In the first of three public meetings intended to “clear the air” about the levels of a toxic metal found in water discharged from South32’s Hermosa Project site in the Patagonia Mountains, Hermosa Project President Pat Risner disputed reports that the mining company attempted to mislead the Arizona Department of Environmental Quality (ADEQ) regarding an October reading in excess of allowable levels.
Addressing the Santa Cruz County Board of Supervisors on Jan. 7, Risner said “We think there [is] a lot of context and information that’s missing or not being provided, or in some cases been misconstrued.”
The Jan. 7 meeting was the first of three scheduled in response to concerns about the levels of antimony, a naturally occurring metal, found in water being pumped out of the ground at the Hermosa site.
District 3 Supervisor John Fanning told the PRT that the county scheduled the meetings “in order to kind of clear the air and not only to find out if there was an error, where that error occurred, but also to make sure that no one is negatively affected health-wise when it comes to antimony.”
The next two meetings will be held on Jan. 21 with a representative from ADEQ and Feb. 4 with hydrogeologist Chris Gardner. Both will begin at 9:30 a.m. in room 120 at the County Complex at 2150 N. Congress Drive in Nogales.
At the Jan. 7 meeting, Risner discussed concerns surrounding the apparent “misreporting” by South32 of a spike in the concentration of antimony in a sample collected on Oct. 3.
South32 is required to submit a notification within five days when antimony levels exceed six parts per billion(ppb), the allowable amount of antimony in drinking water. The sample showed a concentration level of 6.23 ppb.
In a letter to a reporter in December, Alma Suarez, Deputy Public Information Officer for Water Quality at ADEQ, stated, “We did not receive a five-day notice for the APP [Aquifer Protection Permit] exceedance of antimony, failing to meet the APP permit requirements, even though South32 believes it to be a lab error.” The letter also stated that ADEQ “will hold South32 accountable if our investigation determines that the reported exceedance was not a lab error.’’
“We don’t believe we missed any reporting requirements, and that’s an ongoing discussion with ADEQ,” Risner told the supervisors. He explained that South32 left phone messages, but that ADEQ “can’t find the messages.” He also said that the phone number they had been given at ADEQ was not working.
On Jan. 13, Suarez told the PRT that “information submitted to date indicates that South32 attempted to report the exceedance within the five-day timeframe by calling ADEQ; however, the call did not result in positive contact.”
In December, Risner told the PRT there was also confusion over how to notify ADEQ that South32 had ordered a retest after the Oct. 3 sample showed a reading of 6.23ppb. Risner said that the concentration in September had been 2.6ppb, so the 6.23ppb reading didn’t make sense to South32 staff, who told the lab to retest it.
“In the meantime, we had to meet reporting requirements… There’s a code you have to apply to the samples. There was not a code for ‘retesting.’” The closest code South32 staff could find was the laboratory error code, so they used that one.
“We wanted to flag that we were having it retested—we never blamed the exceedance on a lab error,” said Risner. “That statement that’s out there is absolutely false.”
Retesting in early December confirmed that the concentration of antimony was still above the permitted level, with a reading of 6.47ppb, leading South32 to shut off the well responsible for the high levels.
South32 submitted the revised compliance sampling report to ADEQ on Dec. 9 to reflect the antimony exceedance, according to ADEQ’s Suarez. She told the PRT on Dec. 30 that “South32 investigated the cause of the exceedance, took corrective actions and submitted to ADEQ a written report within 30 days of when the exceedance was found. ADEQ compliance staff is currently reviewing the report.”
South32 monitors and reports on the levels of several metals and minerals present in the water—including antimony—as required by two of the permits the company holds, both of which are administered by the ADEQ.
The Arizona Pollutant Discharge Elimination System (AZPDES) program monitors surface water quality. The Aquifer Protection Permit (APP) regulates discharges into the aquifer. It basically monitors groundwater. The AZPDES permit requires sampling to be done over an eight-hour period, while the APP permit, issued by the Environmental Protection Agency (EPA), only requires a single “grab” or sample to be taken.
