Jaipur: The Rajasthan State Pollution Control Board (RSPCB) is now tightening the reins on mine owners to safeguard the environment and promote scientific disposal of mining waste. The board will now allow the establishment of marble sawing units only on the precondition that mine owners will effectively reuse marble slurry within a year of getting licence. This step has been taken as marble dust and slurry are hazardous for the environment. “The excessive use of natural resources and the associated impact on the environment can be lessened by recycling them and designing them in an eco-friendly manner. RSPCB has put together global research database on the use of marble waste for productive purposes. Research substantiates that marble is a rich source of calcium carbonate and can be reused in various ways. They are construction of road pavements, embankments, back fill material for retaining walls, roofing tiles, wall panels, pavement tiles, etc. A report of the Central Building Research Institute (CBRI), on the use of marble dust in brick-making, says that bricks made from marble slurry are stronger and more durable than clay bricks. RSPCB showed PWD the research papers on reuse of marble slurry in road-making, said a source. The state has around 4,000 marble mines and 1,100 marble processing units spread over 16 districts that generate five to six million tons of marble dust in the form of marble slurry during processing and slabing of marble stones. A study indicates that indiscriminate disposal of marble dust on road sides is causing problems of drainage, flow regime, air pollution and damage to agricultural land. The porosity and permeability of the topsoil is reduced and it causes water logging, not allowing the water to percolate down. Central Road Research Institute (CRRI), New Delhi, is carrying out extensive research to utilise it. In Rajasthan, Ajmer (Makrana), Rajsamand, Udaipur, Chittorgarh, Banswara, Alwar, Sirohi and Jaipur are known for marble mining. As a spin off marble mines have at the same time led to growth of many processing units engaged in cutting of marble in the form of gang saw and cutters. The new regulation is likely to see a more scientific and environment friendly approach to mining, he said. Highest marble reserves in state Marble reserves in India are estimated at 1,200 million tons, with Rajasthan accounting for 91% of the reserves, i.e., 1,100 million tons. Nearly 70% of it is wasted for want of superior technology of mining, processing and polishing marble. The processing waste dumped on the river beds is threatening the porosity of aquifer zones. There are 1,100 gang saws operating in Rajasthan, estimate suggests. Around 30% of the marble blocks are converted into powder, which amounts to 1.5 million tons per annum. About 2,750,000 litres of water is required per hour by the plants. “Filter Press” is key to making marble processing ecofriendly as it will help water to be reused for further processing.