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Risks and spatial planning

Highlights

Fait marquant

Mapping of lithological site effects on a European scale

As part of the European H2020 SERA project (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe), BRGM contributed to the European Seismic Risk Model 2020. This concerned simplified mapping of lithological site effects on a European scale (1:1,500,000) and led to several maps being produced, including lithological and stratigraphic maps.

Major asbestos-related projects

Regarding asbestos from buildings, PLASMIANTE and LODAIM, two projects funded by the French Asbestos Research & Development Plan (PRDA), achieved encouraging initial results on the presence of asbestos in the air and in materials. As for the PIMAC process, developed to examine the capacity of quarry materials (aggregates, etc.) to emit asbestos fibres, it is currently being adapted to study loose material in New Caledonia (sand and alluvium).

Technical support with pipeline leaks

A ruptured light-crude-oil pipeline and an aviation fuel leak in the Île-de-France region: BRGM was consulted by the regional and interdepartmental authority for the environment and energy (DRIEE) on two occasions in 2019. It was asked to estimate the time it would take for the pollutants to spread, in order to determine the degree of urgency in implementing measures to cut off the transfer routes and provide recommendations on how to manage this pollution.

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A ruptured pipeline resulted in watercourses being contaminated by oil (Yvelines). BRGM was asked to help circumscribe this pollution. © SDIS 78 - F.B oubet - L. V. Bolivia-Kahn

Remote sensing and natural risks with Geohazard Lab

As part of the Geohazard Lab project, funded by ESA and CNES, BRGM was tasked with promoting and organising a community of users of data from Copernicus satellite missions for studying natural risks. Its initial work involved research on land subsidence in Jakarta (Indonesia), cavities in Rome, and the study of volcanic mechanisms on the island of Santorini.

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Ground displacement map based on multi-temporal interferometric processing by ESA’s Geohazards Exploitation Platform (GEP). © Contains modified Copernicus Sentinel data (2019), processed by ESA GEP, CNR-IREA & BRGM

Acquisition and remote sensing for studying clay-soil shrinkage and swelling

For the past three years, the new experimental site at Chaingy, in the Centre-Val de Loire region, has been monitoring an area that is highly exposed to clay shrinkage and swelling. This monitoring combines in situ observations using extensometers and humidity sensors with time series data acquired by the European Space Agency (ESA) Sentinel-1 and SMOS satellites. The initial findings suggest this could be an innovative method for characterising the phenomenon of shrinkage and swelling using remote sensing.

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Injecting electricity to measure the depth and thickness of the clay layer using electric resistivity tomography (ERT) (Chaingy, Loiret).  © BRGM - A. Burnol

Risks of arsenic exposure from agricultural land

The aim of the AgriAs project, coordinated by the Finnish geological survey (GTK), is to evaluate and manage arsenic contamination in agricultural soil at the European level. BRGM is responsible for quantifying and modelling the effects of agricultural practices on the concentration, bioavailability and mobility of arsenic in water and soil.

Origin of an earthquake and ground movements in Maceio

BRGM conducted expert appraisals in the second half of 2019 on behalf of the Brazilian chemical and mining group BRASKEM. The aim was to determine the origin of an earthquake and ground movements affecting certain districts of the city of Maceio. These events, attributed to mechanical instabilities in salt-leached cavities in a saline formation at a depth of nearly 1000 m, led to a critical analysis of the geophysical methods used for imaging geological formations, structures and cavities.

Assistance with sustainable development for two African countries

Central African Republic: the BRGM-INSUCO-ONFI consortium provided five tools to help with environmental and social protection as part of the country’s natural resources governance project (PGRN). In particular, BRGM contributed to the environmental and social management framework, the pesticide management plan and the operational framework.
Morocco: BRGM is a stakeholder in the Franco-Austrian twinning agreement to support implementation of the National Charter for the Environment and Sustainable Development. BRGM is involved in activities related to strategic environmental assessment, environmental auditing and environmental policing of industrial pollution.

Post-mining / Management of minewater pumping stations

Leaks due to widespread corrosion of part of the pressure line were discovered at the Bernicourt water pumping station (SRE) at Roost-Warendin in the Nord département. This led to fears of flooding over a vast urbanised area and risks to neighbouring buildings in the event of a sudden break in the section. BRGM conducted a comparative review of possible solutions coupled with a risk analysis covering intervention on private property, marshy terrain, presence of HV lines, substantial earthworks and complicated handling operations, unfavourable weather, very tight repair times, etc. Its work helped ensure continuity of service, and the pipe sections were renewed before the facilities were brought back into service.

Post-mining / Reinforced monitoring of Salsigne and the Orbiel valley

After the exceptional rainfall and flooding in late 2018, several measures were introduced to better assess the impact of these bad weather events on the evolution of pollution. Soil quality monitoring at flooded schools, playgrounds and sports facilities revealed levels of pollutants that were incompatible with certain human activities. Signage at polluted former mining sites and fencing around the most sensitive areas was also reinforced.

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Investigations using a portable X-ray fluorescence analyser. © BRGM

Post-mining / Launch of a new website

The website of BRGM’s Mine Safety and Risk Prevention Department (DPSM) has been completely redesigned. The aim is to promote BRGM’s work in the post-mining sector and meet the needs of its partners. Available in three languages (French, English and German) on https://dpsm.brgm.fr, it provides all the latest news on the post-mining mission entrusted to BRGM and carried out by its DPSM. It features articles on studies and monitoring, mining information (essential for sellers of land affected by former mining operations), mining heritage and mining archives, as well as on the post-mining regulatory framework.

Post-mining / Securing the Gros Chêne shaft

Following subsidence in the cemetery of Montjean-sur-Loire (Maine-et-Loire) in 2018, related to a possible cave-in at the Gros Chêne coal shaft, BRGM carried out safety engineering work. The old shaft was found, and a peripheral base was created on the hard rock to support the surface plug. Around 45 tonnes of rockfill and 27 m³ of concrete were needed to fill the structure. A location marker was erected on the centre of the structure as a reminder.

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Drone view of the sinkhole in the Gros Chêne shaft in the middle of the cemetery at Montjean-sur-Loire: 27 m³ of concrete was required to secure it. © BRGM

Post-mining / Demolition of the gas stations of the Lorraine coal basin

When mine safety facilities were transferred to the government and BRGM’s DPSM took over operations in 2008, there were still five gas capture and compression stations together with more than 20 km of pipelines in operation in the Lorraine coal basin. These stations were gradually phased out from late 2011, and those of Simon, St-Charles and Marienau were destroyed in 2019, with demolition of the old workshops, removal of gangways and chimney felling. Work on Peyrimhoff has been planned for 2020-2021, to be followed by dismantling of the pipeline system.