The Blaine County Planning and Zoning Commission has approved a state request to build a road to the Triumph Mine out East Fork Road for the purpose of building a well to monitor the mine’s water pressure.
Rob Hanson, Idaho Department of Environmental Quality mine waste program manager, came before the commission Thursday to request about 9,350 feet of road improvements to allow equipment to go in and construct a monitoring well as part of an effort to clean up the mine.
Hanson said the mine tunnel is blocked by a plug about a quarter of a mile back from its entrance. Water builds up behind the plug and either filters its way through adjacent soil or is collected in an above-ground pond behind the plug.
“Basically, what this pond does is treat the water,” Hanson said, as the water is oxygenated by exposure to the air and the minerals dissolved in the water settle out.
Water pressure has been monitored through a pipe running from the plug, which is attached to a gauge. Hanson said that the last time the gauge was checked, the pressure was at 125 pounds per square inch, an acceptable level.
However, the tunnel leading to the pipe has collapsed, meaning that the DEQ now has no way of gaining access to monitor water pressure. Hanson said that in addition, another collapse could crush the pipe, meaning that water could leak through the plug.
“If a collapse happened and crushed the pipe, that water would be uncontrolled,” he said. “We want that pipe out of there, but first we have to replace it with this monitoring well.”
Hanson said that the road was only being used for three or four weeks to build the well, and would be reseeded once the monitoring well is complete. DEQ crews would then walk up to the site to monitor water pressure and quality.
Hanson said most of the road is already there, and would just need to be regraded and smoothed out to be usable. He said the project would have very little visual impact.
“To try and make it look as good as it is now or better is our objective,” he said.
Hanson said the monitoring well would also be used to inject grout into the plug, sealing it completely for the foreseeable future and limiting the leakage that is currently happening at the site.
But former mine owner Carl Masaro said he was worried that the mine plug would blow out, possibly flooding homes in Triumph.
“The previous president of [Denovo, more recent owner of the mine] suggested the plug was not a good idea,” he said. “My fear is that something could happen and then we’d have a problem that is too big for anyone to pay for. If there was an earthquake or some other disaster, we’d have a huge mess there and we’d have no money to fix it.”
Hanson said the mine plug was built after an extensive public process, and that the 1,300-foot-wide plug is stabilized by rebar in all directions.
“Catastrophic failure is a very minimal risk,” he said. “The greatest risk right now is in that pipe.”
The P&Z tentatively approved the application, with conditions including that the DEQ must reseed the road when done with it to restore the area to something close to its present form. The commission is expected to finalize the approval next month.
Kate Wutz: firstname.lastname@example.org