There are several important factors that determine how deep a sewer line must go. However, figuring out the correct depth on your property takes some work because the line has to slope downward, too. That means the amount of cover will vary, and other factors can change how deep the line needs to be. If you have to install a sewer line, you’ll want to call a professional to have the work done.
How Deep Do Sewer Lines Need to Be?
The required depth of a sewer line varies between municipalities. For example, the state of Kentucky has a guide for homeowners that states that a sewer line must have at least 2 to 3 feet of cover when passing under a driveway, with the specific type of pipe determining if that cover will be 2 or 3 feet. However, individual cities and counties may have their own requirements.
The depth of the sewer line also changes from one end to the other as the line has to slope down and away from your home. That means that the amount of cover at your home (say the type of pipe you use allows the cover to be only 2 feet) will be less than the amount of cover at the point where your line meets city sewers. Sewer depth between manholes, for example, should be 3 feet minimum, and the cover, if the sewer line meets a stream, varies from 1 to more than 3 feet depending on the material the line is buried in.
One very important point is that the line has to be buried below the frost line. So, no matter what the minimum requirement is, if the frost line is lower than that, the sewer line has to be buried even lower.
How Are Repairs Done on Something Buried That Deep?
Repairs to a sewer line can be difficult, but plumbers have options. First, if the repair is just pushing out a clog, plumbers can do that with special drain snakes. Plumbers can also view the interior of the pipe using a sewer camera, which saves a lot of time and work. It lets the plumbers see exactly what’s happening in the pipe so that they can target the exact location of the problem, such as in your bathroom plumbing.
Some repairs require the plumbers to dig only a small hole to insert something like a liner. Others require trenches, which can be invasive and disruptive.
Why Sewer Lines Have to Be Buried Deep
Sewer lines have to be buried very deep for a few reasons. One is the frost line; if soil underneath the line has moisture in it, there’s the risk that the moisture will freeze if temperatures dip. When water freezes, it expands. That pushes against anything near or in the freezing soil. (This is called “frost heave.”) Frozen soil expands and can shift the pipe, leading to cracks and leaks. However, if the line is in the soil that’s below the frost line, that means it’s buried so deep that the soil just never gets cold enough to freeze. In that case, there would be no risk of frost moving the pipe.
A second factor is erosion. Soil can blow away due to high winds or wash away due to water runoff from rain, broken sprinklers, or a broken water line. While water from a leaking water line underground might still be a problem, wind and rain aren’t likely to remove a couple of feet of soil in a day. Burying the pipe deeply helps protect it.
Tree roots are another hidden threat. A leak in your sewer line can attract aggressive tree roots that are spreading out and looking for water and nutrients. The deeper the line, the less risk there is because tree roots that spread out don’t usually grow that far underground. That’s not a guarantee that there will never be a problem or that roots will never ever grow that far underground. You should still be cautious about planting trees too close to the line. But it does help lessen the risk of a problem.
We offer plumbing services that cover everything from kitchen remodeling to drain cleaning, as well as water heaters. Don’t let your sewer line cause you repeated problems. If you need a sewer line inspected, repaired or even replaced in Lexington, contact Pipe Surgeon Plumbing today.
