Tamil Nadu government is planning to have underground sewage network in all the 126 municipalities, nine corporations and 529 town panchayats in the next five years, according to a senior engineer with corporation.

A Vaitheesswaran, CADD engineer and a research scholar with Madras University, presenting his finding during a brain storming session on recent challenges and innovations in environmental management organised by department of geology, said that currently only 20 municipalities have underground sewage network and the state government plans to have a sewage network in all the municipalities and town panchayats in a phased manner in next five years.

The study, which was a result from findings from six municipalities including Valasaravakkam and Alandur (now under Chennai Corporation) besides Kancheepuram, Sathur, Periyakulum and Madurai, stated that the planning of sewerage network was done with unrealistic population projection and it does not match local condition of population growth.

The study stated that currently each house is provided with independent water storage tank by keeping one sump and one overhead tank. Hence minimum two days demand of water is stored in each house.

As a result the concept of hourly water utilisation differs from the hourly water utilisation prescribed by the municipality.

As a result this puts huge pressure on the sewerage network in the municipalities, he added. To handle such a huge flow, the pipe needs to be designed with proper peaking factor.

Dr Karthikeyan, joint chief environmental engineer of Tamil Nadu Pollution Control Board, also spoke on the occasion.