Chandigarh’s aging sewerage and stormwater drainage system set for an upgrade

The Chandigarh municipal corporation (MC) has started the process to upgrade and replace the city’s 50-year-old sewerage system for the first time since the UT came into being.

As a first step, the civic body will appoint a consultant to analyse the existing structure, including the sewage treatment plant capacities, and suggest options to improve it. The report will be completed in eight months. MC has already invited firms to provide consultancy services for the project.

“Improving the system will either require total replacement of the sewers or modifications. Technologies are now available that can improve the existing sewer channels. The consultant’s report will indicate what options can be employed at which places in the city,” said a senior MC official. The consultant will assess how the entire underground sewerage system can be upgraded by adopting latest technology, without hindering the existing functional system.

“A detailed project report (DPR) will be prepared by the consultant, which will have parameters like procurement plan, costs estimates and time-frames for the entire work,” said the official.

Before a plan is finalised, a survey of the entire system will be undertaken, including topo-survey for necessary condition assessment of the existing sewerage infrastructure, sewerage networks, pumping stations and other associated work.

The upgrade will be done keeping in mind the future needs of the city. “To meet the needs of future, the entire city’s sewerage network including pipes and manholes will be mapped. Areas which are still to have sewers will also be mapped. A key part of the consultative process will be prioritisation of the sewers in terms of their existing condition and necessity for rehabilitation or replacement,” said the official.

Why an upgrade?

The official, said “The city’s sewerage system is quite old and requires a major overhaul. At several places, relaying of new sewer lines is much needed.”

Frequent breakdowns of the sewer lines are often reported across the city as it struggles to handle flow much higher than its design capacity. Similarly, the old stormwater drainage system gets flooded every monsoon because of its low capacity.

Chandigarh has both brick and pipe sewers laid in four phases as the city expanded. One of the particular concerns is the brick-and-mortar sewer which became operational shortly after the foundation of the city.

“There are several places where these have majorly thinned out due to continuous erosion. Chemical reactions because of toxic gases in the sewers have caused the damage. There are fears they might even collapse,” said the official. Even the carrying capacity of the sewers is low as the population increases in the city.

“The existing stormwater drainage system is inadequate to manage the discharge during heavy rainfall. The system was designed in phases, for 15mm rainfall per hour in Phase 1 (northern sectors), 20mm in Phase 2 (central sectors), and 25mm in Phase 3 (southern sectors),” said another MC official.

Significantly, the civic body has already initiated the process to upgrade the five sewage treatment plants (STPs) in the city. However, low and poor capacity of the main trunk sewers will handicap any improvement in the STP.