The U.S. Environmental Protection Agency (EPA) said in a Sept. 18 Federal Register notice that it is making final a Federal Implementation Plan (FIP) to address regional haze in Montana that includes requirements for new emissions controls on the coal-fired Colstrip Units 1-2.
EPA developed this FIP in response to the state’s decision in 2006 to not submit a regional haze State Implementation Plan (SIP) revision. The FIP satisfies requirements of the Clean Air Act that require states, or EPA in promulgating a FIP, to assure reasonable progress towards the national goal of preventing any future and remedying any existing man-made impairment of visibility in mandatory Class I areas. This final rule is effective Oct. 18.
EPA’s notice of proposed rulemaking was published in the Federal Register on April 20. In that notice, it proposed a FIP to address regional haze in Montana for the first implementation period (through 2018) including determinations of Best Available Retrofit Technology (BART) for specific sources.
The FIP includes requirements for new separated overfire air (SOFA) and selective noncatalytic reduction (SNCR) equipment on Colstrip Units 1-2 to control NOx, and lime injection and an additional scrubber vessel for each unit to control SO2. Incidentally, the technology mentioned is the technology evaluated as BART, but EPA said companies can use another technology or combination of technologies to meet established emission limits.
Colstrip is co-owned by PPL Corp. (NYSE: PPL) and other parties. In a section of the Sept. 18 notice, EPA addressed comments received on the proposed FIP, including a comment from PPL and others that the proposed BART at Colstrip Units 1 and 2 for both NOX and SO2 would result in no reasonably anticipated visibility benefit, even assuming that EPA’s emissions reduction estimates and modeling are correct. “We disagree that any controls required by our action must demonstrate a perceptible visibility improvement,” EPA responded. “In a situation where the installation of BART may not result in a perceptible improvement in visibility, the visibility benefit may still be significant.”
EPA added: “As stated in our proposal, with respect to Colstrip 1 and 2, we weighed the relatively low costs for lime injection with the additional scrubber vessel against the anticipated visibility impacts and determined that the cost was justified by the visibility improvement. Similarly, we weighed the relatively low cost of separated overfire air (SOFA) + selective noncatalytic reduction (SNCR) against the anticipated visibility benefit and determined that the cost was justified by the visibility benefit.”
The Colstrip power plant consists of four units. Of the four units, only Units 1 and 2 are subject to BART. Units 1 and 2 have a nominal gross capacity of 333 MW each. The boilers began commercial operation in 1975 (Unit 1) and 1976 (Unit 2) and are tangentially fired pulverized coal boilers that burn Powder River Basin sub-bituminous coal from an adjacent mine of Westmoreland Coal (NASDAQ: WLB).