Foundry environment Polluted soils

Complex and multifunctional, soils are at the heart of major environmental challenges such as the availability of quality water, the preservation of biodiversity, food security and the fight against climate change. Soil fulfills essential functions that sometimes conflict with each other (agricultural and forest biomass production, living environment, ecosystem regulator, genetic reservoir).

By declaring 2015 the "International Year of Soil", the UN General Assembly aimed to raise awareness among all players in society of the importance of soil as an inseparable part of an ecosystem whose services are essential to human life.

In soil, the mineral components are particles, such as sand, silt and clay, made up of different chemical elements, while the organic components come from living organisms, including plants, bacteria, fungi, animals and their residues. Soil is a living environment that includes micro-organisms and fauna. These micro-organisms are heavily involved in the decomposition of organic matter and the recycling of carbon, nitrogen, phosphorus and potassium, as well as in the degradation of certain contaminants. One gram of soil contains several hundred thousand fungi and several billion bacteria. Microbial biomass (the quantity of microbial carbon living in the soil) can reach 2.5 t/ha for bacteria and 3.5 t/ha for fungi in a grassland soil.

Soil is the object of numerous threats, long underestimated, but which can no longer be ignored. These threats are linked, on the one hand, to the use of quality soils for urbanization and transport, and on the other, to their physical and chemical degradation under the combined effect of factors of diverse origins (atmospheric, agricultural, urban, industrial).

The pollutant content of many soils is also on the rise. For example, pollution by heavy metals or organic products is increasing not only in critical areas (industrial centers or landfills), but also in certain rural regions due to atmospheric and agricultural pollution.

Regulations governing facilities classified for environmental protection date back to 1976, and many cases of site pollution predate this date, as product and waste management practices were not a major preoccupation of industry or government.

This article describes the specific soil regulations that apply to foundries. The aim is firstly to prevent pollution by better management of foundry materials and waste, and secondly to eliminate diffuse discharges likely to contaminate the soil around metallurgical plants. Rigorous management of gaseous and aqueous emissions is also essential to avoid both potential health risks and loss of property value on industrial sites.

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