Water pollution control measures
Any mining below the earth level disturbs the general water regime. NCL has not only provided water to project affected people but also adopted various Techniques for effective restoration of water regime. Soil conservation, dense afforestation in and around mining area and treating the effluents from Mines, CHPs, Workshops domestic sewage and reuse of treated water are some of the measures taken for water regime restoration. NCL mines are approaching for zero discharge.
Steps has been taken for rainwater harvesting at Nigahi, Bina, Jayant, Block B, Amlori and Khadia Projects, it is being extended to other Projects also. The water is being re-used in most of the mines of NCL and some of the mines like Nigahi, Amlori, Block B and Bina have already achieved zero discharge.Effluent Treatment Plant (ETP):
In NCL Integrated industrial effluent treatment plants (10 Nos.) are constructed for workshops, CHP effluents and mine. The plant contains oil and grease recovery system through traps, removal of suspended solids through clarifiers after chemical dosing at flush mixers, sludge drying beds, conveyance line and pumping arrangements. Treated water is reused for tanker filling; sprinklers etc. dried sludge is buried in lined pits. Two more new ETPs are underway
Domestic sewage treatment plants (8 Nos.) are constructed in the townships with activated sludge process. Plant contains aeration units for oxidation, clarifiers for removal of suspended solids, sludge drying beds, grit removal facilities, sewer lines, manholes, pump houses, control room etc. Treated water is taken for reuse in tree plantation, horticulture and construction activities. Dried sludge is valuable manure for tree plantation and horticulture activities. Two more DSTPs are under process.
Substantial amount of silts are carried along with the run off water. Catch drain with silt arrestors are provided in mines area, which are cleaned at regular intervals. Check dams and siltation ponds are provided to arrest silt flowing to the watercourse. Gabions (loose stones packed in wire crates) on the toe of the active dump and across the watercourse protect silt escape to the water body.
Routine maintenance of HEMM is done to minimize the leakage of oil. Secondary containments like trays and trolleys are used at workshops during maintenance to stop the spillage of oils. Floating oils recovered from oil & grease traps at workshops & ETPs are stored in drums. Drums are stored in a raised paved area having drains to collect back spillages. Permission sought from SPCB for handling waste oil. Drummed oils are sold to the distillation units having requisite license through MSTC (a Govt. of India undertaking) by way of press advertisements.