How to Choose the Right Tools for Digging a Trench

Trenchers are types of equipment designed to excavate straight trenches that are smooth at the sides, flat at the bottom and usually deeper than they are wide. Trenchers can dig trenches more quickly and evenly than excavators.

Excavators are types of heavy equipment designed to dig ditches that are usually wider at the top than the bottom. Compared to trenchers, excavators dig to greater depths, are suitable for all terrain and more easily dispose of soil or rocks.

When digging trenches more than 100 feet long or in dense, rocky terrain, renting a trencher is more effective than using shovels and other hand tools.

There are two types of trenchers based on propulsion.

• “Walk-behind trenchers” are so called because the operator pulls the equipment from behind, walking backwards, rather than pushing it forwards. These trenchers are around 12-31 horsepower and better for softer terrain or trenches that must be dug with more precision. They can dig trenches up to 48 inches deep and are good for installing irrigation, plumbing and cable systems.
• Ride-on trenchers are motorized diggers ridden by the operator. They are around 49-131 horsepower and are better for the longest, deepest trenches, rocky terrain or pavement. They can dig trenches up to 6 feet deep and are less precise or maneuverable than walk-behind trenchers.

Other trencher designs differ by the digging mechanism.

• Chain trenchers have chains or digging belts that resemble chainsaws and can cut deep, narrow trenches that are well-suited for drainage. Avoid using chain trenchers in rocky soil.
• Wheel trenchers have metal wheels with teeth, also known as rockwheels, that are primarily designed for rocky soil, pavement or concrete. They are ideal for road repair but can also be used with softer soil.
• Micro trenchers are designed with smaller than usual rockwheels for cutting smaller trenches of 1-4 feet deep and only inches wide. Their small size makes them suitable for laying fiber optic cable.

Pro Tip: A trencher should be able to dig 100 feet in 12 hours, depending on the type of trench and the terrain.

Trenchers are often identified by the depth of the trenches they can dig. For instance, a 48-in. trencher digs trenches up to 48 inches deep.

Determine the size of the trench you need before choosing your hand tools or renting a trencher.

Estimate the length, width and depth of the trench based on what you need to install underground. For instance, a 4-inch pipe for a French drain should be installed in a trench 6-12 inches wide and 18-24 inches deep. In that case, you will need a 24-inch trencher.

Consider the following general rules for sizing trenches:

• Trenches for electrical wiring are typically 6 inches deep x 4 inches wide.
• Trenches for drainage can be 18 inches deep x 9 inches wide.

For digging smaller trenches, especially on residential properties, consider the following hand tools.

• Trenching shovels have pointed tips for slicing into the ground and squared sides designed for smooth trench walls.
• Pick mattocks have heads with a pickaxe on one side for breaking soil and a mattock blade on the other for chopping roots.
• Drain spades have rounded tips and curved sides for scooping dirt or debris from a trench. Spades usually have shorter handles and smaller blades than shovels. Drain spades are effective for shaping the trench after the initial excavation.
• Grub hoes are a type of draw hoe with a blade designed to chop sod, roots and weeds below ground level. Grub hoes also have a pick end for tilling or turning soil.
• Landscaping rakes are designed for heavy-duty work such as moving loose soil.

Follow these steps when choosing tools and digging a trench.

• Before digging a trench, check with the local municipality for the placement of any underground pipes, electrical wires, gas lines and other potential obstructions.
• Determine whether the trench needs to slope. For instance, French drains require a slope of 1%. (See our guide, How to Install a French Drain.)
• Mark the direction of the trench with marking paint.
• When using hand tools, begin by loosening the soil with a pick mattock or grub hoe and remove rocks and other hard obstructions.
• Dig with a trenching shovel, making sure to shape the walls of the trench.
• Use the grub hoe or rake to remove the loose soil from the trench. Make sure the soil pile will not get in the way of your installation work.
• Make sure the trench has uniform dimensions before installing pipes, wiring, etc.

When using a trencher, wear PPE and follow all operating instructions and safety procedures.

Pro Tip: Estimate 1 hour of work for every 10 feet of trench when digging with shovels and other tools.

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