Highlights from Keystone science panels on hydrology

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 4, 2012 - Panel on hydrology

Scientists who worked as contractors on the Pebble Limited Partnership’s Environmental Baseline Document opened the third day of Keystone Center science panels by presenting information on water balance, hydrologic modeling and water quality. The event, open to members of the public who preregistered, took place at University of Alaska Anchorage’s Consortium Library.

Panelists began with general praise for the sheer amount of data included in the Environmental Baseline Document. In more focused discussion and questions, panelists then homed in on subjective data decisions—such as calibrations or the choice to discard unusually high and low numbers—and challenged consultants to document such decisions more clearly.

The first presentation was by consultant Rod Smith, of Schlumberger Water Services, who described the site-wide “water balance program,” which includes data such as water flow, recharge of water into the system, and precipitation. A software program uses the information to create a groundwater model, he said, which in turn predicts possible future changes to the hydrologic (water) system of the site.

Data format

The sheer size of the tasks of both data collection and review drew a number of comments from panelists and presenters. After Hugh McCreadie said his talk on groundwater modeling was just “scratching the surface,” for example, moderator Kirk Nordland, of the U.S. Geological Survey, replied, “It may be scratching the surface for you, but for most of us it’s a lot of information.”

“I’ve never seen so much data on bedrock in my life,” said Keystone panelist Tom Myers, a hydrology consultant from Nevada. He’s worked on 20 to 25 mine projects, said Myers, and the Environmental Baseline Document includes more data than most of them put together. “It’s some of the coolest data for a hydrologist that I’ve ever seen,” he said. “Now I can reference this [to other mining companies] and say, ‘See, it can be done, folks.’ … [PLP has] done something I’ve been trying to get companies to do for years.”

How easy such data may be to review and analyze, however, is another matter. This came up in a panel session after Myers made a request for additional data, noting, “It would be great to get it in a spreadsheet format instead of a PDF.”

The format issue has been raised multiple times by scientists reviewing the baseline data, but PLP still declines to release data in the spreadsheet format to which scientists are accustomed. PLP’s Jane Whitsett has said that Pebble took the approach of releasing data in an encrypted PDF so that data is “not inadvertently corrupted by users and the integrity of data is retained.”

During the morning panel, Smith and McCreadie both acknowledged the folly of trying to use this format to verify the data: “I don’t know what you would do with a PDF,” said Smith. “That would be an exercise in frustration,” agreed McCreadie.

Myers wanted to review data on how the water balance was calibrated, he said, commenting to Smith: “It appeared as though there were four to five things adjusted.”

Smith explained some of the reasoning used for adjusting certain precipitation measurements: “In early runs we had very high PETs [potential evapotranspiration]. They just didn’t match other people’s measurements of evaporation in the north.” After consultations with other hydrologists, he said, “I reduced it [PET] by 50%.”

Myers noted the importance of documenting such decisions so that others understand exactly what was done and why. “There is a bit of subjectivity to this,” he said. “I don’t know how you would document that. … I think it would be good to have some references for that.”

Distribution of rain and snow by month was another problem area identified by Myers, because it is difficult to know just how much of the precipitation is snow and how much is rain. Smith acknowledged such uncertainty is an issue, and “has been on any job I’ve worked on. This is real, and simply is a part of the analysis. We adjust the temps, look over time, and we move the number a bit so that it averages out.”

The issue is most critical during months like November, said Smith, when the precipitation could be snowfall or rain, because those numbers are fed into the groundwater modeling system and are considered in water recharge measurements. “It’s a source of uncertainty for the groundwater model,” said Smith. “We’re starting with precipitation measurements from Iliamna, and that’s a source of uncertainty as well.”


Myers also cautioned against relying on data suggesting there were bedrock fractures that could inhibit the movement of ground water. He cited two mines in Nevada–the Goldstrike and the Robinson–that got groundwater model predictions wrong. For each mine, there were unintended consequences. “That kind of potential error here would be more problematic than it was there.”

Panelist Tom Al, of the University of New Brunswick, asked McCreadie if they were considering any other type of model, such as the Discrete Fracture Network (DFN), that simulates bedrock flow to explicitly represent every single fracture or representative of that fracture.

“You’re just giving me the shakes here,” said McCreadie with a laugh. He went on to explain that they are using an “equivalent course medium” to represent the fractures, and that tool works “as long as the scale is large enough.”

However, audience member Brian Coyle, a geophysicist who cited a long background working with bedrock and drilling projects, also recommended a DFN approach. “You need to go to a fractured network model. That will have some validity. If you build your model on a bunch of well tests…it’s a house of cards. I saw it with radioactive waste sites I worked on in Europe. They went down the tubes when it went to public inquiry. You have to do the science right, and let the chips fall where they may.”

Traditional knowledge

Paul Frost, of Togiak, also commented on modeling, but his concern was whether any local residents had been consulted to gather their knowledge: “When you are doing these models and extrapolating this information, on a day-by-day or year-by-year basis, is it really possible to come out with information that is really reliable? Are we using models that aren’t from the area? At some point you need someone who has feet on the ground. Are the local people being asked questions?”

PLP CEO John Shively responded that Pebble has a consultant that has gone out through the tribal councils to talk to people and bring in traditional knowledge.

Panelist Myers underscored the importance of local knowledge, noting that, for a particular project he’d worked on in the southwest, “one of the best sources of information was local ranchers. There’s stuff that can be learned from talking to the people.”

Studies continue

Pebble has continued data collection and compilation since it released the Environmental Baseline Document, a fact that created a challenge for Tom Myers, who had reviewed the EBD that was made available to the public in January 2012. After Smith and McCreadie gave their presentations, which included more recent data that is not in the published EBD, Myers said that he would have to skip over some of his comments, because recommendations he had planned to make were already included in the new information he saw presented for the first time that morning.

See additional highlights from other Keystone science panels.

Read the October 2012 newsletter focusing on the science panels.





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