New guidelines for post mining risks management in France

International audienceAfter having intensively exploited for several centuries the mineral resources present in its subsoil, France gradually saw its extraction sites cease their activity. The ending of mining activity did not, however, lead to the disappearance of phenomena likely to affect the surface areas located above or in the vicinity of mine workings. Thus, during a period following exploitation, traditionally called "post-mining", many disorders may develop, sometimes as soon as workings are stopped but also much later. In addition to ground movements phenomena, surface above old mining sites may be affected by rising gases with dangerous compositions. Moreover, the irreversible disturbances caused by extraction work on ground-water flows can be the cause of possible disorders, both in terms of water flow movements (low-level flooding, disturbance of the watercourse regime) and water quality. In order to manage risks associated with these phenomena and thanks to the experience gained in post mining management, the French State has a number of technical and regulatory tools. The purpose of these tools is to gather knowledge of the residual mining risks due to former mining operations in a given area, to locate the surfaces exposed to them and to define the conditions for the construction, occupation and use of lands as well as measures relating to the development, use or exploitation of existing property. In France, in the absence of a valid mining title, or in the event of the disappearance or failure of the operator, the French mine legislation makes the State responsible for compensation for damages caused by former mining operations which it has authorized in the past. This has a significant impact on land use opportunities above mining works. At the request of the French Ministry of Ecology in charge of post-mining risks management, INERIS led the elaboration of two National handbooks with the support of GEODERIS and Cerema: 1 - a generic handbook for the management of post-mining risks, 2 - a handbook for the evaluation of hazards relative to specific post-mining phenomena. These handbooks are intended for all stakeholders involved in the management of mining risks (government departments, local authorities, consulting firms, etc). They are designed as operational handbooks which allow the reader to identify the tools adapted to the local problems. After briefly describing the context of post-mining in France, this paper introduces these two handbooks with a particular highlight on the evaluation of hazards and their impact in terms of land planning