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First Vacuum System in the French Caribbean

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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

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Helping Hurricane affected communities in the Caribbean

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When Hurricane Irma wreaked havoc through the Caribbean Islands in 2017 leaving a trail of destruction, it was clear that many towns would need to be completely rebuild many of their buildings but also their water and sewage infrastructure.

Having already been engaged in other Caribbean countries to install Flovac vacuum sewerage systems the engineers in Grand Case on Saint Martin approached Flovac to see if a vacuum sewerage system would be the best technology for the island.

This area is very flat and has a high water table, which meant that you could not dig more than one meter without finding salt water that would damage a system using gravity piping networks. Until now Grand Case had a network based on septic tanks that was not adequate. After the damage caused by Hurricane Irma, Saint Martin needed urgent repairs and a new, more efficient sanitation system. Work began in Grand Case (Saint Martin)  towards the end of 2019 and it was clear that a vacuum sewerage system was essential in the area.

Shallow Vacuum Main Installation

Often working in narrow streets with other cables and pipes already installed it was clear that a vacuum system was the only system that could be installed with the least amount of impact on the local community. The people of Saint Martin were also very happy to hear that there would be no odors from the system as well as no potential of sewer leaks from the pipes.

As the region had experienced more major storms and hurricanes in recent years it was also important that the system was resilient and would still operate during extended power outages.

Being a remote community with little experience with vacuum sewer technology the local managers and operators were very happy that Flovac installed a monitoring system throughout the network that could be watched and supported by the Flovac operations group in Europe. If there is ever a low vacuum or breakdown, Flovac’s experienced operators could assist.

The main design and installation was handled by Flovac’s project group based out of Barcelona as they had recently installed a system nearby in Canouan. This group, headed by Bruno Galindo and Francisco Rodríguez  is now supporting Saint Martin’s operators.

Grand Case St Martin