2023-06-18 19:11:17
To cope with climatic hazards, nothing is to be excluded, including reactivating the uses of the past. 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 underground Gallo-Roman aqueducts dating back two thousand years to recover undrinkable water. to water its parks and gardens.
This idea only takes place last in the Limoges Sustainable Water Plan, developed by the city to improve sobriety and reduce by 10%, by 2030, a drinking water bill which amounts to almost €700,000 for annual consumption of 255,600 m3. This is unquestionably the most original measure.
The Gallo-Roman aqueducts of Limoges were built from the year 30 of our era on request of the equivalent of the mayor of the time, Postumus, a Romanized Gallic aristocrat. These works of art were used to supply spring water to the city Augustoritum and its approximately 15,000 inhabitants.
The old districts of the city of Limoges thus conceal a very dense network of underground cavities. While some date from the Roman period, most were made between the year 1000 and the 13th century. This underground network is explained by the very dense nature of this trading town, which required limiting the influence of this water network on the surface.
An underground network
The underground network of the ancient aqueducts of Limoges includes ten kilometers of drains and underground galleries. The mother pipe, called Aigoulène, alone measures 1.6 km. The galleries are carved out of the tuff over most of its course, but some parts are masonry, 60 cm wide and 1.2 m high.
During the 19th century, the city of Limoges gradually abandoned these aqueducts, victims of collapses or urban development. From 1876, it chose to capture new sources outside the municipal territory, brought to town by a new network.
“An incredible windfall”
Reconnecting with this long history, the current mayor wishes to put the aqueducts back into service “clean them up” et “put in place the tools to use this water that circulates in the city” and now flows into the sewers, then into the Vienne. “Instead of it being diverted into the sewers, it will be used for watering”he said at the press conference. “It will also prevent the earth from shrinking and the houses from cracking. It is also to keep the city alive”completed the aedile.
This water is “an incredible windfall”, believes for her part Marie-Anne Robert Kerbrat, responsible for sustainable development in the city. 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 in archeology and partner of the town hall in this project, this is not the first time that the city has sought to recover the water flowing under Limoges. “Around 1780, when the Limoges hospital was experiencing major water supply problems, an underground trench had to be dug to connect the so-called “Jacobins” aqueduct to a section of the perfectly preserved Roman aqueduct” , he explained.
To build the Aigoulène aqueduct, the Romans had to extract approximately 11,000 m³ of rock, between 6 and 15 m deep. And to supply the thermal baths, the fountains and certain houses of the city, they had created dams upstream in the gallery, using lead or wooden pipes to spurt out the water under pressure. According to Jean-Pierre Loustaud, it would suffice to use this same technique. “Today’s engineers have to take up the challenge. If the Romans did it, why not us? »
To begin with, the town hall will order a study on the rehabilitation of the aqueducts, in conjunction with the Bureau of Geological and Mining Research (BRGM), a public establishment. If this is conclusive, the return to service of this network could be envisaged in a more concrete way and above all in figures.
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