345kV NYPA (T-LEM) Tower Stub Angle Lower Leg Repair
Transmission Life Extension & Modernization
345kV Tower Stub Angle & Leg Corrosion Remediation
The purpose of this project was to develop boiler plate designs and details on select Client 345kV lattice tower lines. These designs would be used for the repair of corrosion on lattice tower stub angles, main leg members and braces, and grillage members. Further use of these designs included the replacement of base plate stub angles for towers which had anchor bolt connections to concrete foundations, versus embedded stub angles.
This project was commissioned by the Client to remediate corrosion on the lower legs of lattice towers, specifically at the stub angles, as identified in a 2013 study by CG Solutions. There were six (6) tower types identified for this project. Shoring and bracing plans were developed to fully unbolt tower legs and maintain structural integrity of the tower during remediation operations, and to facilitate total replacement of leg members if necessary.
Deliverables included construction sequencing and field procedures, shoring and bracing plans, repair details, and bill of materials for re-developing the original strength of the tower legs and members. Complete specifications, engineering calculations, tower models, and CAD files were also delivered as part of this project.
Realtime utilized PLS-CADD, PLS-Tower, and MFAD software to evaluate tower repair and shoring options. Realtime also offered recommendations to minimize the overall impact of repairing the towers. Considerations included an assessment to minimize line outages, lighting protection, and determining service life of the towers, as well as value engineering to reduce costs.
The cost savings to perform this project over replacing the lattice towers in kind, or with steel poles, was estimated to be the tens of millions of dollars.