An underground coal mine typically has 3 shafts - a men and material shaft (or main shaft), a decline shaft and a ventilation shaft. The main shaft is a vertical shaft and has a large cage for getting people and machinery underground. The decline shaft runs at an angle to the coal seam and contains a conveyor belt system which removes the coal from underground. The ventilation shaft is used to get air underground and circulating in the correct manner.
I've mentioned previously, that I'm part of a shaft sinking project for a new underground coal mine to extend the mine's coal reserves. During sinking, the shaft bottom is blasted and the rock is removed. At first, this is simply done with frontend loaders. As the shaft becomes deeper, the top is lined with concrete to keep the shaft open and stable. To make this process easier, a stage is used. The stage is a flat metal plate which fits into the shaft and is lowered with winches. This allows people to work on the sidewalls and shaft bottom as the shaft gets deeper. During the lining of the shaft with concrete, the stage keeps a metal curb, which goes right around the shaft, in place into which the concrete is then thrown.
During this process of lining the shaft, the stage is kept perfectly still to ensure that the concrete lining is straight and vertical and has the correct thickness. This means that since the stage is not being winched up and down that the only way to get to the stage is by climbing down a rung ladder from the top.
Part of my job includes mapping and inspecting the sidewall of the shaft to make sure no major structural features are present that could cause rock falls (such as jointing and faulting). To not interfere with the production of the shaft sinking team, I inspected the sidewalls during the lining of the concrete ring which translated into lots of ladder climbing.
At first, it was fine since the shaft wasn't that deep. Later, it became quite a full-body exercise. The first step is to get into the harness which you can attach to the metal ladder to keep you from falling. I had to keep quite a game face on since a lot of the older men sometimes refer to me as girlie and I didn't want to give them any more reason to think I couldn't handle my job. Climbing down the ladder is just as bad as climbing up since you have to concentrate on not looking down and not slipping. You are wearing full PPE (personal protective equipment) which is definitely not the lightest clothing. Once you reach the shaft, you need to climb out from under the ring surrounding the ladder and onto the stage. This was very daunting the first time since you can see the shaft bottom below you and it's quite a drop.
Climbing back up was a mission. I was determined not to let the men see I was in any way tired, but when I reached the top, I realized my mistake. My arms and legs were so wobbly and tired that I barely managed to grab the railings at the top of the ladder. My hands flailed around for a bit and my only thought was that it would be beyond stupid to fall now that I've reached the top. Luckily after a few tries I grabbed hold of the railing and pulled myself up and out. Unfortunately, my adventures had not escaped attention. The stage foreman came over and said he saw my hands wildly waving around over the top of the ladder and wondered what I was up to :-). I felt a bit better, though, when the other surveyors and foremen who came up after me were just as exhausted as I was.
I became quite an adrenaline junkie after that first experience. There's something to be said for hanging on to a ladder with only a small harness clip between you and a very hard fall :-).
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