New pumps for refurbishing Atwater pumping station in Montreal
Supplying the residents, commerce and industry in Montreal with drinking water is an enormous task for the city’s water department. It manages six water treatment plants, with Atwater and Charles-J.-Des Baillets being the largest. The water for these two plants is taken from the St Lawrence River. It is then purified in the Charles-J.-Des Baillets plant by a combination of filtration, ozonisation, ultraviolet (UV) water treatment and, finally, chlorination. From here, it is guided to the Atwater plant and distributed via the urban piping system.
Should one of the two plants, Charles-J.-Des Baillets or Atwater, require some downtime, the water can be redirected to the other plant, always ensuring an optimum water level in all seven storage tanks in Greater Montreal. The two treatment plants are connected to each other with large pipes.
Given its historic, technical and architectural value, the Atwater drinking water treatment plant is an important part of Montreal’s cultural heritage. Built in 1868, the Atwater station has seen many changes. The central pumping station was built in 1923, replacing the originally steam-powered pumps with electric pumps. In the last 100 years the station has played a decisive role in the city’s development, reliably supplying residents with water and thus contributing to public health. To increase the production capacity and improve the overall efficiency of the station, the city of Montreal has made significant investments. The latest investment is the refurbishment and expansion of the pumping systems. Replacing the outdated pumps with specially developed pump sets made by the German pump manufacturer KSB has increased the capacity to 700,000 cubic metres of drinking water per day for the Island of Montreal.
As part of the REQUP 1 project, the municipality is refurbishing all drinking water production plants, pumping stations and storage tanks. For this reason, the City of Montreal already in 2018 publicly tendered for six new pump sets and corresponding components to replace the outdated high-pressure pumps in the Atwater drinking water pumping station. This also comprised electric medium-voltage synchronous motors with external excitation as well as the required control cabinets.
Replacing the pumps in an existing infrastructure with piping systems already in place, all located inside a listed historic pump room, posed some challenges for KSB’s engineers. One of them was the special design of the pump sets to be replaced. Given the existing piping infrastructure in the pump room, they had to be single-stage, horizontally split, double-entry double volute casing pumps with a suction nozzle pointing downwards (bottom suction design) and a horizontally arranged discharge nozzle. It also had to be ensured that the equipment to be supplied fitted into the existing pumping station. This meant that all dimensions and distances had to be matched precisely, allowing the service engineers to connect the pumps smoothly to the inlet and discharge lines.
Any modification of the old configuration would have had an enormous impact on the technology and costs. As per contract, the pump manufacturer was not only responsible for supplying the pumps and corresponding electrical parts. KSB employees also supported the operator in the pump sets’ installation and commissioning. In addition, they trained the operating personnel in handling the pumps and equipment.
The pump manufacturer and the City of Montreal have been working together for more than 40 years. At the end of the 1970s, KSB supplied the Charles-J.-Des Baillets water treatment plant with five pumps of the type RDLO 700-980. In 2015, another KSB pump was installed; it was commissioned in 2018 for the plant to be able to be operated at its planned optimum capacity. In spring of 2018, KSB was invited to bid in the tender for supplying pumps for the Atwater station and won the order at the end of the same year. The contract was awarded under the condition that not only the procurement costs but also the operating costs for electrical energy over the next 25 years be considered. The pump sets therefore needed a high efficiency.
To be able to meet the contract criteria, the experts at the German KSB site in Halle had to engineer a pump with bottom suction design. This design is very different from the standard version of an in-line arrangement of discharge nozzle and suction nozzle. The new pump sets further had to meet other important hydraulic and mechanical criteria regarding efficiency and ease of service. Once they were designed, the pumps were manufactured to these requirements and thoroughly tested in the German factory with the motors and control units specified for this project.
The supplied special designs are six single-stage, horizontally split pumps with double-entry radial impeller and a diameter of 948 mm. Every pump is fitted with a 1800 kW synchronous motor with a brushless excitation system. The pump sets are designed for a flow rate of 1580 l/s and a head of 73 m. The scope of supply further included the excitation control unit and the service of electrical connection.
Another requirement was that the station had to remain operational at all times during the refurbishment work. This was achieved by scheduling the installation of the new pumps over a longer period of time, replacing the existing pumps one by one. KSB manufactured all pump sets at the same time and stored them at a site closeby for the two years of refurbishment work.
The condition of the outdated pumps had worsened considerably in the meantime. And no spare parts were available for these pumps any more. The old pumps continued to be supplied with power via the existing 12 kV system, which had also reached the end of its useful life. This caused additional costs for servicing and operating the plant. The new pumps will be supplied with power from a 25 kV system.
All six pumps were manufactured and ready for acceptance testing at the factory in early 2020, coinciding with the start of the COVID 19 pandemic.
The factory in Halle (an der Saale) managed to meet the acceptance test schedule despite sickness-related staff shortages. Hygiene requirements around the world made it impossible for the customer to witness the acceptance tests in Germany in person. This problem was solved by the option of the customer remotely witnessing the test field action in a video conference.
KSB had already developed a process in 2018 that enables reliable and standard-compliant pump acceptance testing. The tests conducted were transmitted live via a specially protected part of the Internet. In an online meeting between pump manufacturer and customer, the inspectors commissioned by the customer watched the live camera view of the pump in the test facility as well as the characteristic curve measurement during testing.
In addition to the pressure and flow data, the test software recorded all further performance data required for a measurement to inspection/testing standard, enabling the derivation and assessment of the pump's efficiency. Prior to the acceptance test, Atwater's test engineers were provided with organisational information, order data sheets and a precise description of the acceptance testing with details on the measuring instruments used, including the corresponding calibration certificates. After the acceptance test, KSB e-mailed the inspectors the certificates to be signed. All tests were conducted successfully; the measured efficiency even exceeded the theoretical calculated value.
KSB delivered the complete plant equipment from Germany to a storage site in the Montreal region, where the stored pump sets were serviced monthly. The first two pumps were installed and commissioned in 2022, and the remaining four pump sets in August 2023.
The engineering contractor was responsible for installing all pumps including electrical equipment and wiring between the control units, the motor control system and the excitation boards. KSB verified the installation of pumps and motors. The subcontractor verified all wiring from and to the above mentioned equipment components. KSB also attended the pump acceptance test on site.
All pumps were tested again on site, and they performed as required. In September/October 2023 a training event was held for the staff responsible for the pumps, motors and control units.
