Characterization of natural anaerobic dechlorination of TCE and 1,1,1-TCA in clay till including isotope fractionation and molecular biological tools

One of the major challenges when using enhanced reductive dechlorination (ERD) as a remediation technology at clay till sites is to obtain good contact between added agents such as donor, bacteria and the contamination. It is unclear whether degradation only takes place in fractures and/or sand lenses/stringers or if degradation in the clay till matrix is possible. In this study a 30 year old contaminated clay till site where natural degradation of chlorinated ethenes and ethanes is occurring is investigated to obtain a better understanding of the processes driving anaerobic dechlorination including the location of degradation in the fracture matrix geology. An extensive field collection of cores and discrete soil sampling has been conducted and samples have been analysed using state of the art microbial and chemical tools including isotope fractionation.