As the owner of an older home, you are responsible for any repairs to or replacement of your home's main sewer line. So, it is important to understand the potential damage that can occur in an aging sewer main. Here are some common causes of a damaged sewer main and options for its replacement.
Depending on the age of your home, you can have one of several different types of sewer pipe buried in your front yard and connecting to the city's sewer main. Many older homes were originally installed with sewer pipe that was not created to last as long as your home. These types of pipe may now have begun to deteriorate and collapse within the soil of your front yard.
Cast iron was frequently used before 1960 as a sewer pipe, and is a durable material to withstand the weight of the soil upon it and intrusion from tree roots. A four-inch cast iron sewer pipe can withstand 4,877 pounds of pressure per linear foot. Unfortunately, it can rust and corrode, over time. The waste water flowing through cast iron pipe etches a channel into the bottom of the pipe, eventually eroding through the pipe and weakening its entire structure. This can occur because the waste running through the pipe creates hydrogen sulfide gas, which can oxidize and produce sulfuric acid to corrode the cast iron. Also, some drain cleaners contain sulfuric acid, which can further corrode the inside of your cast iron sewer pipe.
Another type of older sewer line is Orangeburg pipe, which is made from wood fibers combined with an adhesive and impregnated with tar pitch. This type of lightweight but brittle sewer pipe began to be used as sewer pipe in the mid to late 1940s until the 1960s, when it was replaced by PVC sewer pipe. If you have Orangeburg pipe installed as your home's sewer line, you will most likely need to replace it. Orangeburg commonly collapses after years of moisture have permeated the interior of the pipe, weakening the pipe's walls; then the addition of the weight of the soil around the pipe causes it to collapse. Also, when Orangeburg sewer pipe was installed, the pipe should have been surrounded with a layer of gravel to prevent its collapse under the weight of the surrounding soil. When this step was skipped during installation, it can cause your pipe to collapse after years of soil weight pressing directly upon it.
Clay is another type of sewer pipe that has been used for many years but can degrade and collapse under certain conditions. Although clay is made from inert materials, which make it resistant to chemically degrading, it has a porous surface that tree roots are attracted to. Tree roots growing beneath the soil will seek out and grow toward any high levels of moisture or nutrients, including a leaking connection on a clay sewer pipe. The roots will find their way into a small crack in the pipe to get to the waste materials inside. Once inside, the roots will explode in growth from the nutrient-rich waste, filling the entire sewer pipe with tree roots and causing blockages.
When your sewer main has failed, it can be necessary to replace the pipe with a newer material that is not penetrable by tree roots, such as PVC. In the past, a common method for replacing your sewer line is excavation of the entire pipe to replace it with a new length. This process removes a large amount of soil during excavation of the trench and destroys landscaping and sometimes pavement.
In recent years a more simple trenchless method of replacement has become available, eliminating the need to excavate an entire trench. In a trenchless replacement method, a new pipe is inserted through the lateral location of the old pipe by digging access holes on both sides of the pipe, one at each end of the sewer pipe's connection. Although trenchless replacement can cost 30 to 50 percent more than a traditional trench method, you won't have to spend the money for all the restoration work to your yard.
Use this information to understand how older sewer pipes degrade and how you can replace them. For more information, contact a company like Belfair Plumbing & Drain Service.