How to identify 5,000,000 litres per year of salt water entering your sewer network at a single glance

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For many coastal communities, infiltration from stormwater and inflow from ground water (I&I) causes major problems. Not only are systems not designed to handle large extra flows, but the additional power costs and operational problems can bring a network to its knees.

St Huberts Island

The coastal community of St Huberts on the central coast of New South Wales in Australia is a beautiful town, surrounded by fantastic fishing spots and has a very high water table. As is common in these coastal communities a vacuum sewer system has been installed to handle the wastewater from the houses. The system was installed in the mid nineties and over the years there has been an increase of I&I into the system.

Vacuum systems are usually installed in high water table areas because they are less susceptible to infiltration than are gravity systems. Over time homeowners gravity pipes and even old collection pits can break and allow ground water to enter the system.

Central Coast council realised that they had a problem which left their residents vulnerable to a loss of service and hire Flovac to come up with a solution that would help locate areas within the network where stormwater was entering the network.

Flovacs monitoring system was installed and within weeks it became evident that the system was taking in water, not only during storm events, but also during high tides. Vacuum valves within the vacuum collection network operate pneumatically every time 40 litres of water enters the collection sump. In this community we would expect to see each valve operating 40-50 times per day or 2,000 litres. In the first month we noticed that one pit was activating between 200 and 500 times per day, even when it wasn’t raining. When it rained it activated even more. this represented between 10-17,000 litres of water every day.

The collection pits in most of this community were old and made out of fibreglass. Over the years there was some evidence of wear. when operators investigated this particular pit, highlighted by the monitoring system, they found that the floor of the pit was broken, allowing ground water to enter the sump. once discovered, the pit was replaced and you can see that from mid August the daily valve activations have reduced to only 10 activations per day as it was found that one of the houses connected was empty.

You can see from the video that water is entering the sump from the pit bottom and not from the incoming gravity line. As this is a high water table area, it was discovered that all of this water was salt water from the bay. each year this pit was adding at least 5 million litres of sea water to the system. A program is now in place to locate other points of infiltration.

The operators having had great success with this, also installed monitoring at a nearby town. After the first major storm, more than 20 collection pits had more than 300 activations each, a major amount of infiltration.

Without Flovacs monitoring system it would of been impossible to locate the problem

Contact Flovac to find out how we can solve your I&I problems.

Key Largo using monitoring for hurricane preparedness

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Key Largo, Florida to Install Large Scale Telemetry Monitoring System in its Sanitary Collection System

Installation of FLOVAC Americas radio-telemetry system technology to help prevent SSOs and warn collection system’s operations of potential issues to begin.

Flovac has been contracted by the Key Largo Wastewater Treatment District to install its wireless monitoring system (FMS). The project is partially funded thru a grant from the U.S. Army Corps of Engineers.

The driver of the project to assist the Key Largo’s sanitation system cope when hurricanes and large storms hit the Florida Keys. The monitoring technology is to provide the district with real-time alerts of system issues as a means of mitigating SSOs. The installation is expected to take approximately two years to complete and will utilize a basin-by-basin approach to make such a large-scale project manageable. The monitoring technology will be deployed throughout the district’s vacuum collection system, grinder pump collection systems and force mains. This includes nearly 3,000 collection pits.

Once online, the system will monitor levels and pressures continuously and if changes outside normal operating conditions are detected, alerts will be sent to the district’s staff through Gateway transmission. Changes to the system can be made remotely and this will give operations crews time to conduct a field response to address issues such as low pressure, high flow, or other system failures.

Key Largo’s vacuum sewer pits resemble manholes seen in traditional gravity sewer systems and the monitoring devices will be installed inside of the existing pits/pedestals and so will be hidden and undetectable by residents and will not impact the appearance of neighborhoods.

“We are excited to be working with Key Largo and incorporating our technology into their existing infrastructure. Similar implementations have provided our clients with the ability to see what is happening in their systems in real-time and get ahead of issues before they occur and we look forward to delivering those same benefits and operational cost savings to Key Largo,” shares Michael Pringle, Director of Operations at FLOVAC Americas.

For more information about Flovacs Wireless Monitoring Read Here

Key Largo, Hurricane Irma Devastation. photo by Contessa Brewer CNBC

The Most Difficult Install Ever, Eretrea Greece

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The city of Eretrea in Greece, one of the best known Archaeological sites in the world, has had a much needed upgrade. A Flovac vacuum system has been installed to replace old septic tanks that still serviced the houses in the town.

Two vacuum pump stations were required, as well as 414 collection pits, a cable monitoring system and 28,000 meters of pipework including the house connections. A
vacuum system was chosen due to the difficult ground conditions and the flexibility that the pipework allowed for. A gravity pipe system would require deep trenching and straight lengths of pipe.  Vacuum mains can be installed with full flexibility and can be rerouted around difficult areas.

