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Prestons Residential Development Vacuum Sewer

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The Flovac Vacuum Pump Station was installed in 2015 to service the Prestons residential development in Marshlands Christchurch and has continued to grow with house sales in the area ahead of schedule.

Every effort has been made by the developer Ngai Tahu to ensure that this medium priced housing development for 8,000 residents is world class.

Environmentally Sensitive Development at Prestons

 

Right next to the vacuum pump station, the Marshland School for children aged 5-13 has been completed. When Master Planning a vacuum sewer system it is always important to consider that any flows from schools will be interrupted during school holidays and weekends. So to ensure that plenty of air is entering

Marshlands School

the system, especially close to the station the system needs to be tuned correctly or have an automatic air inlet system that can be programmed to take the change into account.

 

The vacuum sewerage system is the ideal technology for a development like this as it can be very flexible with new additions over time and is resilient to damage from earthquakes. Unlike low pressure pump systems, the only power requirement is at the vacuum pump station, so if an earthquake interrupts power supply the vacuum sewerage network at Prestons will continue to work as there is a back up generator located at the station.

Another resilient feature of the Flovac system is that if any of the vacuum mains break or rupture during an earthquake, the negative pressure in the pipe ensures that no sewage will leak out. A low pressure pump system operates on positive pressure, so if a pipeline breaks sewage will surcharge from the pipe into the surrounding area. In an environmentally sensitive area like Prestons, that could be a disaster.

Another benefit of the vacuum sewer system is its ability to handle high flows into the collection system. A large supermarket complex is being planned in the neighborhood complete with a Foodstuffs supermarket, cafe’s and restaurants. Already built is a large BP service station which houses a cafe and a Jetwash. The Flovac system handles the commercial premises and can handle any flows from the car washing facility.

On the right side of the BP Jetwash you can see three of the Flovac pillars that house the air vents that are required to admit air into the vacuum sewer. These are connected to three separate valve pits which are served via a splitter to handle the high flows. The pillars will also house the wireless monitoring system that is being rolled out. The monitoring system will alert operators to any valve faults or potential overflows from the pit.

The operators looking after the system have been very happy with the operational benefits and have had very few callouts. As the operators have little to no contact with sewage and have no requirements to enter the property of the residents they see real benefits relative to how the low pressure pumps have performed. Many low pressure pumps are located on the property of the resident and any maintenance often leaves residual sewage on the lawns of the residents.

 

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.

Preston’s Housing Development in Christchurch

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It’s a case of one down and 2599 to go at the biggest subdivision in Christchurch.

The single house under construction in the Prestons housing development in Christchurch will not be alone for long.

The milestone of Prestons’ first house was marked by a visit from Prime Minister John Key this week, five years after the giant housing development was first launched. That first house is owned by 87-year-old Cliff Mitten. Since sections in the Marshland subdivision first went on sale last year, about 330 have been sold.

Of the 200 sections in the first stage, known as Korowai, only four remain unsold. Those buyers now have titles to their sections and more construction is due to get underway soon.

In the second stage, Harakeke, 130 of the 230 sections have sold without being officially released to the market. Titles in that stage will be ready for buyers in June next year.

Prestons is the city’s biggest subdivision, designed for 2600 homes and 8000 residents. It is being developed by CDL Land NZ, Ngai Tahu and Foodstuffs South Island.

Section sizes are from 450sqm to 650sqm, and those in stage two are priced at $210,000 to $244,000.

The developers first released their plans for Prestons in 2008.

They were in the process of trying to get the farmland rezoned for housing, in the face of opposition from Environment Canterbury and other parties, when the earthquakes hit.

The decision was put on hold and then the project was given the green light in 2011 under the Canterbury Earthquake Recovery Act.

At 203 hectares, Prestons is on a site bigger than Hagley Park. It is next to the Bottle Lake Forest reserve, and the Waitikiri and Windsor Golf Courses.

The development has been designed to include a shopping area with cafes and restaurants, a New World supermarket, a primary school and parks. David Schwartfeger, development manager for Ngai Tahu Property, says the section buyers so far have come from across the board in both age and location.

He believes the geotechnical report that comes with each section is helping attract buyers.

Most of the land in the development has been classed as TC1, the least earthquake damage- prone of the government’s technical categories, while the remaining TC2 land has been brought up to TC1 level.

As part of that work, the developers did a soil swap with the Waitikiri Golf Club, removing and giving the club 70,000 cubic metres of peat in exchange for 70,000 cubic metres of sand. The subdivision was then stabilised with a 40-tonne elliptical roller which has been used overseas for mining work.

The Flovac vacuum sewerage system was chosen due to concerns about future earthquakes and due to the high water table in the area. This is Flovac’s second project in Christchurch, which is at Shirley.

Earthquake Sewer System for Christchurch NZ

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Vacuum Sewers prove to be the best Earthquake sewer system for Christchurch Shirley vacuum sewer a first for the South Island.

SCIRT partner McConnell Dowell is more than halfway through a big project to build a Flovac vacuum wastewater system in the Christchurch residential suburb of Shirley – the first area of the South Island to use such technology.

The catchment includes about 750 houses, with 7km of vacuum main pipes in streets as well as lateral/ side connecting pipes to homes and businesses. About 6km of mains and 150 out of 195 collection chambers have been built, with a pump station and lateral pipes still in progress. It will take just over a year to complete the project, which began April 2013.

The area targeted for the Flovac vacuum system was badly affected by earthquakes with lateral spread and land-level changes. Previously, the city’s wastewater network has relied totally on a gravity system with pipelines at a gradient to support downhill flow.

After the earthquakes, the slope changed in many parts of the city, so wastewater was running in the wrong direction. The Flovac vacuum system will offer much greater resilience if there are further large earthquakes, especially in areas considered prone to liquefaction.

A further reason for using vacuum in Shirley was to keep excavation depths to a minimum because of the high ground water table and running sand. The system allowed McConnell Dowell to lay the pipes mostly at depths between one and 1.5 metres deep.

This is shallow compared to the traditional gravity system which has pipes plunging to several metres deep to maintain the gravity-feedwhich takes a lot longer to access for maintenance or repair work with subsequent traffic and residential disruption.

Wastewater will arrive at the Shirley catchments new pumping station, on Golf Links Road, from small collection chambers, usually located on the grass berm of a street, each serving up to four properties. The only visible parts in most streets will be collection chamber lids and man-holes at ground-level, while vent stacks will sit against property boundaries.

Like in other parts of the city, wastewater from the new pumping station will go via the normal gravity system southeast to the wastewater treatment plant at Bromley.Shirley NZ Flovac Project

Residents will not notice any change

Shirley residents will not notice any difference when they flush their toilets or see their kitchen and bathroom wastewater draining to the collection chamber on the street via the gully trap/ lateral pipe. There is no additional cost to them for becoming part of this modern system.