However, despite the attraction, there\u2019s still the thorny issue of pollutants and their impact on:<\/p>\n\n\n\n
- \n
- the environment<\/li>\n\n\n\n
- the project\u2019s budget<\/li>\n<\/ul>\n\n\n\n
Besides the financial aspects, managing a contaminated site requires knowledge of geology, chemistry and geochemistry, hydrogeology, health, risks, construction work, etc. The behaviour of pollutants in the various soil strata, as well as underground water and gases, creates a complex equation that calls into question conventional interpretations and mitigation solutions. Each polluted site is unique \u2013 and so is its management.<\/p>\n\n\n\n
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Understanding polluted sites<\/h2>\n\n\n\n<\/div>\n\n\n\nAfin de conna\u00eetre l’ampleur et la nature de la contamination, il est n\u00e9cessaire de r\u00e9aliser une \u00e9tude historique, investiguant l’utilisation ant\u00e9rieure du lieu. Les terrains, ayant pr\u00e9alablement accueilli des activit\u00e9s industrielles intensives ou des infrastructures telles que des stations-service ou des zones de stockage de d\u00e9chets, pr\u00e9sentent souvent une charge polluante \u00e9lev\u00e9e. L’enqu\u00eate historique s’av\u00e8re essentielle pour tracer les origines de la contamination. La gestion d\u2019un site pollu\u00e9 requiert la mise en place d\u2019une strat\u00e9gie de caract\u00e9risation sur la base d\u2019une s\u00e9rie d\u2019\u00e9tudes de donn\u00e9es historiques (origine du site, cession\/vente, modification des process\u2026), de donn\u00e9es de la qualit\u00e9 des sols, des eaux souterraines, des gaz du sol, des interactions entre les polluants, leur milieu et l\u2019environnement, de donn\u00e9es de dimensionnement des travaux \u00e0 mettre en \u0153uvre pour la r\u00e9habilitation du site et enfin des travaux. Toutes ces \u00e9tapes sont aujourd\u2019hui norm\u00e9es et font appel \u00e0 une r\u00e8glementation et une m\u00e9thodologie sur la gestion des sites et sols pollu\u00e9s parfaitement maitris\u00e9es par les acteurs des Sites et Sols Pollu\u00e9s en France (SSP).<\/p>\n\n\n\n
<\/div>\n\n\n\n![\"\"](\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\")
<\/figure>\n<\/div>\n\n\n<\/div>\n\n\n\nUnderstanding a polluted site therefore requires a multi-disciplinary set of skills and stakeholders, as well as investors willing to take up the twofold challenge of:<\/p>\n\n\n\n
- \n
- reducing these sites\u2019 impact on the environment<\/li>\n\n\n\n
- limiting the transformation of natural, agricultural and forest land for construction purposes<\/li>\n<\/ul>\n\n\n\n<\/div>\n\n\n\n
These benefits are what makes brownfield sites<\/a> so attractive on the commercial property market today.<\/p>\n\n\n\n
<\/div>\n\n\n\n
The challenges of decontamination in a highly regulated sector<\/h2>\n\n\n\n<\/div>\n\n\n\nBuilding on polluted brownfields requires a rigorous process when preparing bids and applying for planning permission.\u00a0The data on these sites can easily be called into question. GSE therefore establishes clear phases and milestones for communication on each project. During the sales phase, our in-house expert advice on polluted sites helps to reassure the various stakeholders regarding the levels of risk (planning, budgets, discovery, etc.) and the technical solutions suited to each issue. The aim is to implement virtuous projects while guaranteeing the highest levels of safety, pragmatic management and cost effectiveness.<\/p>\n\n\n\n
<\/div>\n\n\n\nMeanwhile, regulations and standardised methodologies for contaminated sites guarantee the quality of the advice and work provided by specialised contractors and a competent administration<\/p>\n\n\n\n
<\/div>\n\n\n\n\n\nFrance\u2019s Sites et Sols Pollu\u00e9s<\/em> methodology published on 9 April 2017 brings together all the best practices and willing stakeholders to respond to the shortage of land and contain urban sprawl. Today, regulations make it possible to qualify all of the environmental issues related to a site\u2019s liabilities: historical study, soil and groundwater diagnosis, implementation of a pollution mitigation plan, risks associated with residual pollution, works design plan and works execution. These stages are codified, making it easy to understand the operations carried out, their relevance to each project and the associated guarantees.<\/p>\n\n\n\n
<\/div>\n<\/div>\n\n\n\n\n<\/figure>\n<\/div>\n<\/div>\n\n\n\n<\/div>\n\n\n\nOwners and developers are required to comply with these standards, which include mandatory protocols for diagnosis, clean-up and post-rehabilitation environmental monitoring. This combination of technical expertise and regulatory compliance is essential to ensure the environmental rehabilitation and safe use of polluted sites.<\/p>\n\n\n\n