Difficult Installation

The city was an important city in Ancient Greece beginning at the time of the Bronze Age in the 8th century BC and was a seat of trade,  commerce and education. As the site is still under archaeological excavation it is still common to find artifacts while digging into the ground. We often found evidence of graves, walls, bronze artifacts and perfume bottles. Some more than 2,000 years old. At all times during excavation we were accompanied by two archaeologists and no excavation could take place without them. Once something was found, we would have to stop pipelaying and wait until drawings were done. Permission would then needed be granted from the Central Archaeological Institute to continue, which often took a long time.

We also needed to deal with a water table at 60-70 cm (24 inches). You would think that this close to the sea that it would be salt water but no, it was clear sweet fresh water. At 90 cm (36 inches) there is a hard crust which when perforated allowed salt water to ingress.

A very difficult but a very rewarding project.

Gran Marina del Estrecho, a new marina for megayachts

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A New First Class Marina

At the mouth of the Straits of Gibraltar, Gran Marina del Estrecho is set to become one of Europes leading marinas. It will have  first-class facilities, in the Mediterranean and an exceptional base for superyachts up to 200 meters in length. Its location is in Algeciras, in the south of Spain and will be a reference site in the Strait of Gibraltar.

With an investment of 50 million euros, the construction of the ‘Gran Marina del Estrecho’ is already a reality, and is expected to be operational in 2023. The new marina will have 80 moorings of between 30 and 100 meters in length and 2 moorings for cruise ships, distributed in two different docks. All kinds of services will be provided, from the assignment of moorings to the management of repairs in dry docks.

It will be equipped with an esplanade with unique buildings for nautical and commercial services, with more than 11,100 m2 built. It will have everything necessary for shipowners, captains and crew members to safely enjoy all kinds of luxuries. With 30,000 m2 of commercial space dedicated exclusively to leisure, the hospitality sector will have a major impact. The jewel in the crown will be the Yachting Club building and the shopping area, where, in addition to the best nautical equipment, we will find elite fashion and beauty brands.

‘Gran Marina del Estrecho’ and Flovac

Flovac has designed a vacuum sewerage system that will serve all buildings and  ships in the marina precinct.

Thanks to the vacuum sewer technology that Flovac designs in marinas, a single vacuum station and a network of pipes installed at shallow depths allows the wastewater to be transported from each discharge point of the buildings and from each suction point of the boats to the municipal wastewater network, located outside the concession. Not only does it facilitate the movement and disposal of such water, but it also reduces the cost of transport vehicles.

The megayachts will be able to empty their sewage tanks at their own mooring into the sewage network, without the need for vacuum trucks. They will simply connect to the intakes provided in the turrets.

Bilge and Hydrocarbon Water Management

A second network of pipes will allow the transport of bilge water so as not to mix them. Water with traces of hydrocarbons that may be produced in the vicinity of the gas station will also be transported within this network. A second tank located at the vacuum station will receive these waters that require treatment. In the vacuum station itself, the hydrocarbons are separated before being discharged into the municipal sewer. The process carried out by Flovac will facilitate the municipality’s work and help protect the ecosystem with a safe and clean production chain to avoid all types of impurities in the sea.

The vacuum sewage system will allow the Gran Marina del Estrecho to meet the highest standards of environmental protection. Indeed, thanks to the vacuum, even if there is a crack in the pipe, there will be no discharge of sewage or bilge water and will avoid any pollution. In any case, any air ingress into the system will be detected by the vacuum station and repaired as quickly as possible. The processes established here are becoming the standard for all large marina projects.

For more information about other flovac marina projects read here

New Vacuum Sewer Project in Portugal

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A new Flovac vacuum sewer system is being installed in the towns of Arazede and Liceia in the municipality of Montemor-o-Velho in Portugal.

Our client ABMG – Águas do Baixo Mondego e Gândara the main water and wastewater utility for the region has made a video showing the installation which can be seen here.

One vacuum pump station will serve over 230 house connections.  Over 12 km of PEAD PN 10 vacuum mains are being installed in the ground sized from 110 to 200mm. All the Flovac collection Pits are fitted out and tested prior to delivery to the project office.

Grupo MMPS who are doing the installation are the Flovac representative in Portugal and have completed a number of vacuum sewer projects making them the most experienced vacuum sewer company in Portugal and a key reason for them being awarded the project.

The critical reason why vacuum was chosen for the project was for the protection of groundwater. Knowing that sewage could not leak out of the piping network was a key driver for the install.

More than 170 vacuum collection pits with Flovac valves (FV80 Vacuum Valve DN3″) were installed into this old community which dates back nearly 1,000 years. #Válvula de Vácuo FV80.

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

Please contact us for more information

Operational Costs for Vacuum Sewer Systems

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How much does it cost to operate and maintain your vacuum sewer system? Is that high and what is normal? Lets also talk about the best way to reduce your maintenance costs.

Critical Factors

Flovac’s operations group has completed audits of systems in many locations and through our benchmarking process we have determined a number of common factors involved.

Before we dig deeper there are two important statements we can make.

  1. You need to know how much your vacuum systems costs to operate. Most utilities, do not know. Once you understand what the main costs are, you can do something about them
  2. All systems which have monitoring systems installed have significantly lower operational costs as well as reduced risks.

The overall cost varies, smaller versus larger, country to country, so its probably best to focus on what makes up the cost. Try and find what was in the whole of life costs when this system was first being suggested. How accurate was that. If it is different, why is it different and if more expensive, what can be done about it.

