More potable water for Montreal
The Canadian city of Montreal extracts water from the St Lawrence River for two large potable water treatment plants. To satisfy population growth, the city’s water department needed a new large pump for the larger of the two plants. This had to be of the same specifications as the existing KSB pumps – and run efficiently and smoothly.
The project: Increasing the pump capacity of the Charles-J.-Des Baillets plant in Montreal
Charles-J.-Des Baillets (Fig.1) is the second largest plant in Montreal and among the largest in Canada, having a production capacity of 1.136 million cubic metres of water per day. This accounts for 38% of the total production capacity of the City of Montreal. Together with the Atwater plant, it supplies potable water to seven subterranean reservoirs and associated pumping stations throughout Montreal Island and its outlying districts.
Delivering over one million cubic metres of potable water every day, the plant is fed by an adjacent underground reservoir. The water comes from the St Lawrence River and prior to entering the reservoir, it is purified by a combination of filtration, ozonisation, ultraviolet (UV) water treatment and, finally, chlorination. Three pump sets (Fig.2) are dedicated to one line supplying the Atwater piping network, with the remaining units supplying a large reservoir located in the city’s boroughs.
Commissioned in 1978, the Charles-J.-Des Baillets plant was originally designed to accommodate nine high capacity pumps. However, only five pumps were installed initially, these being the KSB ME pumps. Later, in 1990, the plant’s output capacity was increased with the addition of another manufacturer’s pump. Over the 36 years in which the original five KSB pumps have been operating, the city’s water department has not experienced any significant problems.
“When the pumps were first installed, they were overperforming, thus increasing the load on the motors,” reports the city’s engineer. “This issue was easily resolved by trimming the impellers, and since then there have not been any issues. The pumps have delivered the expected performance. They have been easy to service, and the importance given to scheduled maintenance has been a contributing factor to their long service,” he continues. “Because we know in advance when there is going to be a requirement for spare or replacement parts, there is no need for us to hold any major
components. With advance planning, KSB is able to fulfil our requirements.”
Because of this satisfactory performance, the department was motivated to stay with KSB when it came to increasing the plant’s pumping capacity. KSB was asked to tender for another pump of the same design and efficiency, in order to continue to secure the water supply for the growing population.
The client: The City of Montreal
The City of Montreal operates six water treatment plants, including two major ones, namely Charles-J.-Des Baillets and Atwater, both of which supply potable water to seven subterranean reservoirs and associated pumping stations throughout Montreal Island and its outlying districts. Over the years, the city’s population has increased substantially and today the water department supplies approximately two million residents from these two plants. In order to accommodate population growth, in 2013 a decision was made to increase the pumping capacity at Charles-J.-Des Baillets. And this water supply project was given to KSB.
The challenge: Finding replacements for outdated pumps and handling water ingress during construction
The project presented a range of challenges:
- The original KSB water pumps were no longer manufactured.
- The area allocated to the pump was between two existing units and involved a three storey, open high-pressure pump gallery and the excavation of foundations to accommodate the water intake pipework and pump volute (Fig.3).
- Ingress of water from the adjacent underground supply reservoir into the foundations during construction of the suction chamber had to be continuously pumped out of the foundations, for the safety of the engineers during construction
The solution: Optimizing water supply with the KSB MEF pump
Having secured the contract, KSB was quick to react, with the new MEF pump being shipped from KSB’s manufacturing plant in Brazil in late 2013.
Constructed in accordance with the customer’s specifications, the KSB MEF pump is a vertical split-case, single stage pump, and is an updated replica of the original pumps supplied by KSB in 1975. The footprint and layout of the new pump resembles its older counterparts, but up-to-date seals and optimised hydraulic elements enhance its reliability and improve the operating efficiency of the water supply system. Duplicating the older pump configuration simplified the installation of the new unit in the Charles-J.-Des Baillets high-pressure pump gallery.
The 38-ton pump has an impeller diameter of 1,905 mm (Fig.4). With a drive shaft measuring 5 metres in length and operating at a fixed speed of 400 rpm, it delivers 4.2 m³ (100%) per second at a head of 67 m. The footprint and layout are similar to the older pumps, which was important for installation in the confined space of the pump hall: the pump could be installed in exactly the same arrangement as its older counterparts in the pump hall. The hall occupies three floors. The motors and panels are protected from flooding on the upper floor (Fig.5), while the pumps are located on the ground floor. A 5-metre drive shaft from the 5,500 hp engine connects to the underlying pump. Due to its size, the pump had to be disassembled for shipment and reassembled on site.
Work began on the assembly and installation of the pump under the supervision of KSB in April 2015. Between May 2015 and April 2016, the mechanical service provider installed the 5,500 hp synchronous motor and the line shaft, also under the supervision of KSB. Then, between April 2016 and September 2017, cabinets and auxiliary electrical components were configured and commissioned.
In October 2017, the pump was in position and ready for the hydraulic acceptance tests. The scope of the tests verified the contractual efficiency guarantee point of 87% at 4.2 m³/s. Summarising the key results, at the rated flow (4.2 m³/s), the pump efficiency was 90.4%: 3.4% greater than the guaranteed efficiency of 87%. The results show that the performance of the new pump fulfilled the contractual guarantee obligations.
According to the engineer from the City of Montreal’s water department, the addition of the new pump provides more redundancy to the system (Fig.6).
With the installation and commissioning of the new pump, the Charles-J.-Des Baillets plant is now able to operate to its optimum design capability and with full redundancy in the system for the first time in 40 years
Data I Facts I Figures
The City of Montreal
Area: 363.52 km²
Inhabitants: 1,698,062 (as of 2014)
Metropolitan Region: 4,027,100 (as of 2014)
- Flow rate pumping station: 1.136 million cubic metres of water per day using KSB MEF pump sets.
- Commissioning: 2017