Planning, Locating and Digging up the Mainline

• 1). Go to the planning commission in your town or city and ask to see how deep the sewer is in front of your house and ask for the exact location of where your house connects to the sewer. While you are there, pull the permit for the repair. You need this information because it will help with locating the mainline, determining how deep you must dig, and if you will need to shore up the trench.
  
  
• 2). Find out where the mainline exits the foundation. If you can crawl under the house, find the large pipe that runs from the nearest bathroom and follow it. Take careful note of this spot and go outside and use a probe to push into the ground a few inches away for the foundation and locate the pipe.
  If you cannot crawl under the house, then look on the roof and locate a three-inch vent pipe sticking out of the roof. This is usually directly above a bathroom. Push the probe into the ground starting at the closest wall to the vent and work your way toward the front of the house. Usually the mainline is not more than a foot or two below the ground as it exits the foundation. If the probe does not work, then you may have to just pick a spot and dig a couple of test holes looking for the mainline.
  
  
• 3). Measure the distance from the spot where the mainline exits the foundation of your house to the curb. If you know the depth of the mainline as it exits the house you can calculate the depth of your mainline at the curb and how many 10 foot lengths of pipe you will need.
  Since there must be a minimum of one quarter inch per foot fall for the water to drain, you can determine that for every four feet of distance the pipe is one inch lower in the ground as it travels toward the street. For example, If there is 30 feet from the spot that your mainline exits the foundation to the curb, then the pipe will be approximately seven and one-half inches lower at the curb than it is at the house.
  
  
• 4). With the pipe exposed near the house, you will know what kind of pipe you will be removing (clay or plastic), what pipe is exiting the house (cast iron or plastic), and its direction of travel.
  
  
• 5). Remove any sod, plants or shrubs that are in your path. If there is a large tree in your yard, you may want to consider removing or relocating it if it is within two feet of your existing mainline. The roots will damage a mainline and is probably what caused you to have to do this repair in the first place.
  
  
• 6). Expose the entire length of pipe to be removed. The trench should be approximately three to four feet wide so that you can work in the trench comfortably. Before climbing into the trench, shore up the sides to prevent any accidents.
  
  
• 7). Now determine the materials you will need to complete the repair.
  You should have already measured the distance and calculated how many 10-foot lengths of pipe you will need. As a rule, buy one additional 10-foot section of pipe, as you may need it for the clean out or in case of accidents. You will need one coupling to connect two pieces of plastic pipe together. So, if you are connecting three sections of pipe you will need two couplings and two flexible couplings to connect to the existing pipe at each end.
  If you are connecting to clay or cast iron pipe you must use flexible couplings that are made to mate plastic and clay or plastic and cast iron together. It is safe to say that unless your home was built after 1998, you will need one of each of these special flexible couplings.
  You will also need two Wye's. One will be used for inserting the test plug, and other will become a clean out that will make it easier to clear any future clogs in the pipe.
  
  

Replacing the Pipe and Installing Fittings

• 1). With the entire pipe exposed, use soil cutters to cut the section to be replaced at both ends. Make the cut on the opposite or street side of the connection closest to the street. At the house, do not attempt to cut a cast iron pipe, instead cut the clay pipe just in front of the cast iron and use a hammer and a chisel to chip away the clay from the cast iron pipe. Use caution not to damage the cast iron pipe coming out of the house.
  
  
• 2). Remove all the pieces of old pipe from the trench and use a shovel to smooth out the bottom of the trench and preserve the one-quarter-inch-per-foot fall of the original pipe.
  
  
• 3). Position a Wye in the trench so the bend is sloping away from the house. Use a hand saw to cut a one foot section of pipe. You are installing the one foot section of pipe into the end of the fitting closest to the house. First prime both the outside of the pipe and the inside of the fitting;then, put glue on the pipe and in the fitting. Push the pipe into the fitting and hold it in place for several seconds.
  
