Soil washing is an on site clean up technology that focuses on the principle of waste minimisation. Soil washing can, in the right circumstances, vastly reduce the need for landfill disposal, transportation of contaminated soil, and the importation of clean fill.
The soil washing process works on the principle that most contamination coats soil particles, and contamination tends to be concentrated in particles with a high surface to volume ratio such as clay and silt. Soil washing separates finer material from coarser and scrubs the surface of larger particles leaving a contaminated fine fraction, plus clean sand and gravel fraction. The process also floats off organic soil such as wood fragments and peat.
After verification testing, the cleaned material can then be used to backfill excavations, thus reducing the need to import clean soil. Only contaminated soil not suitable for processing and residues from the process itself are removed for disposal.
In 1998, a strategically important 19-acre former gasworks site at Basford, Nottingham saw the first large scale use of soil washing technology in the UK. At Basford lorry movements were reduced from 23,000 to just 8,000, saving on energy and fuel costs, and greatly reducing the disruption to the local community.
Soil washing can vastly reduce the need for
landfill disposal, transportation of contaminated soil and the importation
of clean fill.