The Yates Shaft—primary access

On May 19, 2012, the Yates began full operations, opening the door to science research and providing the infrastructure for continued expansion to the world-class underground laboratory at Sanford Lab.

When the mine closed in 2002, water levels rose to the 4550 Level, leaving portions of the Yates Shaft under water. The shaft needed a complete overhaul, which began in November 2008.

The monumental task included refurbishing the shaft, an 18-month project; designing a new cage specifically to convey the LUX detector; and constructing a tower to support the rope dogs—a safety system designed to stop the cage in an emergency. All to make science possible.

"For science to be successful, equipment, supplies and, of course, researchers all need to travel to and from the underground. Since 2012, the Yates crews have ensured that can happen consistently and reliably. Moving liquid nitrogen, accelerator components, germanium crystals for Majorana and the LUX detector are great examples of how the Yates Shaft has served the Sanford Lab science community over the years." —Jaret Heise, science director

Two men push a large package onto the Yates Cage.

Loading from the top...

Everything that goes underground starts at the top. Most equipment and supplies go inside the cage. But sometimes there simply isn't enough room in there. That's when crews need to "sling" the item under the cage.

One example of this is the Fletcher bolter. The bolter is used to install ground support underground, but was too large to fit under the cage. It was disassembled on the surface, transported under the cage and put together underground. And it had to be done right, requiring excellent communication between the hoist operators, cagers and infrastructure techs.

Above: Infrastructure technicians move the LUX detector into the cage.

Two men pull a tanker out of the cage underground.

To the bottom...

Everything, from equipment and supplies for physics experiments to construction machinery and concrete comes down the Yates Shaft. Take the Majorana Experiment. The shield for this ultra-sensitive experiment includes a brick castle made up of more than 5,000 lead bricks. Hundreds of pallets filled with bricks were loaded onto the cage, then unloaded nearly a mile underground. An interesting note: Majorana's lead shield weighs approximately the same as a 757 jet half full of passengers.

Above: Infrastructure technicians remove liquid nitrogen from the cage on the 4850 Level.

"As the experiment was built, we encountered many challenges, including moving supplies. But the joint efforts of our team and the 'can-do' attitude of the SURF staff allowed us to keep moving forward."
—John Wilkerson, principal investigator of Majorana.

Loading a large metal frame into the cage.

Slinging loads

Occasionally, objects that won't fit inside the cage need to be transported—or slung—below the cage. Large equipment or heavy steel beams are carefully monitored visually through a hole in the floor of the cage. The shaftsmen communicate with the hoist operators by radio to maintain the right speed to prevent the load from swaying or causing damage to the shaft in any way.

Once they reach the Yates station on the 4850 Level, a crew member receives the object and slowly pivots it onto the station with the help of the hoist operator via tight communications on the radio. Slinging loads down the shaft requires extreme logistical planning by the entire crew to ensure efficiency and, most importantly, safe conditions. Over the years, crews have successfully transported thousands of loads underground.

Above: A crew loads a large metal frame into the shaft. The frame was so big, it had to be slung under the cage. It was used to determine whether the LUX dark matter detector would fit in the cage and down the shaft. It did.

A rope man watches a load hanging in the shaft

The rope crew

Think about this: The Yates Shaft is 5,000 feet (1,524 meters) deep. Inside the shaft, the cage hauls people and supplies from the surface to the 4850 Level and back. The cage connects to a 6,000-foot (1,829 meter) hemp and steel rope that is part of the hoist system. How do we know the ropes are safe? We turn to Rick Tinnell, rope technician at Sanford Lab.

Tinnell inspects the ropes weekly—from the sheave wheels at the top of the headframe down to the 4850 Level. “I look for frays in the rope, but I don’t think I’ll ever see one in the lifetime of this rope. They're made that well,” he said.

Tinnell also inspects the rope-dog safety system, which is used to stop the cage in the event of a hoist rope failure. The dogs grip two wire ropes that run 5,200 feet (1,585 meters) along either side of the shaft and are supported by 110-foot (33.5 meter) steel towers inside the headframe.

