Risks and spatial planning

Highlights

BRGM becomes a player in the CoCliCo project, a climate service for coastal adaptation

The purpose of CoCliCo is to develop a climate service for coastal adaptation in Europe. The project will provide data on waves, surges, rising sea levels, flooding and erosion hazards, as well as on the vulnerability and exposure of people and infrastructure, based on several climate change, socio-economic and adaptation scenarios. The target observation scale of 25m complements the high-resolution submersion work conducted by BRGM as part of coastal risk prevention plans. The service will take the form of a platform, implementing the FAIR principles for research data management (Findable, Accessible, Interoperable, Reusable).

Example of a map created using the CoCliCo portal. Here, a map of low-lying areas below the high tide mark, with a 1m rise in the sea level superimposed. © BRGM

Karst risk on Avenue Gaston Galloux in Orléans

BRGM has conducted studies on the karstic risk affecting a busy avenue in the city of Orléans, looking at aspects ranging from hazard mapping to the study of risk management strategies; Crossed by the Loire and providing fast access to the northern and southern sides of the town, Avenue Gaston Galloux is located in an area with a risk of karstic collapse, potentially causing craters up to 10m in diameter. BRGM has assessed the risk of ground movements through in-depth geotechnical studies and an innovative method. The resulting recommendations include a programme of investigations to clarify the risk, together with a series of proposals to integrate these phenomena into crisis management scenarios.

Karstic collapse measuring 6m in diameter and 3.5m in depth at La Levée de la Chevauchée in Saint-Jean-le-Blanc, north-central France. © BRGM - B. Chevrier

Fault characterisation and seismotectonic zoning on the island of Hispaniola

Following the earthquake that devastated the region of Port-au-Prince, capital of Haiti, on 10 January 2010, BRGM carried out several seismic microzoning operations in Haiti and the Dominican Republic. The results obtained were published in a summary study on the characterisation of active faults, with the implementation of seismotectonic zoning across the island of Hispaniola. In addition to providing an overall view of the two countries, these results provide an essential information base for a homogeneous assessment of seismic hazards in Hispaniola.

Map of the seismotectonic zoning of the island of Hispaniola. © BRGM

West Indies: treating arsenic and chlordecone in sargassum

LThe purpose of the ANR SargAs&CLD project coordinated by BRGM in partnership with the universities of Orléans, Pau, French Guiana and the Antillies, together with the company ADERA/UT2A and the University of Texas, is to chemically characterise the juice from the sargassum washed up on the beach or stored inland in the Antillies. The purpose is also to suggest innovative methods for treating both arsenic and chlordecone, an insecticide that is bioaccumulated by sargassum. Lastly, the social acceptability of sargassum storage was analysed. This work made it possible to locate the arsenic and to analyse its speciation in sargassum cells. Analyses showed that arsenic is present primarily on cell walls and, more particularly, that it is found mainly in inorganic form. This suggests that arsenic, which occurs naturally in the sea, builds up spontaneously in sargassum, owing to its chemical similarities with essential nutrients such as phosphates.

Sargassum processing pilot. © DEAL Martinique

Prioritisation of emerging chemical compounds in soils

The approach of the PREMISS R&D project is to prioritise emerging chemical compounds in soils (CECs). Coordinated by BRGM and carried out in partnership with Dutch and Belgian teams, PREMISS has made it possible to synthesise data on the occurrence of CECs in soil, sewage plant sludge, sediment and groundwater in France, Belgium and the Netherlands. A prototype for prioritising CECs according to their concentration (in water and soil) and toxicity has been designed and tested for a set of compounds with heterogeneous properties.

SOILVal: soil quality and legal instruments

BRGM coordinated the European research programme SOILval, funded by the European platform SOILveR, which seeks to promote integrated and cross-border research on soil and land management. The objective was to assess how soil functions, and the associated ecosystem services are recognised and integrated in spatial planning and development in France and Wallonia. A legal analysis looked at the way in which soil quality is considered by legal instruments, while a state-of-the-art review studied soil reclamation solutions. Decision-making tools were produced to support the implementation of these solutions, and a knowledge review carried out concerning soil quality in France and Wallonia. Based on these results, a number of recommendations were drafted and are now available on the SOILveR website.

