Tainted water in Redwell Basin affects local creeks

“Really nasty water” has been flowing into area creeks for decades

For the last 40 years highly acidic, metal-laden water has been pouring out of an abandoned borehole in Redwell Basin just northwest of Crested Butte on the back flank of Mt. Emmons at a rate of approximately 20 gallons per minute. This summer, the Colorado Division of Reclamation, Mining and Safety (CDRMS), in cooperation with local and state groups, is aiming to do something about it.

Likely drilled in the late 1960s, the borehole is presumed to have been part of the mineral exploration that took place throughout the entire basin and on all sides of Mt. Emmons. The hole is thought to be 6,000 to 7,000 feet deep—for reference, the Empire State Building is 1,454 feet tall—and extreme pressure in its depths has caused the development of an artesian-type well, which spews forth water with a pH falling between acid rain and lemon juice and teeming with dissolved cadmium, aluminum, dissolved copper, dissolved lead and dissolved zinc.
This water flows into Redwell Creek, then into Oh Be Joyful Creek and eventually mixes into the Slate River. Reports from the state and from the U.S. Environmental Protection Agency (EPA) have found that these water bodies are impaired and exceed the instream limits for several different metals and nutrients. While not immediately dangerous to humans, this contamination can spell trouble in the short term for aquatic organisms, and can harbor potential long-term effects for the greater ecosystem.
According to the CDRMS, the borehole was recognized as an issue in the early 2000s, around the same time the EPA began looking at the damage left behind from the Standard Mine.
Last year, the CDRMS took the first step to plug the well when it poured more than 3,300 pounds of grout down a stainless steel pipe one inch in diameter that leads into the borehole. The effort was ineffective in stopping the flow of water in part because the hole was much deeper than expected. However, the action did provide insight into the characteristics of the hole and what would be necessary to fix the problem.
“We’re going back to the well this year with a larger arsenal of options,” said CDRMS reclamation specialist Tara Tafi. “Our first option is to pressure-grout the borehole using traditional grouting methods. Using a grout pump, several tons of cement-based grout will be used to fill the entire length of the borehole via the existing pipe until the point of refusal. Our other option is to use a chemical grout that is similar to a polyurethane foam to plug the hole. The grout is water-reactive so we would likely be able to fill only a portion of the hole below the current plug located at 100 feet.”
According to Tafi, a chemical analysis of the water from the borehole indicates it’s coming from a source deep in Mt. Emmons near a molybdenum deposit.
“The entire ground water and geochemical situation in Redwell Basin is complicated,” said Tafi. “Redwell is naturally mineralized, but the Daisy Mine and the borehole introduce a human impact into the system. We know that the water and the metals within it are not coming out of the shallower mineralized water in the area.”
The U.S. Geologic Survey has conducted numerous studies in the Redwell Basin to determine what the normal levels are for pH and naturally occurring metals. By modeling the area, the USGS determined that if the area had never been tapped for mining, the pH would be around 5—acidic but not excessively dangerous. However, with the inputs coming from the borehole and the Daisy Mine, the creek at the mouth of the Redwell Basin has a pH of about 3.5, strong enough to kill all fish, amphibians and mayflies, and to provide many humans with at least a stomach ache if consumed in large amounts, said Tafi.
“Regardless of whatever option we need to use, that hole will be plugged and that water will no longer be entering Redwell Basin,” said Tafi. “Potentially we will see improvements in water quality down lower in the watershed in Oh Be Joyful and in the Slate River.”
After the first attempt at plugging the well failed, Tafi fitted the pipe that runs into the hole with a valve that had to be left open through the winter. Next week she will be going into Redwell Basin to continue her work on the project and to shut off the valve. It’s a temporary fix, but one that might affect how she determines the hole should be closed permanently.
“We’ll plan to take water samples next week, then again a few weeks after the valve has been closed,” Tafi said. “We know we have a lot of really nasty water in the area and by sampling at set times we hope to be able to determine in greater detail where it’s coming from. We’re working to take care of our legacy of mining issues.”