Thunderstorms likely. Gusty winds and small hail are possible. High near 70F. Winds E at 5 to 10 mph. Chance of rain 70%..
Scattered thunderstorms during the evening. Partly cloudy skies after midnight. Gusty winds and small hail are possible. Low 51F. Winds SW at 5 to 10 mph. Chance of rain 60%.
Thunderstorms likely. Gusty winds and small hail are possible. High near 70F. Winds E at 5 to 10 mph. Chance of rain 70%..
Scattered thunderstorms during the evening. Partly cloudy skies after midnight. Gusty winds and small hail are possible. Low 51F. Winds SW at 5 to 10 mph. Chance of rain 60%.
Long Baseline Neutrino Experiment officials continue to monitor and evaluate the dust being blown from the Open Cut in Lead and continue to work on solutions. Pioneer photo by Wendy Pitlick
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Long Baseline Neutrino Experiment officials continue to monitor and evaluate the dust being blown from the Open Cut in Lead and continue to work on solutions. Pioneer photo by Wendy Pitlick
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LEAD — The amount of dust that could pose a risk to long term health emanating from the Open Cut is comparable, and often less, than what monitors pick up at different locations around Rapid City, Black Hawk and Wind Cave National Park, an environmental specialist with the project to build the Long Baseline Neutrino Facility says.
Zach Eivins, the environmental specialist with the project, said last week that monitors Fermilab has set up to survey dust levels at the Open Cut are the same as those which the South Dakota Department of Agriculture and Natural Resources has set up throughout the area. Eivins said he regularly checks monitors near the concrete plant in Rapid City, at Wind Cave National Park, and in Black Hawk, to compare them to levels his monitors are showing from the dust in the Open Cut. Some of those monitors, he said measure for larger dust particles, or PM-10. Others, such as those at Wind Cave, monitor smaller dust particles that pose a health hazard, called PM-2.5. All of the monitors have shown a significantly lower amount of dust in Lead compared to other locations throughout the Black Hills.
“The reason they’re monitoring for (PM-2.5) particles at Wind Cave is because those are fine particles associated with a forest fire,” Eivins said. “The small particulate number is low here. That is because we are discharging the larger particulates and we shouldn’t see much of a PM-2.5 surge, other than if there was a forest fire.”
Eivins went on to explain that the Open Cut monitors measure PM-10 levels, and have been installed since December 2020. Smaller particle, or PM-2.5 monitors to measure for health and safety concerns related to the dust, were installed about a month ago at Dr. Fox’s former dentist office and various locations along Mill Street. The levels from those monitors, he said, have been significantly less than those at Wind Cave National Park on comparative dates.
“They use the same exact device we have at the Open Cut, so it’s apples to apples comparison,” Eivins said.
Josh Willhite, design project manager for LBNF said the reason lower particulate matter readings have been less at the Open Cut than in other areas, is because Fermilab’s crushing and conveying activities generate dust that is at a PM-10 level and above, which is a much larger dust particle that does not get lodged in the lungs.
“When you crush rock you don’t create those super fine particles,” he said. “You create these larger particles, which look bad. They’re not a good thing at all. But they’re not in that tiny particle size that are a concern for public health. That’s why it may seem like you’re seeing dust, and how can it possibly be that we have less small dust than a national park? That’s why. It’s because the particles you’re seeing are much larger than what could present a long term health concern.”
In fact, Willhite said the measured dust particles are well within Fermilab’s air quality permit from the Department of Agriculture and Natural Resources, which is required for discharging the rock. Additionally, he said the fine dust levels are about 20 to 30 times less than what the EPA requires for a federal permit.
Though some residents have questioned whether the EPA standards are trustworthy, Eivins said they are based on extensive studies and the best science available in the world. Additionally, Willhite said the EPA standards are the only ones available to measure air quality.
“It’s the only standard that exists in the United States of America,” he said. “We don’t have a research facility to study this type of thing ourselves. That’s what the Environmental Protection Agency is established to do.”
But that doesn’t mean Fermilab officials aren’t committed to solving the dust issue that has been plaguing Lead for nearly a year.
“We really are committed to this,” said Chris Mossey, project director for the Long Baseline Neutrino Facility. “The current situation is not acceptable. It’s not acceptable to the community and it’s not acceptable to us. We’re sorry that we haven’t been as good of neighbors as we aspire to be. We understand the frustration that people have. We’re going to keep working on this.”
Willhite said his team has been working to mitigate the dust in the Open Cut since May 2021. The team started with foggers and sprinkler systems that seemed to contain the problem for a while. But those systems were tied in with the city’s sprinkler system, which was shut down in October to prepare for cold weather. Once that system shut down, he said the dust started ramping up again in November.
Adding the tackifier solution to bind the rock particles together has been working, Willhite said. But that took some time to get set up, since the LBNF team had to make sure the substance would not affect the S.D. Science and Technology Authority’s water treatment plant or Whitewood Creek. Although the tackifier is food-based and environmentally friendly, he said toxicity tests were necessary to be absolutely sure it would not cause adverse effects to the environment.
Once toxicity tests verified that the tackifier was safe for discharge, Willhite said his crews began spraying 265 gallons of tackifier mixed with 30,000 gallons of city water per week on the rock before it was dumped into the Open Cut, a practice the team continues today. The problem is that while the team was testing the tackifier, a large pile of untreated rock lay on the side of the Open Cut. While officials hoped the tackifier would spread and take care of the untreated rock by acting as a cap, the tackifier proved to be too sticky and did not cover as much area as they had hoped.
