The landscape is like an uninhabited land. Near the entrance, bitumen crust scattered a large pile. On the ground, we can still see the trenches dug into the truck’s tires. And everywhere, piles of sand were scattered where the gorse blossomed and took root. A sign that vegetation is slowly regaining its rights in the remote area of Prévalaye, a natural area south of Rennes. For almost forty years, the Lafarge company has operated two ponds in the area, Lillion and Bougrières, for sand and gravel extraction. Operations ceased in 2018. But it left its mark.
This is evidenced by a study commissioned by Lafarge from a specialized company and obtained by Telegram. Taken in September, it shows soil pollution caused by hydrocarbons in several parts of the region. Specifically here, formerly, there was a construction machinery maintenance area. Experts note an uneasy fact: this “concentration” of pollution, located 1 to 2 meters below the surface, is close to the groundwater table. Is she infected? What is the scope of this field?
Currently, no response, pending additional analysis requested by the company. Person warned: “In the event of a proven impact, groundwater monitoring must be performed (…). Contacted, the Lafarge company wishes to emphasize its volunteering spirit. “It was we who informed the Province and Rennes Métropole of the situation,” said its communications department. “We will do the necessary decontamination work. This is a very limited area on a plot of land with a total area of 60 hectares. We are not saying there is no risk but in our view it is under control.”
The discovery did not come at the best time for the cement producer. Although it has been discontinued for nearly 4 years, it is still unpacked in the end. Before leaving, he was ordered by the Shire and Rennes Métropole to restore the site to its original state. Its first plan, deemed insufficient, was challenged in 2020 by elected city officials. The second version, released in February, got the green light this time in late April. But with the condition that the company must meet certain conditions. Includes additional soil pollution surveys.
Piles of rubble since December 2020
Another reason for Métropole’s interest: the ponds of Lillion and Bougrières are a reserve of water for the inhabitants’ daily needs. It is mobilized especially during times of drought. However, a huge pile of rubble has been left on the shore, a few tens of meters above the water surface since December 2020. The elected official said: “While the file was on. [présenté par Lafarge] indicates that all waste and equipment (…) has been evacuated, and residue (…) remains. It is necessary to ensure that there is no bitumen in these mixtures to confirm that this waste (…) does not pose a risk to water quality. »
Informed by an association, the Regional Authority ensures that the resource, closely monitored at the point of catch, has no detectable traces of contamination. For its part, Lafarge promises that this amount of waste will be eliminated. “They came from roads leading to the site that were demolished in 2020 and stored temporarily. They will be completely evacuated to specialized reprocessing channels.” Restoration work is scheduled to begin in September 2022. They will be completed by the end of 2023 for Bougrières and a year later for Lillion.
Bougrières, the future Apigné?
If Metropolis puts such pressure on Lafarge, it’s also for a different reason. It hopes to reopen two sites, located at the heart of the Vilaine Valley project, to the public. An extensive program aims to make this vast natural space southwest of Rennes more accessible, with walking routes and locations for outdoor activities. It even plans to turn the Bougrières pond into a new bathing site, replacing Apigné, which is regularly closed in the summer to protect the health of bathers.
This ambition may face at least one obstacle: many protected species have populated the two bodies of water since the quarry was decommissioned. This is one of the achievements of research commissioned by Lafarge that has begun to identify the animals present on the site. The Bougrières pond is particularly famous for its nesting birds, some of which are endangered. It is uncertain whether Rennais’ appearance in a bathing suit is appropriate for the conservation of turtle pigeons and other vipers.