Orange silt coated the banks of Poker Creek after the spill at Hi-Crush’s Whitehall frac sand mine in May.
by CHRIS ROGERS
After a spill at Hi-Crush’s Whitehall frac sand mine this May, some Trempealeau County officials are worried, not so much about more spills, but about what might seep into the ground during normal operations at any given frac sand mine in the county. After the incident, some county officials are concerned about the potential for naturally occurring heavy metals to contaminate groundwater. Wisconsin Department of Natural Resources (DNR) representatives said the risk is minimal.
Most frac sand mines wash sand to remove impurities and store wash water in detention ponds. This May, a bulldozer operator at the Hi-Crush mine slid into a detention pond full of wash water. The bulldozer, with the man trapped inside, sunk to the bottom, under 12 feet of water and silt. Thankfully, the bulldozer cabin was airtight and kept the man alive for two hours underwater while first responders tried to figure out how they could rescue the man. Finally, one of the man’s fellow heavy equipment operators used a backhoe to breach an earthen dam and drain the pond. It saved the man’s life and sent 10 million gallons of wash water spilling out across neighboring farmland and into Poker Creek, the Trempealeau River, and the Mississippi River. “This was an intentional release to save a man’s life,” Hi-Crush Chief Operating Officer Scott Preston said at a June meeting. “We avoided a tragedy,” he added.
DNR representatives tested water in the creek and the Trempealeau River following the spill and found high levels of arsenic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, silver, and zinc. A sample taken very near the mine had 1,090 micrograms of lead per liter, according to the DNR.
DNR Water Resources Engineer Pat Oldenberg said that his agency did find high levels of certain metals in the spill, but that those levels were consistent with the amount of naturally occurring heavy metals that the DNR would expect to find in sediment. There is a certain amount of naturally occurring arsenic, lead, copper, mercury, and other chemicals in bedrock. Oldenberg said it is not surprising to find such levels of those metals in silty water that is full of sediment.
Oldenberg also reported that most of the metals detected in the spill were not dissolved in the water, but were bound to sediment particles floating in the water. That means the chemicals were not in a form that aquatic organisms can absorb, he explained. The DNR conducted separate tests to measure the amount of dissolved metals in the creek and the river. Most of those samples were either too low to be detected or low enough that they were not concerning, Oldenberg reported. “From an aquatic life standpoint, our concern is really lessened by that — because we’re not seeing [the metals] in the bioavailable form, and they really seem to be associated with those particles,” he said. In other words, because the metals were bound to sediment, they did not pose a threat to aquatic life.
DNR officials said that they did not observe any fish kills or other signs of environmental harm.
Wisconsin Department of Health Services Toxicologist Sarah Yang advised people might want to wash off after swimming in the Trempealeau River. However, she stated, “The water in the Trempealeau River does not appear to have any sort of immediate health effects for people. We do not think people are going to get sick from swimming in the water or taking their kayak out.”
Asked immediately after the incident if people should avoid contact with sludge left behind from the spill, DNR Communications Director James Dick stated that the mud “may present a slid a slip/trip hazard.”
All of this led some people to conclude that the spill was just muddy water. Others remained concerned.
At a meeting with DNR and Hi-Crush officials in June, Trempealeau County Board member Tim Zeglin, who represents the area most affected by the spill, pointed out that a neighboring farmer lost an entire growing season because sludge from the spill coated one of his fields. He asked Preston what Hi-Crush was doing to prevent another accident, and stated, “I think there is some responsibility to be ascribed here … The incident is something that could have been prevented.” Preston described the bulldozer’s slip into the pond as a bizarre accident. “This is something that, within my history in the industry and mineral association and in talking with my peers, they’ve never seen something like this before,” he stated.
Other county officials were less worried about the spill than what the test results say about frac sand washing operations. “What moved through the river was very short term, and probably the impacts from that were negligible,” Trempealeau County Board member Jon Schultz said in an interview. “My concern is where this material is concentrated.” He added, “What gets shipped out is almost pure silica. So what gets left behind?”
Schultz and Lien are concerned that the mining and washing processes could concentrate naturally heavy metals in wash ponds and that, from there, those metals could contaminate aquifers. They said the DNR needs to study this issue. “Do [metals in wash ponds] just stay there?” Lien asked. “Does it leach through groundwater?” This concern does not only apply to the Whitehall mine. “I would suggest [it applies to] every mine that’s processing and washing sand,” Lien said.
Asked if his concern about heavy metals was reasonable or unreasonable, Schultz responded, “I think we need to know. If it’s not a concern, give us the data so we know that.”
Wastewater ponds are often lined with plastic, concrete, or clay to prevent the water from infiltrating into groundwater. At the June meeting, a county official asserted that the Hi-Crush wash pond that was drained was unlined. Hi-Crush officials did not immediately respond to questions about whether the pond was lined, but at the meeting, DNR Industrial Sand Sector Specialist Roberta Walls explained that there are no state regulations requiring frac sand wash ponds to be lined. County Board members Olin Fimreite and George Brandt were surprised to hear that. Every manure pond has to be lined, but not frac sand wash ponds? Brandt asked. Most retention ponds have strict standards their dikes must meet, and frac sand wash ponds should, too, Fimreite told Walls.
Lien and other county officials claimed that some landowners have seen elevated heavy metal levels in their well water, but Lien declined to comment on specific cases.
DNR spokesman James Dick stated that if mines were releasing metals into groundwater, it would be a violation of state regulations. As for whether that is actually happening, Dick pointed to the low levels of dissolved metals in the recent spill test results as a reassuring sign. “As for the Hi-Crush situation specifically,” he wrote, “Recently gathered data suggest that the metals are bound to solids, not mobile in the soil profile, and therefore may pose minimal risk to groundwater.”
Dick said the DNR is working on a study to examine the concern about heavy metals and other issues involving frac sand mining and groundwater. According to the DNR website, the study was supposed to start last fall. Dick reported that the DNR is still seeking funding for the study from the mining industry and from other potential partners such as the U.S. Geological Survey and the Wisconsin Geological and Natural History Society.