|Project manager:||Dr.-Ing. Hans-Peter Koschitzky, AD|
|Deputy:||Dr.-Ing. Arne Färber|
|Research assistants:||Dipl.-Ing.(FH) Oliver Trötschler|
|Duration:||1.5.2003 - 30.4.2004|
This project is part of the research area:
In-Situ Remediation Technologies
Abstract:A spatial limited contamination of the saturated and unsaturated zone (PCE, 400 m³ of soil) underneath the building was detected and the site owner
Mettler Toledo Albstadt GmbH was obliged by the local authorities to remediate the contamination.
A first attempt to remediate the site was a state-of-art in-situ remediation by pump-and-treat, soil vapour extraction and in-well stripping. Adding a microbiological on-site treatment of the extracted groundwater was installed and operated for 7 years. The total costs summed up to approx. 500,000 EUR.
The site owner had to remediate the contaminant source zone. Innovative technologies had to be selected in order to meet economic and ecologic demands. Based on a contract between the former site owner and the local authorities, the application of a steam-air enhanced soil vapour extraction to remediate the saturated and unsaturated zone was installed.
VEGAS, University of Stuttgart was responsible for the design, the installation work and the operation of the remediation. Drilling works were finished during a production shutdown in summer vacations 2003. The required technical units were installed on-site in a separate room. The remediation started end of October 2003 and was successfully finished in January 2004. A mixture of steam and air was injection into the lower and upper aquifer to heat up subsequently the saturated and unsaturated zone whilst transporting the evaporated contaminants towards the soil vapour extraction wells. Additionally a groundwater extraction system was operated in the extraction wells.
Soil samples indicated a total mass of 300 g of perchloroethene (PCE) in the contaminant source zone. During thermal remediation time of 3 months about 10.6 kg of PCE were extracted; 2.2 kg of PCE were removed by groundwater extraction.
Downstream groundwater concentrations were reduced close to threshold values (factor 2 – 5), the remediation zone was successfully heated (> 90°C) and extraction concentrations of the soil vapour were below detection limits.
It was found evidence for another upstream contamination of PCE. The concentrations of the groundwater flowing into the remediation zone are approx. 70 times higher than the threshold values. The total costs of the innovative remediation were below 150,000 EUR and the remediation time was less than 3 months.
For further information please have a look at the following publications.
Färber et. al. (2004): CHC-REMEDIATION OF THE SATURATED ZONE BY STEAM-AIR INJECTION, Battelle Conference 2004
Trötschler et. al (2004): STEAM-AIR INJECTION; PILOT IN-SITU REMEDIATION OF A PCE CONTAMINATED AQUIFER, powerpoint presentation IMAGE TRAIN course, Stuttgart, 2004