HYDERABAD: Work on rehabilitating the main trunk sewerline on NTR Marg with ‘cured in place pipe’ (CIPP) structural lining by employing trenchless technology will begin in the last week of this month. A portion of the 1600/1800 dia sewerline, that runs between the sewerage treatment plant at Necklace Road and the GHMC’s head office, a distance of around 1.50 km, collapsed in front of NTR Gardens on September 24 last year. It resulted in closure of the road and diversion of traffic for a few days. Traffic was restored after the pipes were replaced in a temporary measure by the Hyderabad Metropolitan Water Supply and Sewerage Board (HMWS&SB).
For the present rehabiliation work, which will cost `18 crore, the required materials such as styrene, perkodox and inhibitor have been imported from the USA and UK. The 1800 mm dia trunk sewer was laid during 1995-96 for a length of 5.5 km from Divya Shakti Apartments to the surplus nala near GHMC head office. It was designed for diversion of sewage (dry weather flow) from Yousufuguda nala, Banjara Nala, Bulkapurnala. The sewage from Rahmathnagar, Madhuranagar, Yousufguda, SR Nagar, Yellareddyguda and Vengalrao Nagar flows through a sewer network that is connected by a 1200 mm dia sewer main at Divya Shakti Apartments. The sewage coming from BJR Nagar, Maha Bharat Nagar, Raj Nagar and Maruthi Nagar areas is also connected to it by a 600 mm dia main near Imax Theatre. At present, an 1800 mm dia main sewer trunk has been receiving sewage flows form five locations. Further, the dry weather flow is diverted from three nalas. The sewer pipes, laid more than 20 years ago, corroded due to hydrogen sulphide and need immediate rehabilitation.
What is CIPP?
In this method, a resin-saturated lining tube is installed in a pipeline by winching or inversion. Once it is in place, the resin is heated to induce a chemical catalyst or hardener that sets off curing process. CIPP is jointless and seamless and it can replace pipelines between manholes. It involves inserting a resin-impregnated fabric liner tube into the section selected for structural strengthening. The water-filled liner is cured so that it becomes a self-supporting pipe within the host pipe. The method needs no digging or excavation, and the work can be completed in shorter time. Moreover, it is cost- effective and less disruptive than the traditional dig-and-replace pipe-repairing method.