<\/div>\n\n\n\nDiagnosis, rehabilitation and adaptation to the environment<\/h2>\n\n\n\n
<\/div>\n\n\n\n\n\n<\/figure>\n<\/div>\n\n\n\n\n<\/div>\n\n\n\nProviding an accurate picture of the impacts of human activity on the environment or on an industrial site requires sampling, surveys, modelling and reporting. And beyond the metrics, thinking about the site\u2019s future use is essential in rehabilitation projects. In addition to financial considerations, the long-term vision is key to the planning of rehabilitation efforts. Simply put, the level of remediation of a site will not be the same for a future industrial facility and a future daycare centre. The rehabilitation effort will depend on the intended future use, the amenities to be offered and the target audience. This will enable local users to adopt the revitalised site. Through thoughtful redevelopment, we avoid the risk of seeing the plot turn once again to wasteland \u2013 in another 5 or 10 years\u2019 time \u2013 and give it a place in the future urban landscape.<\/p>\n\n\n\n
<\/div>\n<\/div>\n<\/div>\n\n\n\n<\/div>\n\n\n\n
What about technology in this grand scheme of things?<\/h2>\n\n\n\n<\/div>\n\n\n\nToday, in mature markets, companies specialising in depollution have a range of technical solutions to meet the demands of planning, cost and environmental & human risks.<\/p>\n\n\n\n
<\/div>\n\n\n\nThese techniques fall into 3 categories:<\/p>\n\n\n\n
Off-site techniques: these solutions handle depollution \u201coff-site\u201d, by excavating materials and removing them. This may include:<\/p>\n\n\n\n
<\/div>\n\n\n\nOff-site techniques : these solutions handle depollution “off-site”, by excavating materials and removing them. This may include : <\/p>\n\n\n\n
- \n
- Grounb excavations<\/li>\n\n\n\n
- Off-site washing<\/li>\n<\/ul>\n\n\n\n<\/div>\n\n\n\n
On-site techniques : these solutions process mat\u00e9rials on site once the polluted soil has been removed. There is an initial management phase, followed by impact treatment. For exemple (depending on the nature of the contamination) : <\/p>\n\n\n\n
- \n
- Ground excavation and particle size sorting<\/li>\n\n\n\n
- Ground excavation and mounding (biological or not)<\/li>\n\n\n\n
- Composting<\/li>\n\n\n\n
- Thermal desorption<\/li>\n<\/ul>\n\n\n\n<\/div>\n\n\n\n
In situ or “in the ground” techniques : these solutions process mat\u00e9rials from the surface, without and dedicated earth movement. Several subsoil strata can be treated at the same time, for exemple (depending on the nature of the contamination) through : <\/p>\n\n\n\n
- \n
- Venting of the unsaturated zone<\/li>\n\n\n\n
- In situ spaging<\/li>\n\n\n\n
- In situ chemical exidation\/reduction<\/li>\n\n\n\n
- Pumping-skimming<\/li>\n<\/ul>\n\n\n\n<\/div>\n\n\n\n
Multi-disciplinary collaboration therefore plays an essential role in remedying pollution and promoting environmental sustainability.<\/p>\n\n\n\n
<\/div>\n\n\n\nThe joint work of GSE\u2019s environmental engineer and our Polluted Sites and Soils (PSS) expert is essential. They have a major responsibility in assessing environmental impacts and developing strategies to mitigate them. Our environmental engineer always aims to preserve the local biodiversity specific to brownfield sites (fauna and flora), to orchestrate the sustainable management of the species identified and to encourage the reconstitution of ecosystems through the renaturation of sealed soils. This final stage enables us to propose the on-site management of contaminated materials (heavy metals in particular) by implementing landscaping solutions with appropriate plant cover, thereby reducing the site\u2019s environmental & health impacts as well as the project\u2019s carbon footprint.<\/p>\n\n\n\n
<\/div>\n\n\n\nPractical case : Ecological rehabilitation of an industrial site<\/h2>\n\n\n\n
<\/div>\n\n\n\n<\/figure>\n\n\n\nA GSE project: Creil \u2013 les Marches de l\u2019Oise.<\/p>\n\n\n\n
<\/div>\n\n\n\nThis site, formerly used for industrial activities, was severely contaminated by heavy metals. The project\u2019s configuration was constrained by a flood control plan (PPRI) near the site. The strategy adopted was to create vegetated rain gardens in line with the recommendations of the water regulations<\/a> dossier, while treating 18,000 m3<\/sup> of soil contaminated by heavy metals. The creation of the gardens enabled rainwater to be managed at the plot level, while securing reabsorption through rehabilitated soil. These steps and opportunities for rehabilitation were proposed to our client, who approved the operations.<\/p>\n\n\n\n
![\"\"](\"https:\/\/www.gsegroup.com\/wp-content\/uploads\/2024\/08\/SSP_2-1024x683.jpg\")
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