Metro authorities to have a relook at groundwater system

Metro authorities to have a relook at groundwater system

Swathi Shivanand

Some experts have voiced concern about aquifers being affected

# City's fractured aquifers go down to 40 ft. at some places
# Groundwater level will be affected if `water veins' are disturbed



EYE-CATCHING: An artist's impression of the elevated stretch of the Metro Rail on M.G. Road.

BANGALORE: The Bangalore Metro Rail Corporation Limited (BMRCL) will soon decide if the underground water system in the city needs to be studied to ensure that in the eagerness to provide rapid transport to the city water sources are not affected.

When work for Metro gets under way on a larger scale, the ground will be dug up to 40 or 50 feet for construction of tunnels and installing wire decks.

While some experts say that at this level it is unlikely that underground water system will be affected, there are others who have raised concerns about aquifers being affected because of the drilling and laying of pipes.

The sources in BMRCL told The Hindu that "The Environment Impact Assessment Report submitted by the Bangalore University had cleared these doubts earlier. But we have decided to have a relook to be on the safe side."

Bangalore's fractured aquifers, made of highly weathered rock, go down up to 40 feet at some places, according to officials at the Mines and Geology Department.

Aquifers are where rainwater gets stored and collected for years.

Water percolates down to the aquifers through "water veins" — fractures and faults in the rock formation.

If the aquifers are damaged at some points or the water veins are disturbed it could affect the groundwater level in those areas, say experts. A.N. Yellappa Reddy, who heads the Environment Committee, said that if the concerns were found valid, designing the procedure of work for Metro would become specific to the site where the work is taking place.

"They will have to ensure that they do not hurt the faults and fractures underneath. If they do that, it will affect the infiltration of rainwater into the ground," he said.

To address these concerns, the BMRCL will soon decide if it needs to collect fresh data about the groundwater system or re-analyse the data available with groundwater authorities.

It will also soon take a decision on what precautionary measures need to be taken in terms of underground protective walls.