Auger for Shale?

[DJ54]

When the contractor rented a post hole auger to put up the partition wall in my barn, the unit came with an aggresive auger like the one in the link. Maybe a rental place near you would have one to fit, or possibly the dealer the Dingo came from. Some do rent equipment too.

All of the utility companies in this area have the aggresive bits on their line trucks, as we have shale, limestone, and sandrock in this region... Granted a much larger unit, but they go slow and easy, and I've watched them bore through pretty hard sandrock.