Chemicals used freely in the quarrying activity around the City, are capable getting absorbed and moving through the soil and eating up concrete pipe lines and corroding the metal pipes. This is bound to affect both the services in the long run.

A study in this regard was conducted by the Department of Environment Science, Bangalore University. It revealed that micro organisms like Sulphur Reducing Bacteria (SRB), Nitrifying Bacteria can produce Sulphuric Acid and Hydro-Nitrous Acid, which can potentially eat up concrete pipes and corrode thousands of miles of sewage pipes in cities like Bangalore.

Dr N Nandini of Environment Science Department, citing the study on `A review on impact assessment of natural stone quarrying and mining in Karnataka,’ said the damage was already being seen in some places. ``We are now looking into the places, where the pipelines are affected and shortly, we will come out with a report,’’ she added.

Organisms like Thiobacillus thioxidans reaches almost 100,000 cells per gram of concrete, creating an acidic environment. In a period of about 12 years, the pipe thickness could get corroded from 80 mm to 32-36 mm.

The life expectation of the pipe would thus be only 20 years, she added. The problem is not just confined to Bangalore alone. The study revealed that places like Tumkur, Gulbarga and Bellary districts also face similar problems, where mining has to be subjected to strict monitoring as per the action plan for proper management of mining and quarrying, prepared by Karnataka State in 2003.

Other hazards
Besides Biogenic acids, quarrying is also causing Acid Mine Drainage (AMD), the report noted. When it rains on overexposed surface mines, it produces highly mineralised run-offs referred as AMD, which percolates and degrades the ground water. When acid water travels through it fractures and fissures of carbonate rocks, calcium carbonate dissolves to form calcium bicarbonate, which is soluble in water, resulting in hard water, the report pointed out.

Ecology affected
The biggest problem of quarrying is solid waste disposal. While 60 per cent of quarried materials is commercial product, rest is rendered as waste which contains hazardous chemicals like heavy metals, which when dumped on the land percolates into ground water.

This quarry waste is dumped in forest areas, destroying the natural vegetation and ecology of the area and adversely affecting the fertility of the soil, contaminating water sources and contributing to drainage problems, the study revealed.