Both sides of Pebble find fault with EPA study
Scientists and attorneys on both sides of the Pebble mine controversy are voicing starkly different opinions of the U.S. Environmental Protection Agency’s Bristol Bay watershed study.
A panel of 12 independent scientists concluded three days of meetings on the study in Anchorage Aug. 7. A report to EPA by the group will be made late this fall, the scientists said.
Bill Riley, a retired EPA mining specialist asked by Bristol Bay Native Corp. to review the agency’s assessment, said that a key challenge facing Pebble is a very large flow of wastewater, many times the volume of other Alaska mines.
“There will be no opportunity for dilution, unlike all other Alaska mines, prior to discharge,” to the environment, Riley told the independent review panel.
The receiving waters, where the wastewater would be discharged, have wild salmon, he said.
Riley also said the annual precipitation, from rain and snow, is what will drive the water management problem at Pebble, and that there is evidence from others that the EPA review document may have underestimated precipitation by 50 percent.
“The design of wastewater collection, conveyance and treatment facilities must be designed to handle extreme flows,” but the assessment document only considers average flows, Riley said.
A key problem is whether, given the lack of dilution, the state standard for water quality can be achieved for water discharges at the “end of the pipe.”
“Can such treatment be sustained and maintained in perpetuity?” Riley asked.
Riley is very familiar with Alaska mines and their permitting requirements. At EPA he was involved in all major mines successfully permitted by the agency from 1984 to 2004, including the Red Dog, Fort Knox, Kensington, Greens Creek and Pogo mines.
Another scientist weighing in was Susan Luetters, a senior environmental scientist and project manager for Bristol Engineering Services Corp., a subsidiary of Bristol Bay Native Corp.
“In my professional opinion the (EPA) watershed assessment is a well thought-out and presented document with its conclusions carefully stated,” Luetters told the review panel. “It is also my opinion that EPA has underestimated the potential impacts from mining, including the direct and indirect impacts to wetlands and aquatic systems.”
EPA estimates of its mine scenario impacts on wetlands were based on aerial photo interpretation of high altitude imaging in National Wetland Inventory maps and had very little, “ground-truthing,” Luetters said.
Pebble Limited Partnership field studies indicated the reach and extent of wetlands in the mine area as shown in the National Wetland Inventory maps were too low. Luetters said she believes the Pebble Partnership’s own studies put the wetlands figures too low.
The groundwater flow through a wetland system is “critical to maintaining water temperature, flow and chemistry which are key to supporting the benthic organisms that are major food sources for rearing salmon,” Luetters told the review panel.
On the other side of this were comments critical of the EPA’s assessment. These included remarks by Michael Kavanaugh, with Geosyntec Consultants, a consulting firm.
Kavanaugh was retained by Northern Dynasty Minerals to review technical aspects of the EPA assessment. Northern Dynasty is one of the mine owners, and a partner in Pebble Limited Partnership with Anglo American.
Kavanaugh told the review panel that the assessment “fails to meet widely accepted quality standards that must be satisfied to produce a credible scientific and technical assessment. The report both significantly exaggerates both the probabilities of failures of all engineered mining components and the environmental consequences of these failure scenarios.”
Three specific shortcomings were pointed out by Kavanaugh:
• Erroneous assumptions based on literature data not relevant to a modern mining scenario, such as culvert failure statistics developed from culverts that were never permitted in the first place;
• Inaccurate calculations that significantly overestimate consequences of those hypothetical system failures, such as using inappropriate geometry in a dam breach analysis, that over-predicts velocity and distance of sediment transport.
• General lack of any attention to mitigation measures for all engineered systems which would be designed with appropriate safety factors, be accepted by regulators, and be designed to minimize the consequences of unlikely failure events, such as placing pipeline shutoff valves immediately before stream crossings instead of 14 kilometers away, thereby limiting the amount of material that would escape if there were a failure.
In his remarks to the review panel Tom Collier, an attorney retained by Northern Dynasty, said the EPA included scenarios of possible tailings dam failures based on 135 past incidents.
“Yet 126 of them involve dam construction of a type not now contemplated by Pebble,” he said.
Of the remaining nine incidents, state-of-the-art technological, engineering and construction improvements have made them “irrelevant,” as examples to use, Collier said. He also criticized EPA for not considering any data from Pebble Partnership’s $120 million program to gather environmental data.
Tim Bradner can be reached at firstname.lastname@example.org.