The chemical in-situ oxidation (ISCO) can be an attractive alternative method for the a fast degradation of various chemicals in soil and groundwater. This technology shows a considerably higher potential of contaminant elimination than classical pump-and-treat measures.

Unlike for microbial degradation, the presence of microbial organisms is not necessary for in-situ oxidation. Degradation occurs strictly via chemical oxidation. This fast-acting measure is particularly suitable for high concentrations in the contamination hot spot, especially in case of free-product zones.

The oxidant can be applied into the contaminated area as a liquid via injection or infiltration galleries, as well as a solid product e.g. via displacement probing or "mixed-in-place“ technologies.

The success of ISCO depends to a high degree in the precise determination and evaluation of the local characteristics. Before starting the actual remediation a field trial is recommended which can be designed as part of the final remediation measure.

To assure a successful remediation the knowledge of the following parameters is of highly relevant:

• Kind and distribution of the target-contaminants.
• Gelogical and petrographic site conditions, particularly soil type and heterogeneity.
• Specific soil oxidant demand (SOD).
• Geochemical site conditions.
• Hydrological characteristics (permability / heterogeneity)
• Potential of mobilisation and degradation of redox-sensitive metals (e.g. chrome VI)
• Risk of rebound effect, i.e. anew increase of contaminant concentration after remediation caused by residual contaminants which were not reached by the substrate.

Finally, the uniform and area-wide distribution of the oxident within the contaminated aquifer is essential for a successful remediation, as well as an accurate dimensioning of oxident mass and dilution and the right choice of the application technique.