Weaverville California State Route 3 Culvert Rehabilitation


welder in workshop welding

Pipe Specifications:

760’ of 36” OD x .500” wall AB Permalok®

110’ of 60” OD x .500” wall T-5 Permalok®




California Department of Transportation

Engineer Firm:



Walter C. Smith

This project’s focus was to replace and repair a series of deteriorating culverts in an area along California State Route 3 near Weaverville. Surrounded by mountainous terrain, the jobsite had limited lay down and construction area to limit the contractor’s options for installation of the seven parallel bores. To address space restriction, the contractor used a dry creek bed for the launch and determined that an auger bore would be the best installation method for soils made up primarily of glacial till.

The site’s challenges seemed a natural environment to introduce our new Permalok® AB (Auger Bore) Joint. The AB Joint allows a straight push on the pipe reducing the impact of trying to manage both the internal auger flighting and the pipe connection in a confined space. The joint also requires less jacking force for full joint engagement. Despite setbacks, the average installation footage exceeded 150 Lineal Feet per shift and every bore was completed within ¼” of line and grade with significant time to spare.

Northwest Pipe developed the AB Joint after many years of research and testing. We incorporated feedback from our customers to help mitigate some of the challenges associated with auger bore installation.