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Constantine submits updated wastewater management plan for controversial Palmer Project

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A map of the proposed wastewater management system, with emphasis on the land application disposal system (LAD) (From the 2022 Waste Management Plan Revised Application)

The company behind a controversial mining prospect near the headwaters of the Chilkat River has a new plan for handling its wastewater. Executives with Constantine Metal Resources and state regulators say the plan would contain any hazardous contaminants, but environmental groups are concerned the risk is too great. KHNS’ Corinne Smith reports.

State regulators put Constantine’s wastewater management plan under review in 2019, pending more research into the surface and groundwater of the Palmer Project site, located roughly 12 miles upstream of Klukwan and 35 miles from Haines. Follow-up studies from the company showed that water in the Glacier Creek watershed could be contaminated under the original plan.

Constantine’s CEO Gafield McVeigh says the new design submitted to the state last month would use a chemical additive to remove solids from the water, which would then be discharged underground.

“It’s really basically all the components of the original design with the addition of a water treatment facility that will, and the purpose of the water treatment is specifically really to remove suspended solids from the discharge water,” McVeigh said.

Environmental groups and residents had raised alarm that the proposed copper-silver-zinc mining project would jeopardize precious Chilkat Valley salmon runs, by heavy metals and run-off leaching into surface water and nearby streams.

In particular, they’re worried about the possibility of unearthing potentially acid-generating rock (known as PAG) in the exploration process, which is hazardous to water and wildlife.

“Massive sulfide mines always pollute downstream waters. And they can do so for thousands of years,” said Jessica Plachta, executive director of Lynn Canal Conservation. She says that’s the point of no return.

“And that’s because of a chemical reaction that begins as soon as that buried rock is mined and crushed,” she said. “The sulfides in the ore react with air and water and produce sulfuric acid, which leeches toxic heavy metals from the crushed rock into the water. Those toxic heavy metals get carried downstream and contaminate everything in their path.”

She says no amount of polluting materials released is acceptable. And, she says the Palmer Project location is especially risky – with the potential for earthquakes, avalanches and inclement weather.

She argued there is no safe way to avoid environmental impacts, and the permit should be denied. She objects to the company’s plan to hold contaminants removed from wastewater in above-ground containers.

“Active water treatment in this case, would actually add chemicals, hazardous chemicals and would end up concentrating some of those heavy metals and other contaminants into a toxic sludge that would need to be dealt with,” Plachta said. “Giant bags of toxic sludge would be sitting upstream of our communities, waiting for an avalanche or landslide or earthquake or heavy rains or just a simple human error to end up in the river.”

Constantine CEO McVeigh says the project includes extensive ground and surface water monitoring, and any hazardous run-off is not allowed under the state permit. The company’s engineers say they don’t expect to encounter the kind of acid-generating rock Plachta describes. In its permit application, the company says it would report, contain, and stockpile the rock and plan to bury it underground permanently after the mine is closed.

Two sediment ponds would be used for overflow and storage. Water would then be discharged through a series of pipes and allowed to seep slowly into the ground, much like a septic system.

McVeigh says he is confident in rock core sampling and water sampling so far indicating the risk of hazardous materials is low.

“If the discharge water has any impact and we can measure that impact from these monitoring wells, you know, as the water moves through the ground. So we’ve got lots of different controls on establishing any potential impact of what we see is actually quite clean discharge water,” he said.

The wastewater permit is required for the next stage of the mining exploration project. Constantine says it plans to tunnel about 1.25 miles – under the Saksaia Glacier and into the mountain. Excavation would begin next year in 2023, and provide access to the main mineral deposits of copper, zinc, gold and silver.

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Constantine’s proposed timeline for construction of the wastewater management system (From the 2022 Waste Management Plan Revised Application)

Gene McCabe is the program manager with the DEC’s Wastewater Discharge Authorization Program, tasked with regulating mining discharge.

“The source of the wastewater is essentially groundwater that they are going to intercept as they dig the tunnel through to do the exploration part of their project,” he said. “So they’ll be intercepting some groundwater that collects in the tunnel, and then it’s pumped out, treated and then discharged into their proposed discharge system.”

His office is now analyzing the design to ensure pollutants would stay below legal limits.

“Well, the only real additional pollutant that would be concerned about is trace amounts of nitrates from any explosives that are used in the development of the tunnel. Other than that, we’re just looking at the typical pollutants that would be that would come up in groundwater, through the adit. And anything that might be added in the tailings disposal areas, if that is applicable,” McCabe said.

According to the permit, those pollutants could include a range of materials, including lead, arsenic and mercury that are known to be hazardous.

Preliminary water quality testing submitted with the permit application found already elevated levels of aluminum, cadmium, iron and magnesium above the threshold for human health and water organisms.

Gene McCabe with DEC says his office and the state regulations are committed to protecting public health, especially drinking water, and environmental impacts.

“So our engineers and our environmental specialists take that to heart. They’ve got a lot of experience, and they’ve got a lot of training to be able to evaluate any discharge, to make sure it complies with the state’s water quality standards. And also make sure that there’s not any kind of unanticipated or secondary effects that could be, you know, work in an adverse way to public health or the environment,” he said.

The permit is now under review by DEC engineers. McCabe says his agency will work with Constantine engineers if revisions are needed before any approval of the permit.

Environmental groups also criticized DEC for failing to hold a public process on the updated wastewater treatment design. A coalition of environmental groups are petitioning DEC requesting for a public process.

McCabe told KHNS via email that the state isn’t going to hold a public comment period for the new plan, because the permit was already approved in 2019. He says there’s no specific timeline on the permit process.

Constantine’s proposed wastewater management plan for the Palmer Project is available now on the Department of Natural Resources’ project page.