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Pogo gold mine water discharge outlined State, federal agencies select alternative water handling process for proposed hard-rock gold mine in Goodpaster River valley Patricia Jones Petroleum News Contributing Writer
Regulatory agencies preparing a draft environmental impact statement for the Pogo gold mine project near Delta Junction have selected as their preferred alternative an off-river treatment process for water discharges at the remote site.
Outlined in the 1,000 page draft EIS released in mid-March, state and federal agencies selected project plans that were proposed by developer Teck-Pogo Inc., except in the area of water discharges. (See story in March 23 issue.)
Teck-Pogo proposed discharging treated water through injection wells during development of the gold mine — the same method that’s been used on-site for four years. During the anticipated 11-year life of the gold mine, Teck-Pogo proposed using injection wells and a soil absorption system, to be located in the Goodpaster River valley adjacent to an existing airstrip, and in a hillside saddle above and southeast of Pogo ridge.
Two other water handling alternatives were considered by regulators — direct discharge of treated water to the Goodpaster River, which flows through the valley below the underground hard rock gold deposit, or an off-river treatment works, an idea floated by agencies during earlier stages of the EIS process.
“Any one of the three would probably do a really good job, and probably only release water to meet water quality standards,” said Ed Fogels, Pogo project manager for the Alaska Department of Natural Resources.
In the draft EIS, agencies identified as the preferred alternative the off-river treatment process, which involves releasing treated water into a gated holding pond, where it can be monitored before a final discharge into the river.
“It’s more controllable and monitorable,” Fogels said. “It’s on the surface, so we can look at it, feel it, touch it.” Water issue caused delays Handling the anticipated volumes of groundwater that would be produced by the underground hard rock gold mine was “one of the most significant issues” of the draft EIS process, Fogels said.
“It took a while to run through all the water issues, to figure out how to make the regulatory part of the water treatment systems work,” he said. “It was a year’s delay in the process to run through that whole loop.”
Teck-Pogo submitted their original plan to permitting authorities in August 2000, more than two and one-half years before the draft EIS was released.
“It’s taken longer than we hoped, it’s taken longer than necessary, but it has not taken longer than we expected,” said Karl Hanneman, Alaska regional manager for Teck Cominco.
Both the developer and regulators describe the Pogo draft EIS as a thorough look at the potential impacts on the area.
“We tried to provide the public and everyone a complete package of what this would look like if it were built,” said Bill Riley, mining coordinator for EPA’s region 10 office.
Agencies proposed water plan The off-river treatment works was a water-handling idea that agencies proposed during the permitting process, Hanneman told Petroleum News Alaska in a March 18 interview.
“They thought it would be a way to better ensure compliance,” he said. “We looked at it hard, and did detailed engineering and modeling work to convince ourselves that it would be viable.
“We think it is and are prepared to proceed if that’s the way they permit the project,” he added.
Teck-Pogo’s concern about the off-river treatment system, which uses a holding pond for the final collection point before treated water is released into the Goodpaster River, involves its operation in winter months.
The company’s proposed injection and soil absorbing system water treatment method would likely be “less susceptible to disruption in winter,” Hanneman said, due to ice cover that will form on the agency proposed holding pond. Wells difficult to monitor Both Fogels and Riley said water discharged through the proposed injection wells would be more difficult to monitor.
“It’s harder to deal with it at that point, because you still have stuff in the ground water,” Fogels said. “There’s less control.”
Increasing the amount of water that will be injected during development and operation, from the existing 100 gallons per minute to an estimated 400 gallons per minute, could have some potential impact on area sloughs, Riley noted.
“We could see mounding of water … it could raise the level of the groundwater, which is only about four feet below the surface and actually have daylighting not far from the injection wells,” he said. “We could not tell where the water was going to go and what effect it might have.”
In addition, regulators said in the draft EIS that discharge from underground injection wells “may not meet criteria for six parameters at least some of the time. This … was considered to have a moderate impact from a permitting and compliance perspective only if mercury only infrequently exceeded its criterion.”
“In contrast, the off-river treatment works option was expected to have a low impact and more permitting certainty,” the draft EIS said, about the agency’s preferred option.
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