The Kentucky Power unit of American Electric Power (NYSE AEP) applied June 15 at the Public Service Commission of Kentucky for approval to close in place the existing Big Sandy Plant coal ash impoundment, since Big Sandy will no longer be a coal-fired power plant.
The Big Sandy Plant consists of the 278-MW coal-fired Unit 1 and the 800-MW coal-fired Unit 2. In order to comply with the 2012 Mercury and Air Toxics Standards, Kentucky Power retired Unit 2 effective May 31 of this year and will convert Unit 1 to a natural gas-fired unit. Unit 1 is expected to cease operating as a coal-fired unit in November 2015.
Fly ash, a coal combustion byproduct from Big Sandy Units 1 and 2, is currently stored in the Big Sandy Impoundment. With the May 31 retirement of Big Sandy Unit 2, and upon the conversion of Big Sandy Unit 1 to natural gas, the Big Sandy Impoundment will no longer qualify for the permit by rule provisions of the Kentucky solid waste regulations and must be closed. Closing the Big Sandy Impoundment in place as proposed in this application is the least cost alternative for addressing the applicable environmental standards affecting the storage of coal combustion byproducts from the Big Sandy Plant, the utility said.
The Big Sandy Impoundment is a 140-acre wet fly ash impoundment formed by the construction of the Horseshoe Creek Dam. The impoundment was constructed and placed in service in 1969 and has a total storage capacity of 8,302 acre-feet when the level of the fly ash in the impoundment reaches an elevation of 705 feet msl (mean sea level). The Big Sandy Impoundment is located near Louisa in Lawrence County, Kentucky, approximately 0.75 miles northwest of and across US Highway 23 from the Big Sandy Plant.
With the cessation of coal-fired generation at the Big Sandy Plant, the Big Sandy Impoundment will no longer be required and must be closed either in place or by excavating the fly ash and transporting it to a permitted landfill. In the absence of a specific pond closure permitting protocol, and with the concurrence of the Kentucky Division of Waste Management (KDWM), the closure of the Big Sandy Impoundment is being pursued via KDWM’s Special Waste Landfill permitting process.
The Big Sandy Impoundment Closure Project is proposed to occur in steps. First, the impoundment will be drained of surface water by digging temporary drainage channels in the deposited ash. The surface water will be discharged in accordance with the company’s current KPDES water permit. Once the impoundment has been drained to the point where the ash is able to support heavy earth moving equipment, the company will begin grading the ash. The grading process will establish the subgrade that sets the elevations needed to channel the storm water flow across the closed impoundment. Once the subgrade is established, the impoundment will be capped with a flexible membrane liner (FML), protective cover soil layer, and, finally, a topsoil layer that will be seeded to establish a vegetative cover. A network of ground water monitoring wells will be installed to support the post closure care and monitoring requirements.
Following receipt of the KDWM permit and all other required approvals, the company anticipates beginning construction in early 2016. The anticipated completion date for the project is the end of 2020.