DEPOLOND2, microwaves to volatilise organic pollutants

In partnership with SUEZ and EDF, BRGM conducted DEPOLOND2, a project whose purpose is to use microwave energy to volatilise organic pollutants.
The experimental set-up consists of a 2m antenna (2.450 GHz, 2 kW) inserted in a column of sand in near-field conditions. The results are promising and contribute to a clearer understanding of heating dynamics, owing to the presence of 62 temperature sensors. The next step will be to support the heating process by injecting air through the antenna in order to better diffuse the heat into the ground.

DEPOLOND2, microwaves to volatilize organic pollutants. © BRGM - Didier Depoorter

Post-mining / Building and commissioning a drawdown system in Lochwiller

Following the sinking of a 140-metre long geothermal probe in 2008, water from a deep confined aquifer (Lettenkohle and Muschelkalk) began to rise, seeping into the anhydrite layers of the Keuper. This anhydrite was turned into gypsum by a process of hydration, and began to push up the surrounding land, damaging buildings, disrupting the lives of local residents and bringing urban development to a halt.

To mitigate or stop this phenomenon, it was decided to pump water out of the deep aquifer. The project aims to neutralise the upward circulation of water along the faulty geothermal borehole to prevent it from hydrating the Keuper levels.

The construction of the first 140-metre piezometer provided extensive information on local hydrogeology, with the execution of numerous tests and logs. These data were used during the course of the project to adjust the dimensions of the other boreholes.
In in its role as delegated project manager for the government. the DPSM built and commissioned a drawdown borehole associated with three control piezometers, This system has made it possible to prevent water from the deep aquifer rising up through the geothermal borehole.

Post-mining / UTAM South: water for heating and cooling from the former Gardanne coal mine

Since the spring of 2021, BRGM's Department of Mine Safety and Prevention has been using water from the former Gardanne coal mine, which closed in 2003, for heating and cooling the 560 m² of office space occupied by UTAM South.

The Yvon Morandat shaft, the biggest mine shaft in Europe, contains approximately 60,000 m³ of available free water at a temperature of nearly 30°C.

Water is pumped from a depth of over 300m and then reinjected into the base of the borehole. The water collected runs through a titanium exchanger on the surface to fill two 50 m³ steel tanks. It is then pumped out and used to deliver fluids at 40°C or 10°C in order to provide heating or cooling, depending on requirements.

Diagram of the geothermal principle. © BRGM

Post-mining / Renovation of water pumping stations

Through its UTAM North entity, the DPSM manages 52 water pumping stations in the French départements of Nord and Pas-de-Calais, on behalf of the government. Sometimes, the stations are in an advanced state of dilapidation and require extensive renovations. This was the case of the Cité Dincq water pumping station in Waziers, northern France. Working in its capacity as delegated project manager, the DPSM fully renovated and upgraded this station in 2021.

Given that the station receives huge inflows of highly corrosive wastewater and anthropogenic waste, it was equipped, among other things, with an automatic screen to prevent clogging, a waste compactor to reduce the volume of some three tonnes of miscellaneous waste per year, and a second pump for use during dry weather to ensure continuity of service, using high-performance technologies. The civil engineering structures were also renovated, with the station acquiring high-quality external cladding, for a perfect fit with the urban fabric and the total satisfaction of local residents.

Post-mining / Management plan for the Auzelles colliery waste tip

The DPSM was commissioned by the DREAL ARA to draw up a management plan for the Auzelles colliery waste tip, which is located in a Natura 2000 nature protection area in central France. This tip of approximately 4 ha has an estimated volume of 150,000 m³ of mine tailings containing high levels of lead, zinc and arsenic. It is also on steeply sloping ground (average gradient of 40%). A detailed understanding of this site was required in order to target and prioritise management measures. The DPSM placed instruments on the site and monitored it for two years in order to refine the conceptual design. Quantification of the transfer pathways showed that water erosion played a dominant role. A zone-based approach was implemented in order to find the best cost-benefit balance. For the different zones, the scenario recommended by the DPSM is based either on conventional solutions (containment) tried and tested at similar sites, or innovative solutions (phytostabilisation) with a lower environmental impact and that are also better suited to sites where access is difficult. The implementation of these management measures is being scheduled.

The Auzelles colliery waste tip. © BRGM - L. De Lary De Latour