How does operating machinery under water complicate mining procedures?
Absolute pressure at the surface is 14.7psi. Absolute pressure at 250 feet of see water for example is 126psi. That puts the machinery and people into a very different world that us surface dwellers from the get go. The BP job was at something like 7000 to 8000 feet if I remember correctly. That's about 3352psi. People can only dive to about 1000 feet of sea water. So on the BP job there were no people down there working. Everything we saw was from ROVs. Remotely Operated Vehicles. Doing things with a claw that is controlled by a joystick through a TV screen is very different from doing it with your own hands when you're right there looking at it. Even when you do have divers down there they usually only have 1 to 4 people. That's a limited team. They do not have a big box full of tools down there with them. They have the surface crew send the tools to them as needed. Salt water is not good for any kind of tool. It makes them rust and makes the seals break down. This leads to tool failure and many trips back and forth for replacements and repairs. The surface crew is usually young guys 18 to 25 who are not the most mature or reliable people in the world. Tool maintenance does not always get done properly. Divers are regular people. They are stubborn, arrogant, lazy, dumb and any other thing that you run into with coworkers anywhere. If they feel like sitting down for a break, the boss can't always keep a proper watch on them or come down and yell at them. We just finished a well abandonment job where we did the same thing with plugging a well with concrete just like the BP job and it took us 6 tries. That technique doesn't work too good at shallower depths either. This stuff is still full of bugs buts the pursuit of money keeps things moving beyond what we truly understand.
Well it severely limits the type of power source you can use, corrosion of metal parts becomes a major factor, manipulation/positioning of machinery becomes extremely complicated, health and safety is even more of a problem, costs increase exponentially
