When a Buildcraft pipe is betwenn the mining pipe and a ore (or maybe it crash when the pipe is under the miner too, haven´t tried it) it will mine it. That result in a Saving Chunks Error. Now you can´t open the world anymore, because of the error the bc pipe is still there and the miner mine it again (takes like 0.1 sec) then you get the same error again.
The only thing that worked to reapir the world is to delete all pipes near the miner withMCEdit.
IC²: 1.15
BC2: 2.2.1