5,000 tons of nitrocellulose at the gates of Toulouse: the rehabilitation of gravel pits in the preparatory phase
How to safely evacuate the 5,000 tonnes of nitrocellulose stored at the bottom of four lakes south of Toulouse? Experts are still working on technical solutions for work planned in two years.
The rehabilitation operation of the gravel pits site near the current Toulouse Oncopole, became last year, is still in its preparation phase. It must be said that the construction site is delicate. It involves extracting from the bottom of the water nearly 5,000 tons of nitrocellulose, a propellant powder used in armaments and manufactured during the First World War in the former national gunpowder factory and stored since then in four artificial lakes, A progress report was made last week by representatives of the State, the Ministry of the Armed Forces and Toulouse Métropole, who met at the prefecture for a presentation of the technical options, which could, eventually, to safely remove the nitrocellulose from the site while preserving the richness of its fauna and flora. During this monitoring committee, the Ministry of the Armed Forces, responsible for this installation classified for the protection of the environment (ICPE), presented the measures taken to maintain the security of this storage site which contains approximately 4,200 tonnes of nitrocellulose powder immersed in the four gravel pits and 500 tonnes of powder scattered in the land along the banks.
Naturalistic and hydrogeological studies
With a useful reminder from a safety point of view: these powders do not explode in the open air and pose no risk to residents or the environment, because nitrocellulose is not soluble in water and does not is not a chemical pollutant. A naturalist study began in April 2021 over four seasons, the conclusions of which are expected soon. The Ministry of the Armed Forces will rely on these to reconcile its commitments on the rehabilitation of the site and the preservation of this rich environmental heritage. A hydrogeological study of the site has also been programmed. In particular, it will make it possible to characterize the hydraulic functioning of this remarkable site that Toulouse Métropole wants to classify, ultimately, as a natural area.
Regarding the search for technical solutions for future work, a call for expressions of interest has already prompted applications from specialists in fields relating to pyrotechnics and the rehabilitation of industrial sites. Ten companies, some of which are international in scope, presented their specific skills as well as their innovative processes. The work should start in 2024, for a duration that is still difficult to assess with regard to environmental requirements.