The U.S. Army Corps of Engineers office in Nashville is taking comment until Sept. 30 on an application by the Tennessee Valley Authority for a Section 404 Clean Water Act permit for a coal combustion residuals (CCR) landfill at the Gallatin power plant.
The plant is located at Cumberland River Mile 240.5R, Old Hickory Lake, Sumner County, Tenn.
“The Tennessee Valley Authority (TVA) proposes to impact 2.24 acres of wetlands, 2,616 linear feet of perennial streams, 310 linear feet of intermittent streams, and 2,876 linear feet of ephemeral streams in association with the construction of a [CCR] landfill and attendant features,” said a Corps notice. “The landfill is needed to support production and disposal of coal combustion products from the new dry fly ash and dry scrubber emissions control at the coal plant. TVA plans to construct the scrubber for air regulatory compliance.”
TVA told the Corps that two areas were identified as suitable for use as a landfill on the Gallatin property. These areas were considered suitable in that they avoid other regulated land uses (ponds and closed disposal areas), they provide buffer areas around cultural resources, and they avoid impacts to other biological resources (including additional wetlands and streams) to the maximum extent practicable. Other onsite wetlands and streams were avoided by siting the landfill at the current proposed locations.
TVA has proposed to mitigate for the wetland impacts through purchasing wetland credits from a mitigation bank or the Tennessee Mitigation Fund (In-Lieu Fee), and for stream impacts through purchasing stream credits from the Tennessee Stream Mitigation Program (In-Lieu Fee).
TVA is considered the lead federal agency for compliance with the National Environmental Policy Act (NEPA). The proposed landfill project is part of a larger project to install emission control equipment and associated facilities at Gallatin. Pursuant to NEPA, TVA prepared an Environmental Assessment (EA) in March 2013 for the proposed installation of emission control equipment and associated facilities at Gallatin.
The scope of review for TVA’s EA included the installation of “additional air emission controls and to take other actions, including constructing a dry coal combustion residue (CCR) landfill.” The Corps’ scope of review would be limited to the construction of the landfill and attendant features. The Corps said it is considering adopting TVA’s EA. However, a separate decision document would be prepared prior to a final decision concerning issuance or denial of the requested Section 404 permit.
New landfill part of broader, $1.1bn project
In order to meet the new Mercury and Air Toxics Standards (MATS), and to comply with air agreements with regulators and environmental groups, TVA plans to construct and operate at Gallatin dry flue gas desulfurization, selective catalytic reduction, pulse jet fabric filter, and activated carbon injection systems.
TVA also proposes to construct and operate a landfill on the Gallatin site for the dry storage of the coal combustion residues. TVA has been converting its wet ash impoundments to dry since a catastrophic failure a few years ago of an impoundment dam at its Kingston coal plant.
The proposed action at Gallatin, with a total pricetag of about $1.1bn, will result in substantial reductions in emissions of SO2, NOx, mercury, and acid gases.
Gallatin has four coal-fired units and combusts an average of 12,350 tons of coal per day. Units 1 and 2 each have generator nameplate ratings of 300 MW, and Units 3 and 4 each have generator nameplate ratings of 327.6 MW. Four combustion-turbine (CT) units were added in the early 1970s, and another four were added in 2000. They are primarily fueled with natural gas but have the capability to use fuel oil.
TVA has installed electrostatic precipitators at Gallatin to reduce particulate matter emissions and low-NOX burners to reduce NOx emissions. TVA also burns low-sulfur blend coal, primarily coal from the Powder River Basin, at Gallatin to reduce emissions of SO2. Currently, about 185,000 dry tons of fly ash and approximately 46,500 dry tons of bottom ash are wet-sluiced to the plant’s surface impoundments each year.
Environmental groups have been opposing the projects, saying that Gallatin should be shut instead. TVA already plans to shut other coal-fired units for the same reasons it now wants to retrofit Gallatin.