SGEvT: wild deposits scrutinized from space

The General Society for Territorial Evaluation (SGEvT) was created in 2015 and has developed a platform that brings together several dozen indicators and decision-making tools intended to support local authorities in the management of their territory. Among these tools, we have recently found a solution to identify, qualify, but also prevent illegal dumping of waste.

An “indicator”. This is what has been developed – and continues to be enriched – by the General Society for the Evaluation of Territories (SGEvT), a Toulouse-based company born in 2015 under the impetus of Nancy Oliveto in particular, lawyer, urban planner and former consultant within sustainable development. Dubbed TEREvAL, this library of indicators and decision support tools now includes almost sixty, intended to guide local authorities in their territorial development projects. The birth of this veritable “dashboard”, like that of the company, is closely linked to the Grenelle de l’environnement. Arnaud André, co-founder and president of SGEvT talks about it: “The Grenelle de l’environnement gave rise to the obligation for local authorities to develop plans for the sustainable development of the area.[1]. The number of subjects to be included in these plans has greatly increased to take into account aspects such as energy efficiency, artificialization of the soil, etc. The second obligation was also for these local authorities to assess the effectiveness of their plans. The company was therefore created based on the idea of ​​providing the local authorities with tools that constitute a dashboard that allows them to monitor the effect of the completed projects over time”.

This platform, which is scalable, is constantly enriched by the needs expressed by SGEvT’s customer communities. “As the projects progressed, various topics emerged, such as the city limits, i.e. the city’s borders. We have therefore created algorithms to help establish this envelope, but also to verify compliance with the regulations that have been made.”, explains Arnaud André. Recently, the SGEvT also addressed a topic of increasing importance: illegal dumping.

Identify, qualify, but also prevent illegal dumping

Led by Ademe, a survey conducted in 2018 among 2,652 local authorities revealed that almost 90% of them then faced the problem of illegal dumping. However, as the agency noted in the report published after the completion of this investigation[2], “There is no exhaustive inventory of the situation of illegal deposits (amounts and types of deposits) at national level”. However, a tool developed by SGEvT could change the situation. Indeed, the company has developed a remote sensing solution that aims to identify but also to qualify these deposits (extent, date of occurrence, risks to the environment, etc.) and even to identify areas that are particularly exposed before the waste occurs. illegal dumping.

Few French communities are not affected by the problem of illegal dumping. However, it is still difficult to establish an inventory at national level. © SGEvT

“Thanks to the connections we have had for years with CNES, we proposed to them to create an offer based on the Pléiades satellite images, crossed with our contextual knowledge of the territory: emergency aid, occupation of the plots, transport networks…”, reveals Arnaud André. Begun in late 2019, the process culminated in 2021 with the commissioning of this unique remote sensing tool. “The development took time. It is actually necessary to detect shapes on satellite images which could be wild deposits, but which could also be simple rocks or rivers for example. Algorithms therefore need time to learn, to gradually correct their mistakes.notes the chairman of SGEvT.

A solution that has already proven itself in the field

The spatial resolution of the images taken by the Pléiades satellites makes it possible to detect deposits from about fifty square meters. © SGEvT

Once discovered, each occurrence is graded according to criteria such as its proximity to a stream, an underground water table, schools or other sensitive locations. “This tool that we have developed contains priority elements that make it possible to answer the question “which filing should be processed first?” », emphasizes Arnaud André. Added to this is the interest in identifying sensitive areas that promote the emergence of wild deposits. Zones that, when demarcated, can thus be subject to enhanced surveillance. “We also provide intervention tools, adds the co-founder of the company. At the end of 2021, we helped the police carry out an effort in the Aude, over several hundred km². We produced sheets for them indicating the size of the depots, the conditions of access to reach them, etc. Thanks to this, the gendarmes went into the field and in one afternoon they were able to do a job that would have taken them several days, maybe even more than a week, without our tool. »

Implemented at the end of 2021 by the Aude gendarmerie using data and indicators provided by SGEvT, an initial intervention campaign proved to be particularly fruitful. © SGEvT

In terms of reliability, the tool offered by SGEvT proves capable of achieving a detection rate of at least 90%, according to the company’s president, who nevertheless admits: “If the deposit is invisible from the satellite, we will obviously not detect it. This is the case, for example, with what is under plant cover. Having said that, it depends on the season.”. In addition to this limitation, the size of the deposits is also important: with a resolution of 50×50 cm, the images from the Pléiades satellites allow the detection of deposits from a few tens of square meters. “A simple plastic bag full of garbage will not be detected”, thus citing Arnaud André as a counterexample. The future Pléiades Neo constellation, with its spatial resolution of 30 centimeters, promises to make the detection threshold a little lower still.

The tool, which is available through the TEREvAL platform, generates in particular intervention sheets to guide the actions carried out in the field. © SGEvT

Expanding its range of tools: SGEvT’s raison d’être

After the success of the project carried out in Aude, SGEvT now hopes to be able to offer its solution to many other local authorities. “There are many interests and subjects to be studied. Not only from local authorities, but also from collection manufacturers who see new opportunities in it”Arnaud André rejoices.

For a subscription of a few tens of thousands of euros per year – depending in particular on the size of the area to be covered – the functionalities for detection, assessment or definition of means of access are thus already available via the TEREvAL platform. “And of course there will be material to complete these functions with other ideas”gives the president of the company.

An extra string is thus added to the bow of the “indicathèque” developed by SGEvT. A platform that will also soon be expanded a little more with the addition of other tools, which Arnaud André finally reveals: “We have a whole offer in relation to proximity, and we work on local health contracts, for example[3]which has become an emergency for many territories”. And the leader concludes: “Providing communities with the widest possible collection of tools is our raison d’être”.


[1] Territorial climate-air-energy plans (PCAET), made mandatory by the Grenelle 2 law for communities with more than 50,000 inhabitants, and now mandatory for all inter-municipalities with more than 20,000 inhabitants (threshold lowered in 2018).

[2] ADEME, ECOGEOS. 2019. Characterization of the waste problem. Report. 84 pages.

[3] Tools carried jointly by the Regional Health Agencies (ARS) and local authorities to reduce territorial and social inequalities in health.

Leave a Comment