Summary: There are many manhole rehabilitation methods available today that all promise solutions to any sewer problems.
Manholes may be the place of residence of the Teenage Mutant Ninja Turtles, but they actually serve a bigger purpose than that. They are one of the important parts of the wastewater collection system. Thus, manhole rehabilitation is more than just ensuring that the manhole cover is well in its place on the ground.
Manhole rehabilitation is necessary to ensure that infiltration or inflow in sanitary sewer collection systems. These manhole problems, if not addresses right away, will result in sewer overflow which can threaten the environment near it. A lot of sewer issues that were ignored led to more serious and damaging problems like contamination of safe water. Recurring inflow of wastewater in the sewer will encourage it to be a nesting grounds of insects and bacteria as well.
There are several factors that cause the need for manhole rehabilitation. Deterioration due to structural fatigue, infiltration, acid attack, corrosive gases and natural wear, are only some of the common reasons why manhole rehabilitation should be done. While there are several methods that can solve some of these problems, only a few of these methods can actually solve all manhole problems.
There are manhole rehabilitation techniques that are done to replace the existing deteriorated manhole. Such techniques include spot repairs, cement coating, chemical coating, and structural repair. For an extremely deteriorated manhole, the structural form repair technique is most effective. This is done by constructing a new manhole by inserting or constructing it within the existing deteriorated one. This technique allows the restoration of the structural reliability without any surface disturbances. Manhole rehabilitation materials used should be able to ward off the effects of some of the factors that influence deterioration like acids, corrosives, roots, and vibrations.
One method used in structural form repair of manhole rehabilitation is the Spraywall, cured-in-place method. This particular method of structural repair uses urethane material which is said to have corrosion resistance properties. The manhole rehabilitation starts with the pressure washing the interior of the existing manhole to temporarily stop any leaks. The urethane is then sprayed continuously by an installer on the walls of the manhole to achieve the thickness according to the design. The urethane in Spraywall cures in about eight seconds and makes it possible to acquire the necessary thickness without spraying in several layers. Manhole can be used when spraying has been completed.
Choosing a manhole rehabilitation technique may not be easy. It would require careful planning, intensive research, and ultimate understanding of the problems. However, preparation for the inevitable will be best so that problems may be addressed as soon as they have only begun to show signs.