Exhaust particles, fuel, oils, tire or pavement wear, heavy metals… A toxic cocktail accumulates on the roads, until they are washed away by the rain which streams on the asphalt.
And after ?
Massively polluted water is supposed to be treated.
In theory only.
Because in practice, it is not uncommon for them to be directly rejected as such in the natural environment, in general indifference ... or almost: the Association for the protection of the environment of Polangis and the quai de la Marne (Asep) in Joinville-le-Pont (Val-de-Marne), is among the indignant.
Forty-five years she has been trying to make her voice heard.
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“We created the association in 1975, when the A86-A4 was built, originally to have noise barriers that we still don't have,” explains Michel Riousset, its president.
And very quickly, with each rain, we saw the water rushing down from the motorway and pouring directly into the Marne, without going through a settling basin, nothing!
“Beyond this chronic pollution, the sector is exposed to a risk of ecological disaster.
“What would happen if a truck overturned with a tank of gasoline or chemicals?
asks Michel Riousset.
Everything would end directly in the Ru de Polangis et la Marne, and too bad for all that lives there!
"
"Each new prefect seems to discover the trick"
The ASEP is not the only one to have seized the problem of the common core A4-A86, the busiest highway in the country with 250,000 vehicles per day on average.
Successive mayors seize the state regularly.
“Each new prefect seems to discover the trick, annoys Olivier Dosne, the mayor (LR) of Joinville-le-Pont.
The State not being there, once again, we have to assume, ”says the elected representative, who has“ good hope of finding a solution with the territorial public establishment or the region ”.
On the common A4 - A86 section, the busiest motorway in France with 250,000 vehicles per day, rainwater becomes loaded with pollutants and flows into a ditch before being discharged directly into the Marne.
Her letter
(read torn)
addressed to Emmanuelle Wargon on November 12, 2019, remained a dead letter, summarizes the whole situation in a few sentences. “It is an essential subject for the quality of the waters of the Marne and therefore for the environment. (…) The State does not seem to want to assume its own responsibilities, all governments combined. “Even though the Baignade plan is supposed to make the Seine and the Marne swimmable on the horizon of the 2024 Olympic and Paralympic Games.
However, in 2011, to a question to the government that Olivier Dosne put to him, Nathalie Kosciusko-Morizet, then Minister of the Environment, replied that the "A4-A86 common core sanitation project is under study" . "It plans (...) to remedy the direct discharge of pollutants to the Marne by building three treatment stations," explained the minister at the time. (Which) requires more in-depth studies and a public utility declaration procedure. These should respectively be carried out in 2011 and 2012. "Ten years later," the file is at a standstill, "laments the mayor of Joinville-le-Pont. Contacted, Nathalie Kosciusko-Morizet could not be reached.
This "black spot" for the environment is not an isolated case, far from it.
Still in Val-de-Marne, the president of the Paris Est Marne et Bois territory split a letter to the prefect, shortly before being elected president of the departmental council.
While "the State is requesting the territory with the objective of de-pollution of the Marne in the perspective of the Olympic Games", recalls Olivier Capitanio (LR) in his letter, "we do not understand that the State does not show the example and we regret that a difficulty reported to the Direction des routes d'Île-de-France
(Dirif)
for years has still not been resolved and leads to pollution of the Gravelle arm in the immediate vicinity of a future bathing point ".
A subject that transcends political parties
This time, the new president of the departmental council wants to be optimistic. "The new prefect took up the file, we went there together in July, meetings were set up with the Dirif," lists Olivier Capitanio. I feel that there is a real will to act. It remains to assess the means… ”When contacted, the prefecture did not respond to our requests.
The subject transcends political colors. Before him, the Communists of the departmental council were also worried about the situation. "The runoff from the highways is the poor relation of the state, deplores a member of the former team. A collector in the Thiais-Rungis sector discharges the water directly into the Seine near Orly-Choisy: it is just a pipe without any development that leads the polluted water as it is to the Seine, draining a watershed extremely important including all the south of the 94 and the northern part of the 91. "
An incident as costly as it was astonishing "highlighted the extent to which the remediation of highways is forgotten by the State". During the construction of the extension of line 14 to the south, the engineers drew up its trajectory and called on all potential owners of any underground network on the route to make themselves known. “The tunnel boring machine started digging and, on October 23, 2019, patatras! Between the Pont-de-Rungis and MIN-Porte-de-Thiais stations, he taps the collector which brings water directly from the motorway to the Seine… ”The episode was the subject of several exchanges between the Dirif, the Intercommunal Sanitation Syndicate of the Paris Agglomeration (SIAAP), the Department of Environmental and Sanitation Services of 94 and the RATP, to try to understand who owns this 2 pipe,10 m in diameter.
"The state is so disinterested in the issue ..."
Finally, "the documentary research leads to a file relating to the construction of a sanitation work on the A86 motorway, whose characteristics correspond to those of the work encountered", indicates the report from the project management department. RATP projects.
