Mackenzie Construction called upon Selwood, a long-standing partner of Mackenzie Construction, to support them in a project for their framework partner Scottish Canals.


The water around the lock gates at Rotherwood Avenue in Glasgow needed bypassing to allow for maintenance work to be carried out to the gates.

Almost 200 litres per second of flow had to be forwarded into the upstream canal system to maintain the water levels needed downstream and successfully maintain the levels within the canal system.

Noise was a key concern to avoid disruption to nearby residents whose homes were situated only 30m from the site. In parallel to this, there was also a need to avoid the risk of fuel pollution and minimise the overall environmental impact.


Historically, pumps would have been chosen to move the water, however, Selwood developed an environmentally friendly siphoning system to assist with the crucial works, using nothing more than pipes, gravity and specialist control systems.

Having demonstrated the benefits of using a siphoning system to the client on previous works, the client trusted in Selwood’s expertise in using this untraditional method.


Selwood’s teams carefully carried out a site survey to demonstrate a siphoning system was viable.

Selwood ran 150m of 14inch MDPE bauered pipework on one lock and 80m of pipework on the other, chosen for its flexibility and ease of use on uneven ground. The pipework was also fitted with a gate valve on each set-up to regulate flow rates. Two dry vacuum pumps in a duty/standby format were used to remove air from the pipework, controlled by a monitoring panel that could self-prime and trigger the siphon.

The vacuum pressure was continually monitored by two Selwood pressure monitoring panels that enabled the system to start automatically if the vacuum started to drop below the required levels.

Using a siphoning system negated the requirement to run pumps and burn fuel 24/7 in order to drain the lock, helping to overcome all challenges.


During the initial phase of the project, it was realised that should the canal not supply the required rate of flow, the system could not prime as required. As a result of this, Selwood marked out critical levels on the walls of canals, to maintain water levels in the locks and ensure siphoning systems work for the duration of the job without interruption.

The installation took just over one week and once the siphon was up and running, it required very little maintenance with only occasional checks on the priming system. 181,440,000 litres of water were moved from the two locks during the operation.

Around 576 litres of fuel per day was saved by replacing a traditional pump set-up with a siphoning system, equating to 1555kg of CO2 emissions saved across the duration of the project. This not only protected residents from harmful CO2 emissions, but also aquatic life in the canal.

The client was able to generate significant savings in cost as well as CO2 through negating the need to burn fuel and run a pump. Noise levels were kept to a minimum which ensured that the residents were not disturbed.

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