Assessment of Treatment and Disposal Options

Abstract

Summary Driven by science, engineering and daily practice in sediment management a big variety of technologies for treatment and disposal is available. Main fields for further development with respect to sediment management is to find the way to compare different complex scenarios of treatment and disposal (assessment) and to build up the markets for treatment of sediments. The SedNet mission makes obvious that sustainability is only achievable on a new spatial and time scale. Since the present structures for decision-making are mostly local or regional acting administrations, however their actions have often consequences on a bigger scale, the river basin scale. Additionally, to build up a sustainable sediment management long-termeffects over the time span of a generation or more have to be considered. According to the aim of a sustainable sediment management we recommend assessment on a river basin scale considering a sustainable time scale of one generation! A sustainable river basin model has to integrate social, environmental and economic aspects, but so far a model offering this is only vague: In a river basin the members of the society are the driving force, economy can be seen as the sum of activities and the environment is part of the “capital stock” that is available for development and activities of the society. Some parts of this “capital” is not renewable. Consequently, in a broader view of economy, neglecting environmental effects bears the risk of a loss of capital stocks, consequently decreasing the economy and social welfare on the long term. What are the consequences of this new river basin view? The people are the driving part in the system. In general, people can only react rationally with respect to economy and environment, if they are informed. Knowledge is the basis for understanding processes and mutual interaction and at least informed people will understand and accept rational decisions based on assessment procedures. Besides information of the public an assessment procedure is the second column for decision making. The outcome of such an assessment is a ranking of treatment alternatives offered for a sediment problem. Such an assessment should not base on a single tool e.g. a cost calculation or LCA, because no tool covers all fields necessary to be considered (economy, environment, society). It must be recommended that a combination of tools (Costs, LCA, cost-benefit evaluation, risk assessment studies) should become routine before decisionmaking. European standards for assessing treatment and disposal alternatives should consider the present know-how about long-term effects (e.g. the life-cycle of sediments and products and effects on mobility and bio-availability of pollutants with time) and the differences between the results of biological and chemical methods applied for the same sediments. Thinking about assessment standards leads to the necessity of harmonizing those standards Europewide in order to avoid transport of sediments across boarders between regions and countries in Europe applying different standards. Looking at sustainability some benefits like the reduction of space consumption, climate or re-use of secondary material substituting primary resources are complicated to be evaluated. We will come closer to sustainability the more we have an overall or comprehensive model considering economic factors as well as the environment. The example of the European Guideline for Trading Emission Certificates (2003/87/EC) can be seen as a general approach how to combine economy and ecology in a way accepted from the society. So we recommend to conduct research in fields that provide us with parameters or better tools to evaluate goods like “the landscape”, “space consumption”, etc. useful to improve decision making. Accordingly, an integration of broader economic know-how into the assessment procedures is needed in order to evaluate benefits outside common budgets on to consider “hidden costs” and superior issues like source control or resource demands, which are not covered by the responsibility and budget of water and sediment management authorities today.