Highlights from Keystone science panels on geology and geochemistry

The Keystone Center, funded by Pebble Limited Partnership (PLP), organized six days of science panels, held in October 2012, to discuss the Environmental Baseline Document (EBD) published by PLP. Pebble Watch attended many of these panels, and has provided highlights of those discussions.

October 2 and 3 – Geology/geochemistry

Keystone Center’s science panel on geology and geochemistry concluded Wednesday morning at the Consortium Library on the University of Alaska Anchorage campus, with panelists providing recommendations for further study in some areas where they had concerns. Members of the public also had a chance ask questions –  in person, and by email for those watching the proceedings online.

Paul Frost, a commercial fisherman from Togiak, addressed the panel with questions about how exactly Pebble would get “the minerals … the money … separated from the dirt.” He wanted to know if it was clear how weather issues would affect the site, how the above- and below-ground river systems would be affected, and how negative effects would be mitigated. While he said he was thankful for the studies, Frost also said he was having a hard time envisioning how it would all work. He was also worried about the quality of how a mine plan would be implemented. “At some point it’s going to be a construction guy like me with the 966 [wheel loader], and the boss is sitting over there with a cup of coffee.”

The panel format involved scientists contracted by the Pebble Limited Partnership describing research they had completed in the Bristol Bay area between 2004 and 2008. Members of the science panels who had reviewed the studies came to the meetings ready to provide their take on Pebble’s science.

Pebble Limited Partnership (PLP)-contracted scientist Clare Linklater of SRK Consulting responded to Frost’s comments, saying, “I sympathize completely. The studies we’ve been presenting are baseline to get an understanding of how the materials behave.” But without the benefit of a mine plan, scientists do not know which strategies will be employed to mitigate any negative effects during construction, mine life, or reclamation/maintenance periods after the mine is closed.

PLP CEO John Shively told the panel: “Some people think we are delaying a mine plan for nefarious reasons, but this is complicated. We’re trying to get the process right.”

However, some panel members also spoke to the difficulty of simply considering the baseline data itself without the benefit of a mine plan. “I’ve reviewed five years of study, but it’s hard to let it go at that and not think about the future,” said Larry Gough of the U.S. Geological Survey. That echoed a sentiment raised by Jeremy Richards, of the University of Alberta, in Tuesday’s panel: “Perhaps we’re all struggling with the role of this document. The EBD doesn’t address impacts and it doesn’t address possible mining scenarios. But we’re all sort of thinking forward to “what does it mean?” As a peer reviewer, this document is like a paper without a conclusion, we’re waiting for a punch line — and that depends on what is going to be done. Clearly, how we interpret the EBD is what everyone is concerned with. Should we just stop at this point and say it’s a data-collection exercise and we shouldn’t go beyond that?”

Not knowing the amount of pyrite or how it would be treated was an issue for panelist Tom Al, University of New Brunswick. “There’s not enough information to assess tailings very well. We don’t have a mine plan. There are a small number of samples.” He explained that pyrite generates acid, but also can contain gold. “There’s no indication of how gold will be recovered from the pyrite concentrate. This has significant implications for the tailings geochemistry. That’s a gap in knowledge at this point.”

“This is an area where there needs to be more thought, more innovation,” said Science Advisory Committee member Kirk Nordstrom, of the U.S. Geological Survey, who was moderating the session. He said he thinks every bit of waste could be useful for something, but it’s not economically viable. Shively addressed this point, too, saying that the volume of waste rock is too large to be a “viable economic rock.” He did note that developers are still discussing the issue, and have even considered processing the pyrite concentrate in another location.

Individual panelists added the following comments and recommendations:

Larry Gough, U.S. Geological Survey

  • Integrate the three soil studies that exist in different chapters of the document (Soils, Trace Elements and Vegetation).
  • Take advantage of local expertise and existing studies when planning reclamation activities.

Steve McNutt, University of South Florida

  • There is justification to complete more risk assessment work in the area of seismic activity. Developers should consider effects on the transportation corridor and likely risks of an earthquake during the active mine period. They should include shaking hazards in tailings dam design, and determine whether the Lake Clark fault extends further to the southwest.
  • The Pebble study includes state-of-the-art mapping of surficial geology in great detail, but more work could be done to characterize the surface geology of the transportation corridor. Using mapping at a scale of 1:250 is too small for this area. Slope stability and landslides are a concern in this area.

Chris Waythomas, Alaska Volcano Observatory

  • Ashfall from a volcanic eruption needs to be considered, especially as it could interrupt air travel for weeks. Developers should study Katmai, Novarupta and Aniakchak volcanoes.
  • Consider existing literature on volcanic lakes, which can help us understand impacts and recovery from acidic spills. In 2005, volcanic lake Chiginagak on the Alaska Peninsula breached, and a substantial amount of acidic material flowed into Mother Goose Lake. The pH went from neutral to 4.1, destroying the aquatic habitat. There was no fish run that year, but a few years later the runs came back.

Tom Al, University of New Brunswick

  • We have to be very careful with questions of prediction and acknowledge there is uncertainty with kinetic tests that Pebble conducted as predictors of acid generation.
  • There is not enough data on tailings disposal. We don’t know enough about the pyrite or how it’s going to be treated.
  • Work that has been done is good.
  • Segregation of potentially acid-producing materials from other materials is important. There needs to be a program for doing that with confidence. I haven’t seen that yet.
  • The identification of non-acid generating rock (NAG) and potentially acid generating rock (PAG) will be a significant challenge. Pebble is using a neutralization potential ratio (NPR) of 1.6 to identify certain rock as NAG. To do this is risky and has no safety factor. It’s based on humidity cell tests that I don’t have a lot of confidence in. The precautionary principle says that if 3 is the number used generally [for NPR], then we need to have a good reason why to lower it.

Jeremy Richards, University of Alberta

  • The deposit itself is great – flat, no worries about landslides. Compared to some deposits, it’s a pretty easy task to engineer a good mine. But in a broader context with the fishery, there are more challenges. Building in redundancies and failsafes is necessary. One solution is not going to be enough to ensure there never is a significant spill. It’s probably a challenge the engineers are up to. It depends on the economics.
  • Would like engineers from Day 1 to think about how to build the mine to be shut down and not cause any risk to the environment long-term.
  • There is concern about possible risk of a spillage in the transportation corridor, especially where it passes near Lake Iliamna’s north shore. Any plan is going to require a pipeline, so that region and the risk need to be evaluated. There could be a significant spill if a landslide took out the road and five pipelines.

Discussion continues Thursday with panels on hydrology and water quality.