There are different types of soil and some augers work better than others in specific types of conditions. If you have clay soil, you will have to learn how to use a post hole digger in clay to get your holes drilled.
Read on to learn exactly how to use your post hole auger in soil that is clay based.
The Best Tool for Digging in Clay
By far, the best way to dig up clay soil is with the best post hole auger. But there are a ton of different auger brands and bits to choose from. Some folks are keen on using a tractor auger, or going completely old school and digging out the holes with a hand auger called a clam shell digger.
Clay soil compacts easily while drilling holes with an auger, making it the most challenging soil to drill. It's a battle where you make super slow progress. Like only being able to drill a few inches in an hour, and that's even with a powerful auger and a few helpers.
Best Post Hole Digger for Clay Soil
Usually, the 1 man augers that you see for sale don't come with enough torque to get through clay soil, even after you've drilled pilot holes and soaked the clay soil with water. Even when you repeat soaking the soil over and over again, you won't have much success.
2 man augers don't seem to work any better in my experience.
We've been seeing a new tool for manually digging out clay soil called the Slammer Tool. It's pretty neat, but is a bit on the expensive side. It's like a digging bar, shovel and axe rolled into one, specifically made to conquer clay soils.
We like using a tractor or PTO auger for drilling in clay, because they have so much more pounds of torque. But, even though they have enough weight to handle the toughest soils, a tractor auger is barely better than a 2 man auger.
The best post hole digger for clay soil, isn’t even a post hole digger. It’s a jack hammer. Using a jack hammer to break up clay soil that is dry works so much better and is easier on your body than trying to use any type of auger. First, you jack hammer the soil to loosen it up, then you can use an auger to drill down, which makes the hole perfectly round for your fence posts or foundations etc. etc. Having a shovel or clam shell digger to remove the clay soil from the hole is a great idea.
Best Auger Bit for Clay Soil
There really isn't a best auger bit for clay soil. Clay soil is a beast and will beat up your auger and any bits you throw at it.
Drilling Through Clay Soil: How to Use a Post Hole Digger in Clay
- Mark out your holes and any pipes/underground utilities that you must avoid when drilling.
- Using a shovel or clam shell digger, make yourself small starter holes at each point that you want to drill. These should be anywhere from 4-10 inches deep, enough to hold some water at least.
- Fill your holes with water which softens up the clay soil, making it easier to dig.
- Have your digging bar handy to break apart stubborn parts of your clay soil, roots, or loosen up rocks. This also helps you to make sure the water reaches all the soil in the hole.
- Wait for the water in each hole to soak into the soil.
- Holding your post hole auger at a 90 degree angle in the center of your starter hole, get drilling!
- Add more water as you drill, repeating the process above until you're finished each hole you need drilled.
If the above doesn’t work, or is just so painfully slow that you want to give up and hire someone…don’t. Get yourself a jack hammer and follow the procedure below.
You may need to clean off your auger bit because clay tends to stick and clump on surfaces, including your auger blade. Apply some WD 40 or another type of oil to your bit to form a barrier and help the dirt come off easier.
Drilling Through Clay Soil with a Jack Hammer Instead
- Mark out your holes.
- Don’t get the soil wet because clay is easier to jack hammer when its dry.
- Dig a tiny starter hole.
- Place your jack hammer into the center of the hole and start hammering to loosen up the clay soil.
- Once you have loosened some soil, then you can use an auger to drill down, which makes the hole perfectly round for your fence posts or foundations etc. etc.
*Having a shovel or clam shell digger to remove the clay soil from the hole is a great idea.*
How to use a post hole digger in clay isn't hard when you start off with knowing that you'll need some super human strength and patience to get through those holes. You can drill your holes in clay once you know the secret is to use an auger, digging bar and a jack hammer. Happy drilling!