Natural attenuation at tar oil contaminated sites - Results from the German funding priority KORA

In 2002, the German Ministry of Education and Research (BMBF) established the funding priority Retention and Degradation Processes to Reduce Contamination in Groundwater and Soil' (KORA, see also: http:// www.natural-attenuation.de). The overall objective of the project is to identify the conditions under which pollutants can be retarded and degraded naturally, and how these natural attenuation (NA) processes (such as sorption and biodegradation) can be exploited to clean up contaminated sites. The projects in the research programme are divided into eight different thematic networks (TN) involving various contaminated sites and pollution histories. TN 2 deals with sites contaminated by tar oil due to their previous use for manufactured gas plants, coking plants, coal tar processing and wood preservation facilities. Four sites are being investigated, each of which is characterised by a particular pollutant consortium with specific geological and hydro-geological conditions. Although several guidelines are available for monitored NA (MNA) at sites contaminated by BTEX or chlorinated hydrocarbons, there are as yet no recommendations for tackling tar oil contamination. TN 2 examines the suitability of NA processes for tar oil contaminated sites by identifying and quantifying the constituents of tar oil including NSO-heterocyclic compounds and metabolites along with their mobility and degradability under in situ conditions. A priority list will be provided for the compounds investigated. This presentation summarises the results of TN 2 so far and then discusses the performance goals for the implementation of MNA.