Slurries of relatively fine particles of solids wastes and similar materials are disposed of through injection wells which penetrate earth formation disposal zones which have a minimum in situ compressive stress generally less than an overburden zone and an underburden zone adjacent to the disposal zone....http://www.google.de/patents/US5314265?utm_source=gb-gplus-sharePatent US5314265 - Waste disposal in hydraulically fractured earth formations
