New Hogan Spillway
Arm Gate Replacement

Location: Calaveras County
Completed: February 2020

A client of TCB contacted our Hydro Division team to replace six spillway gate arms to three of their gates. During the replacement the client upgraded the gates from bushings to grease-less bushings. The project was conducted in two phases allowing one gate to always be available to release water in the event of an emergency. TCB's fabrication division constructed support arms and anchored them to the wall to ensure the gates stay in place, during the removal of the gate arms.

• Scan spillway walls for rebar before drilling anchor holes

• Drill anchor holes and epoxy anchors into wall

• Install temporary bracing on to wall and spillway gate to
assure the gate does not move when old arms are taken off

• Take as-found measurements of the gate location

• Begin to remove one gate arm at a time

• Core drill the trunnion block for the new rods. These new
rods will bolt up the new trunnion to the trunnion block

• Assemble the arms in 4 parts the top and bottom section
of the arm along with the trunnion that connects at bottom

• Sand blast the plate connection locations

• Weld the top section of the arm to the lower section

• All welds will be profiled down to allow proper transition

• A third party welding inspection company will perform
UT, RT, and MT of all welds before the arm can be released

• Torque all bolts at the gate plate connections to the
proper specs in 3 stages 50%, 75% and 100% of the
torque value assure that the plate is torqued evenly

• Take as-found measurements of the gate location

• A final operational test was then taken