Using an auger in rocky soil can be challenging.
Post diggers can't drill through rock. You'll need extra tools and know-how to get your holes dug properly and without a ton of hassle.
Read about using an auger in rocky soil below and digging post holes in rocky ground.
The fact is that most soil will have rocks in it. Can you use an auger in rocky soil? Of course. That doesn’t mean you can’t drill a hole. It just means you will need to use some extra tools when using an auger in rocky soil. It will take more time to do it by yourself than if you were using a 2 person auger.
What is the Best Post Hole Digger for Rocky Soil?
2 person augers are also packed with a ton of power to handle tough soil situations like rocks and roots.
Another kind of auger to use is a 3 point post auger that you attach to a tractor or backhoe.
Augers in Rocky Soil: Before Your Dig
Make sure you know before digging about any utility lines on your property. Also, you should know what type of soil you’re dealing with. Is it all rocky? What about tons of roots? Is it topsoil for a foot or two and then solid bedrock?
And, this advice is gold: get a new tetanus shot before playing around in the dirt. They need to be renewed every 10 years or so, check with your doctor.
Knowing these essentials before digging will steer your project in the right direction and keep you safe.
Using an Auger in Rocky Soil: Tools for Digging in Rocky Soil
Once you’ve got the all clear to go ahead and drill, digging with an auger in rocky soil requires a few extra tools on hand to help you deal with when your auger is hitting rocks (or roots).
Here is our short list of supplies you’ll need to have so you can handle any rocks or roots that come across your path.
A digging bar is an essential tool here. When you are drilling a post hole in rocky ground and you get to the rocky part, you use the bar to loosen and pry the rocks from the ground.
Shovel and/or Clam Shell Digger
Taking your shovel or clamshell digger, remove the extra soil from the hole. Take your digging bar and stab and pry at the hard ground and rocks to loosen them. Your shovel and/or clam shell digger is used to remove extra soil and rocks from your post hole.
Use your wheels to store and cart away extra dirt and any post hole rock you remove. I save any extra soil and rock for later: it might have a use down the road.
How Do You Dig Holes in Rocky Soil
Using an auger in rocky soil means a lot of starting, stopping and removing rocks from each hole as you drill. Digging post holes in rocky ground is not the best situation to be working in, but it might be your only choice.
Follow our directions below to dig holes and footings in rocky soil and remove post hole rock.
Using an Auger in Rocky Soil: How to Break Up Rock in a Post Hole
Once you’ve started drilling, how do you know if you’ve hit a rock? You know you’ve hit a rock if your auger stop rotating and/or starts bogging down and slowing while drilling. Use your reverse function or pull your auger out of the hole and turn it off. Dig out any loose dirt that is in your hole.
Look into your hole and check for rocks. If they are stuck in the soil, use your digging bar to loosen them up. Grab them out with your clam shell digger, shovel or hands and put it in your wheelbarrow.
Loosen all the soil at the bottom of your hole to make sure you’ve gotten all the rocks. Another way is to flood the hole with water to loosen up any rocks that are in your way, let the water soak up and then pry out the rocks with a digging bar.
Place your auger back in the hole and start drilling again. Repeat this process with each rock you hit until you’ve drilled your hole as deep as you want.
How to Get a Big Rock out of a Post Hole
Rocks are heavy. Not only that, you might hit a rock that is larger than the post hole you are trying to drill. What then? You might need to bring out the big guns here and use a gas powered jack hammer to break up the large rock that’s in your way.
Other methods include heating up the rock and then dropping very cold water onto it to split it, and hammering a few holes into the rock and using a tapered punch and a hammer to split the rock.
If it’s just not possible to get that rock out of your way, you may have to anchor your structure to it somehow. Check with your local codes and see what methods are allowed in your area.
Using an auger in rocky soil can be done. There will be a few extra steps to getting that post hole dug in rocky ground, but following the tips above, you'll get it done without issue.