Related by context. Frequent words. (Click for all words.) 66 fracking 63 hydraulic fracturing 61 Fracking 59 hydrofracking 53 drilling fluids 53 toxic chemicals 52 contaminants 52 drillers 52 solvents 52 groundwater contamination 52 slurry 52 groundwater 51 contaminated groundwater 51 brine 51 chemicals 51 chemical additives 51 methane 51 hydrogen sulfide 49 Marcellus Shale formation 49 trichlorethylene 49 shale formations 48 perc 48 leachate 48 benzene 48 hazardous chemicals 48 sludge 48 chlorine 48 MTBE 48 wastewater 48 vapors 47 volatile organic compounds 47 Ammonia 47 coal ash 47 shale 47 underground aquifers 47 toxic substances 47 harmful chemicals 47 chemical 47 methane gas 47 contaminant 47 dispersant 46 hydrogen sulphide 46 Marcellus shale 46 carcinogens 46 dispersants 46 coal tar 46 tritium 46 perchlorate 46 vinyl chloride 46 Marcellus Shale 46 coal seam 45 toxic 45 Safe Drinking Water 45 hydrochloric acid 45 arsenic 45 VOCs 44 hazardous waste 44 H2S 44 radium 44 liquids 44 wells 44 hydraulic fluid 44 toxins 44 barium 44 contaminated soil 44 Benzene 44 sodium hydroxide 44 coalbed methane 44 hexavalent chromium 44 aquifer 44 frac 44 gasoline additive 44 poultry litter 44 effluent 43 Sludge 43 sewage sludge 43 DEP 43 pollutants 43 Methane 43 nitric acid 43 chlorinated 43 hydrocarbons 43 horizontal drilling 43 leak 43 PFOA 43 biosolids 43 chromium 43 flammable 43 toxic pollutants 43 PAHs 42 gases 42 sodium chloride 42 toxic waste 42 vapor 42 radon 42 Range Resources 42 contamination 42 coal seams 42 pollutant 42 manure 42 ammonia