Lock & Dam 25 Lock Wall Modifications - NESP Phase 1 - ST. Louis District

Performing Lock Wall Modifications at Lock & Dam 25 located on the Mississippi River - approximately 61.5 river miles upstream from St. Louis and 241.5 miles above the mouth of the Ohio River. The project consists of a main lock, an incomplete auxiliary lock, a dam containing fourteen tainter gates, and three roller gates. The main lock is 600 ft by 110 ft with a set of miter gates at the upstream and downstream ends. The contract is anticipated to be a Firm-Fixed-Price Construction contract using Subjective Best Value Trade-off evaluation methods. - Work will consist of furnishing all labor, equipment, operators, supervision, supplies and materials, and incidentals necessary to perform the Lock and Dam 25 Lock Wall Modifications that is Phase 1 of the Navigation Ecosystem Restoration Program (NESP) Lock and Dam 25 Project. These modifications include installation of new Floating Mooring Bitts (FMB) and Line Hooks at three (3) locations and filling in the existing miter gate recess along the river side of the intermediate wall. The work is anticipated to be accomplished with traditional river marine construction equipment, such as floating plant and barge mounted crane. Contractor staging will be from the river side of the intermediate wall as the lock will be continuously open to river traffic in the main lock during the construction period. This construction work will be performed in localized cofferdams so the work can occur in-the-dry prior to completion of the new 1200-ft lock chamber when the chamber can be un-watered. Structural work on the project includes, but is not limited to the following: - Installation of contractor furnished cofferdam to perform the work in-the-dry, use of marine divers to install cofferdam. Removal of existing riprap scour protection to facilitate installation of the cofferdam and reinstallation of scour protection following completion of work. - Concrete removal via diamond wire saw or other conventional methods, installation of reinforcing steel, formwork, miscellaneous metal and appurtenances for FMB recesses and Line Hooks, and placement of new concrete. - Concrete removal and existing concrete surface preparation via conventional methods within the unused miter gate recess and miter gate machinery pits, installation of reinforcing steel and dowels and placement of reinforced concrete to fill in the miter gate recess. - Fabrication of miscellaneous metals and other lock wall appurtenances for FMB recesses and Line Hooks, and installation of the floating mooring bitts within the newly constructed recesses. Mechanical work on the project includes, but is not limited to the following: - Fabrication of new floating mooring bitts (FMB) including the ultra-high molecular weight (UHMW) sliding blocks. - Testing and adjusting new FMB to provide proper flotation height. Electrical work includes, but is not limited to the following: - Temporary power for high mast lighting (HML) and navigation light circuits prior to structural demolition for new floating mooring bitt (FMB) - New conduit and wiring for HML and navigation light circuits in vicinity of new FMB- Construction of new electrical duct bank between existing manholes - New feeder to include embedded conduit and cable for relocated boat davit on the river wall

Dam/Tunnel, Renovation.

Division 02 -	Existing Conditions, Subsurface Investigation.
Division 31 -	Earthwork, Site Clearing, Grading, Excavation and Fill, Subgrade Preparation, Excavation, Shoring, Tunneling and Mining, Tunnel Excavation.
Division 35 -	Waterway and Marine Construction, Dam Construction and Equipment.