Gate Stem Repairs, West Thompson Lake, North Grosvenordale

There are three hydraulically operated gates located in the Intake Tower at West Thompson Dam located in North Grosvenordale, CT. The dam and its operating equipment are approximately 58 years old and therefore the gate cylinder and gate assembly components are beginning to show signs of wear. The work for this project will likely include, but not be limited to, the following:Refurbish all three hydraulic cylinders located in the gate chamberReplace gate leaf stemsPolish gate stem extension rodsHone inside of hydraulic cylinder barrelReplace lower/upper gate stem oil packings and gate stem water packingsReplace middle piston ring with rubber sealReplace cylinder gaskets and gate stem O-ringsReplace digital gate height indicator system, including transducers, digital displays, and wiring/conduitRemove the middle piston ring on both pistons and replace with a new hydrolysis resistant polyurethane (HPU) piston seal manufactured to operate within specified hydraulic fluid type, pressures, and temperatures. New composite stop logs and lifting beam shall be fabricated and new stop logs shall be installed prior to the start of construction. Stop logs shall be of equivalent dimensional size, quantity, and strength and shall be designed by a Registered professional Engineering in the State of Connecticut. Upon completion of the work, the stop logs and lifting beam shall be turned over to the Government.The Contractor will be required to coordinate operational restrictions with the Contracting Officers Representative and onsite personnel. Proper work sequencing will be critical for project success. Full dewatering of the conduits may be required to perform work. Contractor shall field verify extent of dewatering requirements to obtain safe working conditions and to ensure that the space below the bonnet cover is not pressurized prior to any work beginning. Contractor shall then coordinate sufficient time ahead of required dewatering to allow for local personnel to draw down the existing pool elevation.A 5-ton capacity crane rail is located on the operating floor; however, the electric operated hoist system shown on the record drawings has since been removed. The Contractor may use the existing crane rail to develop a hoist system to assist in the disassembly and assembly of the hydraulic cylinders. Prior to use, a competent person, employed by the Contractor, shall verify the rail capacity and confirm the proposed hoisting system will be compatible with the crane rail. The Contractor shall refer to EM-385-1-1, Section 16, Load Handling Equipment and Section 15, Rigging, for additional requirements.Work shall be done on only one gate at a time and at no time shall more than one conduit be out of service. One conduit at a time can be isolated at the upstream end by use of a stop log system. The Contractor shall be responsible for verifying the condition of the stop log channels and providing stop logs to be used for this project. The Contractor shall submit a plan for utilizing stop log systems to ensure safe and reliable operation for dewatering the conduit for approval to the Contracting Officer prior to proceeding with work.

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