"An element of the highway sanitation network that the state had not reported!"
indignant a connoisseur of the file.
He then discarded himself by asserting that he had transferred it to communities decades earlier, without ever being able to prove it.
The state is so disinterested in the issue that it no longer even knows how the network is made up.
It must be said that the Dirif workforce is melting like snow in the sun… ”
While the managers of conceded motorways, such as the SAPN for part of the A1, A4, A13 and A16 motorways, communicate widely on their investments to create new basins along the motorways built before 1992, the information is collected on account- drops for state-run roads. Contacted several times to draw up an inventory of black spots in Île-de-France, as well as the list of highways where work is scheduled or carried out, the Ministry of Ecological Transition has “unfortunately no additional information or further details to be communicated on this subject ”.
The Dirif as well as the water police are not more open on the question. "The rainwater treatment of the roads and highways in the Ile-de-France region was designed, during their construction, according to the standards of the time, sometimes with direct discharges of rainwater into the natural environment, recognizes the Regional and Interdepartmental Directorate for the Environment. , planning and transport (DRIEAT), which oversees the two services. The State is committed to the modernization of these rainwater networks, which is being done gradually in order to take into account the new discharge standards, depending on budgetary availability and local technical constraints which do not always allow easily land allowing the installation of the necessary settling basins. "
Concretely ?
Any request for clarification, in particular on the work already carried out and the schedule of scheduled sites, is met with an end of inadmissibility.
“We will not go further than the response previously provided,” concludes DRIEAT.
Pollution volumes are known
However, in 2014, the Ministry of Ecology at the time, questioned by Jean-Louis Masson, senator from Moselle worried about the pollution of a river by rainwater from a portion of the A4, provided a firmer response: “The A4 motorway having been brought into service in 1976, the motorway concession companies were not yet subject to these environmental requirements. However, following the publication of the 1992 water law, they had to carry out the necessary work in order to intercept pollution caused by rainwater runoff from their roads. However, it happens that the work has not yet been carried out everywhere. If pollution is observed following poor management of rainwater from the A4 motorway,the Prefect can be called upon (…) to set specific prescriptions in order to remedy this. If this proves to be justified, the Prefect may then require the Société des Autoroutes du Nord et de l'Est de la France (Sanef) to settle the pollution peaks of which it is the source through the installation of management structures. and rainwater treatment. "
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Only in Île-de-France, most of the highways are not entrusted to private operators but managed directly by the services of the State… which refuses to communicate on what is necessary or not.
However, he is well aware of the pollution generated by the roads. In 2002, a report by the Parliamentary Office for the Evaluation of Scientific and Technological Choices on the Quality of Water and Sanitation in France devoted an appendix to rainwater on highways and airports, based on the hearing two research directors from the Ponts et Chaussées central laboratory. "Automobile traffic is the source of several polluting deposits: hydrocarbons (oil and gasoline), nitrogen oxides (from exhaust gases), chlorides (de-icing salts), metals from tires (zinc, cadmium) , brakes (copper), or pavement (erosion of bitumen coverings, zinc guardrails) ”, begins the report.
The study of the quality of rainwater in peri-urban areas, carried out on a regional motorway roadway (A11 in Nantes), made it possible to precisely quantify the pollution volumes: "A medium-sized motorway (25,000 vehicles per day) ) produces one tonne of suspended solids per kilometer per year, including 25 kg of hydrocarbons, 4 kg of zinc, 0.5 kg of lead.
Sandblasting, a mixture of sand and salts, represents an input of material of the order of 5 to 10 tonnes per kilometer.
The A4-A86 section is ten times more frequented.
Billions of liters of polluted water potentially released each year
First lesson: the indicators of pollution in the runoff water of the motorway studied are higher than those of a regional airport.
Worse still, they have been compared to “the regulated values of discharges from installations classified for environmental protection (ICPE) and quality limits for the production of water intended for human consumption”.
The results are clear: “The importance of suspended solids, hydrocarbons and chlorides observed in runoff from highway water greatly exceeds the aforementioned regulatory values.
"
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If the authorities do not communicate, they have nevertheless made arrangements, in particular by creating pipes along the A6 motorway in Essonne, to direct this polluted water to a treatment station. Only, “this is not the solution, annoys a hydrologist campaigning against soil permeabilization. While the small rains could perfectly be treated on site, by filtration with adapted plants and minerals before reaching the subsoil, we clog the stations that can not cope. It's like putting a glass of water at the foot of a gutter: it overflows. While a small garden absorbs water and well-chosen arrangements filter pollution. "
In Île-de-France, the Dirif manages “1,300 km of national roads and non-licensed highways, where 10,000 to 250,000 vehicles circulate per day depending on the axis, the equivalent of 2,500 football fields”.
With 650 millimeters of precipitation per year, or 650 liters per square meter, the multiplication makes you dizzy: a dozen billion liters of polluted water potentially released into the natural environment each year.