Developments in evaluating environmental impact from utilization of bulk inert waste using laboratory leaching tests and field verification

In recent years leaching tests for construction materials and wastes have been developed with the emphasis on using them as prediction tools for release in the long term rather than as arbitrary pass/fail tests. In the first stages of development, the mechanisms of release and release-controlling parameters have been assessed. For each of these aspects leaching tests have been selected, developed and in part standardized. Not all relevant aspects of leaching are yet coverered. The reducing properties of materials, for example, are still not taken into account properly. The need for these more elaborate tests is increasing as the policy of re-using waste materials in construction is expanding. As a consequence, the desire to improve material quality is increasing. For this purpose more detailed knowledge on the chemical speciation of contaminants is needed, as a treatment of waste carried out to reduce a few contaminants with too high leach rates may lead to an undesired increase in the release of other contaminants, which were previously not a problem. This requires a more integral approach and a good understanding of the consequences of changes in material properties. Tests focused on two main aspects of leaching can be identified: (1) release as a function of time; (2) release as a function of main leaching controlling parameters, such as pH, redox and complexation. The relation between these tests and the data interpretation associated with them is discussed. Another distinction in the use of tests is related to the lever of understanding needed. In CEN TC 292 tests have been distinguished as: characterization tests, compliance tests, and on-site verification tests. An important aspect of the new development of tests with release prediction capabilities is the verification of such predictions in the field. An example of the relation between predictions of release from laboratory test data and held observations is presented: release from MSWI bottom ash monofills. Finally, recent developments in the EC DGXII Standard, Measurements & Testing Programme and CEN TC 292 Characterization of Wastes are addressed. Copyright (C) 1996 Elsevier Science Ltd