Rocks of intermediate depth (100-1000 m) and those in the deep (greater than 1 km) subsurface represent an environmental resource to aid the energy transition and to achieve improved environmental outcomes. Porous and permeable sediments can be used to store fluid and solid wastes through processes of injection. Suitable porosity and permeability are needed for fluids disposal (CO2, waste water, acid gas), and slurried solids may be disposed in sediments through fracture injection, a process that has been taking place in the oil industry for over 40 years. Particular emphasise is placed on the potential for sedimentary rocks to accommodate injection and to dissipate pressures, but caution is warranted: the huge volumes of CO2 proposed for injection will exceed the sediments’ capacities in many areas, leading to regional pressurization and increased escape risks.