HSE

Sources for Increased DOC-Concentrations in the Groundwater Downstream of the Landfill Hohne (DEA)

Construction waste together with drilling mud and oil-contaminated soil had been deposited in the landfill Hohne from 1971. Four groundwater monitoring sites had been installed: one monitoring site upstream and three sites downstream of the landfill in three different directions. Downstream of the landfill increased concentrations of chloride, sulphate, sodium and DOC (dissolved organic carbon) had been measured over a period of years. Particularly the source of the DOC has remained unclear. Assumptions were (i) leaking of contaminants from the landfill and degradation under the landfill by microbes or plants or (ii) leaching of DOC from the soil under the landfill caused by a change in the redox potential. The determination of the DOC source was the major subject of this study.
In particular, the origin of DOC in the downstream has been largely unclear. Working hypotheses were that (i) organic pollutants escape below the landfill and are degraded microbially or by plants or (ii) the already demonstrated change in redox potential below the landfill leads to the dissolution of soil-borne carbon.
The goal of the project was to provide evidence of a DOC source.