Solvay continues to manage soil contamination from historical or acquired activities. Soil environmental legacies are managed in order to protect health and the environment, with a long-term vision, and at a controlled cost.

Solvay’s policy aims to prevent soil contamination by:

  • characterizing soil conditions whenever needed, at both active and closed sites; and
  • managing soil and/or groundwater contamination in the surroundings.

The group systematically assesses soil conditions and risk as a key step in selecting the most appropriate management measures.

Successful soil remediation: new in situ technology in Mulhouse (France)

High levels of industrial and chemical activity for more than 115 years

The Rhodia Mulhouse brownfield site is located on land that has housed high levels of industrial and chemical activity for more than 115 years. The area is around 10 hectares. Rhodia produced organic intermediates for, inter alia, pharmaceuticals, veterinary preparations, cosmetics and crop protection products. Operations ceased in 2007, and the site is earmarked again for industrial or logistical use. In order to make this a reality, facilities have been dismantled and most of the buildings destroyed.


The land has suffered historic soil contamination, which is concentrated in a few areas. The contaminants which need to be treated are semi-volatile, highly persistent, non-degradable and extremely foul-smelling (nitrochlorobenzenes, nitrotoluenes, BTEX - Benzene, Toluene, Ethylbenzene and Xylenes, etc.).

Water pumped at 150 m3/h

The site is currently confined by a hydraulic barrier that stops the contaminants from being carried beyond the site by groundwater. The water is pumped at 150 m3/h and treated with activated carbon to trap the contaminants before being released into a river. In order to make the brownfield usable for a new industrial purpose, it is essential that the contamination is reduced to a level compatible with the future use. The fact that the site is enclosed within a habitat area adds a further constraint owing to the disturbances the remediation work is liable to cause (noise or olfactory pollution from the excavation of the contaminated soil).

A pilot program to extract 1,500 kg of contaminants

As a result, the group needed an innovative, unconventional technology to get rid of the contaminants. What it found was the Soil Venting Thermal Extraction (SVTE) technique developed by GRS Valtech. In 2015, a pilot program covering 270m2 of land (1,300m3 of soil) was successfully executed, and has facilitated the recovery of some 1,500 kg of contaminants, thereby demonstrating the efficiency of the technology, which will be applied to all “source areas” in the zone in question (2,000m2 including the pilot area).

Unconventional technology: volatilizing the contaminants

The process uses in situ thermal desorption to treat soil through the extraction and phase change techniques to the contaminants contained therein by bringing the soil matrix temperature to the volatilization point. SVTE treatment consists of heating the soil to a temperature that will raise the vapour pressure of the contaminants sufficiently to remove them through “venting”. The contaminants enter the gaseous state in the soil and are then captured by a series of intermediary extraction wells to be treated through a variety of procedures (condensation/incineration of the liquid phase and treatment of residual gas with activated carbon). The surface of the treated soil is insulated to reduced heat loss and prevent rainwater infiltration.

2,000 m2 to be treated over a depth of five meters

The land that is still contaminated at the site will be treated over a depth of five meters in several phases, each lasting a period of two months. The nature of the contaminants and the treatment envisaged required an in-depth study of both industrial hygiene and procedure safety (risk of inflammability and explosion). In view of the innovative nature of the technique, the pilot received funding from the local Water authorities.

Environment expenses

Environment expenses have been restructured following recent significant acquisitions. This year, consolidated figures are presented again.

€ 110 million

Environment Operating Expenses

€ 52 million

Environment Capital Expenditures (excluding variable costs savings)

Environment Operating Expenses

Reported operating expenses (OPEX) related to the environment include the following items:

  • Estimated personnel costs from any staff working in the environmental field (FTE x average labor cost)
  • External expenses for waste treatment
  • External expenses for ongoing remediation activities
  • Fees paid to consultants to prepare environmental dossiers (impact studies, etc.)
  • License fees for specific environmental software packages (compliance, waste, etc.)
  • External expenses linked to obtaining or renewing external accreditations (ISO 14001)
  • Fees paid to external laboratories for compliance measurements
  • Discharge fees paid to local authorities

Environment Capital Expenditures (Capex)

Since 2016, all capital investments are declared and approved within a Group-wide information system and all feature a classification allowing them to be assigned to “environment protection”.

Other project investments that may have an environmental impact (which are categorized as “variable costs savings”) are not included in these Environment Capital Expenditures. Among such variable costs savings, raw materials or energy consumption reduction projects have not been considered as Environment Capital Expenditures.