On Jan. 11, experts from Arizona Department of Environmental Quality (ADEQ) addressed an audience of approximately 60 people in a public meeting held at the Patagonia School cafeteria. ADEQ presented a review of South32’s request for an Air Quality Permit for the underground mining of the Taylor deposit (zinc, lead and silver), and the Clark deposit (zinc, manganese and silver) referred to as the ‘Hermosa Project,’ located five miles from Patagonia.
Balaji Vaidyanathan, manager of ADEQ Air Permits and Compliance, discussed the South32 permit status and processes, and responded to questions and comments from the audience.
Many of the public’s comments focused on the lack of a federal standard for manganese exposure. Vaidyanathan explained that although the Environmental Protection Agency (EPA) has classified manganese as a hazardous air pollutant, it has not established an air quality standard for use in permitting. He stated that ADEQ uses the Agency for Toxic Substances and Disease Registry (ATSDR) minimal risk levels as a guideline. Unlike EPA, ATSDR is not a regulatory agency, it is a public health agency that advises EPA.
One attendee expressed concern saying, “I’m personally not reassured by the standard developed by South32 and ADEQ.” Several audience members requested that the permit not be issued until an official standard for manganese exposure is developed in the United States.
Vaidyanathan responded, saying, “Unfortunately, our program is not set up to do that. Our authority is not discretionary. The science has not caught up, but the reality is we have to act on the permit based on the information we have and write the most responsible permits that we can.” He added that when a standard is developed, by law, they would have to go back and put it in the permit.
Vaidyanathan reported that both South32 and ADEQ had conducted air dispersion modeling for manganese using the ATSDR standard for respirable manganese
dust, which is 0.0003/cubic meter. The highest modeled concentration of manganese at the mine site fence line was measured at 0.000216 (below the standard). Concentration levels at local communities were predicted to be much lower.
As the jurisdiction of the ADEQ permit lies only within the confines of the mine itself, ADEQ has no jurisdiction on public roads and did not require South32 to monitor the air quality outside the site. Risner stated that the company will monitor it anyway. He said that the exact locations for ambient air monitors are pending but will be placed along transportation routes and wherever the processing facility is built, and the data will be posted to the public on a website.
Manganese is not the only air pollutant to be monitored at the Hermosa Project. Because the project is classified as a major source of potential emissions including nitrogen oxide, carbon monoxide and other hazardous air pollutants which exceed ‘major threshold’ limits, it requires a class 1 permit from ADEQ.
Vaidyanathan stated that ADEQ has a very comprehensive enforcement program to address violations. He said the agency has “a lot of ways to correct or mitigate the violation to make sure it does not happen again.” However, he stated, “We have capacity issues. We rely on a lot of self-policing.”
About 60 people attended the meeting including several from the Patagonia Area Resource Alliance (PARA) who works with coalitions such as Calabasas Alliance and Save Rio Rico. Several people in the audience held up signs stating “Public Health Above Corporate Profits,” “Clean Water and Clean Air Are Basic Human Rights” and “Our Water’s Future is in Our Hands.” Legislative District 21 Representative Stephanie Stahl Hamilton, Santa Cruz County District 3 Supervisor Bruce Bracker, County Manager Jesus Valdez, Patagonia Mayor Andrea Wood and Hermosa Project President Pat Risner all attended.
The public comment period that was opened on Jan. 5, 2024 will close on Feb. 26, 2024. The date was extended by ADEQ following public concerns that the previous time period was too short to review the complex documents made available to the public. There will be a public hearing on the closing date at Patagonia High School at 6:00pm.
The next steps include a responsiveness summary, an EPA review and a permit decision. To comment, visit azdeq.gov/public-notice-new-air-quality-permit-south32-hermosa-project.