The Arizona Department of Environmental Quality and the city of Cottonwood hosted a community meeting regarding the Minerals Research & Recovery Inc. slag mining operation at Birch and Cherry Streets on Dec. 13 that featured more than 10 representatives of different ADEQ departments.
Air permits and compliance manager Balaji Vaidyanathan presented an air quality update on MRI’s operations in response to multiple comments regarding slag dust and heavy metal exposure. MRI is processing the copper slag pile to produce roofing granules, abrasive blasting media and pavement aggregate. Vaidyanathan pointed out that blasting is intermittent rather than daily.
MRI submitted a permit determination request to ADEQ in September 2009 and was informed in December of that year that no permit was required for its planned Cottonwood operations. The company began recovery operations in 2015. ADEQ directed MRI to obtain a crushing and screening general permit in July 2018 and issued the company a notice of violation on Sept. 11 of this year for failing to obtain the correct permit. MRI submitted an application for an air quality permit on Oct. 31.
Between 2015 and 2022, Vaidyanathan said, MRI had zero violations after 10 site inspections. In 2023, MRI had three violations from seven site inspections. Violations included leaks from process equipment on two occasions, faulty water spray bars and failure to obtain an appropriate permit. ADEQ performs the inspections randomly and unannounced.
MRI voluntarily ceased operations on Oct. 5 while working to obtain the correct permit. On Oct. 12, MRI and ADEQ entered a consent order that outlined the requirements for MRI’s facility and required the development of a fugitive dust control plan. Operations resumed under the consent order on Oct. 13.
ADEQ will also collect air sampling data near MRI for an air quality monitoring plan to aid the Arizona Department of Health Services’ development of a health consultation.
Vaidyanathan pointed out that the consent order is a temporary legal mechanism for MRI to continue operations legally, not a substitute for a permit.
“We have no reason to believe that they’re violating the consent order,” Vaidyanathan said.
In a few weeks, ADEQ will be placing equipment trailers by the children’s park and the VFW to take samples for PM-10, PM2.5 and lead. Vaidyanathan said that these are the only things they can test for, as ADEQ doesn’t have authority over heavy metals, a measure which requires consultation with the Arizona Department of Health Services. Vaidyanathan estimated that MRI emitted 0.004 tons of heavy metals per year.
PM-10 particles are those 10 microns in diameter, while PM-2.5 particles are those smaller than 2.5 microns.
Dust from the MRI facility may contain metals such as antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, nickel and selenium. While these are classified as hazardous health pollutants by the U.S. Environmental Protection Agency, the agency has not established safe levels of these substances for use in air quality permitting.
One resident who spoke during the meeting claimed that MRI gave their employees no protection to prevent them from inhaling particulates, saying that her brother who worked there for many years died after many lung-related illnesses.
A nearby business owner said their property is covered in slag dust, while another resident who rented an office near MRI also complained about the dust. One man who frequented the VFW said he almost filled an entire bucket with dust he swept off the post’s back porch.
Another resident asked about harmful gases like carbon monoxide. Vaidyanathan said that such pollutants are produced in very minimal quantities by the operation and heavy metals in the dust are the primary concern.
Regarding runoff into the Verde River, a groundwater representative said that his surface water colleagues currently have no concerns. He added that the water is sampled and tested frequently, and that residents can volunteer to do so as well.
As air quality samples will be taken at only two locations, one resident asked if two more sites could be added to account for the wind going in all directions. Vaidyanathan said that was possible. He also explained that, like most ADEQ projects, the collection will be funded by permitting fees.
A public hearing will be held prior to a decision on the permit.
