Highlights from the Draft NPDES:
- The draft permit definition of the capture zone as “the surface area over which recharge would be captured by the mine” fails to fully describe the intent of the capture zone, which is supposed to be the farthest extent that mine contaminants are allowed to spread. The language in the current permit states that the capture zone includes the underground mine workings, the surge pond, and all ore and development rock stockpiles. This language is not in the draft permit but should be in the final. The permit should be clear that the company is required to capture all mine contaminants from all mine facilities.
- The draft permit contains only one set of values for background water quality levels that must be met outside the capture zone, and these numbers were derived from the highest measured values. Groundwater naturally contains higher values of many substances (e.g., metals) than surface water. By oversimplifying the figures into one set for all locations, many of the compliance values will not adequately protect surface water.
- The draft permit requires all waste rock and ore that is brought to the surface to be placed on liners. This should have been done five years ago; now there is little doubt that the large quantities of waste rock on the surface have leached contaminants to shallow groundwater into Gold Bowl Creek. Crown is now on its way to removing most of this surface waste rock, as it all needs to be placed underground at mine closure.
- The draft permit increases the frequency of monitoring at some existing locations, but falls short of requiring additional monitoring locations that are needed to better identify where and why mine contaminants are escaping. Crown should be required to immediately develop a plan to identify the sources of contaminants and how to stop their escape. There are numerous piezometers (smaller wells that only measure groundwater levels) that could be retrofitted to monitor water quality and/or to serve as dewatering wells.
Pacific Groundwater Group has created a 3D visualization
for OHA as part of and in support of OHA's NPDES comments. It begins with a visualization of the Buckhorn Mine underground workings with relevant faults and monitoring wells. It transitions to show, first the 2006 FSEIS capture zone, then the expansion of the capture zone proposed in the draft NPDES and then OHA’s proposed capture zone as seen from the south looking north. OHA’s proposed capture zone consists of the draft NPDES depiction in the north south and west and with the 2006 FSEIS depicted on the east side. The visualization then transitions to a view looking south west from north east of Buckhorn Mountain and repeats display of the same sequence of capture zones.
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