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The gradual restoration of water service to the distribution network resumed on Saturday, June 20, after a seven-day sudden interruption caused by the rupture—the cause of which remains unexplained at this time—of the walls of a buffer reservoir at the Sidem plant in Public. The process is proceeding gradually, in stages, with the entire population being asked to exercise moderation in their water consumption. This applies in particular to residents of the lower-lying areas of the island. Although the reasons may seem obvious, Willy Latchman, director for the Antilles and French Guiana at SAUR—the company responsible for water distribution on the island—offers some explanations.
How does the process of restoring water to the network work?
The Colombier reservoir is located in the upper part of the island, at an elevation of 150 meters—to put it simply. From there, water is distributed down to sea level. This is the case in Gustavia, the port, Saint-Jean, and Lorient. So when the reservoir is filled, the water first flows to the lower areas. As the pipes in the lower areas fill up, the water flows back up. That’s why the lower areas always get water first. So, if people in the lower-lying areas use a lot of water, it takes that much longer for the water to flow back up to the higher-lying areas.
What are the challenges and risks involved in restoring water pressure to the system?
For us, it’s not a matter of sending large quantities of water. You have a reservoir located 150 meters above sea level. Right now, the pipes are empty. So air is taking the place of water. When we restart the system and begin filling it, the water pushes out the air in the pipes. This triggers a phenomenon known in hydraulic engineering as “water hammer.” When water enters the pipe too suddenly, the air gets compressed and creates a spring-like effect. This generates enormous overpressure that can cause the pipes to burst. That’s why it’s so important for us to fill the system gradually. In addition, we have components in the system that allow us to vent this air and regulate the pressure. That’s why we don’t send a very large initial flow into the pipes. All of this helps restore water to the system, but it takes longer to supply the various points.
The Collectivité is threatening to penalize excessive consumption during the restoration. How will this be done?
Today, we have connected meters. We receive data the next day from all the meters in Saint Barth, which allows us to monitor consumption. So, if we detect excessive consumption during this period when we’re asking for civic-minded behavior, agents will be able to go out and shut off the meter in question. (Three meters on the island have been shut off since this interview, Ed.)
What is the condition of the island’s water distribution network?
Together with the Collectivité, we have a network renewal program and are identifying the sections to be replaced. We’re working based on the age of the pipes, but it’s not necessarily the oldest ones that need to be replaced. Some are under much greater strain than others—particularly the sections that are subjected to high pressure and are prone to leaks. So we’re developing a renewal program. In this regard, the Collectivité is responsive. When we identify sections that need to be replaced—as we saw with the work at Anse des Cayes, for example—a contract was awarded and renewal work was launched. Overall, in terms of the renewal rate—that is, the length of pipeline replaced each year relative to the total length—Saint-Barth is among the local authorities with a rate higher than what is typical elsewhere.