Additional tests, called non-destructive rope tests, are done twice a year. A sensor clamped around the rope at the collar and near the hoist drum determines wear and tear.

“We want to make sure the ropes get retired at the proper time because we don’t want to put lives at risk.”
—Mechanical Engineer Mike Johnson

"We use mostly radio when we move loads under the cage. And we have to lower the cage real slow to avoid swinging or swaying."
—Nathan Engle, Yates hoist operator

Moving people, too

Hoists operate on a tight schedule—and only at certain times of the day—to convey materials and people and allow for maintenance every day. If you miss a scheduled cage, you simply wait for the next. Or miss your shift.

Scientists, administrators and the shaft crews mingle during the 15-minute cage ride. With up to 28 people on each cage, it can get a bit snug. But in the event of an emergency, it gets even tighter, with up to 36 people on the cage.

Transporting people a mile below the surface is not as simple as pushing a button in a department store elevator. Skilled technicians operate the hoists and make sure the cage ride is safe for everyone.

Infrastructure techs move the cage into the shaft.

A cage for science

To prepare for science, Sanford Lab needed a whole new cage. The cages used during Homestake mining days simply weren’t high enough for the needs of some physics experiments, like the Large Underground Xenon experiment (LUX).

Sanford Lab engineers turned to OJ Industries for help. The company designed and built the current 14,000-pound (6,350 kilogram) cage specifically to carry the LUX dark matter detector safely and securely to the 4850 Level. Similar in design to the previous cage, the interior of the new version can carry up to 10,000 pounds (4,536 kilograms) and, at 9 feet tall (2.7 meters), was high enough to transport the LUX dark matter detector, as well as other equipment and machines.

Above: Infrastructure technicians install the cage into the south cage compartment.

Shaft compartments

The Yates Shaft replaced the crumbling Ellison Shaft. It was constructed of timber due to a steel shortage during World War II and finished to the 4100 Level in 1941. The shaft contains seven compartments; two cages for moving people and equipment, two skips for moving ore, one for utilities and one for emergency access. In 1954, the Yates Shaft was completed to the 4850 Level.

Today, safety is key to how we care and maintain the shaft. When first built lacing was the only barrier between the ground and the shaft compartments. Through our top-down maintenance program, we're replacing all of the lacing in the shaft and installing ground support.

“Moving LUX underground was quite literally the smoothest operation of the whole project. We did a full-scale mockup to see how it would move from the Surface Lab to the Davis Campus. When we moved the real detector, one could have placed an overfull cup of coffee on top of it, and not a drop would have been spilled the whole journey. It literally floated on air.”
—Rick Gaitskell, co-spokesperson for LUX.

37,057

pounds of rope (16,809 kilograms) connect the cage to the hoists.

6,000

feet of rope (1,829 meters) winds around each hoist.

The hoists

In the late 1930s, Homestake installed two state-of-the-art hoists to run the cages up and down the Yates Shaft. Today, those same hoists support the various science experiments underground.

Wire ropes that are more than 5,100 feet (1,555 meters) long, wind around conical drums in a single layer. This design protects the ropes from wear and tear as the cages and skips travel the shafts. The wire rope, itself, far outweighs the loads it carries, which could have been a problem.

In the 1930s engineers at Nordberg in the 1930s found a clever solution—they made the drums smaller at one end. In essence, they traded speed for torque: with every rotation of the drum, the load travels a shorter distance. They also tied two conveyances together as counterweights, reducing power requirements, and used 70-ton flywheels to store energy for starting and stopping the conveyances.

Hoist operators

Without the Yates Shaft hoists, nothing would be able to go down—or come back up. And Sanford Lab is the only place in the world that uses them. That means our hoist operators have highly specialized jobs that require on-site training.

Hoist operators train for up to a year-and-a-half, one of the longest training periods for any job at Sanford Lab. “They’re all really good hoist operators by the time they get released from training," said Gary Larson, facility maintenance foreman. "All of the hoist operators have to agree that the trainee is ready. I’m pretty lucky because we have people that have experience from Homestake and Sanford Lab and they know how to train others."

