I recommend the Digital Miner from Mekanism. You can tell it to mine a defined block and replace the mined block with a block of your choice in a 32-block radius in any depth interval of your choice. You have to supply the replacement blocks though, and it's slow even if fully upgraded and uses up quite a bit of power. I see you have a really big turbine though, that should take care of any power needs.
Edit:
Ah, I see this already occurred to some. This works, the only problem is that the interface of the miner may be a little misleading if you're using a texture pack because it has changed recently. Now the replacement block goes into the filter config into an extra slot right of the filter block id which may not be visible, but works nonetheless. The global replacement slot on the main config page doesn't work anymore.