Water is being discharged at a rate of up to 2.5 million gallons per day from seven 5,000-foot wells that the company has drilled to mine underground for zinc, manganese, silver and lead. The water is treated at an on-site facility and then discharged into Harshaw Creek, which travels down toward the town of Patagonia.
According to Risner, South 32 initially did not treat the water pumped up to the surface for antimony because their samples showed that the levels were below the standard set by ADEQ and the EPA. Last winter, he said, they noticed that one of the seven wells was discharging water with a higher concentration of the metal.
“We shut that well off in February and kept it off for seven months,” Risner told the PRT. “In August we decided to make some changes to the plant to be able to treat antimony before we brought that well back up, just to make sure we can stay in compliance. We added the antimony treatment [to the plant] in August and brought the well back up in September.”
Chris Gardner, a hydrogeologist working with The Friends of Sonoita Creek (FOSC) and the Patagonia Area Resource Alliance (PARA), has been tracking the data submitted by South32 to ADEQ. He noticed that the July report to AZPDES showed the level of antimony to be 4.81ppb, just above the alert level of 4.8ppb.
Antimony levels stayed below the alert level for the next two months but spiked in October. On Nov. 26 the company reported that the October APP sample had shown the concentration of antimony to have risen to 6.23ppb. The AZPDES sample for the same date registered at 5.73ppb.
Meanwhile, downstream at a private well owned by Susan Wethington that is monitored by both South 32 and FOSC, antimony levels spiked sharply to 12ppb in a sample taken in October by the FOSC.
“I was shocked, absolutely shocked,” Gardner said. “I’ve never seen a level that high. “I expected it, based on the trend, to be above 5…but I didn’t expect 12.”
According to Gardner, other wells in the area have not reported a similar spike.
Risner does not believe the mine’s dewatering efforts are related to the high level of antimony in the Wethington’s well.
“We’re not doing anything that would cause a spike in antimony,” he said. “That’s naturally occurring groundwater. It’s naturally occurring in the geology and it’s variable over time. It’s a range of metals; it’s not just one or two. If you think about it, anything that’s been mined in the mountains historically has the potential to show up in the water because it leeches.
“It doesn’t concern me. We’re treating seven wells. We’re dealing with Mother Nature. Obviously, the range of what’s coming into the plant is always highly variable…The plant is flexible enough to adapt to incoming water quality variations. and we have the ability to treat antimony.”
Patagonia Town Manager Ron Robinson told the PRT “we don’t have any concerns” about antimony in the town’s water supply, although the town began monitoring the town’s water supply weekly for antimony in January, and expects to get the results of the first samples shortly.
Watchdog groups like the Calabasas Alliance and Patagonia Area Resource Alliance do see reasons for concern, however.
“I’m concerned that the technology for industrial treatment of high concentrations of antimony in the water to safe levels may not exist,” Gardner told the County Supervisors at the Board of Supervisors meeting on Dec. 17.
Gardner will be addressing the Patagonia Town Council with his concerns on Jan. 14. In a Jan. 12 interview, Gardner expressed his worries about South32’s water treatment system.
“My concern is that this plant was not designed to treat antimony,” he said. “I’d like to see [South32] treat the antimony similarly to the way others who have antimony issues have done so. A case in point is the water treatment plant in Park City, Utah, which was installed about a year and a half ago, and they’ve been successfully treating high concentrations of antimony.
“It seems South32 is addressing the problem after they designed this whole treatment plan, whereas Park City said ‘what’s the worst case scenario that we’re going to have to deal with,’ and they designed the plant around that.
“It was well known that there’s antimony issues associated with this mine because of the waste rock. The leach tests from the waste rock show high concentrations of antimony. To be surprised that there’s high concentrations of antimony is not taking that issue seriously.”
At the Dec. 17 County Supervisors meeting Gardner urged the county to schedule study sessions with representatives from South32 and ADEQ. The supervisors agreed to the idea of a series of public meetings.
“I think Chris Gardner said it best when he said we need to have some type of an open meeting where we’re able to discuss this a little bit more in depth,” Fanning told the PRT.