The Public Service Commission of Wisconsin on June 14 approved a March 11 application from Wisconsin Power and Light (WP&L) for authority to replace the bottom ash handling system at the Edgewater Generating Station Unit 5 in Sheboygan County, Wisconsin.
WP&L proposed to replace the existing 30-year old bottom ash handling system to address both operational and maintenance issues associated with the existing wet bottom ash handling system and to comply with more stringent environmental regulations. The estimated cost of the project is $24.4 million, excluding allowance for funds used during construction (AFUDC).
Edgewater Unit 5 is located along the shoreline of Lake Michigan. It was placed into service in 1985 and has a nameplate capacity of 380 MW. The unit is the newest and most operationally flexible coal-fired unit in WP&L’s generation fleet.
WP&L stated that two key factors are driving the decision to replace the original wet bottom ash handling system.
- First, the existing system is at the end of its normal service life and is in need of significant repairs or replacement.
- Second, WP&L needs to comply with more stringent environmental regulations and effluent limits in the wastewater permit for the facility, including an upcoming restriction on the discharge of bottom ash transport water and a more stringent numeric arsenic permit limit.
The existing wet bottom ash handling system was installed when the unit was placed in service in 1985, and the normal service life of an ash handling system is approximately 30 years. If WP&L were to extend the service life of the existing system, and more specifically the hydrobin within the system, WP&L would be required to make repairs, and replace and re-configure various components of the system. Because the current system uses water to handle the ash, WP&L would have to remove the arsenic from the process wastewater in order to comply with upcoming environmental regulations. Compliance may require WP&L to build a wastewater treatment facility to remove arsenic before discharging the water, which would increase the overall cost of compliance.
Construction is expected to begin by the third quarter of 2017, with completion by the second quarter of 2018.
Said the June 14 order: “WP&L is granted a Certificate of Authority authorizing WP&L to replace the existing bottom ash handling system at Edgewater Unit 5, as described in its application and as modified by this Final Decision, at an estimated total cost of $24.4 million.”