Fixing a sewer by camera
Gaping holes in streets, broken sidewalks, piles of sand and heavy earth-moving machinery have become part of the urban landscape.
Gaping holes in streets, broken sidewalks, piles of sand and heavy earth-moving machinery have become part of the urban landscape. Every time a municipal government decides to improve the city's infrastructure, roads are torn up for a few months and the streets are closed to vehicular and pedestrian traffic.
An innovative method purports to reduce the hassles that accompany the upgrading of water and sewage pipes by facilitating repair of the pipes without digging up the roads and disrupting traffic. Even though this method has been implemented in Israel for 15 years already and in other countries for close to 30 years, it has only recently begun to gain momentum.
The method is based on the insertion of a camera through a hole in the water or sewage pipe to locate problems. The situation report generated after the filming includes photographs of the findings, the exact location of each problem and recommended solutions.
The second stage, in which the damaged pipe is repaired, is also done without digging. Yoav Golan, manager of Dori Golan Engineers, which repairs pipes using this method, told Ha'aretz that one of the most common methods in the world for restoring a pipeline is based on the insertion of a flexible sleeve saturated with various resins. The sleeve is inserted by using water pressure, Golan said. First, however, the pipe is cleaned, video films are made and bypasses are created for the flow of sewage. The bypasses are constructed by laying an alternate sewage pipe on the ground beside the road, thereby allowing the sewage to flow freely.
Golan claims that the final product is a new, continuous pipe, just inside the walls of the existing pipe, that is completely sealed along its entire length. He says that the new pipe is of the same quality as a regular pipe from the point of view of its strength. The length of time required to complete the work is much shorter than the time required when the surface of a road is opened. Some jobs that could take up to two weeks to complete using any other method can be completed in a single day using the sleeve method.
This method was used to repair the sewage pipe under King David Street in Tel Aviv, at Hof Shemen in Haifa and near the diamond exchange in Ramat Gan. The method is also good for localized problems. A leaky pipe can be repaired by inserting a resin-saturated felt sleeve into the existing pipe and sticking it to the inside wall of the pipe by inflating a balloon inside the sleeve at the point of the problem. The whole process is supervised by video camera, which is used to pinpoint the exact location of the problem and oversee the repair.
Golan notes that the method is more expensive than opening up a road, but much cheaper if one takes into account the cost of safety and security measures and the closure of the road during the repairs.
During the first two years in which this method was used, it was quite costly, because of the initial expenses for equipment, materials and the training of personnel. In recent years, however, the raw materials have come down in price and personnel in Israel are better trained, so the cost of a job has also gone down.
Even so, local authorities are in no hurry to use this method, and more often choose the old familiar one. A survey by Golan among engineers, consultants and other workers in the water and sewage industry revealed several reasons for the reluctance to use the new method. Among the main reasons cited were the conservativeness of the local authorities, a lack of awareness of the new method due to inadequate marketing and the misconception that it is more expensive.