From: on behalf of Panel Registry Subject: FW: TNG registration of ...

Stratus Consulting Memorandum (4/16/2010)
on these data. Given this overall level of uncertainty in their water balance, it is troubling that
they have not included in their mine plan specific contingencies for active water capture and
treatment (in perpetuity) and specific sources of water to maintain TSF water levels in the event
of drought or groundwater losses.
3. Experience <strong>From</strong> Other Mines
As discussed in the previous section, the underlying data on which the water quality predictions
at this mine are based are flawed. We do not believe the Proponents have adequate data to
accurately quantify the impacts of this mine. Generally, we can state from our experience
assessing mine sites worldwide that the scenario presented in the EIS (open pit copper mine with
TSF, no active water treatment, and little to no anticipated adverse impacts) is not a scenario that
we have ever seen at any other mine site. Dr. Maest will briefly discuss other reports and case
studies that can inform the panel of the risks of this mine.
While every mine site is unique in its characteristics such as mineral occurrences (e.g., massive
sulfide vs. porphyritic), mining techniques (e.g., open pit vs. underground), or ore processing
(e.g., heap leach vs. flotation), many mines with differing characteristics have had water quality
impacts, and mine with characteristics that are similar to the Prosperity Project have had impacts
that were not predicted. These impacts have resulted in adverse downstream impacts, or costly
unplanned water capture and treatment systems that in many cases must be operated in
perpetuity, or both.
3.1 Predicted vs. Actual Water Quality at U.S. Mines
Dr. Maest will discuss the studies of the accuracy of water quality predictions at mine sites. She
will summarize data from a study that she conducted with James Kuipers, PE, and others in
2005�2006. This study was an in-depth review of state-of-the-art characterization and modeling
approaches for predicting mine water quality (Maest et al., 2005) and a comparison of predicted
water quality impacts to actual water quality impacts at mines in the United States (Kuipers
et al., 2006 – hereafter referred to collectively as the Maest-Kuipers study). In addition,
Dr. Maest may discuss similar data from Schafer (2008).
The Maest-Kuipers study reviewed over 100 mines in the U.S. that received permits after
submitting an EIS. They chose 25 case studies in which they had sufficient data to evaluate the
accuracy of the water quality impacts predicted in the EIS. Dr. Maest will summarize the results,
discussing the relationship between “inherent factors” (e.g., proximity to water resources,
contaminant leaching potential) at a mine and its effects on the environment. She will show that
nearly every mine with inherent factors similar to Prosperity released contaminants sufficient to
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