Project Overview
Designed to support the homeporting and maintenance of SEAWOLF-class submarines, the P-834 Service Pier Extension at Naval Base Kitsap-Bangor in Silverdale, Wash., offers a mission-critical infrastructure upgrade for the U.S. Navy. With the need to boast a 50-year service life and to accommodate extreme tidal fluctuations, seismic activity, and high operational demands, the project team turned to precast, prestressed concrete as the backbone of a resilient, efficient, and low-maintenance solution. Concrete Technology Corporation of Tacoma, Wash., worked closely with the Navy and Federal Way, Wash.–based engineer of record BergerABAM on the effort.
Marine-Grade Muscle
The pier extension comprises a 68 × 520-ft pile-supported addition that’s structurally independent from the existing pier via a 24-in. seismic joint. Precast, prestressed concrete deck panels form the superstructure, topped with cast-in-place concrete to create a composite system capable of withstanding heavy loads and harsh marine conditions. The decision to use precast concrete was driven by several key factors, including durability in splash zones, an accelerated construction timeline, and the ability to maintain tight tolerances.
Due to the complex nature of the work, the project team encountered several challenges, and precast concrete played a pivotal role in addressing them. The site’s glacial till soils and seismic risk demanded a robust fender system. Square precast, prestressed concrete fender piles were specified for their energy absorption capacity and long-term durability, outperforming alternatives in both cost and maintenance. Installed at 10-ft intervals, these piles provide a resilient berthing face for submarines and small craft.
One of the most innovative applications of precast concrete was in the design and fabrication of two floating concrete camels. These massive structures, used for submarine mooring, incorporated precast concrete walls and deck panels made with marine-grade lightweight concrete. The lightweight concrete reduced the camels’ draft, enabling launch from a shallow dry dock while meeting the Navy’s stringent durability requirements, including low chloride permeability and extended service-life modeling. The camels’ asymmetrical, sloped berthing face introduced unique stability and fabrication challenges. Precast concrete components were cast face down with a 13.5-degree slope, then rotated and assembled in a dry dock using cast-in-place closure pours and post-tensioning. This approach minimized on-site labor, improved dimensional control, and ensured watertight joints, all critical considerations for long-term performance in a high-moisture environment.
Additional precast concrete components included utility trench lids, wave screen panels, and foam-filled small-craft floats. The wave screen, constructed from 10-in.-thick vertical precast concrete panels, protects the landside mooring area from wave action while minimizing future maintenance. The trench lids, reinforced for heavy vehicular loads, were designed for easy removal and replacement, supporting long-term utility access. The use of precast concrete not only accelerated the construction schedule, which allowed critical-path activities to proceed concurrently, but also delivered a high-performance, low-maintenance solution tailored to the Navy’s operational and environmental demands.
The P-834 Service Pier Extension serves as a prime example of how innovative engineering, environmental stewardship, and precast concrete can coalesce to deliver a complex infrastructure project, all while meeting mission-critical demands.
Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013. |