SURF Completes 3650 Level pump room overhaul in first phase of dewatering system upgrade

America’s Underground Lab includes 370 miles of tunnels and shafts. The vast facility is continually filling with water—on average, about 750 gallons per minute percolate into the deep underground from both surface precipitation and underground sources.

To keep the space dry, a series of pumps stair-step up from the deep pool at the 6,000-foot level to feed the pumps at the 5,000, 3,650, 2450, and 1250-foot levels. These pumps provide a line to the surface that feeds an average of about 348 million gallons of water each year to SURF’s water treatment plant.  At the plant, the underground water is mixed with water from an offsite former mine tailings pond before being cleaned and discharged into the trout stream below. Since 2008, SURF has discharged more than 10-billion gallons of water with zero water quality violations.

The dewatering system at SURF requires a crew of engineers and technicians who do the heavy lifting to maintain the network of pipes, pools and pumps. Each of the large pumps plays an important role in supporting the facility’s efforts to advance world-class science.

Much of the dewatering system has been in place since the former Homestake Gold Mine closed in the early 2000s. Today, the facility is upgrading each pump in the system.

The recent overhaul of the 3650 pump room was undertaken alongside a more routine replacement of the deep well pump that sits near the 6000-foot level. This 35-foot-long pump includes a seal and motor stack that is attached to a 1500-foot-long pipe. The pump is a little like the end of a straw that draws water from the deep pool—it’s the first stage in the series. The contractor, Hydro Resources, worked alongside SURF technicians and engineers to complete the job in record time. Wendy Straub, the Chief Operations Officer at SURF credits the crews and contractors for their excellent work on both the 3650 and Deep Well pumps. 

“You might ask, ‘Why are we spending our money on new pumps?’ The existing pumping system is all legacy Homestake. We are at the point where the cost of rebuilding a legacy pump can equal the price of a new pump. This is why we are carrying on this program of rehabbing all of these pumps and pipes,” Straub said.

Andrew Brosnahan, a professional engineer at SURF, is leading the engineering and design effort for the pump room upgrades. Brosnahan gives praise to both the crews and the contractors, West Plains Engineering who completed the design and Harrison Western who helped with the installation, for the installation of the first phase of the rehab. This includes the new pumps and pipes at the 3,650-foot level.

“Harrison Western has been a great partner in working through a lot of challenges that come up on a project like this. They have been real team players. So, this install went much better than it could have thanks to them,” Brosnahan said.

In many cases, a contractor would install a pump of this size in a surface building. At SURF, however, the pump is located 3,650 feet underground. This meant that crews had to deliver each component via the cage, or elevator, that moves people and equipment at SURF.  The massive 3650 Level pump and motor weighed 15,600 pounds alone. This project also required 1200 feet of new pipe weighing more than 40,000 pounds—and 1000 feet of electrical cable connecting the pump and a 1500 kVA transformer weighing in at 12,000 pounds. 

 Brosnahan credits the Ross Shaft crews, rigging specialists and technicians for their incredible work.

“These were just these really large loads that had to go underground for this project,” Brosnahan said. “The shaft crew and the riggers handled and shipped everything, and that was a monumental contribution from SURF to this project. It was no small feat.”

Any installation of this magnitude is bound to encounter challenges. Brosnahan applauds the problem-solving skills of the crews at SURF; they always finding a way to get the job done.

“When the design didn't quite match up, we had to modify quite a bit of these prefab pipe support structures. The surface operations—the maintenance support facility—did a tremendous job making them fit very well. I can’t say enough about the expertise we have on staff and the value we bring in making a project like this happen.”

The pump room overhaul at the 3,650-foot level marks the first milestone in the ongoing infrastructure maintenance efforts at SURF. These efforts ensure science will proceed uninterrupted at America’s Underground Lab in the decades to come.