In the bad old days, solid waste was often left in open air dumps. Liquid waste was pumped into surface waters and toxic waste was left in open trenches and pools. Although these methods were unsightly and left toxic compounds and pathogenic bacteria in the surface environment they did have some advantages to them. Furthermore some types of degradation are aided by solar energy. Modern waste disposal is largely in the subsurface.
Solid waste is disposed of in engineered sanitary landfill.
Subsurface disposal has lots of advantages. With a landfill, there is less risk of air or water pollution. However, degradation of the waste in the subsurface is much slower. The waste may not remain isolated in the subsurface landfill, but can escape into ground water and thus into the hydrological cycle. This lab investigates some of the controls on the movement of pollution through groundwater.