Contamination documented at reclaimed mine drill sites

DNR report states that mine operator was consistent to industry best management practices

A new study on reclaimed drill sites at the Pebble mine in Southwest Alaska says it is evident that there may be long-term reclamation and maintenance issues at the exploration site of copper, gold and molybdenum prospect.

Currently the Alaska Department of Natural Resources requires no reclamation plan and has exempted the Pebble Limited Partnership from reclamation bond,” notes the report by the Center for Science in Public Participation for United Tribes of Bristol Bay, a tribal consortium representing 14 tribes working to protect the Yu’pik, Denai’na, and Alutiq was of life in Bristol Bay.

“It is obvious that the amount required to properly reclaim the well sites is significant. If the PLP were to go bankrupt, taxpayers would be liable for the costs of this reclamation,” the report said.

Alannah Hurley, executive director of United Tribes, said she is concerned that DNR is on the cusp of renewing a permit for the mine after not living up to permit requirements, and that Pebble should be required to clean up before taxpayers are stuck with the bill.

According to the Pebble Limited Partnership, the PLP initiated a comprehensive inspection program of all drill sites with the initial goal of inspecting all sites at least once during any five-year period. As of this September, all sites met this threshold and the PLP continually refines its inspection protocols to meet or exceed industry best practices and more efficiently identify sites that require more frequent inspection.

An updated inspection plan for 2017 was to be submitted to DNR with the annual reclamation report in December.


DNR spokeswoman Elizabeth Bluemink said there is no one person in the agency responsible for inspections at the mine site, but that there is a relatively large multi-agency team that works together on developing field inspections.

The latest DNR field monitoring report, which is posted online, was for an annual inspection and follow-up compliance inspection conducted on July 26 and July 27. The report was amended on Nov. 3.

It states that a total of 141 sites within the Pebble project area were inspected over two days, and that DNR found that the mine operator had identified and addressed maintenance and repair issues on site and was consistent to industry best management practices. The state inspectors said 107 boreholes were observed to be in stable condition with no evidence of water or other instability, and that nine sites needed further investigation, but that none posed a significant environmental or compliance risk.

The complete DNR report is online at

While there is no widespread contamination, there are localized areas with elevated copper and other elements in soil and water, the CSP2 report said.

About 10 percent of the sites inspected had fine-grained, oxidized drill cuttings around the casing or leading in a trail away from the casing. If these are flushing periodically, this suggests that either the holes were not cemented, or that the cement has failed, said study authors David Chambers and Kendra Zamzow.

Kendra Zamzow  Photo by Margaret Bauman
Kendra Zamzow Photo by Margaret Bauman

Chambers, founder and president of CSP2, has extensive experience in mineral exploration and the mineral exploration industry, and former Cordova resident Zamzow, an environmental geochemist who lives in Alaska’s Matanuska Valley, has worked as a contract fisheries biologist with the Alaska Department of Fish and Game, the Forest Service and the National Marine Fisheries Service, and was the field coordinator for marine mammal biologists in False Pass and Prince William Sound.

Zamzow, who did extensive field work at the Pebble site for the report, said she found much higher levels of copper, aluminum and other metals at the mine site than a former CSP2 researcher, Carol Ann Woody, found in 2011.  “They were not at levels toxic to aquatic life, but the copper was in order of magnitude higher than in 2011,” she said.

Zamzow said they also found that all the vegetation on the settling ponds, also called sumps, was dead, so there was concern that something in the soil was affecting the vegetation, but the soil, when tested, was fine, so it is possible that the tundra itself was mishandled, allowed to freeze or dry out.

A bandaged-up well casing at the Pebble exploration site.  Photo by Kendra Zamzow
A bandaged-up well casing at the Pebble exploration site. Photo by Kendra Zamzow

Zamzow also said that water is still emerging at a slow rate out of some of the geotechnical holes, that some of the wells are duct taped, Ziplocked and spray foamed. “They are supposed to, if they are not using them, cut them off below ground level after the hold has been completely cemented and grouted to be sure no water comes up,” she said.

The study authors also found thee artesian sites that the Alaska Department of Natural Resources did not, and DNR found two sites that Pebble had not reported, she said.

Alannah Hurley, executive director of United Tribes of Bristol Bay, said that the acidic soils with high metal concentrations, leaking wells, dead vegetation and improper drill casting closures at inspected drill sites were all causes of concern for the safety and water quality of Bristol Bay, home of the world’s largest sockeye salmon run.

“Allowing drill waste to be placed directly on the tundra, where it is exposed to oxygen and water, has led to acid generation in the waste,” Hurley said. “The Alaska Department of Natural Resources has been complacent in allowing drill waste to be placed directly on the ground at Pebble, and other sulfide-deposit exploration sites,” Chambers said.

“At a minimum, we need to see improved monitoring and a complete inventory of all problem sites so we know the scope of the contaminants left by Pebble on our public lands,” said Hurley. “We also need a full reclamation program so we can deal with the issues safely and completely,” she said.

Of particular concern, Hurley said, is the presence of drill casings, which have not been cut below ground level, as required by law. “Once the area is snowed in, these two to three foot steel pipes will be lurking right below the snow line. Subsistence hunters on snow machines heavily use this area in the winter. It is only a matter of time before someone is seriously injured,” she said.