Environmental remediation efforts are intensifying at the Chevron Qusta Mine site, which was shut down permanently in 2014 after almost 100 years of underground molybdenum and surface mining.
Chevron bought the Questa Mine in 2005 after it acquired the Uncocal Corporation. This was a century-old oil company that had oil fields in Asia that were very attractive to Chevron. The Questa molybdenum mining property and its tailings site were added to the National Priorities List in 2011. They were declared federal Superfund sites and required to be cleaned.
Last Friday, April 8, was a mine tour. Company officials informed the Taos News that cleanup and restoration activities are likely to continue into the 2050s. Underground water pumping and treatment operations are expected to continue “in perpetuity.”
Contaminated water is pumped from underground collection points throughout the mine site to the treatment facility. Seepage from springs along the mine edge near the Red River is controlled through a series French drains trenches filled in piping and gravel that allow water flow outward.
Rachel Conn, Amigos Bravos’ deputy director, stated that the water protection group continues to be concerned about Spring 13, which is releasing contaminated water to Red River at higher volumes than expected.
“We hope Chevron will quickly address this issue,” she added, noting that the U.S. Environmental Protection Agency had denied Chevron’s request for a phase-out of Clean Water Act permit coverage at the mine. Clean Water Act permit coverage is vital to ensure water quality and allow regular public participation. Amigos Bravos has been fighting Chevron’s request for many years and we are happy with EPA’s decision.
Tommy Lyles, Chevron’s manager of risk mitigation communications, stated that the mine’s wastewater treatment plant is located in the “largest building in Taos County.” It can treat between 800 and 905 gallons per minute and discharges approximately one million gallons of water each day.
Cindy Gulde is a regulatory affairs advisor at Chevron. She stated that prior problems with excessive aluminum contamination in Red River had been resolved. She said that people used to see white foam on the banks in certain places during low flows. The company has already completed many major remediation projects, including the restoration Eagle Rock Lake, an old gravel pit that had been heavily polluted over time.
Monthly meetings with representatives of the EPA, state Environment Department and New Mexico Energy, Minerals and Natural Resources Department take place at the offices of the remediation project, perched atop the former minesite at an elevation well above 8,000 feet.
Granite Construction project manager Jim Merrigan said, “It can drop to about 25 degrees below zero up there not counting the windchill,” Merrigan loves his job, despite the cold temperatures and springtime winds.
Merrigan stated, “I think that we’ve moved over 1.25 million cubic yards of dirt from October 2021,” when operations accelerated.
He oversees one the main projects currently underway. His crew is using a fleet of six-wheel-drive, 45-ton articulated haul trucks, large bulldozers, and other earth-moving equipment to level, install drainage, and prepare to cover the Capulin waste rock heap. It’s one nine tall rock piles with steep sides. They contain around 300 million tons worth of waste material.
Chevron Field Engineer Don Bush said, looking down at the rock pile, that “We’re rebuilding rock piles into stable configuration.” Below, dangerous-looking main access roads are called “Stairway to Heaven”, and “Highway to Hell.” He stated that each rock pile will have slope indicators and piezometers installed. The slope of the rock piles must be between 2:1 and 3:1 to prevent erosion and encourage revegetation. This means that they can’t rise more than a 3-foot for every foot of distance.
Because the waste rock material is acidic, it causes precipitation to turn acidic. The final phase in the rock pile reclamation involves laying a 3-foot “evapotranspiration” cover of approved material. This material will be sourced and from one neighboring pile. It will then be run through a screening station that also tests for contamination.
According to company officials each rock pile project will require five to seven years of work.
“The cover will contain material less than 8 inches that is non-acid-generating, meets the molybdenum. [content]Gulde stated that the standard is 600 parts per Million, but that no timeline was given for when groundcover would be laid.
A pilot project utilizing three different methods of laying down cover material on the Goathill rock pile has already yielded results. Chevron believes they are close to determining the best way to cover the ground to avoid erosion. Chamisa is the only vegetation visible to the naked eye at the most successful experimental plot. Gulde reported that the pilot project was supposed to be completed in 2024. However, it has been extended into 2027.
A pilot project similar to ground cover revegetation is currently underway at the mine tailings location, which is located miles away from the mine. It has produced some sparse plant growth. Officials could not identify which types of vegetation were most successful on the test plot. It was intended to support Chevron’s plan for remediating the tailings site with 2 feet of cover, rather than the 3 feet recommended in the project’s guiding document.
Christian Isely (Chevron’s public affairs advisor) stated that the seed mix is “a mixture of native forbs grasses and shrubs”. Gulde stated that the company plans to intensify its remediation work at tailings site in the next year.
Although 300 miners were expected to have been laid off following the closure of the mine, close to two-thirds of them are currently working on restoration and cleanup projects.
“There are currently 173 active employees on-site on daily basis,” stated Isely, who lives and works in Questa. Questa has struggled with its post-mine economy, despite Chevron’s support.
Isely stated that 79 of those workers are long-term residents and represent 46 percent of our workforce on-site. These numbers include Chevron [employees]Together with our business partners Granite Construction and Entact, Entact WSP-Golder, Securitas, and Arcadis, Entact. He indicated that there are opportunities for employment with all five companies contracted and stressed the stability of the employment.
Isely stated that the sequencing of the different projects is being done to preserve the workforce benefit. He also explained that workers won’t experience any gaps in employment during the next phases of remediation work. “When we’re done with Goathill we’ll move to the tailings site. Then it’s back on to the next rock pile.”
Rachel Conn praised Chevron’s efforts for the workforce.
She stated that Chevron has taken workers into consideration and scheduled restoration and remediation to ensure that there are no employment gaps. “Amigos Bravos believes that strong restoration requirements are important for both jobs as well as the environment.