Chennai is one of the fast growing Metropolitan cities in our country. The area of the Corporation was expanded from 176 sq.km to 426 sq.km in the year 2011. The Population of the Chennai city is fast approaching 1 crore. The Greater Chennai Corporation has taken various steps to provide necessary infrastructure facilities in the newly added areas of the City.

Statutory Provision

Section 176 of the Chennai City Municipal Corporation Act, 1919 entails the Greater Chennai Corporation to provide and maintain a sufficient system of public drains throughout the city.

The flat terrain of Chennai City needs effective Storm Water Drainage System to prevent water stagnation in roads. The average level of the land in the city is only 2.0m above the Mean Sea Level (MSL). Because of this flat terrain and tidal effects, flooding and water stagnation happens in the city during the monsoons. In order to mitigate flooding in low lying areas and flood prone areas of Chennai city, it is necessary to provide Storm water drain net work.

Storm Water Drain is normally provided in roads of 7m width and above. The minimum size of the drain will be 600X750 mm. The size will be designed depending upon the catchments area, land pattern and discharge. Storm Water drains are designed to relieve water stagnation in the water logging areas irrespective of the width of the road. The height of the drain top will be 6 inches above the road level. The top level of the slab and man hole doors should be flush with the footpath level. In all roads crossing the slab should be flush with road level. The drain should be in straight alignment. FRC (Fibre Reinforced Concrete) / FRP (Fibre Reinforcement Polymer) Man hole door with chute pipes is provided at every 5 m intervals. In addition to that Inlet chambers, silt catch pit with Rain Water Harvesting structures is also provided at every 30m intervals to collect the rain water and to increase the ground water level. Pre-cast RCC drains are proposed according to the site condition with inlets at 10m interval. PVC pipes is provided to accommodate the electrical and other utilities in Storm Water Drain crossings.

The Canals are provided with flood protection retaining wall and canal lining with chain link fencing preventing caving of earth during flood and gives an aesthetic appearance to the canal. Due to lining of the canal men and machineries can move through the canal and desilting works can be carried out easily.

In order to alleviate flooding, a comprehensive proposal was prepared by the Greater Chennai Corporation in association with the Public Works Department (PWD). This proposal was approved by the State Level Sanctioning Committee, and subsequently appraised and sanctioned by the Central Sanctioning and Monitoring Committee, Ministry of Housing and Urban Affairs, Government of India.

To prepare the detailed project report for the construction of the stormwater drain in the core city M/s. Aarvee Associates was engaged by Greater Chennai Corporation on 19.06.2008. During 2009, detailed project report for the construction of storm water drain was prepared by the consultant M/s Aarvee Associates and was vetted by the Central Public Health and Environmental Engineering Organization (CPHEEO).

On the basis of topographical survey and detailed analysis the Chennai city was divided into 4 watershed basins, Viz., North Basin, Central Basin, South Basin and East Basin and comprises of 12 major watersheds and stormwater drain works proposed in the DPR has been taken up under JnNURM funding.

SWD to a length of 345 km has been completed under JnNURM funding at a cost of Rs. 640 crores in the core city

Construction of Storm Water Drain in extended areas

Chennai city is prone for floods and cyclones. Though, the core city has integrated storm water drain facilities the added areas of the Greater Chennai Corporation has to provided infrastructure facilities. Hence it was requested to TNUIFSL for preparation of Detailed Project Report for providing integrated storm water drains in the extended areas.

A hydrology consultant namely M/s Tetratech has been engaged on 2011 to prepare DPR for the construction of integrated storm water drain network in the extended areas and they have submitted the DPR  during 2012 for the extended areas and Integrated Stormwater drain has been designed dividing the extended areas in four basins.

Adyar and Coovum Basin

In first phase, detailed project report prepared for the construction of the integrated stormwater drian in Cooum and Adyar basins at an estimate amount of    Rs.1101.43 crore. have been have been taken up under World Bank funding under Tamil Nadu Sustainable Urban Development Project (TNSUDP). The work has been taken up in 35 packages for the construction of Integrated Stormwater drian and improvements to canals in 29 packages. The integrated stormwater drain has been completed for a length of 406 km at a cost of Rs.1387crore. The above works are carried out in zonal areas of Ambattur, Valasaravakkam and Alandur.

Kovalam Basin

Tamil Nadu has accorded Administrative sanction for the construction of Integrated Stormwater drain in Kovalam Basin for a length of 360 km at an estimate amount of Rs.1714 crore under funding from KfW, a German Development Bank. The construction of Integrated Stormwater drain are being carried out  in 12 packages for a length of 160.33km at an estimate of Rs.597.48 crore. CRZ clearance  has been obtained for the construction of Integrated Stormwater drain in M2 component  for a length of 139.84 km at an estimate amount of Rs.735 crore and tenders to be called after obtaining the NOC from KfW bank.

Kosasthalaiyar Basin

Tamil Nadu has accorded Administrative sanction for the construction of Integrated Stormwater drain in Kosasthalaiyar Basin for a length of 769 km at an estimate amount of Rs.3220 crore under funding from Asian Development Bank (ADB). The construction of Integrated Stormwater drain are being carried out  in 46 packages and works have been completed for 508km and balance work will be completed by March2024.

Stormwater drain works in Core City

Several areas in Chennai City has been severely affected due to the flooding during monsoon 2021. Tamil Nadu Government has appointed Advisory Committee headed by Th. Thirupugazh. I.A.S(Rtd.) and has accorded sanction of construction of Stormwater drain for an amount of Rs.1000 crore.

As per the recommendation of the Advisory Committee, the construction of Stormwater drain work has been completed for a length of 225km at an estimate of Rs.699crore under funding from Singara Chennai 2.0, Flood Relief fund, World Bank fund, I & A fund, CGF fund. Further the construction of Stormwater drain works are in progress for a length of 70.26 km at a cost of Rs.276.54 crore under funding from SDMF, Capital Fund and Singara Chennai 2.0.

Maintenance Work: Desilting of Storm Water Drains and Canals

De-silting of the Stormwater Drains are being carried out by the respective zones. Desilting of the Stormwater Drains is done in a cyclic manner and is carried out twice in a year. The desilting of the stormwater drain are being carried out in a weekly programmed manner throughout the year by using the super sucker machines and through contractors. The removed silt is cleared immediately and transported to the dumping yards. The in-let chambers and chute pipes are cleaned periodically.