27-660. Safety requirements Any person engaged in the drilling of a well for geothermal resources in an area wherein fluids, gases or steam under high pressure are known to exist, or any person drilling a well for geothermal resources in any area where pressures are not known, shall case in a watertight manner the borehole to a depth sufficient to protect against surface-cratering in the event of a blow out with pipe of adequate strength, and equip the well with a blow out preventor and other safety devices, in accordance with pipe and equipment specifications and procedures approved by the commission, and shall further exercise due caution in all drilling operations to prevent blow outs, explosions or fires.
Arizona Legal Code