DEVELOPMENT OF A RISK BASED POLICY FOR CONTAMINATED SITES OF THE WALLOON REGION, BELGIUM

摘要

Past industrial and economical activities accomplished on the territory of the Walloon Region (16.844 km~2, South of Belgium) have left over some 2,044 abandoned and (potentially) contaminated sites, covering a total area of 9,000 hectares. While the need to rehabilitate these sites - in view of enabling them to support new economical activities - has been identified, as early as in the late 1980's, improvements up to now are still globally insufficient. Appropriate tools for early decision making relying upon risk acceptance and in helping making objective choices, i.e. setting priorities in studies and required remedial actions, are lacking. This has been recently recognized as a crucial constraint, and has led to initiate the development of a specific risk based policy for contaminated soils and sites. Ongoing work has been split into three pools working in a concerted and integrated way, devoted to the setting up of a strategic plan, a technical- and a juridical frame of the future policy, respectively. In a general way, risk assessment is advanced as a key concept to define the investigation procedures and to help administrative decision makers. A general frame (figure 1) has been proposed for site management, corresponding to a - now widespread- 3 step procedure including a "pre-diagnosis" study, a preliminary soil investigation, and an in-depth investigation, respectively. Each of the three steps includes a specific risk sounded interpretation phase, leading to an administrative decision (either soil investigation necessity, preliminary risk acceptance, or risk acceptance/clean-up, respectively). Two specific tools have been developed in order to help the administration to decide on the site status and/or on the future actions needed: 1) A specific tool has been developed for decision makers to establish remedial- and investigation priorities. The inputs are the data collected in steps 1 and/or 2. The particular features of this ranking system are presented in point 2. 2) Within the framework of preliminary investigations, (step 2) a methodology for early decision making based on risk acceptance of contamination data, is currently under development. It constitutes an alternative between a typical normative approach (as used in the Flemish Region, North of Belgium) and a typical "site specific risk evaluation" approach (as used in France). The important features of the procedure are highlighted in point 3.