Ranchi PSU brings sea to Chennai taps

Coastline metropolis Chennai suffering from chronic water shortage is like Coleridge's "�water, water everywhere, not any drop to drink'. But now, Ranchi-based PSU Mecon, which helped Chennai Metropolitan Water Supply and Sewage Board, better known as Metrowater, build the city's second desalination plant, has changed the name of the game.

The Rs 908-crore seawater reverse osmosis project at Nemmeli, 36km between the Tamil Nadu capital and Mahabalipuram, inaugurated recently by Tamil Nadu chief minister J. Jayalalithaa, treats 265 million litres of seawater to supply 100 million litres of drinking water to 15 lakh residents. Mecon was involved in planning, design and execution of the project.

Simply put, it means the Tamil Nadu capital won't have to rely wholly on its four rain-fed reservoirs during the long summer. "Seawater is drawn through a one-km-long, 16m-diameter pipeline from the sea a kilometre away and processed at the plant to make it fit for human consumption. Wastewater is sent back to the sea through a 740m-long, 1,200mm-diameter pipe 8m below sea level. Mecon is confident of setting up more such plants on coastline cities," said a Mecon official.

Production cost has also been watered down at Rs 35 per kilo litre, cheaper by Rs 13 compared to supply bought by Metrowater from the processing plant at Minjur. "It's a great idea that has been well-executed with public money. Processing cost has been reduced intelligently," said Manoj Kumar, Mecon senior manager and project coordinator. Accolades are coming in from the horse's mouth.

"The Nemmeli plant uses a compact and faster treatment process compared to the conventional filtration system in Minjur, north Chennai," Metrowater managing director B. Chandramohan said.

It's a proud moment for the Ranchi PSU involved in this big-ticket project. In January 2008, it had prepared the plant's detailed project report, basic design and detailed engineering and placed it before the government of Tamil Nadu. Subsequently, the Tamil Nadu government sought the Centre's nod to clear the project, paving the way for a central grant of Rs 871 crore in January 2009.

Mecon stepped in as Metrowater's project management consultant for plant construction that started in 2010. Other outsourced agencies implemented Mecon's pre-engineered design and detailed concepts. Larsen & Toubro (L&T) got the work to construct the 65km distribution pipeline and pumping station. The indigenously designed marine intake and pre-treatment systems use filters, followed by reverse osmosis membrane and post-treatment facilities to reintroduce carbons and minerals in the treated water.

Though this is for the first time sea water is treated for human consumption, in the Gulf countries this is the major source of drinking water.