Rockfall and even landslides may occur as a result of quarrying activities in Thane district as no “benches” are maintained while cutting the hills, which are being cut indiscriminately without any scientific mining method, according to the primary observation of an expert committee set up following recommendations of the State Environment Impact Assessment Authority (SEIAA) in September this year.
The committee recently submitted a report on the “environmental impact of hill cutting for quarrying in Thane district” to SEIAA.
“Thane district presents a picture of indiscriminate and relentless hill-cutting for quarrying for more than three decades,” says the report.
The team found that the quarries did not follow the rule to cut the hill in steps to prevent landslide or rockfalls from above or below the quarry. A vertical cut of the height more than 80 metre was observed by the committee at some quarries.
“The habitat above the quarry, if degraded further, can lead to both sheet erosion and unstable soil conditions, making parts of the hill slope above to become landslide-prone during the monsoon. Settlements below such quarries could be at great risk and a Malin-like episode could well take place,” said the report.
The expert committee comprised T C Benjamin, D A Hiremath, Balbir Singh from the State Level Expert Appraisal Committee (SEAC), experts like Dr Ramesh Dod, Dr Erach Bharucha, Dr D M Dewaikar, besides the Thane district mining officer and Joy Thakur from the state environment department.
“Because of indiscriminate cutting of hills, the aquifers or water pools in between the basaltic hill structure are exposed and the water evaporates. These perched aquifers and confined aquifers should not be disturbed and hills that hold water should be preserved, especially given that our state is facing water scarcity and the ground water is depleting,” said an expert committee member.
To limit damage to hills and surrounding ecology, the committee has recommended that quarrying should only be allowed in the recharge zone of hills at their base or flat areas, not in the run-off or storage zones of the hill. It has recommended that in the upper reaches of the hill, a retaining wall may be built and tree cover may be maintained at the upper end of the quarry to prevent soil from eroding into the mine below and causing landslides.
Further, the committee has proposed that no quarry should be allowed within 300 metres of any habitation or human activity, and blasting with electronic detonations should be done to avoid excessive rock breakages and line drilling and free splitting should be done to minimise distribution of the present rock mass.
The Maharashtra Minor Mineral Extraction (Development & Regulation) Rules 2013 stipulates mandatory environmental clearance and mining plan. Records until September 1, however, show that out of 142 quarries in Thane district, 29 do not have permission from the environment department and 45 quarries do not have a mining plan. “The lease period of most of the quarries in
Thane district will expire in 2016. I hope the state accepts our recommendations while approving quarrying activities,” said an expert member.
Additional Chief Secretary (Environment) Medha Gadgil said that SEIAA, of which she is a member secretary, was going through the report and would take necessary action.