Marina Vela Vacuum Sewer System, Barcelona.

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Marina Vela, the newest upscale Marina in the heart of Barcelona has opened for business. The new Marina which utilizes the latest in Flovac vacuum sewer technology has 136 marina berths which can cater for boats up to 50 meters in length.

Barcelona’s new Hotel W will be attached to the marina along with a number of restaurants, bars and shops. The marina is very central to city centre and the beach.

Flovac has installed a number of systems in marina’s In Barcelona including Port Vela, as well as in a number of other countries worldwide include Flisvos Marina in Greece, Marina di Pisa in Italy  and Marina Hindmarsh in Australia. The latest marina project outside Barcelona will be in Canouan in the Caribbean and will be profiled in an upcoming newsletter.

Marina Vela  has the latest in monitoring systems which allows the operator to be aware of any potential overflows, breakdowns or misuse by the boats crew. Not only is sewage taken care of but also any bilge water is taken off the boat and can be separated and reused. Details in Spanish can be found on our Flovac Spain website 

Largest Vacuum Sewer System in Greece is Completed

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Flovac Greece has just completed the largest vacuum sewerage system ever undertaken in Greece covering the towns of Mitrousi and Skoutari in the Serres Region of northern Greece.

The system which has two large vacuum pump stations, 800 collection pits and 45km of vacuum pipework. The system takes away the sewage of 3,600 residents in Mitrousi and over 4,100 residents in Skoutari. This makes it one of the largest systems ever installed in Europe.

The Serres region is an environmentally important area which won a European sustainable tourism award for aquatourism. A large artificial lake, Lake Kerkini was created nearby to make use of the extensive marshlands in the area. This is also behind the need for vacuum sewers in the villages as the water table is very high and actually visible on the surface in some areas.

As the vacuum sewer pipework can be laid at minimum depth and avoid de-watering is was seen as the only way in which a proper sewer system could be installed.

Vacuum sewer system are also popular in Greece because of the flexibility in the laying of the pipe. On many occasions archaeological artifacts are found during the construction of a system and rather than hold up construction for weeks or months while a site is investigated, the vacuum pipework can be diverted around a sensitive area, thus saving time and money. The Serres region is known for a number of antiquities including important sites from the time of Alexander the Great in 300 BC.

Flovac’s partners in Northern Greece, Environmental Engineering S.A., based in Thessaloniki, are the largest installers and operators of vacuum sewers in Greece and have been involved in a number of important projects since it was founded in 1993. The company principals Miltos Chatziiliou and Spiros Kolovoi have been very involved in engineering design, product development,

construction works, treatment as well as the operations and maintenance of a number of systems. Miltos works very closely With Harry Gerpinis who looks after Flovac’s interests in Southern Greece and has been instrumental in a number of significant projects including many large marina’s.

Flood Affected Sewer Systems

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Vacuum sewerage systems are ideal in areas that are subject to flooding

Nearly all vacuum sewerage systems are found in coastal area’s many of which are subject to flooding from rain/storms or rising sea levels. We all understand the problems that occur if I&I is present, we all know what causes it to occur.

We have operated a number of systems during major floods without the system going down. In one Sydney system major floods occurred every two years (see photo above), our operations contract stated that if any homeowner could not continue to use their plumbing they would be put up at a hotel at our cost. Happily we did not spend a cent on hotel costs.

For the vacuum valve to meet the European standard it must be able to operate under a full 10 inches of water. To meet the Australian standard it must operate without problem under 18 inches of water. By ensuring all hose clips are properly in place and the controller breather is clear of any water , the system will continue to operate.

In area’s where flooding is common we tend to put the controller and controller breather in a pillar besides the pit to ensure that the operator can still fire the valve without trying to access the pit through the flood water which might not always be possible.

Water infiltration from the homeowners property.

We have found that the main source of stormwater entering a system comes from the homeowners property. In some flood areas we have seen that certain sections of the town will regularly go under water. This usually means that residents have to be evacuated and in the past the water inundation from that area could risk the whole system. In this case we would install a remotely controlled division valve that would cut off that section of the town from the vacuum system. It is controlled from the operations base so that operators are not put at risk trying to isolate the area.

In some older towns we find that some houses, or more often camping grounds or caravan parks are set at ground levels

that are blow the legislated 100 year old flood levels that people can build at. If we find houses affected in this way, they must pump into the vacuum system rather than drain into it so that the system is not put at risk.

Candycanes/Gooseneck house breather vents when placed on properties will often be a source of infiltration, usually due them either being cut down by homeowners who object to them being in the middle of their yard or by gardeners knocking them over with their lawn mowers. At times they are placed too low to the ground, under the flood level. In these cases we would install a  Dedicated Pillar or think carefully about where the gooseneck vent is placed. Putting it in the middle of the yard risks it being cut down allowing water to enter the system. Putting it at the roof or garage top or against the house wall will limit water entering the system.

Smart Monitoring

As technology has improved, many asset managers have embraced the ability to locate exactly where and when I&I may be occurring. A sensor on a vacuum valve giving the open/close status will also be able to tell the operator the number of activations in a day. It is very easy for the operator to set up an alert to advise if any particular valve is operating more frequently than the general average, especially during wet weather events.

