The Montana Department of Environmental Quality is out for comment on an air permit change covering its recent approval for PPL Montana (PPLM) to get a one-year extension, to April 2016, on the compliance deadline under the federal Mercury and Air Toxics Standards (MATS) at the Colstrip power plant.
In September 2014, PPLM submitted a written request for a one-year compliance extension under the MATS rule. As the administrator of the Federal Clean Air Act in Montana, the department has the authority to grant up to one additional year for an emissions source to comply with a new standard if that time is deemed necessary for the installation of pollution controls. To demonstrate compliance with the standards PPLM has proposed to use the weighted average emission rates from all four affected units at Colstrip as allowed for by the MATS rule. In order to achieve this, PPLM needs to enhance the pollution control scrubbers on Units 1 and 2 by installing sieve trays to improve their performance for each of the three main MATS pollutants.
The company has proposed an installation schedule during times of preplanned unit outages in order to minimize the impact to their electric supply obligations. The department announced its intention to conditionally approve the compliance deadline request in December 2014 and accepted public comments on the proposed Title V permit conditions until Jan. 2. Numerous comments were received both in support and in opposition to the compliance deadline extension request; however, no submittals contained information that impacted the department’s conclusion to conditionally approve the request as allowed for by the Federal Clean Air Act.
On Jan. 5, the department issued PPLM a letter that granted the compliance deadline request. On Jan. 20, PPLM submitted a request to update its Title V Operating Permit for a minor modification to incorporate the terms of the conditional approval as instructed by the letter granting the compliance deadline extension. That is the change now up for comment, said the department in a Feb. 19 notice.
The 2,094-MW Colstrip power plant, located east of Billings, operates four coal-fired generating units. Units 1 and 2 began commercial operation in 1975 and 1976, and Units 3 and 4 started in 1984 and 1986. PPL Montana’s share in the plant’s generating capacity is 529 MW and its operates the plant for various partners. Low-sulfur coal and state-of-the-art scrubbers restrict SO2 emissions. Notable is that the parent of PPL Montana, PPL Corp. (NYSE: PPL), plans to turn over its share of the plant to the planned Talen Energy.