What kind of environmental impact will the new B Line of the Rennes Metro have? What kind of “compensatory” measures will be put in place for the local fauna? All throughout the construction site, an ecologist is tasked with the analysis and protection of ecosystems.
After civil engineering comes environmental engineering. At the construction site for the B Line of the metro, an in-depth examination about its environmental impact will be carried out. Which species will be disturbed by the metro passage? How can these problems be resolved? Paul Bernard is an ecologist for DM Eau, a company that is joining Semtcar in the process of ecological monitoring. “Our profession is not new, but it is becoming broader in scope. We evaluate the project’s negative impact on biodiversity, then we propose compensatory measures, techniques for improving the natural habitats of threatened species.”
The tunnel section beneath the downtown area will only have a very small impact on the environment. The affected zones are located at the far ends, in Saint-Jacques and in Courrouze (a cut-and-cover tunnel) and also in Longs Champs and in Cesson-Sévigné. “From now on, the law requires a process of ecological monitoring that can be summarized as 'avoid, reduce, and offset.' A natural habitat can only be eliminated if it is impossible to do things differently. Everything must be justified by the National Council for the Protection of Nature," explains Paul Bernard.
Making Up for 1,000 Trees to be Cut Down
If the analysis of Line B’s path did not reveal any challenges vis-à-vis the flora, the case for local fauna was another story. In Rennes, many protected species of birds will be disturbed: chickadees, robins, woodpeckers, sparrows, as well as flying mammals like bats. “More than 1,000 trees are going to have to be cut down throughout the city. It will be necessary to recreate this habitat. The other species affected include amphibians (newts, salamanders, frogs), hedgehogs, squirrels, lizards, and insects like the longhorn beetle.
DM Eau have made a number of suggestions, such as setting up nest boxes for the species living in a wooded area, putting up fences to prevent access to the construction site, landscape support for the viaduct, the creation of a pond near the future garage-studio La Maltière... “More than seventeen hectares will be developed near the proposed layout, to which it will be necessary to add 8.5 hectares of open area or semi-open (prairies, groves, etc) area. In other words, more than twenty-five hectares of ecological environment altogether.
All of this has a cost, “to be judiciously taken on,” assured Thierry Courrau, spokesperson for Semtcar. The deal with DM Eau adds up to 200,000 euros and all suggestions made by the ecological engineer have yet to be calculated but, according to him, it could come to “more than a million euros.” There’s no joking around when it comes to environmental protection.
How large of a priority should ecological concerns be for infrastructure projects? Should environmental engineering necessarily be subordinated to other concerns in all cases?
Credits: Images and data linked to sources.
Original article, originally published in French, here.