After 6 months of maintenance, Yates Shaft back up and running | Local News

LEAD — A timber shaft such as the Yates will always have issues associated with it, but after six months of being shut down for repairs, officials have declared the shaft safe and stable — for now.

But just as Wendy Straub, director of hoists and shafts at the Sanford Underground Research Facility (SURF), reopened the shaft up for science and maintenance travel to the 4,850-level, the South Dakota Science and Technology Authority (SDSTA) ordered a feasibility study . The authority contracted with mining engineering firm Stantec Engineering to determine cost estimates and the best way to replace the timber in the Yates with the steel that is more commonly used today. The project could become part of the lab’s long-term facility plan.

Built during World War II, when steel was in short supply, the Yates Shaft differs from the steel Ross Shaft, as it is composed entirely of timber. In order to remain functional, timber should be kept wet, but in the Northern Hills Straub said that is difficult to do because of freezing temperatures and low humidity.

“We’re constantly having this timber wet and it dries out, and that’s not good on timber,” she said.

But until the authority is able to completely replace the timber sets of the Yates Shaft with steel, Straub and her team remain committed to safety and conducting routine weekly inspections on the Yates Shaft. This method ensures all parts are always working correctly, with crews making repairs as they inspect.

The routine weekly inspections are how the team discovered a broken wall plate at the back of the shaft. Each part of the shaft is connected, and anything broken or out of place triggers safety issues. But in this particular location, Straub said the issue was especially concerning.

“We have some strategic locations within the shaft that we survey for movement because we know, for whatever reason, there are bearing beams that were never installed,” she said, referring to large beams of timber that are support structures in the shaft. “In the particular area where we were focused between the 1,700-foot level and the 2,300-foot level, there are no bearing beams.”

Straub added that while there is a bearing beam at the 2,300-foot level, it failed at some point in the 1980s.

“So, the 2,600 Level had the weight of the world kind of sitting on it,” she said. “It finally got to the point where it said, ‘I’m tired.'”

When crews discovered the broken wall plate in that location, Straub said she immediately issued a stop work order, to get everyone out of the shaft. Staff from the SDSTA then spent the next six months building working platforms in an area where there are no conveyances or easy access solutions. Crews built platforms through the shaft as they went, using a jackleg drill to install ground support, all the while wearing fall protection, to access and fix the problem.

“There is one guy in a video that SURF Communications took, and he is crouched over,” she said. “Some of the guys had to bend over when they were running the jackleg. I guess that would be the case in any shaft, but particularly the wooden shaft, just because the configuration of what we had was challenging.”

In order to safely repair the Yates Shaft, Straub said the Authority shut it down to all activity, except for a weekly delivery of liquid nitrogen to scientists. That meant that all scientists, maintenance crews, and LBNF excavation crews with Thyssen Mining, Inc. had to use the Ross Shaft for access.

“It got a little crazy and planning was key,” she said.

For example, with using the Ross Shaft for access, scientists had to walk a little less than a mile, through the excavation area, to access their experiments at the Davis Campus. With active blasting scheduled throughout the day for LBNF excavation, that meant scientists had to catch the 6 am cage down to the Davis Campus, and they could not come back up until 6 pm Additionally, the representatives from Thyssen Mining Inc. always escorted scientists through the excavation area.

But closing the Yates Shaft allowed Straub and her crew the time they needed to ensure stability at the shaft.

“At the Yates Shaft we were able to get the work done safely and have that time we needed to really take a look at things and do the repairs that we needed to do,” she said. “The guys did a terrific job.

“As crazy as it was, I think we all learned a lot,” she continued. “There are not a lot of wooden shafts left in the world.”

While they were busy trying to fix the wall plate, Straub said crews discovered a new hazard that needed immediate attention. An old rotten pipe was left hanging down the shaft. With no way of knowing where the pipe was secured, or how many other pipes there might be, the obstruction threatened to fall and pose a serious safety hazard.

“So the campaign started as we were securing things, to cut all of that pipe out,” Straub said, adding that crews removed approximately 150,000 pounds of steel that was mostly from the old pipe.

Once crews were able to get to the 2,300 Level, a detailed inspection all the way down to the 4,850 Level revealed even more damage in the shaft, which delayed opening the Yates for another three months. The project that was originally scheduled for a September completion, was pushed back to December for an expected opening date, which frustrated users even more.

While they were working, getting supplies for the timber shaft was another challenge. Once that was done, putting everything back together, like Jenga, took some time.

“It’s such a fine art and everything has to go together just so, and there aren’t a lot of people left who know how those things work and how those things go together,” Straub said of the timber shaft.

Overall, throughout the course of the project Straub said she was impressed with how well everyone worked together under difficult circumstances.

“I felt like this was a good example of everybody working together to do something for the better of the property,” she said. “I think science did great. I think the Fermi Research Alliance (FRA) and their contractors worked with us very well. The infrastructure technicians, the hoist operators, and the engineers helped us with a lot of support as well. Science was definitely chomping at the bit to get the Yates up and running, but they wanted it to be safe, too. Scientists tried to run their systems remotely if they had that option. Not that I would want to do this all the time, but I think it went fairly smoothly.”

Straub will be one of the SURF employees on hand to discuss her work on the Yates Shaft during a Deep Talks Presentation, scheduled for April 21 from 5-7 pm at the Sanford Lab Homestake Visitor’s Center. The presentation will feature a series of updates about progress and science at the Sanford Underground Research Facility. The public is invited to attend.

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