CHENNAI: In a contentious decision that would prove detrimental to the fragile Ennore ecosystem, the Chennai Metropolitan Water Supply and Sewerage Board (CWSSB) is proposing to build a giant pipeline having an 800-mm diameter underneath the Ennore creek that would potentially affect the hydraulic flow of critical waterbody which drains flood waters of Kosasthalaiyar and Araniyar rivers.
The pipeline is being planned to convey treated water from the 45-MLD tertiary treatment and reverse osmosis (TTRO) plant at Kodungaiyur to the industries on the Manali-Ennore corridor.
Senior Chennai Metro Water officials confirmed to Express that such a proposal was mooted and an application for Coastal Regulation Zone (CRZ) amendment has been filed before the Union Environment Ministry and the proposal is coming up for deliberation at the next Expert Appraisal Committee (EAC) meeting scheduled in New Delhi for September 17.
As per the original plan, the pipeline was to be built across the Ennore creek with the help of stilts or pillars without affecting the hydraulic flow of water. But, the Public Works Department (PWD) has not granted permission following which Metro Water has decided to go underwater.
Interestingly, the project was appraised by the Tamil Nadu State Coastal Zone Management Authority and the Union Environment Ministry granted environment and CRZ clearance last year on the condition that project work will not affect marine/creek environment during construction and operational phases and there are no blockages and free flow of water is maintained in the canal/creek during the process of laying of pipelines.
When contacted, an assistant engineer of Metro Water associated with the Kodungaiyur TTRO plant said: “The pipeline will be laid four metres under the water. Dredging machines will be used to deepen the waterbody, which is currently filled with silt and fly ash deposits. To ensure safety and durability, an extra coat of pipeline will be provided. We will ensure the flow of water is not affected,” the official said.
Officials said the underconstruction 45-MLD TTRO plant was a crucial project as it would reduce fresh water consumption by industries considerably and recycle and reuse sewage water.
A total of 63 MLD of secondary treated sewage from STPs at Kodungaiyur will be taken to produce 45 MLD of treated water through the ultra filtration system which will be supplied to the industries, power plants and institutions on the Manali-Minjur corridor and the Manali-Ennore Corridor in North Chennai. The rejects and backwash effluents from the ultra filtration system will be blended and disposed of into the Buckingham canal.
- The Chennai city is covered with 98% sewer network. There are 12 sewage treatment plants at 4 locations covering 5 zones of sewerage system
- TTRO project area falls under Zone I & II, covering an area of 86.14 sq km with a population of 16.5 lakhs (As per 2011 census)
- There are three treatment plants of 80 MLD, 80 MLD and 110 MLD capacity totalling 270 MLD at Kodungaiyur for treating the sewage generated in the North Chennai & parts of Central Chennai City area and adjacent urbanised areas of Mahavaram and Kathivakkam
- The present generation of sewage from Zone I & II and adjacent urbanised areas is about 225 MLD