Specifications include, but are not limited to: 1. Placement of scaffolding to facilitate safe structural inspection of interior of both primary digesters. 2. Removal of debris from and cleaning of the active primary digester. 3. Replacement of the primary digester fixed covers. 4. Replacement of Primary Digester Control House roof and grade level entrance doors. Replacement of grade level entrance stair access with a loading dock. 5. Replacement of Cogeneration Building roof. 6. Replacement of Boiler Building roof. 7. Replacement of digester gas mixing system with mechanical linear motion mixer, one for each digester. 8. Replacement of external and internal gas feed and draw-off piping. 9. Replacement of internal sludge feed piping. 10. Replacement of internal sludge draw-off piping. 11. Replacement of all process piping within the Primary Digester Control House; piping is being designed to terminate at existing wall castings, floor castings, existing heat exchanger equipment (to remain), and the transition interface between the Primary Digester Control House and Pipe Tunnel No. 2 to the nearest fitting.