Pollution plume simulated using the MARTHE® modelling software.
In order to maintain an environmentally responsible approach, construction waste must only be reused with proper consideration for the protection of the environment, and groundwater in particular. This aspect has been studied by a national Working Group under the aegis of the Ministry of the Ecological and Inclusive Transition.
The potential impact of the use of construction materials on groundwater quality was studied by modelling the different attenuation phenomena that occur in groundwater (including dilution, dispersion, adsorption and degradation) and that tend to decrease concentrations in groundwater the greater the distance from the area of reuse. Numerical modelling can simulate these phenomena and calculate groundwater concentrations in the target area to be protected (e.g. a drinking water supply intake), downstream from the material reuse area.
The simulations, carried out using the MARTHE® tool, enabled BRGM to assess the impact of this reuse on groundwater by taking into account the various factors that can influence the migration of pollutants:
- the density of the different types of structures for which the materials are to be reused;
- the meteorological context;
- the type of aquifer formations;
- the flow rate of the aquifer;
- the distance from the reuse area.
Using the results
The results of these models enable a definition of the reuse values (called threshold values) of the waste generated during the construction or demolition of a building in several types of installations (foundations, paving, etc.), in order to guarantee the protection of groundwater.
The possibility of reusing these materials is part of an approach that favours the reuse and recycling of waste rather than its disposal in storage facilities.
- Ministry for the Ecological and Inclusive Transition – General Directorate for Risk Prevention – Waste management planning department,
Principle of migration of a pollution plume downstream of the reuse area (2019).