The 1.5 mile long outfall for the Georgia Pacific Corporation paper mill in Bellingham, WA, was constructed to carry treated effluent to the mouth of Bellingham Bay. 100-ton precast/prestressed pipe beams span between pile bents composed of precast pile caps and steel pipe piles. Each pipe is designed to carry dead, live, and earthquake loads as a beam between the pile cap and piles.
The precast pipes have a rubber "O" ring in a bell and spigot joint over the pile caps that allowed for rapid underwater assembly, adjustment for construction tolerances, and articulated movement in the event of seismic activity.
Long-span pipe beams minimized the number of pile bents needed for the outfall foundation.
Maximum use of precast concrete elements kept expensive and difficult on-site work at a minimum.
Use of precast concrete allowed a high level of quality control, rapid production of standard units, and durable concrete for severe exposure conditions.