Pothole on Sriramapuram Second Street junction

According to Corporation chief engineer (stormwater drains) L Nandakumar, the civic body recently completed creating sunken wells (recharge wells) at 208 locations, including civic body offices. “We started the drive a year ago and the 10-feet-deep wells help recharge the groundwater,” he said.

When asked whether the civic body has taken any steps to create rainwater harvesting structures on stormwater drains, Nandakumar explained that such structures are being created in several parts of the city. 

The civic body is creating rainwater harvesting structures by inserting 10-feet pipes into the ground, either inside the stormwater drain or near the inlet.

As per Corporation data, there are 8,319 rainwater harvesting structures (10-feet pipe structures) on stormwater drains across the city. Of the total structures, 6,882 are on integrated stormwater drain network in Adyar and Cooum basin.

It is learnt that the civic body had built brick stormwater drains with rainwater harvesting pits in certain intervals more than a decade ago. “However, many residents let sewage water into the drains, resulting in groundwater contamination. 

Several residents complained about this and we started to build concrete structures. Again, we are providing rainwater harvesting in stormwater drains in areas where sewage entry is arrested,” Nandakumar added.

Meanwhile, the civic body has proposed to build stormwater drains in Kovalam basin with rainwater harvesting pits every 10 meters.

Explaining the flooding and letting huge quantity of rainwater into the sea, the official said that the soil condition of Chennai only allows 20 per cent of rainwater to percolate into the ground. 

If 1 sqft of clayey surface receives 100 litres of rainwater, only 20 litres would go into the ground. In the case of sandy surface, 30 litres would percolate.

Based on an announcement made in the State Assembly, the Chennai Corporation has decided to create 10 new recharge wells in each of the 200 wards.

“The recharge wells will be created at government offices, playgrounds and other places. We have started a trial in Besant Nagar,” a civic body engineer said.

Apart from this, the civic body has already started inspecting buildings in the city and creating awareness among residents.

“We have constituted ward-level teams, who will identify 1,000 buildings without rainwater harvesting in each ward and implore owners to construct them. The move will create 2 lakh new rainwater harvesting structures in Chennai,” G Prakash, Corporation Commissioner, said.

On the other hand, water expert and director of Rain Centre Sekhar Raghavan pointed out that creating rainwater harvesting structures with 10-feet pipe in stormwater drains would need periodic maintenance and the civic officials tend to overlook their maintenance once the harvesting pits are ready.

“If the civic body builds recharge wells, it can be cleaned and desilted periodically. But, the pipes cannot be cleaned,” he said.

Sekhar added that his organisation receives at least 20 calls from building owners seeking assistance in creating recharge wells every day. 

Depending on the roof area of the building, plot area and other aspects, cost of constructing rainwater harvesting structures may vary. However, to build an effective structure, a minimum of Rs 20,000 is required, he explained.

Meanwhile, following the rains in Chennai, city residents have been creating rainwater harvesting structures in their houses and posting photographs and video clips on Twitter under hashtags #MyHomeMyRWH and #MyHouseMyRWH.

While the residents of the city are realising the need for rainwater harvesting structures and creating such structures at their houses, residents of Chitlapakkam have gone one step ahead and started to create recharge wells in public parks.

“We requested the Chitlapakkam panchayat officials to allow us to create recharge wells in public places. Initially, we received permission to create wells at eight parks and a pond,” R Balachandar, a volunteer of Chitlapakkam Rising Team, said.

Balachandar added that groundwater levels in the locality depleted as early as February and residents are travelling to the other parts of the city to fetch water.

“Our aim is to avoid water shortage next year. Expenses of recharge wells are being met by the money collected from volunteers. The number of new wells will depend on the money we would manage to collect,” he added.

Meanwhile, Sunil Jayaraman, another volunteer of the team has constructed a rainwater harvesting structure on a street of State Bank Colony.