Xylem Water Solutions Canada - Bringing waste water handling into the 21st century

Bringing waste water handling into the 21st century

For centuries, the river Thames has been London's commercial life. At 339 kilometers, the Thames is the longest river in England and its sheer size, its tidal flow and its position have made it a valuable trading channel throughout recorded history. Today, rather than being in the twilight of its years, the Thames and its hinterlands are the site of new development.

The distinctive and award-winning exterior of the Isle of Dogs pumping station was designed by John Outram Associates. the central fan is believed to be the largest external architectural propeller in the world.

In the early eighties, the London Docklands Development Corporation (LDDC) was commissioned to revive and develop the 14 square kilometers of disused wharves, warehouses and river frontage left abandoned for decades. This area was called the Enterprise Zone and its purpose was to inject new life into an area in the heart of London that had been superseded for trading purposes by container ports. When complete, Docklands will feature elegant offices and spectacular accommodation blocks as well as modern rail connections and a business airport, already complete with London's bigger airports on European flights.

An ambitious infrastructure for an ambitious development
The Enterprise Zone became the largest building site in Britain as well as one of the largest projects in the world. And to service the results of this building site - the offices, shops and new residential accommodation springing up on this site - radical improvements were needed for the infrastructure. Historically waste water from the Docklands area had been discharged directly into the Thames where tidal flow had been relied upon to disperse effluent. ITT Flygt tendered successfully for the Isle of Dogs pumping station in Docklands with a complete package for the pumping of sewage and surface water for the whole redeveloped area. In keeping with the ambition of the Docklands redevelopment the package is also unique and is even housed in an architectural prize winning building.

"By keeping storm water controlled, we ensure that the local sewage works can operate more effectively and economically"

ITT Flygt involvement in the Docklands development falls into two parts. In the first stage, the Isle of Dogs project, we have designed and installed a pump system to ensure that surface water can be discharged directly into the river without overloading the local sewage works. Our system, installed in the award winning postmodernist building by John Outram Associates, features two submersible CP 3300 pumps for dry weather flow. One pump is sufficient, the second is there as a stand-by. In addition, ten CP 3500 pumps are available for storm conditions. This gives a total station capacity of 12,000 liters/second at a total head of 10 meters.

Using more, smaller pumps improves the hydraulic dynamics within the sump chamber. This reduces swirl and hydraulic losses and the minimum water depth requirement with a subsequent reduction in construction costs.

The pumps are located in a wet well 13 meters by 11 meters. They are ranged in two rows and on several levels. The use of ITT Flygt system technology not only provided a solution at a lower civil construction cost, but significant operating and maintenance savings were made while also avoiding the need for costly valve arrangements.

Following the success of the Isle of Dog project, ITT Flygt in the UK has been engaged in a major engineering project - the Tidal Basin Pumping Station in London's Royal Docks. This station is one of the world's five largest using submersible technology and has a capacity of 8,000 l/sec.

Installed inside a wet well 28 meters deep in parts (as deep as a 10-story building is high) are 16 Flygt CP 3311 pumps for handling storm water. Each of these 210 kW pumps has a 500 l/sec capacity to a head of 25 meters. These are complemented by 2 Flygt CP 3300 drainage pumps. The 54 kW drainage pumps have a capacity of 125 l/sec to 24 meters head per unit.

The pumps are positioned radially within a station and they discharge siphonically into a central chamber above the inlet chamber. The construction was chosen to optimize operation and reduce building costs.

In addition to the pumps themselves, ITT Flygt supplies the pumps control equipment , the discharge pipe, ventilation systems, electrical equipment, station control systems, screens and penstocks.

"We believe we've got the largest pumping station in the world"
In both projects, Flygt's submersible pumping systems have been able to demonstrate optimal performance with minimal maintenance and operating costs. Sophisticated design, testing and modeling systems allow dimensioning to be optimized at the planning stage, eliminating trial and error. It is hoped that these are but two of London's Docklands waste-water handling problems ITT Flygt will be called upon to solve.

At the Isle of Dogs, the pumps are installed in two rows for improved inflow. Two smaller pumps are located at the lowest level on a mini-sump to handle low level inflow and also to pump out sediment.

Isle of Dogs pumping station

Application:	Dry weather flow and storm water

Design capacity:	12,000 l/sec

Design head:	10 meters

Outfall:	River Thames

Solution:	Twin level wet well submersible pumps sets with siphonic discharge into surge chamber

Dry weather pumps:

Type:	Flygt CP 3300, cast iron (explosion proof motors)

Duty:	150 l/sec to 15 meters head

Rated power:	45 kW

Storm water pumps:

Type:	Flygt CP 3500, cast iron (explosion proof motors)

Duty:	1000 l/sec to 10 meters head

Rated power:	140 kW

Tidal Basin pumping station

Application:	Storm water

Design capacity:	8,000 l/sec

Design head:	25 meters

Outfall:	River Thames

Solution:	Circular pump station with radially positioned wet well pumps discharging siphonically into a central chamber above the inlet chamber

Storm water pumps:

Type:	Flygt CP 3311, cast iron (explosion proof motors)

Duty:	500 l/sec to 25 meters head

Rated power:	210 kW

Drain pumps:

Type:	Flygt CP 3300, cast iron (explosion proof motors)

Duty:	125 l/sec to 24 meters head

Rated power:	54 kW

At the Isle of Dogs, ITT Flygt's proposal at the Tidal Basin for the installation of a larger number of smaller, submersible pumps and siphonic discharge to eliminate the need for costly valves. Furthermore, by utilizing a circular concept in the sump design, the overall station volume was reduced by 57%. The resulting saving in building cost virtually paid for the entire mechanical and electrical package.