In an emergency, hoist operators are the first point of contact for those working underground. They monitor radios, Femco phones and regular phones for pertinent communications and must be apprised of all activity underground that could create unsafe working conditions.

“Everyone knows those hoists are the number one most important thing for this place to keep in operation. We’re real lucky as far as crews go,” he said. “The safety aspect of the people on the other end of the rope is huge. It’s a real big responsibility and they handle it very well. I'm really proud of the work they do.” —Gary Larson, facility maintenance foreman

The safety of those traveling on the cage rests in the hands of the hoist operators who “drive” the cages up and down the shaft. While they do not actually see the people they transporting, the hoist operators are always aware of their human cargo and strive to make their trip up or down as safe and comfortable as possible.

But they do more than just run the hoists. During their 12-hour shifts, hoist operators perform regular maintenance on the equipment between running loads.

Nathan Engle and Greg Crotty, both hoist operators at the Yates Shaft, agree safety is a high priority. But good communication and trusting the people they work with is essential. “I’d say everybody has good communication and are professional,” Crotty said. “Safety has got to be the number one priority for everybody.”

“You have to trust everybody.” —Nathan Engle, hoist operator.

Not only must operators learn how to operate the machines, they must learn the proper terminology, much of which carried over from the mining days. “Mining has it’s own terminology,” said Engle. “What we would call a pulley, they call a sheave head.”

Crotty has been a hoist operator since the Homestake mining days. “We went through parts quickly and wore out a lot more things when we were mining,” said Crotty. “We were running these hoist a lot harder, too—more speed and more weight. We used to run the drums around 30 rpms and now we only run them at 7 rpms.”

1,250

Two motors power the cage hoists each capable of 1250 horsepower. That's three times the horsepower of an average sports car.

70 tons

The weight of the flywheel for the the ore—or about the average weight of six male African elephants.

Hoist operators have a unique view from their chair. Analog dials indicate where the cage is in the shaft at any given time. While the equipment may be old—it was produced in 1939—it is incredibly reliable and accurate. Parts must be specially fabricated when replacements are needed.

It takes a lot of energy to move a cage filled with people or equipment up and down the shaft. To power these hoists, electricity must be converted from alternating current to direct current. The motors attached to the back of each drum each have 1,250 horsepower.

500

The cage is lowered and raised at 500 feet per minute (152 meters per minute). It's about a 12-minute ride to the 4850 Level.

2,000

During mining days, the cage ran at 2,000 feet per minute (610 meters)—about a 3-minute ride to the 4850 Level.

5 guys discussing a safety plan before work

Shaft safety

The safety of every person who enters the Yates Shaft is the number one priority at Sanford Lab—whether performing maintenance in the shaft, operating the cage, or riding in the cage to perform scientific research.

Safety consciousness starts at the top and filters down. “Safety has to be practiced the way it’s preached,” said Peter Girtz, a technical support lead. “We have a good understanding of safety from the top down. We always talk about safety and that’s critical.”

The entire crew takes safety seriously. “You do everything as safely as you can and you always want to be aware. Everyone watches out for each other,” said Joe Sigdestad, an infrastructure tech. “We have some people who worked here in the Homestake years, they pass along knowledge.”

“The workers in that environment are very safety conscious,” Girtz said. “That’s why there are so few incidents. Every day the guys go to work in a high-risk environment and they are doing it safely. Big recognition goes to those who put it to use every day at work.” —Pete Girtz, technical support lead.

Safety is always a continuous improvement process. “Safety programs by their very nature are constantly evolving,” said John Emick, safety specialist. "We need to stay ahead of it, which requires due diligence on all parts.”

Top Down Maintenance

In an 80-year-old timber shaft, top-down maintenance becomes more than important—it becomes critical. Every day, crews of infrastructure technicians convey people and equipment up and down the Yates Shaft. What we don’t see is the work the crews do to ensure every person—and everything—gets where they need to be, safely.

