SOUDAN- The Lake Vermilion-Soudan Underground Mine State Park has canceled underground mine tours until next spring due to an estimated nine-and-a-half-feet of standing water that remains in the mine’s 27th level from torrential rains that hit the area on June 18.
“We’ve got a lot of work to do between now and then, but we should be back in business by next spring,” said mine assistant manager Jim DeVries.
Water on the 27th level – where underground tours take place – is usually pumped directly to a sump on the mine’s 22nd level, where it is then pumped to the 12th level and finally sent to the surface. But the sump on the 22nd level has filled with silt and gravel left behind by the flooding which was causing excessive wear on the pump that would normally drain the sump. With that pump on the 22nd level currently shut down, there’s no way to remove the water from the 27th level.
A suspected lightning strike left the mine without power for an estimated 11 to 12 hours on June 18 as torrential rains hit the area. In that downtime, the pump on the 27th level was submerged and shorted out and by the time the power was back on, the 27th level was flooded.
As reported by the Timberjay, a new pump on the 27th level was installed on June 25 to drain the flood water, but until the 22nd level’s sump is cleared of silt and gravel, water from the 27th level will have nowhere to go. Activating the 22nd level’s pump at this point would further wear the pump’s components down quickly, as was discovered after a pump failure.
“We had a failure of a pump on 22 and discovered that the silt that is in that system was actually destroying the impellers on the pump and wearing down the shaft,” DeVries said.
DeVries says the mine’s 27th level hasn’t lost or gained much water since June’s torrential rains and believes attempting to pump water out of the 22nd and 27th levels would be short-sighted at this point.
“We could put another pump in right away, but it would last maybe three weeks, and then we’d be back to buying a new pump,” DeVries said. “They’re way too expensive, they’re not disposable. So the better option would be to clean out that silt, so we have clean water going in there, then we can take that water up and out.”
Cleaning the sump is proving to be a laborious process. For now, park officials are scooping and shoveling silt and gravel from the 22nd level’s sump into five-gallon buckets, passing them down a line of workers until the buckets can be dumped onto a conveyor belt, which will dump its contents into a tub on the mine’s elevator. Once brought to the surface, the silt will be stored at the edge of the mine, in open pits that were dug in the mine’s early days.
“It’ll be stored on the edge of the mine so that if it does wash back, it’ll wash back towards the mine itself,” DeVries said. “That way, it does not leave the property. It’s the easiest and correct way to deal with it.”
In an email, DeVries said it’s too early to tell what challenges park officials will face when it is time to drain the 27th level. Workers are unable to do a damage assessment of the level until the water is drained.
Interpreters who worked as underground guides are now conducting tours above ground, explaining the history of the park, the roles of its buildings, and other park features. Free tours are conducted daily from 10 a.m. to 4 p.m. The tour season typically ends on the third weekend of October.