Chennai Metrowater prepares to tap new quarries to augment supply

Surplus water from rivers may also be diverted to quarries for future use

Updated - August 06, 2019 08:56 am IST

Published - August 06, 2019 01:28 am IST - CHENNAI

CHENNAI,TAMIL NADU, 04/08/2019 : FOR STAND ALONE : Another source of water for chennai city under depletion at Sikkarayapuram quarry near Mangadu on Sunday.Photo : B. Velankanni Raj

CHENNAI,TAMIL NADU, 04/08/2019 : FOR STAND ALONE : Another source of water for chennai city under depletion at Sikkarayapuram quarry near Mangadu on Sunday.Photo : B. Velankanni Raj

Chennai Metrowater is preparing estimates to tap water from newly identified abandoned quarries in a neighbouring district. The agency is also mulling tapping surplus water from rivers and diverting them to quarries to augment the city’s water supply.

At present, about 10 million litres a day (mld) is being drawn from quarries in Erumaiyur and sent to the facility in Chembarambakkam for treatment. This is one of the sources that contributes to the city’s supply of 525 mld.

Sources in Metrowater said that though the water in the quarries identified may not be tapped immediately, estimates are being prepared and permission has been sought from government agencies, including Tamil Nadu State Disaster Management Authority. Nearly 70 mld of water could be tapped from quarries in Pulipakkam near Chengalpattu region and Keerapakkkam near Vandalur. Similarly, quarries have been identified near Thalakananchery and Nallambakkam.

The water agency is considering diverting a portion of surplus water from Palar river to the quarries in Pulipakkam. Water could be pumped from a check dam at Neenjal Maduvu near Chengalpattu, which is three km from Pulipakkam. Such arrangements would help strengthen water source infrastructure.

Similarly, the possibility of diverting a portion of water stored in proposed check dams across the Palar river to quarries would also be explored. These measures would help turn the quarries into storage structures and function as permanent infrastructure to tackle the water needs of the city. The Department of Geology, Anna University, has teamed with IIT Madras to look into ways to augment water sources, including diverting floodwater from rivers to quarries, and mitigate floods in the Chennai river basin.

Describing it as a welcome move, L. Elango, Professor, Department of Geology, said the raw water collected in most quarries was found to be of good quality. The total dissolved solids level was about 400 mg/litre, which is actually less than the limit of 500 mg/l for drinking purposes. The proposal to divert surplus water from rivers would help store water in quarries. However, only 20% of the surplus water may be used for conservation. In the backdrop of climate change and ocean acidification, the sea would also need fresh water flow and sediments. “We cannot completely deprive fresh water flow into the sea. It is not right to say all water draining into the sea is wasted,” he added.

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