In order to meet the vagaries of the weather, nothing can be ruled out, including the reactivation of past uses. In this state of mind, the mayor of the city of Limoges, Émile Roger Lombertie (LR), announced on Friday June 16 that he wanted to reuse the two thousand-year-old underground Gallo-Roman aqueducts to extract undrinkable water from parks and gardens.
This idea comes last in the Limoges Sustainable Water Plan developed by the city to improve sobriety and cut drinking water bills, which total almost €700,000 for an annual consumption of 255,600 m3, by 10% by 2030 to lower. This is undoubtedly the most original measure.
The Gallo-Roman aqueducts of Limoges were built from the 30th century AD at the request of the then mayor Postumus, a romanized Gallic aristocrat. These works of art served to supply the town of Augustoritum and its approximately 15,000 inhabitants with spring water.
The old districts of the city of Limoges thus hide a very dense network of underground cavities. While some date back to Roman times, most were made between the year 1000 and the 13th century. This underground network is explained by the very dense nature of this commercial city, which made it necessary to limit the influence of this water network on the surface.
An underground network
The underground network of the ancient Limoges aqueducts includes ten kilometers of drains and underground galleries. The mother tube alone, called Aigoulène, measures 1.6 km. The galleries are mostly hewn from tufa, but some parts are made of masonry, 60 cm wide and 1.2 m high.
During the 19th century, the city of Limoges gradually abandoned these aqueducts as they fell victim to collapse or urban development. From 1876 it was decided to collect new springs outside the municipal area, which were brought to the city via a new network.
“An incredible stroke of luck”
The current mayor builds on this long history and wants to get the aqueducts back into service “Clean Up” etc “Put the tools to use this water circulating in the city” and now flows into the sewers, then into the Vienne. “Instead of being diverted to the sewer system, it’s being used for irrigation.”he said at the press conference. “It will also prevent the earth from shrinking and the houses from cracking. It’s also about keeping the city alive.”completed the aedile.
This water is “An incredible stroke of luck”, believes Marie-Anne Robert Kerbrat, responsible for the city’s sustainable development. In the 19th century, the main Aigoulène aqueduct had a flow rate of 2,500 m3 per day. Such a flow could be found today.
For Jean-Pierre Loustaud, Doctor of Archeology and City Hall partner on the project, this is not the first time the city has tried to recover the water flowing under Limoges. “Around 1780, when the Limoges Hospital was experiencing serious problems with the water supply, an underground ditch had to be dug to connect the so-called ‘Jacobin’ aqueduct to a section of the perfectly preserved Roman aqueduct.” he explained.
For the construction of the Aigoulène aqueduct, the Romans had to excavate around 11,000 m³ of rock at a depth of between 6 and 15 m. And to supply the thermal baths, the fountains and certain houses in the city, they had built dams upstream in the gallery, from which the water spurted out under pressure from pipes made of lead or wood. According to Jean-Pierre Loustaud, using the same technique would suffice. “Today’s engineers have to face this challenge. If the Romans did it, why didn’t we? »
First, City Hall will commission a study to clean up the aqueducts in collaboration with the Bureau of Geological and Mining Research (BRGM), a public body. If this is conclusive, the reopening of this network could be envisaged in more concrete terms and, above all, in figures.