Once the operator has established which collection pit is activating more frequently than the other valves in the area, they can then troubleshoot the problem. The likely problems are that the homeowner has cut their house vent or inspection point to allow rainwater to enter the system or may have connected up their stormwater system to the sewer system or have a cracked gravity line feeding from the house to the pit. A letter to the homeowner to make the necessary rectifications is required.

There may also be groundwater or stormwater entering the collection pit due to incorrect pipework entering the pit allowing for water to enter. This is usually picked up at commissioning, if not should now be rectified.

You should also make sure that the pit lid is made for area’s that have flooding and has a seal and no holes to allow water to enter. the pit should not be located at a low point in the street.

The monitoring system makes it possible to identify these problems and fix them. this is not possible in a gravity system.

System Design

When designing a gravity sewer consideration must be made for Infiltration and Inflow on the pipes, the pump stations and the treatment plant.

Stormwater cannot enter the vacuum system via the vacuum pipework as it must remain tight for the vacuum pressure to hold tight. If a break occurs in a main it is immediately noticed and repaired.

An allowance is made for I&I but only for a small amount of the network, that being the homeowner gravity lines. So the system is not designed for infiltration and all steps must be taken to ensure that it does not occur. Luckily in a vacuum system the source of any I&I can be located.

If you have any leaks into your system, contact an expert for advice.

Historic Project in France

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Commune De Saint Julien De Concelles

This historic village nestled on the banks of the Loire River near the French city of Nantes on the Atlantic coast of France is the site of the latest Flovac system in Europe.

The site is first mentioned in history books as far back as the year 615 where is started life as a Roman town.  Ruins of a villa and ancient Roman baths can be found in the area. Vacuum sewers have been used in a number of area’s where there is such architectural significance as a way to ensure no damage is done during the construction of the sewer. Often during construction, significant finds may take place which the vacuum system can avoid by going around  at a safe distance without holding up works.

The town is in the heart of an important agricultural area and has very flat and sandy soil, ideal for a vacuum system. It is also known as the town that first developed the beurre blanc sauce, often used in french cuisine. There are also vines on the hills around the town that grow a muscadet wine that is very popular.

The project size is quite small with the Flovac system connecting 168 houses with 100 collection pits and 4 km of vacuum pipework.

It is important when doing installation work into existing townships that there is very little disruption to the way of life for the people in the town. One of the best reasons for utilising a vacuum system is that the trenching for the pipework is very narrow and in an area such as this, there is no need for dewatering as the installation stays above the water table. This ensures that the water table is not changed and so there is no detrimental affect on local agriculture.

The system is able to be installed with only a single vacuum pump station which is also important in an old town like Saint Julien in that space is a precious commodity. It was also important to keep energy use as low as possible, and with a single small vacuum pump station, this is possible.

The Saint Julien project is the first project in France that has incorporated the Flovac wireless monitoring Information about the monitoring systems can be found on our french webpage. https://www.assainissement-sous-vide.fr/

The project is just the latest for Flovac’s partners in France, LSE who have had a long history with vacuum systems.

In June we were finally able to attend the national water and wastewater show in Paris which had unfortunately been delayed due to terrorism in the capital. It was attended by Flovac’s chairman Mr Willem Gooren as well as local Flovac managers Philippe and Nicolas Frasier.

What is the Asset Life of a Vacuum Sewer System?

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As vacuum sewers are relatively new it is difficult for many engineers to develop good whole of life models when doing a comparative analysis on alternative sewer systems.

Although vacuum systems are newcomers to the sewerage industry we are seeing some systems just reaching their 50th anniversaries. Materials and designs have changed significantly since the first systems were installed in the mid sixties and although many are still operating they are nearing the end of their design life of the time.

Expectations on asset life have changed industry wide and any sewage infrastructure is expected to last significantly longer. The only national code or standard which stipulates Asset Life is the Australian WSAA Vacuum Sewerage code published in 2004. There are discussions in the WEF Alternate Sewers Guide on operational costs, but these are based on too many old systems to be relevant with modern systems.

The vacuum sewerage system is made up of two main components, the reticulation and the vacuum pump station. many of these components have commonalities with gravity sewers and so their asset life life cycle costs will be very much the same.

To give some idea of a comparison with alternate sewers, grinder pumps are required to have a 25 year asset design life.

When looking at whole of life costs the primary maintenance item in the vacuum pump station are the vacuum pumps. Liquid ring pumps have lower ongoing costs but use a lot of water which can be expensive. Rotary vane Pumps require oil changes and filter changes and rebuilds are more common.

Discharge pumps in vacuum sewer systems have lower operational costs as they are a step removed  from risks commonly found with gravity sewer systems. Ragging and impacts from rocks are less common due to the collection tank location.

The vacuum interface valve has very few mechanical parts but will require a rebuild once every ten years on average. The parts required for this rebuild will cost less than $100 for each valve per rebuild.

To get a more detailed life cycle analysis of vacuum sewer systems, including their operational costs please contact your nearest Flovac office.