Ground Control, Part 2

I had barely enough time to acquaint myself with my new job in Engineering when things got busy. Things were always busy in Ground Control, what with my installing instruments, working with suppliers, testing new types of support, and having to lay out the support required for driving layouts and audit every heading. I had blast monitors to install and retrieve. We had to inspect every ground failure and support failure reported. I had rehab prints to put out. I had AutoCAD to learn. And I had to play politics with Captains and Superintendents. But things were about to get especially busy.

How? We were about to experience unparalleled ground failure from rock bursts like we’d never experienced before.

I was not involved in the first. My partner was. He was called down to inspect a lengthy collapse of the 7100 01 S after a 3.2 Mn (magnitude) burst. That’s the main drift that follows the orebody on the south side of the Level access. All production was accessed by this drift. In fact, without it, nothing could be done on that side of the Level. There are no side drifts, no bypasses of any sort. Think about it. No drilling, no blasting no mucking, no money. We were motivated to fix it. And we did. It took some time, almost six months, but we finally got it done just as I joined the group, just in time for the next burst, six months after that.

It was a big one, a 3.8. In fact it was the largest we’d ever experienced, the largest we would ever experience. To put than in perspective, a bad earthquake is about 5.0, but the epicenter is usually deep underground and can be five kilometers or more below the surface. Consider the damage such a quake can cause. Now consider a 3.8 Mn earthquake epicenter mere meters from where you’re standing. It causes the earth to move, to flow as though it were fluid and not solid; and when it finds an open space, it tries to crush it; rock fractures, it splinters, it’s thrown vast distances, all in the notion of closing the void it finds. It’s like a bomb going off right beside you.

It was large enough to damage, 6800, 6900, and 7000. It damaged 7100 again, but the new support held or it too might have been knocked out of commission too. It might have suffered the same fate as those Levels below it. It collapsed the accesses to 7300, 7400, 7500 and 7700, our main production block at the time. It also damaged 7800 and 7900.

It was a disaster. It cut off most of our active production at the time and forced us to shuffle production over the entire Mine too keep us from having to temporarily lay off the workforce. It did cause a break in production, the first we’d had since we’d undermined a fifty-million tonne wedge fifteen years earlier, when we’d almost crushed the Mine and our main shaft with it. That might have closed the Mine, but we were lucky and it didn’t. The workforce was sent home for a week then; it was sent home for a week now, to give us time to assess the damage and ensure it was safe to send anyone back underground.
I was lucky. I’d been standing under the worst of it on 7500 just seven hours before the event. I happened to be in the area, inspecting an unrelated event when my eyes wandered over the back (the ceiling) at the Level access intersection. The shotcrete had always been thin there, the surface riddled with cracks that snaked here and there. They’d never bothered me before. But they did that day. I thought they might be getting worse, so I noted it in my notebook, to remind myself to put together a rehab plan for the entire area. I drew pictures. I took pictures to show my boss, hoping that they might help me convince him that the area required a little TLC. Maybe a lot of TLC. A mechanic was even luckier than I was. He’d been lined up to work on a scooptram that had broken down in that exact same place. He’d stopped for a cup of tea before starting his shift, otherwise he’d have been working on that scoop when the event happened. He would have crushed under ten meters of fall of ground, along with that scoop. But that day was his lucky day. One should always take time for a cup of tea. It may save your life.

When I say that we sent the workforce home to assess that it was safe for them to return, that did not include me. I was in Ground Control. I was the guy who was always heading north with a clipboard and a camera when everyone else was running south, screaming that the sky was falling. I spent the rest of the week listening to the ground creak and grown, crawling over muck piles, making notes, drawing little maps, taking a lot of pictures. It was the quietest I’d ever heard the Mine. Aside for the creaks and groans and cracks that is.

I never once felt like I was in jeopardy. Maybe I’m a little reckless, maybe a little stupid, maybe danger doesn’t faze me. Either way, I was never worried, never scared. I had to tell a few supervisors and engineers who was accompanying me on those investigations to “grow a pair” more than once as they hung back or jumped at the slightest ping of ground. I forged on, hugging the wall, passing under the damage, but close enough to what support still existed to expect that it might still be holding back the back. And if it didn’t, I wouldn’t know for long. My exposure time was short, I reasoned; just a blink of an eye. What could possibly happen? They followed me. They always followed me. I think I shamed them into it. I never once told them that I might have a lump in my throat as I slid past that gaping maw of a damaged drift. I almost never did, though. Like I said, stupid.

We got hit by another 3.2 Mn burst 6 months later, ripping through the same Levels that were already damaged, almost killing a rehab team installing burst rated support. That’s what saved their lives. The ground snapped and undulated. The crew said the ground actually flowed until it met the new support they were installing and the damage was held at bay, stopping the wholesale collapse cold.
Looking back, we’d missed the signs. There were plenty of them but we hadn’t seen them. We ought to have. Maybe not me, though. I was too green and for as long as I’d been in Ground Control there were rock bursts. Prior to that, it had been a long time since I’d been in the field. When I was, it was with backfill, always at the tail end of a stope, always under shitty ground, so I’d grown desensitized to it. After that, I was in Oreflow, never straying too far from the shaft and oblivious to the goings on throughout the production levels of the Mine. So what did I know?

A lot, it turned out.

I began with Ground Control in June 2007, experiencing my first seismic damage inspections in July. The next was in October. There were more in February and April, then two in August. Two more in September, and another in October. All procurers to the main event in January. More followed in May and June. The third big one hit in mid-June, the one that almost killed that rehab crew on 7500.

Kidd never once tried to kill me during that time. She’d tried before. Many times. But she never did. She’d given up trying to kill me by them. Or maybe I’d just developed a sixth sense for when she was going to try again. No matter, I felt invulnerable all through that period. To think otherwise would have been foolhardy. Had I thought about it, I’d have never gone underground again.

As a matter of fact, I hadn’t been scared underground in decades. I don’t think I’ve ever been. What would have been the point in that?