Vacuum systems should always be cheaper to operate than a low pressure pump system and in a similar difficult location should have cheaper operations costs than a gravity system with multiple pump stations.

Cost Breakdown

  1. Energy Costs (30{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}). For many utilities this is one of the easiest things to focus on and also easiest to get accurate data on.  It could be that your pumps are just old and it’s time for a rebuild/service or replacement. With vacuum systems, energy costs are highly correlated with the air/liquid ratio of the system. That’s our first design principal and our first operational health check. Air transports the sewage to the station. The amount of air is measured by the vacuum pump run times and the size of the pumps. If there is too much air, either due to leaks in the system, old valves or badly tuned valves then your vacuum pumps will run longer than needed. In most systems vacuum pumps should run approximately 6 hours per day. Sewage pump run times are determined by the amount of sewage in the system. If you have infiltration or a user dumping in more than they should, then your pump run time will increase. In most vacuum systems the sewage pumps should run about 2-3 hours per day. You need to check what the optimal air to liquid ratio is for your system. When it is at its optimal level your energy costs should be at their lowest possible point.
  2. Consumables (20{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}) In vacuum systems consumables can either be related to parts for the vacuum valves and controllers, or related to pump station equipment. This is different to long term capital replacements, pump and valve replacements, this is covering annual spending on oil and filters and valve/controller parts. In our experience of sales of parts to systems, valve and controller parts should only be required every ten years. It is highly unusual for sales to be any more frequent than this. In most pump stations the main cost is oil and filters for rotary vane vacuum pumps. Liquid ring pumps and claw vacuum pumps require a lot less maintenance but might not handle the required duty for your system. The best way to reduce your oil costs is to reduce the run time on your pumps. See the above section on energy costs. If you are watching the air/liquid ratio and keeping your pump run times at optimal levels then your oil requirements will be minimal.
  3. Preventative Maintenance (30{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}) A number of systems do no preventative maintenance at all and so this 30{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} cost will be lumped in with call-outs. We would tend to visit each pit once a year to check the pit condition, valve condition and controller timing. At every ten years we replace the required parts in the valve and controller. With monitoring a lot of our preventative maintenance time is spent at the computer. Analysing data to show infiltration, air/liquid ratio, changes to end of line pressure, failing components and remotely adjusting the timing of certain controllers to take into account seasonal flows as required.
  4. Call-Outs (20{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}) If preventative maintenance is done correctly then this number should remain low.  We have outline in the following graph the breakdown of callouts to a vacuum system. A system with 200 vacuum valves should have a 5{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} call-out rate, meaning that there should be 10 callouts in the year.  The biggest cost here is time spent in the field finding the fault. In many projects we have found that a refresher training program for the operators can help reduce time in the field a lot. The other biggest cost reduction comes from installing a monitoring system. Have the operator being directed directly to a problem or being told ahead of time when a controller is going to fail can save significant money and resources.

    Follow Up

    If you would like to follow up on any of these points please contact your closest Flovac office.  You can contact our Operations group about audits or training courses, or just some advice about your system. If you would like to see some more information about monitoring systems you can Click Here

How do Variable Flow Rates Affect Your Design

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Vacuum Systems operate on a ratio between air and water, either too much air or too much water can negatively impact on the system which could lead to failures or higher operating costs.

Systems are designed and built for an average flow rate but in many of the communities where vacuum systems are built they never perform at the average flow.

To look at a couple of examples

  • A Coastal Holiday Town that during the winter has 500 people but in the height of summer has 5,000 people. During the winter more air is required to keep sewage flowing. Less air is required in summer when valves are all operating frequently.
  • A wealthy community where residents are building 10 bedroom mansions. For most of the year only 2 people live in the house, but at Thanksgiving and Christmas twenty people are living in the house. Can the system cope with a large increase in flows.
  • A community that has a section with a caravan park (RV Park) and a camping ground area. During certain holiday periods massive flows occur at these locations.
  • A system which on one line has a large secondary school and a primary school. During the summer holidays no flow enters the system along this stretch. Will that impact on collection pits further upstream?

One of the unique features of the Flovac Monitoring System (FMS) is its ability to communicate two ways. We have developed controllers for our valves that can receive messages to open for a period of time.

The smart controller can open for longer during extreme wet weather events or during quiet winter off season periods or less air during very busy periods. It can be programmed to only admit more air when it senses flooding is occurring in the vacuum main which more air would help.

If the client would like to, they can remotely fire the controller to assist the system.

One client is programming a number of valves to open at 5 am prior to peak so that the vacuum mains can be emptied prior to the large peak flows and this reduces the peak impact on the system. This system is also being operated prior to large wet weather events.

Imagine if the weather forecast suggested a large storm would occur in the afternoon. The operator could fire a few valves injecting air into the system which could empty the vacuum mains completely prior to the wet weather occurring. Not only would the vacuum system handle the storm better but so would the treatment plant which would have received excess flows prior to the start of the storm.

Eco Resort, affected by seasonal flows

To read more about this Click Here