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Institute of Hydraulic Engineering

Research: VEGAS - Research Facility for Subsurface Remediation

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Application of the „TUBA“-technique to remediate a CHC-contamination beyond a hazardous waste site (Model site Mühlacker)
Project manager:Dr.-Ing. Hans-Peter Koschitzky, AD
Research assistants:Dipl.-Ing. Tilman Theurer
Dr.-Ing. Arne Färber
Duration:1.10.1998 - 30.6.2000
Funding:Kommunaler Altlastenfond des Landes Baden Württemberg und Stadt Mühlacker
Comments:

This project is part of the research area:
In-Situ Remediation Technologies

Publications: Link

Abstract:

The pilot study was carried out at a former hazardous waste deposit near the city of Mühlacker, state of Baden-Württemberg, Germany.
The landfill was opened in 1968 in a natural layer of loamy clay, and was used for depositing of galvanic sludge, paint production remains and solvents up to 1976. In the year 1987 the location was taken into the "model site program" of the state of Baden-Württemberg. Various site investigations were done in 1991 and 1992, showing that between the landfill itself and the groundwater, located 30 m below ground surface, a huge contamination exists mainly consisting of CHC.

A conventional soil vapor extraction (SVE) system started to operate in 1998. Because a distinct reduction on contaminant concentrations of the soil air was not achieved within one year, a more effective and efficient innovative treatment technique was to be tested.

VEGAS proposed to enhance SVE by heating the subsurface by injecting steam. For demonstration purposes, a portion with about the size of an eighth of the landfill with high contaminant concentration was selected to be cleaned by steam injection. The success was to be shown by subsequent soil sampling.

The test field with a total soil volume of 2500 m^3 was equipped with 6 extraction wells for both liquid and gas phase extraction and a single steam injection well. The extraction wells were located circularly around the injection well to avoid eventual transport of contaminant to regions outside the test field.

Although the pilot study of steam injection had to face several difficult conditions, a successful, economic and fast remediation of the test field was achieved. By adapting the equipment and the operation modes to the site-specific requirements, it was possible to remove 2.8 tons of contaminant mass from the subsurface within 10.5 months of steam injection.

In this case, the prognosis for the cleanup time with conventional SVE technique lead to a time saving of 8 to 9 years and a direct cost advantage for the steam injection. Also, there is a potential for financial success by selling or reusing the site earlier.

A more detailed project description is available here.

For the puplication "Thermal In-situ remediation of the unsaturated zone by steam injection" in Annual Report 2002, NATO/CCMS Pilot Study, Evaluation of demonstrated and emerging technologies for the treatment and clean up of contaminated land and groundwater (phase III), Rome, Italy, May 5-10, 2002, pp134-137 please click here.