  
• 4). Use a flexible coupling to attach the opposite end of the one foot section to the mainline exiting the foundation. Before tightening the bands on the coupling, ensure that the opening on the Wye is facing straight up; then, use the torque T-wrench to tighten the bands. The T-wrench will click or slip once the bands are tight. Do not overtighten the bands.
  
  
• 5). With the Wye in place, insert one end of the pipe you already cut into the Wye so that it sticks straight up in the air. Cut this piece of pipe long enough so that it will stick up at least two inches above the surface of the dirt once the trench is filled in. Prime and glue the pipe into the top of the Wye. You can also install the cap on to the end of this pipe now. This is now your clean out, if there is ever a backup in the sewer or the mainline beyond this point. The water will come out through the cap rather than in your home.
  
  
• 6). Prime and glue one of the 10-foot sections of pipe into the opposite Wye. Now you will have to measure, cut, and dry fit the remaining pieces in place. It is generally easier if you install the second Wye near the street before cutting any other pieces of pipe. The slope of the Wye will be just as it was at the house. Do not tighten the bands on the coupling at this time, as you will need room to move this end assembly while installing the pipes.
  
  
• 7). Lay 10-foot sections of pipe and couplings in the trench between the two Wye's and dry fit all the pieces in place. Then, measure and cut the pipes as needed to fit.
  
  
• 8). Before gluing the pieces in place, put a level on top of the pipe. If the level shows a quarter of a bubble slope toward the street, then your slope is OK. If needed, remove any excess dirt from under the pipe until you get the proper slope; then, continue to the next step. Be sure to check each section of pipe. Do not assume that just because one section is good that they all are.
  
  
• 9). Once you are satisfied with the fit, prime and glue all the pieces together;then, use the torque t-wrench to tighten the bands on the flexible coupling near the street. If you have not already done so, install a small piece of pipe and a cap on the Wye near the street. This cap does not have to come above ground level.
  
  
• 10
  
  You are now done with the installation, but do not remove the shorting or back fill the trench just yet. Continue on to the next section.
  
  

Testing and Inspection

• 1). Call the inspector and set up a date and time for him to inspect the job.
  
  
• 2). Before the inspector arrives, remove the cap from the Wye near the street and insert the test plug into the pipe. Fill the test plug with water or air, depending on which test plug you have to form a water tight seal inside the pipe.
  
  
• 3). Remove the cap from the clean out, near the house and use a garden hose to fill the pipe with water. The water does not have to overflow the top of the clean out. But it should be visible. Be sure to document the time once the pipe is filled.
  
  
• 4). The test is generally 20 minutes long. Some inspectors will insist that they observe the water level for 20 minutes. But if you filled it before he arrives and can give him the time that you filled the line, he may include that time in the test time. It is at their discretion.
  
  
• 5). If the water level stayed steady for at least 20 minutes; then, the inspector should sign off on the repair. He will probably also put a level on the top of the pipe to check to see that there is a one quarter inch per foot fall to the pipe.
  
  

Completing the Job

• 1). If the inspector signed off on the inspection, remove the test plug and let the water run out.
  
  
• 2). Install the caps on the Wye near the street and the clean out. Do not overtighten the clean out cap as this will defeat one of the purposes of a clean out, which is to prevent water from backing up into your house if the sewer or mainline is clogged beyond it.
  
  
• 3). Remove all the shoring from the trench and start back filling the trench near the street.
  
  
• 4). As you back fill the trench compact each layer of dirt tightly either by simply using your feet to stomp the dirt down, or rent a compactor.
  
  
• 5). Replace any sod and plants that you may have removed. You have now successfully replaced your mainline.
  Keep in mind to replace a small section is essentially the same task, you must locate the pipe, dig it up, remove the section, install the new pipe, test for leaks, then back fill the hole. Spot fixes rarely fix the problem, as sewer gas escapes into the ground from any crack or opening in clay pipe, roots find their way into the pipe and damage it.