A section of scientists has expressed concern about the Department of Mining and Geology's proposal to use abandoned quarries in the district as landfill for solid waste disposal. The scientists feel that it would contaminate groundwater sources and create an environmental nightmare.
The concerns largely centre around the engineering skills needed to establish a sanitary landfill and the investment to create and maintain the necessary environmental safeguards.
K.P. Thrivikramji, UGC Emeritus Fellow, Department of Geology, University of Kerala, says only dry quarries with proper drainage channels, like those situated in sloping terrains, can be used as landfill.
“It is important to ensure that the leachate does not contaminate groundwater,” said Prof. Thrivikramji who chaired the expert committee set up by the government for rehabilitation of abandoned quarries.
According to E. Shaji, Assistant Professor in the department, the proposal is unsuitable for Kerala, though it is widely practised in many countries.
He explains that engineering the sites for controlled sanitary landfill is difficult. “It is important to insulate the bottom and sidewalls of the quarry to contain leachate, rainwater, groundwater pressure and landfill gas pressure. Once the groundwater sources are polluted, it will be difficult to restore the quality.”
Mr. Shaji points out that the infiltration of rainwater through the waste could transfer the pollutants to rivers and wells through groundwater flow. “The site will have to be provided a good roofing to prevent rainwater entry. Also, the water stored in abandoned quarries is mostly groundwater. Pumping out the water could lead to de-saturation in the aquifer, depleting the water table in the surrounding area.”
Sealing the deep-seated cracks and joints on the rocky bed that help recharge the aquifers is another challenge. “Sealing these cracks is not easy, and not advisable in a hydrologic system. Many open wells that are used by local people for drinking water needs are located very close to the quarries. There is a high chance of pollution of these wells if the quarries are used for waste disposal.”
Engineered sanitary landfills are required to have a High Density Polyethylene (HDPE) bottom liner, mechanisms for leachate collection, storm water drainage and methane gas collection and groundwater monitoring. The waste is compacted and shredded before being deposited in layers, and covered daily with compacted soil to prevent odour and keep scavenging birds and rodents away.
A temporary solution
George Chackachery, executive director, Suchitwa Mission, said the proposal to use quarries as landfill was only a temporary solution, aimed at preventing further accumulation of garbage in the city. “We decided to explore the option after the Health Department issued a warning about the possibility of an epidemic outbreak.”
Mr. Chackachery, a scientist, formerly with the Centre for Water Resources Development and Management (CWRDM), said all possible safeguards would be adopted to ensure that the landfill site did not pollute the environment. “We are zeroing in on a site with minimum inhabitation in the neighbourhood. The landfill will be provided with enough insulation to prevent contamination of groundwater. It will have a roof to keep rainwater out, and facilities to pump out the leachate. We will leave nothing to chance.”
Citizens and elected representatives have already come out against the proposal, voicing fears over its impact on the environment and public health.
