CHENNAI: Recognising that several stormwater drain (SWD) projects were implemented in Chennai over the years in an unscientific manner leading to water stagnation during monsoons, the Chennai Corporation has initiated steps to rectify them.
As a first step, the civic body has identified 568 places across the city prone to water stagnation during rain. Of these, it was found that stagnant water took five or more days to drain in at least 100 places. As a temporary solution, the civic body has been resorting to relay pumping where several pumps were used to drain water. But the method was only 30% effective compared to water getting drained naturally.
“Earlier, corporation engineers would take a call on the length and capacity of drains to be installed at a particular spot purely based on their experience and float tenders for the project. This unscientific method has failed. Now, for the first time, we have asked contractors to come up with drain designs,” said a senior corporation official.
Contractors who have bagged the contracts for projects will now come up with hydrological modelling with the help of specialists and their designs will be vetted by IIT-M experts. “In the hydrological model, micro and macro watersheds are mapped in each location. Rainfall simulation is used to estimate the quantum of rain it takes for the drains to run full in each street at its present capacity, and designs are finalised accordingly,” said the official.
Apart from designing and construction/reconstruction of drains, the corporation has identified around 350 locations with defunct drains where water does not flow due to reasons such as cracks in the line or accumulation of silt.
In order to resolve the issues associated with SWDs before monsoon, the city corporation floated tenders for critical areas including Alwarpet, Rajamannar Salai, Postal Colony, and Sydenhams Road before the model code of conduct for local body elections came into force.
Additionally, the corporation has now set deadlines for contractors. “Earlier, if you take up a `20-crore project, it will take a year to be completed. Now whatever be the project, it has to be completed within four months,” R Rama Rao, president, Greater Chennai Corporation Contractors’ Association, said. To stick to the deadlines, contractors are now deploying multiple teams to work simultaneously across the entire stretch of the drain instead of just working at one point at a time.
“Though work pressure is high considering the fact that we have to navigate through several illegal sewage connections and face labour shortage our payments are better streamlined now. Earlier, payments were sometimes pending even for up to six months but now we get paid every week promptly,” Rao said.