Deep Foundations

Location: Juneau, AK

Project Partner: Manson Construction Co.

Challenge: Installation of extremely long, high capacity tiedown anchors and large diameter rock sockets in an unpredictable and severe marine environment.

Overview: Condon-Johnson was contracted to install 49 high capacity tiedown anchors for the construction of the new Juneau cruise ship facilities. All of the work was performed over the waters of the Gastineau Channel, off the coast of Juneau.

Results: Condon-Johnson, by working in close coordination with the project partner and owner, was able to complete all the tiedown anchors successfully, and was able to accelerate the project schedule. The tiedown anchors were installed inside pipe piles driven by Manson Construction to bedrock with depths of the pipe pile often in excess of 180 feet. Condon-Johnson then drilled 40 feet into the bedrock and installed the reinforcing bar; tiedown anchor lengths reached up to 250 feet depending on the bedrock quality and elevation. Each tiedown was load tested to 600,000 pounds, and post-tensioned to 500,000 pounds.

The project also called for six 48-inch diameter rock sockets, 20 feet into the bed rock that pipe piles would be driven into to fasten a floating pontoon dock. Condon-Johnson mobilized specialized crew and equipment, including a 48-inch diameter cluster hammer, to successfully complete the rock sockets. The rock sockets were challenging because the rock slope was very steep and near vertical at some socket locations. Further compounding the problems, all drilling occurred in the winter with an average high temperature of 15 degrees plus with wind speeds recorded up to 103 MPH.