Since the Dingo was not able to bore through the tough Palouse clay, we rented a Bobcat with a 24" auger bit. The Bobcat weights 4 times more than the Dingo, and this extra weight allowed us to ultimately push through the clay and excavate our holes for our pier foundation.
Our 10x14 footprint is small enough that navigating the Bobcat between the holes was a challenge.
Using the auger on the Bobcat was so simple and easy, that we ultimately dug our holes deeper than 50", when we only needed to go around 30". The extra depth will only serve to make a stronger, more stable foundation.
If you look closely at the following picture, you will see some local wildlife hanging out in the holes.
All six pier holes were close to their ideal location. However, some work was necessary to clean out the holes and make sure we could position our bigfoot footers and sonotubes correctly.
After that, its time to prepare to pour the concrete...