The development project involves the construction of a secondary school and a socio-educational centre supported by the Vienne department, the community of municipalities and the municipality of Mirebeau (86). The project is located on Rue René Mabilleau in MIREBEAU (86). The plan is to create a complex comprising: a secondary school, a gymnasium and a dojo, a leisure centre, a network of mobile childminders, a parent-child drop-in centre, a childminder centre, a micro-crèche and staff accommodation.

A soil quality assessment was carried out by a third party in 2022 and highlighted anomalies in the future spoil from the project, generating additional disposal costs estimated at €165k.

The Vienne Department asked ABO ERG ENVIRONNEMENT to secure the financial and health aspects of the project and to avoid any land use restrictions in relation to the project.

The mission entrusted to us is a comprehensive project management assistance mission for the decontamination/rubbish management operations for the project as a whole.

ABO-ERG ENVIRONNEMENT thus provided the following services during the period from January to November 2024:
– Carry out additional investigations into the soil environment in order to gain a better understanding of the volumes of non-inert spoil and health aspects: 23 excavations using a mechanical shovel to a depth of 2 metres, sampling and laboratory analysis of soil samples.,
– Drafting investigation reports,
– Develop the Project Study/Management Plan in line with the project's characteristics, including a health risk analysis.,
– Assist the Vienne Department with the works contract, monitoring and acceptance of works.

The results of the additional diagnostic tests confirm:
– Metal anomalies in surface soils identified in the previous assessment carried out by a third party. Based on experience, the unacceptable risk of soil ingestion cannot be ruled out in relation to maximum arsenic and mercury levels. This aspect was taken into account by carrying out a predictive Residual Risk Analysis.,
– No anomalies found for the organic compounds tested for (HCT, PAH, BTEX and PCB) in the soil (levels below the reference values and below the analytical quantification limit).

The results of this additional assessment enabled the volume and management of spoil to be optimised in the event of off-site disposal. Unlike the previous assessment, a developed ISDI (or ISDI+) type facility was preferred to an ISDND facility.
After proposing three possible management scenarios, the client opted for off-site disposal of non-inert waste that was not compatible with health standards.
Overall, after earthworks, COLAS France removed a total of 868.7 tonnes of waste, which was disposed of in various ways under the supervision of ABO ERG Environnement:
– 96.5 tonnes in ISDI; ;
– 655.9 tonnes in ISDI+; ;
– 116.3 tonnes in the «Asbestos» sector (excluding the market).
Following this work and in view of the residual levels in the soil, the residual health risk becomes acceptable without any restrictions on use under the development project.
The cost of decontamination ultimately amounted to €32,000.