Need for Storm Water Drainage System
The flat terrain of Chennai City needs effective Storm Water Drainage System to prevent water stagnation in roads. The terrain of Chennai city is flat and average level of the land in the city is only 2.5m above the Mean Sea Level (MSL). Because of this flat terrain and partial coverage of roads with storm water drains, flooding and water stagnation happens in the city during the monsoons.
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.
Storm Water Drain Department
In accordance with the Statutory rule, the Storm Water Drain Department of Greater Chennai Corporation Constructs and maintains a network of Storm Water Drains and Canals.
Greater Chennai Corporation developed and maintains a Storm Water Drain network of 1660.31 km in the city.
Greater Chennai Corporation also maintains 31 canals criss crossing across the Chennai City. Rain Water runoff gets drained through Storm Water Drain network & canals and reaches the Sea Via five Waterways-Otteri Nullah, Buckingham Canal, Adyar River, Cooum River a and XXand Kosathalaiyar River -running across the city
Construction of Storm Water Drain and Canals
Usually Storm Water Drain will be Provided in 12 m road 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. Under JnNURM Scheme, Storm Water drains are designed to relieve Water Stagnation in the Water logging areas irrespective of the width of the road. In Bus Route Roads Storm Water drains are provided usually in the footpath. The height of the drain top will be 6 inch above the road level. The Slab level should be lowered at all the entrance gates. The top Level of the Slab and man hole doors should be flush with the footpath Slab level. In all roads crossing the Slab Should be flush with road level. The drain should be in straight alignment. SFRC (Steel Fibre Reinforced Concrete) / FRP (Fibre Reinforcement Polymer) Man hole door with chute pipes to be provided at every 5 m interval with chute pipe. In addition to that Inlet Chambers with Rain Water Harvesting 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 should be provided to accommodate the electrical and other utilities in Storm Water Drain crossings. The Canals are constructed with retaining wall which retains the earthen banks and gives an aesthetic appearance to the canal. The flooring facilities is such that men and machineries to carry out desilting works easily. In addition to that Inlet Chambers with Rain Water Harvesting is also provided to collect the rain water and to increase the ground water level.
Improvement of Micro and Macro Storm Water Drainage network in Chennai under JnNURM
In order to alleviate a flooding 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 Urban Development, Government of India if four packages.
The details the four basins are tabulated below:
||Name of Basin
||Greater Chennai Corporation Component
- On the basis of a topographical survey and its detailed analysis, the city was divided into 4 drainage basins and these basins further sub divided into 12 watersheds.
- North Basin
- Kolathur Water Shed
- Captain Cotton Canal Water Shed
- Otteri Nullah Water Shed
- Central Basin
- Mambalam & Nandanam Water Shed
- Cooum Water Shed
- Virugambakkam & Arumbakkam Water Shed
- East Basin
- Royapuram Water Shed
- North B Canal Water Shed
- Central B Canal Water Shed
- South Canal Water Shed
- South Basin
- Adyar Water Shed
- Velachery Water Shed
The Government of India grant component under the JNNURM scheme is Rs.285.25 crores being 35% share, Government of Tamil Nadu contribution is Rs.122.25 crores being 15% share of expenditure and the balance of Rs.407.44 crores being 50% share has to the borne by the local body i.e., Greater Chennai Corporation. The Administrative Sanction has been accorded for the project in G.O.(Ms).No.116, Municipal Administration and Water Supply Department dated 06.07.2009 by the Government. The Greater Chennai Corporation proposes to meet its share of Rs.407.44 crore by availing a loan of Rs.203.72 crores from Tamil Nadu Urban finance and Infrastructure Development Corporation Ltd. (TUFIDCO), Rs.150 crores from Tamilnadu Urban Infrastructure Financial Services Ltd., (TNUIFSL) and balance Rs.53.72 crores from Greater Chennai Corporation’s own funds.
- The Greater Chennai Corporation component of the project involves
Remodeling of 337 nos for a length of 182.95 kilometers of micro drains at a cost of Rs.277.24 crore. Presently 87 nos. of works are in progress.
Construction of new drains of 701 nos for a length of 320.90 kilometers
in un-served areas of the city at a cost of Rs.380.12 Crore
Improvements of 16 Canals to a length of 28.64 kilometers at a cost of Rs.159.57 crore.