Slot trenching is a type of excavation. It is the process of digging a hole that is deeper than it is wide. Most of the time, slot trenches are between seven inches and one foot wide. They are often used for the installation of pipes, cables or other subsurface utilities. Hydro excavation is the preferred method for slot trenching because of its precision, non-destructive system and efficient operation.

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The Difference Between Excavation and Slot Trenching

Excavation is the process of digging into the surface of the ground. The hole can be any size or shape. Meanwhile, slot trenching is a type of excavation where the hole is deeper than it is wide. Unlike excavation, slot trenches must be less than fifteen feet wide. Slot trenching is an elongated narrow excavation. Ultimately, a slot trench is a type of excavation, but the reverse is not true.

Slot Trenching Applications

Slot trenching has many different applications when done with vacuum excavation. It can be used to install signs and posts, but we often use slot trenching to install subsurface utilities.

There are a lot of times when we are called to install utilities with vacuum excavation in substations where heavy machinery is not permitted. If a line needs to be exposed for repairs, we can excavate the area using slot trenching to provide enough workspace for the workers to repair the utility line. 

Another use is called exploratory slot trenching where we would clear an area or confirm the location of existing utilities, including unlocatable utilities like plastic or nonconductive lines.

Benefits of Slot Trenching with Vacuum Excavation

Using hydro excavation for slot trenching is a safer alternative than traditional digging. The latter method either uses big, heavy equipment or manual labor of workers digging with spades and shovels. Traditional digging can result in harm to workers on-site or nearby, as well as damages to the utilities. Both of these outcomes cost time and money. 

By choosing vacuum excavation to do your slot trenching, you can substantially lower all of the risks associated with traditional digging methods. Vacuum excavation is classified as a non-destructive method, so the risk of actually damaging a utility is very low. Additionally, it is less labor-intensive because it is more precise, which makes it more cost-effective and efficient for your project’s budget. Since one of the goals of slot trenching is to remove the least amount of dirt, vacuum excavation also offers a more environmentally friendly option compared to traditional digging.

How Slot Trenching Works

Understand the Project Requirements

It is important for us to understand the scope of the project from the customer. Having this information allows us to determine which application of trenching is best for the specific needs of the client.

Conduct Exploratory Trenching at Location

Once we have the location of the project, we coordinate with our site contact and use their knowledge of the area to narrow down where we need to be when exploratory trenching occurs. We also have technicians use ground performing radar (GPR) at the site to confirm the exact location of where the vacuum excavation should occur.

Perform Vacuum Excavation

Vacuum excavation consists of high-pressure air or water used to precisely break up the ground while a large vacuum is used to suck up all of the broken dirt and soil pieces into the debris tank on the back of the truck. When it comes to trenching, the team will move down the line, as opposed to, staying in one hole like a classic vacuum excavation. The soil will need to be refilled after it is excavated.

Trench in a Z-Formation

When the area is 100% cleared, the technicians will EM and GPR scan the area. Next, the team will come in and trench in a Z formation to cross the area three times to confirm the entire area is clear. The reason a Z is used is that it is the most efficient path to use across any potential utilities running through the scope of work, regardless of which direction the utility is going.

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