Related by context. Frequent words. (Click for all words.) 51 coal slurry 50 coal ash 47 mine tailings 47 ash ponds 45 coal seam 44 contaminated groundwater 44 methane gas 44 coke ovens 43 coal mines 43 tailings 43 fly ash 43 sludge 42 tailings dam 42 coal mine 42 coal mining 42 methane 42 Hydraulic fracturing 42 impoundments 41 leachate 41 Edwardsport 41 Kingston Fossil Plant 41 coal seams 40 slurry 40 radioactive contaminants 40 coke oven 40 Widows Creek 40 coal 40 limestone quarry 40 Taum Sauk 39 red sludge 39 tailings ponds 39 Rulison 39 coal gasification plant 39 valley fills 39 Nevada Yucca Mountain 39 mining 38 coal gasification 38 chlorine dioxide 38 coalbed methane 38 dissolved solids 38 sediment 38 Coal Mine 38 copper smelting 38 hydrofluoric acid 38 dewatering 38 tritium 37 mine 37 Whitesburg 37 zinc smelter 37 toxic sludge 37 contaminate groundwater 37 coalfields 37 contaminated soil 37 radioactive tritium 37 wastewater discharge 37 contaminants 37 lignite coal 37 contaminated soils 37 oil sands 36 radioactive wastes 36 sulfur dioxide 36 bituminous coal 36 wastewater discharges 36 Jeff Gillenwater 36 Saskatchewan potash 36 Waste Isolation Pilot 36 Marsh Fork 36 suspected carcinogen 36 smelting 36 hazardous chemicals 36 shale formations 36 shale 36 Superfund cleanup 36 radionuclides 36 landfill 36 Copper Mine 36 contaminated sediments 35 coalmines 35 contaminated sediment 35 phosphate mining 35 bed methane 35 hydraulic fracturing 35 ruptured pipe 35 lignite 35 coalmine 35 Steam Plant 35 copper smelter 35 earthen dam 35 ammonia 35 PIKEVILLE Ky. 35 radioactive waste 35 smelter 35 cavern 35 combustible dust 35 mines 35 Songhua 35 total dissolved solids 35 longwall mining 35 brine 35 pulverized coal 34 Phosphate