North Dakota’s oil industry is pushing to change the state’s radioactive waste disposal laws as part of a broad effort to conserve cash as oil prices tumble. The waste, which becomes slightly radioactive as part of the hydraulic fracturing process that churns up isotopes locked underground, must be trucked out of state. That’s because rules prohibit North Dakota landfills from accepting anything but miniscule amounts of radiation. The most common form of radioactive waste is a filter sock, a mesh tube resembling a sandbag through which fracking water is pumped before it’s injected back into the earth. Tank and pipeline sludge are also radioactive. It’s not clear how much of this waste is generated, as North Dakota officials only began requiring tracking last year; final 2014 reports aren’t due until next month. Some put the number at 70 tons per day; others say 27 tons. […]