Cleaning and televising lines are used to help identify any problems that may have occurred within the sewer. Before lines are televised, they must be cleaned by either pigging the lines or jetting. Pigging the lines is when you drag a large rubber pig or plug through the lines, while jetting is sending a high-pressure water jet through. Jets can also be used to pull a cable through the pipe, which will then be connected to the television camera to pull it through.
It is important to monitor the debris that is being removed while the lines are being cleaned. The contents of this debris will give you some indication of the condition of the sewer and the possible trouble sources.
If there is grease, you may need to install or better maintain your grease traps. If there are roots, root intrusion may have caused cracks or joint separation. You may wish to regularly rod the lines or apply chemical root killers. If the removed debris includes dirt and pieces of broken pipe, you’ve probably got missing sections of pipe and may have to replace parts of the line.
Televising should be done during wet weather or with dyed water flooding of the surface. Wet weather is most effective because it will also show sources of inflow. As the camera is drawn through the sewer, it will record exact locations of water entering the pipe and show the structural conditions of the line. An expert can determine by watching the tapes how much water is entering in each defect in gallons per minute and if there are signs of hydrogen sulfide-induced corrosion.
Nonemergency sewer line cleaning and inspecting sewer lines are essential to maintaining the capacity of the sewer and maintaining a properly functioning system. These activities further a community’s reinvestment into its wastewater infrastructure. In many systems, the sewer lines have low flow between midnight and 5 a.m., and many of the sewer lines can be temporarily plugged during this time frame.
Televising is an expensive investigation technique – about $2 per linear foot – plus the cost of light or heavy cleaning, which will add about another $1 per foot. Televising rigs can be purchased for about $100,000, yet most facilities find that it is more cost effective to hire a local sewer service company when this work is needed.