Illegal quarrying takes root as demand for gravel rises

Nellore: Normally people think that gravel is an undervalued mineral, but its increasing use in aqua industry has shot up the demand while giving rise to illegal quarrying in the district. It is used as bio-filters for culture microorganisms in aquaculture. Nellore has huge resource of rocky areas in many upland mandals that exist in western parts of the district. This is almost untapped resource since majority of entrepreneurs focus on mica and other minerals, and the gravel is being illegally explored by traders who supply for aqua farmers.

Kodavalur, Buchireddipalem, Chillakur, Gudur, Kavali, and others mandals are famous for this gravel. Untapped resource is available in many upland mandals like Udayagiri, Sitaramapuram and Duttalur. Submerged Bed Filters are familiar to anyone who owns an aquarium. An under gravel filter is a classic down flow submerged bed filter. These bed filters have been used extensively for small-scale aquaculture and backyard water feature systems. They filters can be operated in up flow, down flow or horizontal flow.

Though these old gravel based systems are not suitable for modern aquaculture still they were adopting in many areas in the district. But, aquaculture requires fine gravel with equal shape or round surface for arranging the filter beds. Modern submerged bed filters are very efficient to be used as natural bio-filters that are easy to build and maintain. A modern submerged filter uses structured media in a horizontal flow mode which is found to be the ideal bio-filter than any other type and the key difference is the type of media and the water flow path, according to experts.

Considering minimal expenditure and accessibility, aqua farmers prefer the material for filtering process in the hatcheries and aquariums along with fluidized bed sand filters that have several advantages. These bio-filters pack more biologically active surface area into a given volume than any other type. Basically, people search for D-Form lands where they are not being used for any agriculture activity on lease basis and start exploring the gravel for making huge bucks.

They are spending very minute amount like Rs. 1,000 for a ton of gravel and were getting Rs. 12,000-16,000. They pay only Rs. 10-15 for every 10 kilograms of small and fine stones to people who are engaged in collection in the fields. This is being continued for many years and the officials have also not realised the significance. They grade the collected material into three to four varieties and sell in cities like Vijayawada, Chennai, and other places.

“The activity is prevalent in many areas and people should not resort to illegal exploration. They are continuing as there are no restrictions on them. Interestingly, gravel is being exploited in many government lands. This has to be focused,” said an official from the Industries department. The problem would be disastrous when these pits filled with rainwater that pose threat for lives of children who play in these temporary water ponds during vacation, he added.