Oil Contaminated Soil Remediation
Contamination in Soil
Hydrocarbon in soil does not stay where it was spilled. It migrates with groundwater, restricts what the land can be used for and carries a remediation obligation. Soil washing separates the hydrocarbon from the mineral fraction so that the bulk of the excavated material can be returned rather than sent away as contaminated waste.
| Step | Purpose |
|---|---|
| Screening | Oversize material and debris taken out ahead of the wash stage |
| Washing | Hydrocarbon released from the soil particles into the wash water |
| Separation | Decanter resolves the wash stream into oil, water and mineral solids |
| Water recycle | Treated wash water returned to the wash stage to limit fresh water demand |
| Verification | Treated soil checked against the target before it is placed back |
The separated water and oil are handled as their own duties: see contaminated water treatment and slop oil treatment.
Wash and Separation Sequence
The wash stage releases hydrocarbon bound to the soil particles, which is what allows the mineral fraction to be recovered rather than disposed of.
Wash water is recycled through the circuit, so fresh water demand is limited to make up rather than to full throughput.
The decanter applies centrifugal force to the wash stream, parting the oil, the water and the mineral solids in one continuous operation.
Residual hydrocarbon left in the treated soil is driven down to the level the remediation target requires.
Treated mineral material is returned to the excavation, so the volume classed as contaminated waste is reduced to the separated fractions.
Cost is governed by the tonnage that must leave site. Returning treated material to the excavation is what moves that figure.
Engineering FAQ
How does soil washing work?
Oversize material and debris are screened out, the wash stage releases hydrocarbon bound to the soil particles, and a decanter resolves the wash stream into oil, water and mineral solids.
Can the treated soil be put back?
That is the objective. Washing separates hydrocarbon from the mineral fraction so the bulk of the excavated material can be returned rather than sent away as contaminated waste. It is checked against the remediation target before it is placed back.
How much fresh water does the process need?
Wash water is recycled through the circuit, so fresh water demand is limited to make up rather than to full throughput.
Talk to an Engineer
Send the soil analysis, the contaminated volume and the remediation target that applies. We will return a scope of work and a mobilisation plan. Other services: services.