Montreal’s water supply system gets an additional pump to increase capacity and flexibility

The Charles-J.-Des Baillets plant in Montreal, Canada

It’s always satisfying for a pump manufacturer to learn that its products are living up to expectations, even after many years of service. For KSB Pumps Inc., Canada, this was the scenario when the City of Montreal, Montreal, Canada, approached them in 2013 to submit a tender for an additional pump set in order to expand its Charles-J.-Des Baillets drinking water production plant where five KSB ME type pumps had been operating since 1978 and producing 1,136 million cubic metres of water per day, accounting for 38 per cent of the total production capacity of the city of Montreal alone.

The city operates six water treatment plants, with 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.

Charles-J.-Des Baillets is the second largest plant in Montreal, and one of the largest in Canada, having a production capacity of 1.136 million cubic metres of water per day, accounting for 38 per cent of the total production capacity of the city of Montreal.

Fed by water from a large underground reservoir that is, in turn, charged by the St Lawrence River, the Charles-J.-Des Baillets plant purifies the water with a combination of filtration, ozonisation, ultraviolet (UV) water treatment and chlorination before allowing it to enter the potable water reservoir. Three pump sets are dedicated to one line, with the remaining units supplying a large reservoir located in the city’s boroughs.

The city’s population has increased substantially, and today the water department supplies approximately two million residents, and both production plants are interconnected through sizable piping, making it such that in the unlikely event of one plant going down, water can still be supplied to the reservoirs. The Charles-J.-Des Baillets plant was originally designed to accommodate nine high capacity pumps. However, only five KSB ME pumps were installed initially. Later, in 1990, the plant’s output capacity was increased with the introduction of another pump.

Although the plant was built to accommodate nine pumps, the water facilities could only support a maximum of seven pumps. However, based on their satisfaction with the original five pumps, the City of Montreal requested that KSB submit a tender for another pump of the same design and capability.

Unfortunately, after such a long interval, the original pumps were no longer in production. However, KSB circumvented the issue by coming up with a plan that involved making an updated replica – a proposal that ended in them winning the order.

The 38-ton pump with an impeller diameter of 1905mm

Constructed in accordance with customer specifications, the KSB MEF pump is a vertical split-case, single stage pump, that is an updated version of the original pumps supplied in 1975.

The footprint and layout of the new pump resembles its older counterparts, but up-to-date seals and optimised hydraulic elements have enhanced its reliability and improved operating efficiency. Duplicating the older pump configuration also simplified the installation of the new unit in the CharlesJ.-Des Baillets high-pressure pump gallery

Having secured the contract, KSB manufactured the new MEF pump in Brazil, and shipped out the 38-ton pump with an impeller diameter of 1,905mm in late 2013. With a drive shaft measuring 5 metres in length and operating at a fixed speed of 400 rpm, it delivers 4.2m³ per second at a head of 67m. Initially planned to be used as a back-up unit, the pump also operates in parallel with the existing large-capacity pumps. Due to its size, the pump had to be disassembled for shipment and reassembled on site.

In April 2015, work commenced on the assembly and installation of the pump at the Charles-J.-Des Baillets water filtration plant under KSB’s supervision. Between May 2015 and April 2016, installation of the 5,500 HP synchronous motor and line shaft was performed by the mechanical contractor. The next phase was the commissioning and configuration of the control panels and auxiliary electrical components undertaken between April 2016 and September 2017, with performance and acceptance tests of the pump conducted in October 2017.

The hydraulic acceptance tests were performed on the new pump unit with the scope of the tests being to verify the contractual efficiency guarantee point of 87 per cent at 4.2 m³/s. Summarising the key results, at the rated flow of 4.2m³ per second, the pump efficiency was 90.4 per cent; 3.4 per cent greater than the guarantee efficiency of 87 per cent. The results show that the performance of the pump GP5 fulfilled the contractual guarantee obligations.

Installing a new pump set involved the evacuation of foundations to accommodate the water intake pipework and pump volute

Installing the new pump set was not without its challenges, given that the area allocated 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.

The pump gallery was constructed on three storeys with the motors and the control panels mounted on the upper floor and the pumps three storeys directly below on the bottom level. A five-metre-long drive shaft from the 5,500 HP motor on the upper floor couples to the pump below. Because the new pump had the same hydraulic configuration as its older counterparts, it was installed alongside them in exactly the same arrangement.

KSB engineers played a significant role in overseeing the installation and commissioning of the new pump as the process was somewhat complicated by the ingress of water from the adjacent underground supply reservoir. Each pump intake was secured by two sets of stop logs, as compared to large gate valves, creating a serious problem with water infiltration into each intake chamber in which the pumps are mounted. Thus, it was necessary for the safety of the engineers and the construction personnel to continually pump water from the foundations during the construction of the intake chamber of the new pump.

The new KSB pump, installed and fully operational

According to an engineer from the City of Montreal’s water department, the addition of the new pump provides more redundancy to the system.

Under normal operating conditions, two or three pumps operate each morning according to the demand placed on the supply system. During the day, demand fluctuates, as does the number of pumps operating, and as such, the pumps are used at night to replenish water in the city’s reservoirs.

Moreover, the department was motivated to stay with KSB as the pumps had performed very well over the 36 years since the original five KSB pumps had been in operation, with the city’s water department never experiencing any significant problems.

“When the pumps were first installed, they were over performing, thus increasing the load on the motors. 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 and have been easy to service, though the importance given to scheduled maintenance has been a contributing factor in the long service,” reported the city’s engineer.

“Because we know in advance when there is going to be a requisite 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.”

And 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.

All images are credited to KSB.