A Guide For Digging Trenches For Utility Installation

Digging utility trenches guide tips

For utility companies, burying utilities just makes sense. They're protected from severe weather, it's easier to access them for repairs and updates, and they just look nicer than the alternative. If you're the one doing the burying, it's not really so simple — installing underground utilities involves a lot of planning, situation-specific considerations, and heavy machinery. Here's a brief guide on the best practices for digging utility trenches in a variety of substrates, from soil to concrete:

1. A hole is more than a hole.

Buried utilities go in trenches, which are defined by the U.S. Occupational Safety and Health Administration as an excavation longer than it is wide. Creating a proper trench is more than just digging a hole. Even if you're just temporarily displacing soil, you can't go into the job assuming it's as easy as digging a trench and getting on with it.

2. Know your soil.

Before you ever break the ground, you need to know what you're digging into. There are different classifications of soil based on particle size. This ranges from very small particles, like silt or clay, to sand and gravel. This might seem unimportant, but it's something that could save your life.

A cubic meter of water-saturated soil can weigh as much as 3000 pounds. That's not something that you want to experience if your trench caves in. Trenching is one of the most dangerous activities tracked by the U.S. Department of Labor, but knowing what you're working with and how to handle it can make it safer.

3. Know your utilities.

In addition to accounting for soil type, you also need to know exactly what you're burying. Trenches for wet and dry utilities are subject to a lot of regulations to protect the people they service, the utility companies, and the environment.

Wet utilities are things like water, sewer lines, and stormwater management. Dry utilities are gas, electricity, telephone lines, and fiber optic internet. Each of these utilities has a different negative impact if lines get damaged and making sure they're installed properly is the first step toward preventing that.

4. Be ready to cut into the pavement.

Say you know your soil classifications like the back of your hand. There's only one problem — sometimes, that soil might be located under a parking lot. For new construction, you might be digging trenches before there's any asphalt or concrete down. For existing pavement, you'll have to dig a trench through that and the underlying substrate in order to properly bury utilities.

There's no real way around that, which means one of two things: You need to either break up the asphalt or concrete, haul the waste material off in trucks, and repave the area, or use a trencher. Trenchers, like the Street Works Street Trencher, are able to cut a trench, pulverize the cut-away paving material, and backfill the area. There's no need for jackhammers or dump trucks, and the entire process takes a fraction of what it would to cut it the old way. For a job as lengthy and complicated as burying utilities, a good trencher can be a huge labor-saving tool.

5. Measure twice, and dig once.

Before you move a single particle of soil, there's another thing to consider: What other utilities are in the area? You don't want to dig a trench just to find that you're either bisecting existing lines or worse. The position of existing buried utilities should never be a surprise.

The most accurate way to find existing utilities is by using magnetic or ground-penetrating locator equipment. The effectiveness of these depends largely on the utilities that you're looking for — magnetic equipment is best for anything buried with a metal pipe or ferromagnetic tags. Ground-penetrating equipment emits a frequency through the soil and picks up what's re-radiated back. This allows it to create a picture of what's going on beneath the surface.

6. Plan your depth, grade, and width first.

Along with everything mentioned above, it's important to plan out exactly how your trench needs to look. How deep should it be? How wide? How much will the trench need to slope in order to maintain the correct depth? Every piece of terrain has its own natural variations in slope and soil composition, so you need to plan for your job's specific location. Even something that seems perfectly flat, like a paved lot, will usually have a small change in slope.

When people hear about digging trenches, they usually imagine a team of workers with shovels planning their route as they go. In reality, creating a trench that's safe, follows regulations, and is suitable for what it needs to hold requires a lot of planning and equipment. As long as you follow these practices and properly plan your trenching projects, you'll be able to save time and money while keeping your employees safe.

POSTED: December 8, 2022