Abstract: The present invention relates to a plant for treating waste materials, which plant performs a safe and permanent depositing of waste materials as they are treated to obtain an injectable mass which may be injected in porous, underground formations. The plant according to this invention is treating waste materials including substantial portions of solid materials, and in particular drill cuttings, in connection with drill operations in connection with oil and gas wells in marine environments. The plant comprises a crushing machine (1) having two separate input ports (2 and 46), the first (2) primarily adapted for solid materials and the second (46) primarily for liquid materials, and produces a dispersion of diminutive solid particles dispersed in the liquid. The plant comprises possibly feedback means (23, 9 and 25, 35) for solid materials and circulating means (e.g. 31, 40) for the finished dispersion and also injected devices (32, 36, 37, 46).