Fence installation can be a challenge in rocky, frozen, or marshy ground where it is impossible to efficiently drill wells or install poles with a tractor-mounted pestle. Options for rock drilling in Brisbane include drilling holes with a backhoe or a rock chipper, if it is a formation that will crack and fracture; rock smashing with a hand bar; or using a hammer drill.
In some terrain, where it is not very steep and there are shallow rocks, you can build a cage of rocks above the ground as a post to stabilize the fence.
Gather or stack the rocks and secure them with wire mesh, or make a cage and put the rocks in. If the terrain is too rocky for wooden posts, you can usually put steel posts deep enough to hold them, using rock baskets every now and then for the brackets.
Another strategy for rock or frozen ground when using a pestle is to create a pilot hole. Often a metal pilot shaft will pass through rocky ground if it is not solid rock – it will push the rock aside and pierce the frozen ground; while the wooden pole is forced out of the line or crashed.
The pilot shaft is only 3 or 4 inches in diameter and creates a hole for the wood shaft. The tapered bottom is a solid perforated steel about 3 feet long to break rock. The cone of the drill stem won’t hold up, but a steel drill at the tip will break most rocks or push them away, he says.
It is relatively easy to dig holes for fence posts in sandy or clay soil, but the presence of rocks in the soil turns the easy task into a long and lengthy process. When the blades of your tools come into contact with rocks, you should constantly stop what you’re doing and tackle the rock instead of just quickly removing shovels full of soil. Digging tools such as shovels, post scalloped hole diggers, and drill rods are heavy and have sharp points and blades that help loosen hard soil and rock from the shaft hole.
Fence Post Installation Guide
- Remove the sod layer of soil to form the fence post and at least twice the diameter of the post, using a digging shovel. Push the spade blade through the sod into the soil with your foot to cut the roots of the sod, usually about 4 to 6 inches deep. Pull the spade handle back to get the softened sod up, then cut and loosen it completely around the perimeter of the shaft hole. Lift loose grass from the soil with a shovel or by hand, and set it aside to place it around the pole once the backing is permanently in place.
- Push the tip of the blade of the drill rod into the soil around the edges of the post-hole area. Pull the handle back, and use it as a large pry rod to loosen the soil in the center of the post-hole area. When using a drill bar, stand with your feet square with your shoulders apart, and spread your feet shoulder width apart to prevent straining your back from continued use.
- Drive the drill rod at an angle under and around the rocks to loosen the hard soil holding the rocks in place. Pull the drill rod back using the edge of the shaft hole as a lever to lift and loosen the rocks. It may take several attempts at staring at different angles around the edge of the rock to completely break it down. Some of the rock may settle out of space, so expect the hole to be drilled wider than the desired width of the shaft hole.
- Pick out the big rocks from the soil as you free them from the soil; Don’t worry about picking out small rocks. Use larger rocks later elsewhere in the garden, such as making flower bed borders, or reserve them to fill in the shaft hole after the pole is installed. Don’t worry about picking out small rocks, because you can remove them later while raking the soil.
- Cut back large trees and plant roots that may grow in the subsequent hole and block access to rocks inside the hole, using a hand saw or reciprocating saw. Thoroughly cut the roots with a hacksaw, pushing them against the walls beyond the hole. Pull the cut roots out of the shaft hole by hand or using post whole diggers.
- Remove loose soil and rocks from the hole using post scalloped hole excavators. Hold the handles of the scalloped excavators together to keep the blades open. Insert the post-hole excavators into the loose soil, and pull the post-hole digger handles away to close the blades and pick up the loose soil. Lift the post-diggers out of the hole, pushing the handles together to drop loose soil into a pile.
- Straighten the shaft hole walls with a round trowel. Slide the bucket blade straight down into the post-hole wall soil with your foot. Pull the bucket handle back to remove soil from the post walls of the hole. Use post scalloped hole excavators to remove loose soil from the bottom of the hole.
- Alternate between using a drill rod to break up large boulders, shell excavators to extract loose soil and a round point shovel to shape the sides, until you reach the desired depth of the shaft hole. Post-pit depth varies greatly depending on the material of the shaft, the length of the props, and the type of soil.