May 22, 2009
DEQ seeks more pollution data on gas-fired plant By KARL PUCKETT Tribune Staff Writer
The state Department of Environmental Quality wants more details on how a developer arrived at projected pollution emissions from a natural gas-fired power plant proposed east of Great Falls.
"We have to accurately account for plant emissions in order to determine the best emissions-control technology," said Brent Lignell, an environmental engineer for the DEQ's Air Resources Management Bureau.
Southern Montana Electric Generation and Transmission is applying for permission from the DEQ to construct a 120-megawatt gas-fired plant, instead of the coal-fired facility it originally planned for the Highwood Generating Station site about eight miles east of Great Falls.
On Wednesday, the DEQ sent a letter to SME that said its construction application was incomplete because of "insufficient analysis and/or lack of transparency in methods and calculations."
The letter asks SME to provide formulas and explanatory narrative on emissions calculations. The developer has until July 20 to respond.
"They are asking for some additional explanation, i.e. a road map," said Jeff Chaffee, vice president of Bison Engineering, a consultant on the project.
Lignell and Chaffee said the request for additional clarification isn't uncommon, adding it is part of the back-and-forth between the agency and developers following an initial construction application.
Chaffee said he's confident SME will be able to address the questions, noting the developer plans to respond in a week to 10 days.
According to SME's application, the annual emissions at the gas-fired plant would be an estimated 171 tons of nitrogen oxides, 380 tons of carbon monoxide, 20 tons of volatile organic compounds, 64 tons of particulate matter, 6 tons of sulfur dioxide, and 250,000 tons of the greenhouse gas carbon dioxide.
Annual emission projections for the coal-fired facility were higher. For example, emissions of carbon dioxide from the plant would be 2.4 million tons. Particulate matter emissions at the coal-fired facility would be an estimated 366 tons, compared with 64 tons from the gas-fired plant.
The DEQ wants to figure out how SME came up with its numbers so they can be reproduced and understood by the agency and the public, Lignell said.
Under permitting rules, both the coal- and gas-fired facilities are considered to be the same source of emissions, even though the coal-fired power plant is on hold, according to the DEQ.
As a result, SME still must quantify the impacts of the coal-fired plant, which could impact emissions limits for the gas-fired plant.
The DEQ also is asking SME for clarification about the relationship between the two facilities.
"The application states the gas plant will not operate when the coal plant boiler is in operation, but fails to address specifics such as nonboiler emissions or lag time following boiler shutdown," the DEQ letter states.
SME states in its application that the two plants would never operate at the same time.