Reclamation Does Its Part to Preserve History at the Yankee Fork Gold Dredge in Idaho

The Yankee Fork Gold Dredge is located in the central mountains of Idaho on the Yankee Fork tributary of the Salmon River. Built in 1940 by the Bucyrus-Erie Company, the dredge ran for 12 years before being buried and abandoned in its current location.Located 22 miles northeast of Stanley, Idaho, next to the Custer Ghost Town in Bonanza City, lies one of the best preserved and presented dredges in the lower 48 states. The Yankee Fork Gold Dredge, located in a tributary of the Salmon River, was built in the 1940s. Designed for the excavation of gold, the dredge ran for 12 years before finally being shut down in 1952. In 1953, the dredge was turned on one final time and dug in to its current position where it has rested ever since.

Donated to the U.S. Forest Service in the mid-1960s, the Yankee Fork Gold Dredge is now a tourist attraction that provides guided and self-guided tours of the historic machine.

Like everything, time and the elements have taken its toll on the dredge. Recently, Reclamation has participated in salmon and Steelhead habitat projects which have involved moving cobble and gravel mounds stacked by the dredge. As part of the mitigation for the habitat projects the Idaho State Historic Preservation Office and the Forest Service asked Reclamation to help in the preservation of the large dredging machine. Chrissy Henderson, a Materials Engineer with Reclamation’s Materials & Corrosion Laboratory, took the lead on this project and in July 2016, Henderson and her team determined that they could help design and install a cathodic Protection system to protect the dredge from further corrosion.

The cathodic protection system protects metallic structures from corrosion, such as the dredge’s 25 steel pontoons, which served the purpose of providing buoyancy. This particular cathodic protection system uses sacrificial magnesium anodes, similar to the sacrificial type of protection found in water heaters, to transfer current to the dredge. In essence, the magnesium anodes are consumed in order to protect the dredge from further metal loss.

For four days in September, Henderson, fellow Materials Engineer Daryl Little and a team of technicians and engineers, led by Jeff Peterson, from Reclamation’s Pacific Northwest Region installed 144 galvanic anodes within the 23 pontoons they were able to enter.

“This project is being done in two phases. We finished the first phase in September. Essentially, we installed a cathodic protection system inside of the pontoons in order to stop the loss of material from inside of the steel pontoons of the dredge,” said Henderson. “In late spring, we plan to install rod anodes along the outside of the dredge to protect the submerged/buried portions from further degradation. Because cathodic protection needs to be ‘in line of sight’ to function, the inside and outside of the dredge needed to be protected separately.”

The last phase of the project is to place long anode rods horizontally in the soil and muck surrounding the dredge, something Henderson and her team plan to finish in spring 2018.

To learn more about protecting historic structures, please contact Chrissy Henderson at chenderson@usbr.gov.

Bill Richard, an Electronics Technician from Reclamation’s Pacific Northwest Region, looks over the stack of anodes during the installation process at Yankees Fork Gold Dredge, Sept. 24-28, 2017. Each anode, weighing 44 pounds each, had to be lowered into each pontoon of the dredge by ropes.

Anodes were lowered by rope into a pontoon of the Yankee Fork Gold Dredge during the cathodic protection system installation, Sept 24-28, 2017. Fall protection system is attached to Henderson inside the pontoon and a rope is attached to the anode, to ensure the safe lowering of the 44-pound anode.

Published on November 01, 2017