Systems and methods for processing solid wastes from oil field operations are described, which may include or encompass removal of wastes from oil tanks, solid particle size reduction and recovery, and disposal by injection into a subterranean formation. Removal of liquefied solid wastes from oil tanks may be achieved by a washout and vacuum conveyance system. Solid wastes may be processed through a particle size reduction system. The particle size reduction system may include one or more separators each having an appropriate particle size threshold, one or more slurry tanks, an apparatus such as a grinder configured for reducing particle size, and one or more slurry pumps that transfer the slurry through one or more recirculation circuits or transfer conduits. Particle size may be further reduced by high velocity transport through the recirculation circuits. The processed slurry may be disposed of by re-injection into a subterranean injection zone.