Work on constructing a third desalination plant at Nemmeli, along East Coast Road, is set to begin by the month-end.
The new plant, with a capacity to treat 150 million litres of sea water a day (mld), will come up on a 10.5-acre space on the same premises as the earlier 100-mld plant.
Metrowater officials said materials had been sought for the work to commence. The new plant too will employ the reverse osmosis process. But it will have additional components in the pre-treatment process such as dissolved air flotation and ultra filtration, to keep out sea algae and other particles in seawater from hindering the production process.
A 49-km-long pipeline will be laid to distribute the treated water. This plant will serve nearly 9 lakh people in south Chennai areas, including Alandur, Sholinganallur, Medavakkam, Nanmangalam, Kovilambakkam and St.Thomas Mount. The ₹1,259.38-crore project, partly funded by KfW, the German Development Bank, will be completed by December 2021.
While the production cost for treated water at the 100-mld Nemmeli plant is ₹36 per kl, it will work out to ₹42 per kl in the new plant. Metrowater is purchasing water at a rate of ₹55 per kl from the Minjur desalination plant as per an agreement.
The existing Nemmeli plant produces 93 mld on an average now and the issues related to white fibrous particles choking the filtration process have been sorted out.
Design in a few weeks
Tamil Nadu Water Investment Company Limited, which is the project management consultant, is preparing the structural and process designs for the facility.
The consultant has to monitor and manage the entire project, including finalising the design of the plant and technology, ensure quality materials are procured and supervise the construction. The number of treatment units would be known in a couple of weeks after the company finalises the design.
It took nearly six years for the construction of the plant to begin since the announcement was made in April 2013. Officials noted that the process to obtain environmental clearance for the site, prepare a detailed report, and rope in a funding agency had taken up a lot of time.
Cobra Spain-Techton Engineering would have to build and also operate and maintain the plant for two decades. Pipeline for a distance of nearly 1 km would be laid in the sea and at a depth of 10 metres to draw seawater and for a length of 750 metres to discharge the waste water, officials said.
Fourth plant in works
The water agency has also obtained administrative sanction for building another desalination plant within a distance of one km in Perur on ECR to treat 400 mld of seawater. The ₹6,078 project would serve nearly 23 lakh people in the southern suburbs and areas such as Virugambakkam and Porur.
Officials said the tender is under evaluation for choosing a project management consultant. “We will finalise the consultant after the concurrence of Japan International Cooperation Agency, the project’s funding agency, by this month-end,” one of them said. The chosen consultant would supervise design and operations till the treated water is linked to the distribution network, including a metering system.
On the conditions laid by Union Ministry of Environment and Forests related to environmental impact, officials said the consultant would have to suggest solutions to mitigate ecological issues.
Metrowater is also exploring new technologies such as containerised desalination plants. These would be of small capacity and could be used as buffer sources during drought.
