503-682-9925
10050 SW Wilsonville Road
Wilsonville, OR 97070
Marine Industrial Construction services the Northwest region

March 2015 – McNary Dam – Downstream Navlock Interim Repairs

DESCRIPTION OF WORK:

Perform structural and mechanical interim repairs on the McNary Navigation Lock Downstream Gate. The McNary Navigation Lock Downstream Gate is a two-leaf arched miter gate and measures 106 feet tall by 86 feet wide and was placed in service in 1954.

Miter Gate Gudgeon Repairs — Procedures include line boring the perpendicular gudgeon plates (2 plates total) and gudgeon linkage eye bar (1 bar total) of each of the miter gate leaves. The gudgeon plates are embedded to the concrete structure of the navigation lock and allow for the attachment to the navigation lock miter gate through the gudgeon linkage eye bar. Therefore the field line boring is required through 3 layers of material with a total thickness of 8.25 inches (gudgeon plates are 1.75 thick each and linkage eye bar is 4.75 inches thick), the bore size shall be increased from 7-inches to 7.125-inches. Gudgeon material is low yield steel and therefore welding operations shall be kept to a minimum as to not alter its properties.

Two new linkage pins (one per side) shall be provided to match the new gudgeon plate-linkage eye bar bore diameter. The gudgeon repair work will require jacking and shoring support of the miter gate leaf structures. Each miter gate leaf weighs approximately 400 tons. The miter gate leaves will be required to be jacked and supported during the pin removal, line boring, and pin replacement operations. A jacking and shoring plan is a required deliverable and must be designed by a licensed engineer.

Coal Tar Coating System Removal — Remove all existing coal tar and coal tar/primer from the lower 24-feet of the downstream side structural components on both Downstream Miter Gate Leaves. Acceptable removal of the coating system is defined as the removal of all visible coal tar and primer coat. Bare steel is required to permit structural inspections. The existing coal tar material was applied to the gate structure in 1949 and was confirmed to be asbestos-free by laboratory testing in 2014. The coal tar was originally manufactured to meet the requirements of American Water Works Association Specification 7A-5-1940. The coal tar was hot-applied to a minimum thickness of 3/32-inch and is anticipated to have a maximum thickness of 1-inch. The existing primer material consists of a coal tar pitch primer originally manufactured to meet the requirements of American Water Works Association Specification 7A-5-1940. The design and installation of suitable containment measures are required to protect the immediate and adjacent areas on the gate structure and Navigation Lock floor from contamination from the removal activities. Removal and off-site disposal of all resulting coal tar coating waste is required to be in accordance with Federal, State, and local laws and regulations.

Structural Inspection of Downstream Miter Gate — Provide the services of professional engineers and Non-Destructive Testing (NDT) technicians to perform structural inspection of the lower 24-feet of the downstream side of the miter gate and the upstream side of the miter and quoin areas (non-skin plate body areas) of the miter gate. Structural Engineers that are state licensed professional engineers, and NDT Level II or Level III qualified technicians will be required by this contract. Due to elevated inspection and NDT requirements, Society of Professional Rope Access Technicians (SPRAT) Level III personnel will be required to supervise the inspection teams. Based on the aggressive schedule requirements of this contract, multiple inspection/NDT teams may be required to work on both miter gate leaves concurrently. Structural inspections require the design and installation of an engineered fall protection system and personnel fall protection equipment meeting the requirements of EM 385-1-1.

Crack Repair on Structural Members of Downstream Miter Gate — Perform various forms of crack repair to include stop-drilling, bolted plate repairs, partial penetration welds, and complex complete joint penetration welds. Weld repairs will be performed on non-fracture critical members and fracture critical members. Welding shall conform to American Welding Society (AWS) D1.5 and welders shall be qualified in accordance with AWS D1.5. Crack repair requires the submission of welding procedures for each weld to be made. Welding repairs require preheating and interpass temperature control. The contract will require full time services of Certified Welding Inspectors certified in accordance with AWS QC1 during all on-site welding activities.

Repaint Structural Members of Downstream Miter Gate — Upon completion of all crack repairs, paint all surfaces that were previously coated with coal tar with Vinyl Paint System 4. The Vinyl Paint System 4 consists of five coats of alternating white and gray formula V-766e double-spray coats. Surface preparation for the Vinyl Paint System will require white metal blast in accordance with SSPC SP 5.

Quoin and Miter Surface Repair — Resurface the quoin and miter surfaces on the lower 30-feet of the north miter gate leaf and the lower 60-feet of the quoin surface and the lower 30-feet of the miter surfaces on the south miter gate leaf. This work will consist of welding up the deficient areas and machining down the surfaces to remove defects and to restore the surface plates to their original thickness.

Replace Wood Timber Fenders – Replace twenty (20) wood timber fenders and mounting hardware (bolts, washers, nuts) on the downstream side of the miter gate leaves. Fenders are approximately 7 quote mark x 12 quote mark x 27′ long each. New wooden timbers will be provided as Government Furnished Material and shall be installed by the Contractor. Mounting hardware shall be provided by the Contractor.

Temporary Removal of Cathodic Protection – To facilitate the coal tar removal, structural inspections, crack repairs, and repainting, remove the existing Impressed Current Cathodic Protection components from the downstream side of the miter gate leaves. Upon completion of the required repairs and repainting, reinstall the Cathodic Protection components.

McNary Dam Downstream South Gate

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Looking Upstream From Downstream Side

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Looking Down into Dewatered Lock Chamber