“The tackifier does seem to be doing what it is meant to do,” Willhite said. “Everywhere that tackifier has reached when you watch the pile, you do not see dust coming off of that tackified material. But now we’ve got this nice streak down the middle of the pile that is not creating dust, and we’ve got the old stuff outside of that streak.”
That old pile is what the wind has been picking up and blowing across town. Though from a distance it appears to be small, Willhite said it is about 700 feet long by 500 feet across, and the closest his crews can get to it is from the end of the chute on the conveyor belt.
“I know there has been a lot of talk about trying to get more water down there,” he said. “The idea is to use big water nozzles and try to spray it. At least that we’ve been able to find, there is no water nozzle made that can project water as far as the bottom of that pile.”
Additionally, Willhite said sending crews down into the Open Cut to treat the material is not really an option. Homestake stopped maintaining the Open Cut for occupation in 2003, and since then rock slides and other hazards along the Open Cut benches pose a significant safety hazard for personnel.
“Homestake historically would take equipment around each of these benches and make sure there was nothing hanging off the benches that could fall on people working down inside the pit,” he said. “That hasn’t happened for nearly 20 years. “(Now) it is a high risk activity to go anywhere inside of that Open Cut.”
The sheer size and depth of the rock pile combined with safety concerns are exactly why Willhite said he has been working with Williams Drone Co., of Lake Preston, S.D. to fly a drone that can apply a capping agent to the rock pile. The capping agent, which is also food-based and environmentally safe, is commonly applied to full coal trains to prevent coal dust from flying off in transit. Though it may have to be re-applied regularly, Willhite and his team said they have high hopes that once they can get a drone to spray the compound, the dust problem will be contained.
But getting a drone to fly in the Open Cut can be challenging, as the LBNF team discovered during their first flight run in February, when Williams Drone tried to fly two drones. The first flight was unsuccessful due to a battery failure. But the second drone was equipped with an automatic crash avoidance mechanism that caused it to make an “emergency landing” in the Open Cut.
“If you’re flying in a field of corn, you would have just walked over and picked it up, no problem,” Willhite said. “Unfortunately, it landed on a pile and tipped on its side, and at that point there was no way for us to recover it.”
New technology with drones has improved the software for crash avoidance, and Willhite said he looks forward to flying another drone as soon as the snow has dissipated from the rock pile, possibly either at the end of March or early April.
Didn’t you anticipate the dust when you did an environmental analysis for the project?
Yes, Willhite said. During the extensive environmental analysis that was conducted before the project to build the Long Baseline Neutrino Facility even began, studies showed that this project had a potential to emit (PTE) three to four tons of dust particles per year.
“EPA writes federal permits if your potential to emit is greater than 100 tons per year,” Willhite said. “So we’re 20 to 30 times less than that.”
Extensive crushing analyses of the rock and a chemical analysis also examined dust management. At that time, Willhite said a final report provided by Canadian company SGS Canada, Inc. said the dust could be handled with about 2% moisture.
“Whether that is true or not, we certainly haven’t been able to manage it completely with water,” Willhite said.
Do you have any alternatives to dumping the rock into the Open Cut?
Alternatives to transporting excavated rock through the conveyor belt and dumping it into the Open Cut were examined during the environmental assessment, and each option was considered for its environmental impact and public safety, Willhite said. One of the other alternatives that was discussed, Willhite said, included using trucks to transport the rock to Gilt Edge Mine. That option, he said, would require at least 60 to 160 large gravel trucks per day to transport rock through Lead.
“This (conveyor belt) is the lowest impact to public safety because it is completely captured within control areas on the conveyor,” Willhite said. “We’re not using trucks and we’re not putting the public at risk with truck after truck after truck traveling. It’s a very well known technology, and so that was a big factor that went into the decision to use this.”
Can you just shut it down?
According to officials on the LBNF team, shutting down the conveyor belt until the dust problem is solved would cause more problems than it solves. That’s because whether the conveyor belt of tackifier-treated rock runs or not, the untreated rock in the Open Cut continues to cause problems. That is where officials are focused on dust control.
“We really do believe the tackifier is addressing the issue with the rock that is coming off the conveyor,” Mossey said. “Frankly, we have to figure out how to deal with this rock that is on the side of the hill. Whether the conveyor is running or not, we have to deal with it. That’s the principal source of the dust.”
Willhite agreed, saying that most of the dust issues that have occurred since January have happened when the conveyor belt was not operating. Additionally, he said the more tackified rock that is dumped on the untreated pile, the more surface area that rock covers, acting as a capping agent for the untreated rock.
“The lack of operation doesn’t keep the dust from happening,” Willhite said. “We need to deal with the problem that is in the pit to stop the dust. Continuing the conveyor is not solving the problem the way we want it to, but it is helping to solve the problem as it continues to grow that cap of tackified material over the top.
“People think we should just stop and start trucking,” Willhite continued. “I would challenge the people who are saying that to consider that we are producing about 1,000 tons per day. We expect that to get up to 2,500 tons per day. The standard, over the road truck that you would see hauling this is 15, maybe 20 tons. That is over 60 truck loads a day with today’s production, and it’s over 160 truck loads a day when we peak. I think most people would agree that would be less tolerable because our route would have to be through the city of Lead, one way or the other.”
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