Not really an "epic" fail, but after finding out I'd be going out of town and unable to play Minecraft for a while, I set up a maximum-size quarry powered by some magmatic engines that were fed by a massive Xycraft tank of lava. There was one pre-charged redstone energy cell between them to serve as a buffer in case anything went horribly wrong. After making sure they wouldn't overheat, I whacked the conduit feeding into the quarry with a wrench to get the power flowing, logged out, and left on my trip. I figured that the quarry would mine out a decent amount of resources before the lava ran out, and I'd come back to a bunch of new materials for building and crafting awesome stuff.
So I came back a week later, only to find that there was only around 3000 dirt in the storage system that the quarry was supposed to feed into. I went to check on the quarry, and saw that it had only mined out the top layer of dirt. The redstone cell was completely drained. The lava tank was still full. And the engines were off.
I had never turned on the engines. I had set up a lever to keep them turned off while I was adding all the conduits, so they wouldn't overheat. They were still turned off when I left, and remained turned off for the duration of my trip.
Like I said, it's not an epic fail, but it still made me facepalm.
So, a little update on my quarry.
a.k.a. Ember Quill derped again. Or, rather, Ember Quill just noticed a previous derp long after it stopped being fixable.
Since I need Apatite in addition to all the other reasources I'm looking for, I went ahead and made a single-biome Extreme Hills Flat Mystcraft age for mining. I was planning to open it up to the rest of the server (the server I'm playing on is a small one that I host by myself) after seeing how the ore generation looked. That's where I built the quarry I was talking about in that last post.
You can probably guess what my mistake was.
I didn't even think about how ore generation works when I made the age. I just figured Extreme Hills = Apatite and went from there. And I built my quarry on the flat plane at Y level 180 or so. And then I had the problem with my engines, of course, so I fixed that, got everything running, got rid of the pointless energy cell once I saw that every MJ of energy was going straight through it to the quarry, and logged off for a bit.
Fast forward a couple days (I've been too busy to play often). I log back in to see that my lava tank is almost empty. My quarry has mined down 50 layers or so. "Sweet!" I say to myself. "I must have a bunch of resources now!"
...Nope. Over a thousand Apatite, a small amount of amber, over ten thousand dirt, and about 225k cobble (thankfully, my AE system dumps all the cobble and dirt into DSUs so there's still plenty of space).
50 layers down from 180 is 130, which is still high enough that nothing but Apatite and amber spawn. Lesson learned. I'm probably scrapping this age and writing a new one after my quarry finally hits bedrock (which will take a few days of constant operation, at this rate). Apatite is great and all, but a mining age that requires you to go through a hundred layers of almost nothing but stone and Apatite just to get to the rest of the ores is not at all useful.
Even Emerald (the other reason why I went with Extreme Hills) doesn't spawn above level 32! So I'm screwed for resources for another day or two unless I want to write ANOTHER age and move the whole setup over there.
