Background: Multi-level shaft mine high in the Colorado Rockies a number of years ago before the advent of mine radios.
Halloween night, just finished dinner and getting ready to take the kiddos out. I was on the mine’s emergency call-out sheet and I get a call from the hoistman “We lost main power and the hoist, compressor and main fan are down. Cager is reporting smoke in the shaft (cager was at the bottom of the intake shaft). Main pumps (in the intake shaft) are off and I am getting high-water alarms in the shaft. I haven’t reached anyone else. What do you want me to do?”
The main fan was underground. When they built the mine, they brought power down both the intake and exhaust shafts and switching could be done from either hoist room.
My response was “Feed the main fan from the exhaust side and reverse ventilation (ie, exhaust became intake and intake became the exhaust). Dump stench in the compressed air (large surface receiver tank held hours of supply). Get Bill (the night watchman) to help answer the mine phone for anyone who calls up. Have the cager and crusherman climb up to the level. Call another hoistman and have them go to the exhaust shaft (now intake). Keep calling the call out list, mine rescue and electricians. I am on my way there.” Told my wife she was on her own for the night.
When I got to the mine, I talked to the hoistman and night watchman and explained the plan. As soon as possible, we would begin evacuating the mine through the exhaust shaft since it was now fresh air. I told the watch man to make a list of who was UG (based on the brass board) make a copy and give one to the hoist man. I then told the watchman to grab a company truck and meet me at the other hoist. The hoistman had another hoistman on the way to the escape shaft. About that time, the safety guy showed up, I explained my plan. He said he was going to call MSHA, do a gas test at the primary shaft and he would meet me at the escape shaft.
I got to the escape shaft, open the gate, plowed a path to the hoist room (I took a plowtruck because of the snow on the ground) opened the door, warmed everything up and made preparations for checking the dogs. The hoistman showed up next, confirmed main fan power and direction, got everything moving and we started checking the dogs. Nightwatch man showed up next, I had him plow out a space for parking. Safety guy showed up and we completed safety checks. Shortly thereafter, got a call from UG on the mine phone and we sent the cage down to pickup the first two miners (both mine rescue members). Took the nightwatchman and the two miners over to the other shaft to bring more vehicles over for transport. Left the safety guy with the escapeway hoistman in case anyone was injured (safety guy was an EMT).
Arrived at the primary shaft right behind a mine foreman. Got calls back from the exhaust (now intake shaft) and learned 80% had been evacuated with no injuries reported. There were two more MR member on site so I had them take gas samples on the collar with a scott air pak while the rest of the team got the draegers benched and ready. Got enough vehicles headed to the other shaft to bring everyone over and have them brass out. Got a call from the utility district acknowledging the issue and confirming we were not back feeding the dead line. While we were benching draegers, the mine foreman and I discussed what to do next. The cager smelled smoke which most likely came from the pump station below him. The biggest immediate threat to the mine was the rising water. Water was collected on the lowest level and flowed toward the intake shaft to a sump and pump station. We confirmed that the locomotives were now on the escapeway side. Our plan was to have four of us (me, the mine foreman, the safety guy and a MR member) descend down the escape under oxygen, use a loci for transport, open all the sumps on the lowest level and build a sandbag dam in a drift from an area that produced the most water. We would have a full MR team as a backup if there were any issues. We finished up about 2am, cleaned the draegers and I went home to get some sleep.
Back at the mine at 6am, briefed the rest of the management team on the issues and response. Got a call from the utility company that they would restore power, but it would be a short window (under 24 hours). Gas testing throughout the night did not show any issues. It was decided to change ventilation back to normal using escapeway power. When power was restored to the primary side, we fired up the shaft heater to prevent icing the intake shaft.
Attempts to resume pumping resulted in one pump firing up. There were three pumps in the pump station. One ran all the time, a second kicked in as need and a third was down for maintenance. MR- trained electricians inspected the pump station and found water up to close to the bases of the electric motors. They melded the number one pump to the number three motor and got two pumps running. We hoped we would have twelve hours of pumping. Smoke came from shorted out #1 motor and wiring. Motor was extracted and transported to Denver to be re-wound.
MR members moved all mine equipment to the highest ground available and we built another three sandbag dams in drifts to minimize flow. The utility company showed up about five pm and said power would be off within the hour. They said a bear had climbed the utility pole and touched two phases of the feed lines (I think they were 14.4 but may have 2400v). They said we would have power by 9am the next day.
