Flovac has recently commissioned the first vacuum sewer system in Grand Case in the French Caribbean. Other systems have already been installed by Flovac in Saint Vincent and the Grenadines, Puerto Rico and the Netherland Antilles.
Grand Case is a small tourist town on the French side of the island of Saint-Martin, with a long beach with turquoise waters. It is well known for the large number of bars and restaurants located next to the beach and along its main street.
Flat and sandy terrain with a high-water table
With such a high-water table a conventional gravity sewer would have been too difficult and expensive to install and would have required multiple pump stations. Fortunately, by installing vacuum mains, all pipework could be laid between 1.2-1.8 meters (4-6 feet) deep and above the water level.
Another advantage of installing vacuum mains is the absence of ground water infiltration into the network. This is very hard to prevent in gravity networks when the pipes are laid under the sea level. When gravity pipes take in ground water it causes problems at the treatment plant. Not just through increased flows but also through the salinity of the water.
Just as you don’t get infiltration, it is also impossible to get exfiltration. The negative pressure in the vacuum mains shows sewage cannot leak out. (shown here)
The leak tightness test is done daily throughout the pipe installation. As Grand Case is an important tourism area, it relies on fresh seafood for its restaurant area and clean beaches.
A single pump station
Only one vacuum station is required to service the entire area, even with its very busy bar and restaurant area. A stainless steel collection tank collects the sewage and a generator os provided to ensure continual power supply to the vacuum pumps and sewage pumps. The area is at risk from major storms and hurricanes and was devasted in 2017 from Hurricane Irma, so power at only a single location can keep the systems running. See more about the hurricane impact here
Please contact us for more information