How Are San Francisco Pier Structures Rehabilitated?

Underwater inspection is a specialized discipline. Commercial divers or remotely operated cameras examine each pile from the mudline to the pile cap, cleaning marine growth at sample locations to expose the actual pile surface. Timber piles are probed for marine borer tunnels and section loss; concrete piles are checked for cracking, spalling, and exposed or corroded reinforcement; steel piles are measured for corrosion thickness loss. Each pile gets a condition grade, and the engineer maps the grades across the pier to find patterns, such as a zone of accelerated deterioration where currents or discharges concentrate. Above water, the survey continues across the deck structure: pile caps, beams, bracing, and the deck itself are measured, cored, or tested as needed to establish material properties. The engineer then load-rates the pier, calculating what the deteriorated structure can safely carry today versus what the proposed use demands. This gap analysis sets the rehabilitation scope: some piers need only localized pile replacement and deck repair, while others require systematic strengthening of the entire bent system. The investigation report, with its pile-by-pile findings, becomes the basis of the construction drawings and the permit submittal.

Pile repair follows a decision tree driven by remaining capacity. Piles with sound cores but damaged surfaces receive concrete jackets: forms placed around the pile and filled with high-strength, low-permeability concrete that restores the section and seals out saltwater. Composite fiber wraps offer a thinner alternative where clearance matters. Piles beyond repair are cut off and replaced, with new piles driven alongside and connected into the existing cap, or the cap itself is replaced where deterioration is widespread. All new concrete in the tidal zone uses mixes designed for marine exposure, and steel gets heavy-duty coating systems. Deck and lateral strengthening run in parallel. The engineer adds or upgrades bracing between bents to create a reliable lateral system for seismic and berthing loads, strengthens pile-to-cap connections for ductility, and repairs or replaces deck panels for the service loads of the new occupancy. Seismic retrofits may add new piles or a landside tie-back system where the original pier has no coherent lateral path. Cathodic protection systems are installed on critical steel where the investigation shows active corrosion. The construction sequence is planned bent by bent so the pier remains stable throughout, and load restrictions protect partially completed work until every connection is made.