The site of the heating power station and former gasworks in Plauen is contaminated over a wide area with pollutants specific to gasworks - above all BTX aromatics, PAH (polycyclic aromatic hydrocarbons), tar oils, phenols and ammonium - down to a depth of six metres. According to expert opinion, a soil volume of some 20000 m3 must urgently be cleaned up. A remediation concept has been prepared at the request of the municipality of Plauen, based on the use-related potential assessment for the site. The assessment concludes that there is an acute environmental hazard for the directly adjoining river 'Weisse Elster'. The approach pursued in this project represents a new solution to the problem of contaminated sites. Instead of using ex-situ methods for carrying out a complete cleanup of the contaminated site, as practised so far, in-situ methods are used. In this way, the acute hazard potential is eliminated, leaving only a tolerable amount of residual pollution. This objective will be achieved through a combination of pneumatic, hydraulic and microbiological in-situ measures. The efficiency will be further increased by specific pollutant mobilization. The technical feasibility has been confirmed by soil air suction tests and pumping tests on sites as well as microbiological laboratory analyses. The in-situ decontamination is superior to the traditional ex-situ methods in terms of economic efficiency, waste prevention and reducing traffic movements. The innovative methods proposed here involve, in particular, hot-steam injections and controlled oxyhydrogen gas explosions that will increase the availability of immobile pollutants attached to the soil grain.
Hydraulische Sanierungsverfahren basieren auf dem Aufbringen von Gradienten, um das Stroemungs- und Transportverhalten im Boden gezielt zu beeinflussen. Nicht mischbare, aufschwimmende Schadstoffe (z.B. Mineraloel) koennen mit den ueblichen Sanierungsverfahren nur sehr ineffizient entfernt werden. Im vorliegenden Vorhaben sollen neben hydraulischen auch pneumatische Gradienten durch das Absaugen von Bodenluft in horizontal verlegten Drainrohren aufgebracht werden. Hierbei wird das (kontaminierte) Bodenwasser im Untergrund zur Drainageleitung hin befoerdert. Insbesondere erlaubt die vorgesehene Konfiguration eine - auch bei schwankendem Grundwasserstand - tiefenangepasste Wasserentnahme im besonders stark belasteten Kapillarsaum. Das quantitative Verstaendnis der massgeblichen Wechselwirkungsprozesse soll in diesem Forschungsvorhaben experimentell (grossskaliger Versuchsbehaelter 7,5 mal 2 mal 1 m) und numerisch untersucht werden.