In the Nordic countries there is an increasing interest in the use of leaching-based criteria in the regulation of utilisation and landfilling of waste materials and contaminated soil. As a consequence, Nordtest decided in early 1999 to fund a project with the objective to investigate the feasibility of adapting the existing Nordtest batch leaching method for granular, inorganic waste materials, NT ENVIR 005 - procedure 1, to the testing the leaching of inorganic components, particularly trace elements, from soil.
The project, which was finalised during the spring of 2000, has resulted in a proposal for a test protocol for a batch leaching test applicable to soil, based on an experimentally based study of the influence of various test conditions on the performance and results of the test.
The project activities have included the collection and characterisation of a substantial number of uncontaminated and contaminated Danish soil samples. Laboratory experiments were conducted to evaluate the influence of contact time (between soil and leachant), contact with air (open/closed system) and filter size on the results and practical performance characteristics of the batch leaching test when it is applied to soils.
The results of the project indicates that the contact time (when it exceeds 6 hours) does not have a significant influence on pH, conductivity and redox potential of the eluate, and that an equilibrium-like condition is reached relatively quickly within the test system.