COUNTY-STATE: Floyd County, Indiana. | APPLICANT: Duke Energy | PROJECT PURPOSE: The purpose of the Phase II portion of the Project is to remove existing Gallagher Station structures from the Ohio River and final grading of the property associated with the decommissioning and demolition of the Station.
DESCRIPTION OF WORK: The proposed facility modification would consist of the filling and removal of the north and south intake structures, the decommissioning and removal of the coal unloader, installation of temporary docks, relocating of the coal pile stormwater ditch and subsequent outfall, removal of the associated cells and final grading. The approximately 5-acre Limits of Disturbance (LOD) surrounds the existing Gallagher Station intake coal barge and dock cells extending into the Ohio River. The abandonment of the intake, coal unloader, dock cell structures, and temporary installation of a boat dock structures will involve in-stream work below Ordinary High Water Mark (OHW) elevation, which is at 408.5-feet as established by the Navigational Chart for the Ohio River and USACE Project Coordinator. Dock cell deconstruction will begin at the upstream cell C1 and diversion cells D1-D7, then move downstream to dock cell A1 and go upstream from there. See Figure 3 for numbering of the dock cells. Deconstruction will be accomplished utilizing three barges: a 120-foot by 50-foot spud barge with 250-ton crane, and two 195-foot by 35-foot hopper barges for materials. The spud barge will have two to four spuds driven into the river bottom for stability, and the hopper barges will be tied to the spud barge/each other. No mooring to dock cells or to deadman on shore will be necessary. Barges will be tended and moved by tug boat as necessary. Once the barges are in place at a dock cell, a turbidity curtain will be installed around the cell (except for cells D1-D7). The existing aggregate (rock) fill will be removed via clamshell crane and placed into a hopper barge for holding. Once empty, the steel wall of the cell will be cut at the existing substrate/mudline by divers utilizing a tender boat. The removed steel wall will be placed in a hopper barge for disposal. The total net fill of the project consists of approximately 1320 cubic yards. A temporary dock will be constructed around dock cell A2 to facilitate removal of the rock and steel structures from the site, as well as a load out location for the hopper barges utilized during the deconstruction processes. This will utilize “Z” sheet pile along 2 sides of the cell, held in place with threaded bars and caps, with a dock face at each end. The temporary dock will be filled with aggregate recovered from demolished river cells, with aggregate placed between the dock and the shoreline to provide an equipment ramp onto the dock. A turbidity curtain (290-linear feet) will be installed around the temporary dock structure within the Ohio River, enclosing 0.26-acre, to prevent sediment migration away from the temporary disturbance location. This dock will be removed at the conclusion of the deconstruction work. Total amount of net fill will be approximately 1770 cubic yard of clean fill consisting of aggregate, native soil and grouted riprap.