“During the day, we mostly cater to science,” said Pat Urbaniak, team lead. “The night shift is where we do most of the challenging work.”

TDM focuses on inspecting every piece of timber, then rating them according to life expectancy. If a piece of timber is rated T-3, it needs attention sooner rather than later. The crews also remove lacing and debris—up to 25 tons of debris every month—all with shovels, pelican picks and 5-gallon buckets.

Above: This station shows old infrastructure at one of the Levels at the Yates Shaft.

Step-by-step

A step-by-step of top-down maintenance (TDM) for the 3200 Level station. Crews began their work three sets above with the removal of shaft lacing and installation of overhead protection.

Removed face lacing, which abuts the shaft wall, one slab at a time, to better control the removal of debris from behind the lacing.
Removed debris that has accumulated behind the lacing, which is done manually with shovels, pelican picks and 5-gallon (19 liter) buckets.
Inspected the shaft for soundness and removed additional loose material.
Used jackleg drills to install new ground support, which included 5-foot (1.5 meter) and 7-foot (2.1 meter) rock bolts, screens and lacing.

Urbaniak, who worked with Homestake for 10 years and with Sanford Lab for five years, said his main goal is to ensure the safety of his crew. “I don’t want anyone to get hurt. If we have questions about a procedure, we slow down or stop work to re-evaluate things.”

Above the 3200 station completed with new ground support installed.

“We really enjoy working with science. They come in with these great ideas and seem excited to tell us what’s happening. We don’t always understand what they do, and they don’t always understand what we do. But we know their work is important and we make sure they can do their work safely. As long as they’re happy, we’re happy.”
—Pat Urbaniak, infrastructure technician

Clean up

Skips were once used to haul ore out of the mine and are now used as maintenance vehicles for the Yates shaft crew. “We used to do 3,500 tons per 24 hour shift of skipping in the mining days,” said Jack Stratton, Yates shaft foreman. Skips can haul 11 tons of material at a time. These days a crew can fill a skip with debris about once per shift during shaft maintenance.

Image on left: Inside the headframe Alexis Novtany and Alvin Burns empty the skip bucket full of old debris taken out of the shaft.

Infrastructure technicians

“We tend to focus on science and other areas, like the Ross Shaft, which have finite goals. But for the crews in the Yates, there’s no real end point. They just keep up maintenance and despite challenges every day, they get the work done and make sure science can happen.

“Over the years, they’ve grown so much and really know this 80-year-old shaft. They address concerns quickly and safely. I’m proud of the work they do every day.”

—Mike Headley, Laboratory Director

An infrastructure technician and a scientist work together

These guys make it happen.

There are so many things these crews do that no one sees—safety checks, shaft inspections, rope inspections, top-down maintenance, removing muck from the shaft, putting in ground support. When science shows up, they are ready to go. At the time of the this writing these are the guys that make it happen.

Shaft Crews:

David Schaffer, Alvin Burns, Patrick Urbaniak, Casey Schaff and Ricky Allen
Charles Roth, Michael Harvey, Russell Bauer, Dustin Mund, and Joe Sigdestad
Ashana Baumberger, Alexis Novotny, Jerry Sjomeling, Neil Engle, and Dick Goetz

Bryan Silvernail and Al Pfarr are shaft crew members who transferred in the past 6 months.

Hoist Operators:

Leon Bachand, Greg Crotty, Curtis Rang, Nathan Engle and Dan Horton

"As Sanford Lab's capabilities expand, expectations from our science experiments are able to grow in kind. Each of us plays a strong role as we continue to evolve and mature as a laboratory, and the Yates Shaft crew presents a good example. Providing transportation for equipment and personnel has transformed over time into ensuring liquid nitrogen deliveries and dewar swaps take place over weekends or during emergency situations. Bottom line is that the Yates Shaft crew helps ensure safe and successful operation of many of the experiments at our facility." —Jaret Heise, science director

This article was written by Constance Walter, Christel Peters and Matt Kapust. Photography by Matt Kapust.