Sutro Tower: combating corrosion 1,000 feet high

Client needs

The iconic Sutro Tower, a 1,000-foot-high transmission facility supporting 11 television stations, four FM radio stations, and 20 wireless communication services in the San Francisco Bay area, required specialized industrial corrosion control and asset protection. To combat the severe degradation affecting the tower’s massive structural legs, the client contracted our team to perform structural remediation and apply high-performance protective coatings to the interior steel framework across all three legs, as well as the internal components within two of the legs.

The challenges

• Aggressive coastal fog and high moisture: Situated high above the bay, the structure was frequently enveloped in heavy coastal fog and extreme humidity, introducing constant moisture that threatens paint adhesion and accelerates corrosion.
• Severe access and vertical transport bottlenecks: The tower’s external elevator had a strict two-person limit (or one person with tools and materials) and required an arduous 30-minute round-trip transit time, severely constraining crew deployment and material logistics.
• Restricted internal leg entry and rigging: Access to the interior of the tower legs required crews to enter from the top utilizing full-body fall-arrest harnesses, with all tools and coatings rigorously secured against drops during frequent material replenishment trips.
• Confined spaces and fume management: Working within extremely tight internal quarters demanded continuous respiratory protection to safeguard technicians against airborne particles, dust, and solvent fumes.

Our solution

• Comprehensive safety infrastructure and on-site direction: Prioritized total workforce protection by deploying rigorous fall-arrest systems, implementing mandatory daily safety briefings, and stationing a dedicated on-site safety director to oversee all operations.
• Mechanical surface preparation and flash-rust prevention: Utilized heavy-duty mechanical grinders for broad structural steel surfaces and pneumatic needle-gun scalers for tight corners to eradicate existing rust and establish an optimal anchor profile.
• Tandem phased application crews: Divided operations into specialized, closely coordinated teams, a preparation crew followed immediately by a dedicated coating crew, to eliminate exposure windows and prevent flash rust in the hyper-humid environment.
• High-performance multi-coat epoxy system: Applied an immediate rust-inhibiting epoxy primer directly following surface prep, followed by successive layers of high-durability epoxy engineered to deliver complete environmental sealing and a 10-year maintenance-free lifespan.

Project outcome

The initial phases covering the first two legs were successfully delivered on time and within budget, meeting rigorous quality standards and earning high praise from the client. By overcoming extreme vertical access limitations, complex rigging, and constant bay fog, our team significantly extended the structural service life of the transmission facility. The client expressed complete satisfaction with the execution, positioning our contracting team for the upcoming final leg and subsequent budgeted phases.