Ex-situ or in-situ treatment that mixes contaminated soil with binders (Portland cement, fly ash, lime, slag, soluble silicates) to chemically immobilize contaminants and physically encapsulate the matrix in a low-permeability monolith. A containment remedy, not destruction.
Stabilization and Solidification is the dominant remedy for inorganic contaminants (lead, arsenic, chromium, mercury) and for radiologically contaminated soils where destruction is impossible. Stabilization changes contaminant speciation to less-mobile forms; solidification reduces hydraulic conductivity and surface area by forming a cementitious monolith. Treated material is verified by leaching tests (TCLP, SPLP) rather than total concentration.
S/S is fast, well established, and inexpensive relative to thermal treatment, but the contaminant remains on or near the site and depends on the long-term integrity of the binder. Regulatory acceptance is strong for metals and radionuclides and weaker for persistent organics, which can diffuse out of the monolith over decades. S/S is rarely accepted as a permanent remedy for PFAS, dioxins, or PCBs.
Also known as: S/S, stabilization, solidification, stabilisation and solidification.
Heavy Metals (Arsenic, Mercury, Chromium, Lead): treatment approach
Regulated inorganic trace elements — including arsenic, mercury, hexavalent chromium, lead, cadmium, and nickel — that are toxic at parts-per-billion to parts-per-million levels, do not biodegrade, and are managed by immobilization, physical separation, or valence-state conversion.
An ex-situ soil treatment process that heats contaminated soil to volatilize and separate organic contaminants from the soil matrix, after which the liberated vapors are captured and treated, usually in a high-temperature oxidizer.
A thermal desorption configuration where the heat source contacts the soil directly inside the rotary unit, delivering high heat-transfer efficiency and supporting higher treatment temperatures.
A thermal desorption configuration where heat is conducted through the wall of the treatment vessel without combustion gases contacting the soil, producing a concentrated, lower-volume vapor stream suitable for condensation and recovery.
Treatment that heats contaminated soil and groundwater in place, typically with electrical resistance, thermal conduction, or steam injection, to volatilize and recover contaminants without excavation. Used where excavation is impractical or where the contaminant zone sits beneath active infrastructure.