate BART limits, it decided to base the PM10 BART limit on a May 2009 BART review memo for Cheswick which referred to conditions of certain permits for Cheswick as BART, and the review memo listed Cheswick’s potential to emit at 361 tpy. However, PADEP later discovered the PM10 potential to emit included in the May 2009 BART review memo was incorrect and that Cheswick’s permits included a PM10 emission limit of 180 pounds per hour (lbs/hr). The March 2014 SIP revision replaces the incorrect PM10 emission limit of 361 tpy with the correct BART PM10 emission limit for Boiler No. 1 of 180 lbs/hr, which includes condensable particulate matter, but excludes sulfuric acid mist (H2SO4).
EPA said it will take separate action concerning the remainder of the March 2014 SIP revision which included revised BART emission limits for sulfur dioxide and nitrogen oxides. In a separate Jan. 21 notice in the Federal Register, the agency will publish a proposed rule on the SO2 and NOx issue that will be up for 30 days of public comment.
In March 2014, the PADEP submitted a SIP revision to revise the incorrect PM BART emission limit for Cheswick’s Boiler No. 1 and to remove the errant inclusion of the SO2 emission limit of 67,452 tpy and the NOx emission limit of 10,840 tpy for Cheswick’s Boiler No. 1 from the regional haze SIP because Pennsylvania intended the Clean Air Interstate Rule (CAIR) as SO2 and NOx BART for all electric generating units, including Cheswick. In the March 2014 SIP revision submittal, PADEP stated the SO2 and NOx BART emission limits for Cheswick were included in error.
A November 2012 BART review memo explained that Cheswick has stringent pollution controls installed including flue gas desulfurization (FGD) for SO2 control, selective catalytic reduction (SCR) for NOx control, and an electrostatic precipitator (ESP) for PM control. The November 2012 BART review memo also indicated that two separate modeling studies show that visibility impacts from Cheswick are minimal.
Cheswick is owned by NRG Energy (NYSE: NRG). Said the NRG website about the plant: “The Cheswick Generating Station is a fully scrubbed single-unit, coal-fueled generation station located on an 82-acre site in the borough of Springdale, approximately 18 miles northeast of Pittsburgh. Cheswick, which began commercial operation in 1970, operates as a baseload facility. Since the station’s initial commissioning, additional environmental control systems have been installed to comply with more stringent emission requirements. Emissions controls include the flue-gas desulfurization (FGD) system (scrubber) designed to remove at least 98 percent of the sulfur dioxide from the exhaust, as well as reduce mercury emissions, an electrostatic precipitator and flue gas conditioning systems to remove particulate matter and a low-NOx system to reduce nitrogen oxides (NOx) emissions.”