Combination remediation tackles land under residential area

The production site of a former paint and varnish producing company turned out to be contaminated with solvents. The contamination spread with the groundwater flow. The source of contamination was identified to be at the production site. The contaminant plume spread with groundwater into a residential area and the site of a shopping mall with parking lot.

This soil contamination was frustrating development plans for the residential area and the authorities had demanded that the site owner remediate the soil and groundwater contamination .

In-situ Technieken remediated the soil using a combination of techniques: chemical oxidation and enhancement of biological degradation. Large amounts of reagents were injected into the soil over a long period. Due to the involvement of a residential area, special attention was given to safety and the reduction of nuisance. Good coordination and communication with residents were points that received a great deal of attention.

Remedial design

We conducted a pilot remediation test on site to measure / verify relevant design parameters. Based on the results obtained, In-Situ Technieken designed in detail and built a dosage system for the chemicals. The full-scale remediation was done by injection of persulphate for chemical oxidation in source areas and injection of molasses to enhance biodegradation in the contaminant plume.

The approach included the preparation of diluted solutions from concentrated chemicals (outside of the residential area) and the transport of diluted solutions through underground feed lines to the injection wells at the site and in the residential area.

In order to achieve efficient treatment of the contamination, some injection wells were installed at an angle of 45° to make injections possible under the houses.

Inactive periods were planned between injection sessions in order to allow the oxidation and degradation processes to proceed.


The approach resulted in a successful and safe soil remediation with very limited nuisance for the public. The constraints to development plans for the area were removed.

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