Stopped since March due to pollution, this construction site in the city center of Saint-Nazaire is restarting

After only two months of work, rue Jean-Jaurès, the construction site of the Maison de l’Habitat in Saint-Nazaire (Loire-Atlantique) was already at a standstill. On Wednesday March 13, 2024, the Burgeap-Ginger design office, mandated on this project, informed the Saint-Nazaire metropolitan area that recent pollution had been detected in the soil. “Hydrocarbons have been detected. During the surveys carried out in October 2022 as part of the soil study prior to the construction site, the analysis results did not reveal any pollution,” explained the City of Saint-Nazaire in a press release.

A complaint had been filed by Carene. “The occurrence of pollution in the city center is not trivial and could come from a malicious act,” explained the agglomeration.

Clean up the site

Stopped since today, the construction site resumed this Wednesday, June 26, 2024.

The necessary samples and analyzes were carried out. The results are now known and decontamination of the site can begin.

The new samples have confirmed pollution discovered in March 2024. But the “results do not make it possible to define its origin”.

The measurements of the air quality and drinking water carried out on the two riverside plots “did not reveal any pollution above regulatory thresholds”. A second campaign will be scheduled this summer to confirm these results in summer weather conditions.

Polluted land evacuated

The depollution of the site will be carried out in two stages. The first step consists of a deep excavation of the soil where the pollution was discovered. “During extraction, in order to minimize olfactory discomfort, a suction system will be put in place as well as a odor masker », specifies the agglomeration. The extracted earth will be evacuated off-site through the usual approved treatment channels.

The second stage will consist of treating the soil by biological oxidation in order to accelerate the natural degradation of hydrocarbons.

Its action will be to restore the soil and water table in the most natural way possible.

Air quality monitored

The decontamination should be finished at the end of July. The structural work will start after the summer break. “As a precautionary measure, a crawl space will be created throughout the building to allow mechanical ventilation and thus capture any residual gases. »

A sensor in the patio will allow air quality to be monitored over time.

The cost of this work is estimated at just over1 million d’euros. Saint-Nazaire agglomeration will submit a subsidy application to obtain State participation as part of the brownfield fund.

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