Drainage pipes-known as sewer lines-are usually made of PVC or ABS black plastic. However, older sewer lines can be made of lead, cast iron or clay. Damage to an underground sewer line can be caused by the ground shifting or even a slight earthquake. With no room to leverage the pipe to fit new rigid plastic couplings, a new piece of pipe is installed using flexible rubber couplings. Once the hole has been dug, the job is fairly simple to carry out.
Dig a hole down to the area of broken sewer pipe. Make sure that 6 inches of earth is removed below the broken pipe area.
Cut through the pipe 2 inches on each side of the broken area. Mark the pipe first with a felt-tip pen, and use a hacksaw or power saw to make the cut. Be sure that the cut is straight and remove any burrs with a utility knife. For lead pipes, also use a hacksaw. For clay pipes, use a cut-off saw; and for cast iron pipes, use a reciprocating saw with a metal-cutting blade.
Measure the distance between the two pipe cuts and cut a new piece of PVC pipe to that length. Make sure the new pipe is the same diameter as the existing sewer pipe.
Push flexible rubber couplings fully onto each of the existing cut pipe ends. Apply soapy water around each pipe end if the coupling is hard to slip on.
Place the new piece of PVC pipe between the two existing pipe cuts and slip both flexible couplings onto the new pipe section, so that half of each coupling is on the old pipe and half on the new pipe. Tighten the metal straps surrounding each end of one coupling with a screwdriver. Now tighten the straps on the other coupling.
Pour fine gravel around the sewer pipe for support and to fill in the hole.