Soil Processing
Keywords
Soil processing, screening, picking station, volume reduction, pre-treatment, waste processing, hand picking.
Introduction/principles Soil processing is perhaps the simplest form of treatment but is also a a vital precursor to many ex-situ soil remediation treatment processes. This treatment can reduce the volume of contaminated material requiring further treatment (e.g. ex-situ bioremediation or stabilisation)
Selective excavation and stockpiling of contaminated and non contaminated materials reduces the volume of contaminated material requiring remediation.
Screening and detailed processing removes solid metals, timber and non-biodegradable materials (plastics etc) from the soil which can inhibit other remediation processes such as bioremediation. Removal of these items is also required for structural fill requirements (6F2, site won materials etc) when back filling excavations which are to be built on after remedial works. Screening produces an homogenous soil mass better suited to further treatment.
Additionally plastics and metals from the contaminated medium can be recycled offsite.
It can also be used to separate and segregate certain soil fractions (e.g. fines) from made ground where perhaps a large portion of the contaminant mass may be present.
Contaminants
Fabrics
General waste
Finely divided contamination such as heavy metals
Metals, steel etc
Plastics
Solid tar
Concrete
Oversized objects requiring crushing
Plant Description
Soil processing equipment includes:
* Screens
* Picking stations
* Crushers
* Excavators
* Processing buckets
Selective excavation is a vitally important method of contaminated material reduction, excavation of contaminant hotspots by excavators supervised by an experienced environmental engineer and banksman can significantly reduce volumes of contaminated material by ensuring visually contaminated soils are not stored or mixed with visually uncontaminated soils.
Example
VertaseFLI were contracted for the reclamation of a former landfill located in South Wales.
Over 360,000m3 of industrial waste, household waste and soil was excavated and processed using four specialist screening plants along with hand picking stations.
* Over 325,000m 3 of material was separated off ready for reuse * Over 15,000m 3 of material was separated and stockpiled for further remediation (bioremediation and solidification/ stabilisation) * 31,000m 3 of untreatable waste material (plastics, fabric, etc) was disposed off site to suitably licensed facilities * Separation of 250m 3 of asbestos and asbestos containing materials * All remaining materials were recycled for restoration works on site
Advantages and Limitations
Advantages:
* Reduction of contaminated material requiring further treatment
* Products suitable for engineering fill
* Creates an homogenous soil mass better suited to further treatment
Limitations:
* Does not fully remediate all contamination
* Further treatment may be required
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