Challenge
Scottish Water and Xylem were undertaking a planned maintenance task at St Nicholas Sewage Pumping Station, a large strategic site in St Andrews that receives flows from five upstream pumping stations.
The original scope of works included replacing an inlet gate valve and non-return valve (NRV) on Line 2, along with pump impellers and wear plates.
During the works, Xylem engineers discovered the isolation valve was not sealing the flow off when closed, causing pressure to backflow down the line. This meant the NRV could not be safely replaced without fully draining the line back into the wet well.
Engineers initially attempted to reseal the flanges, but the pressure had damaged the gasket beyond repair. Normally, such backflow could be managed through tankering.
However, due to the high combined inflows from gravity sewers and the five upstream pumping stations, the volume of wastewater exceeded the tankering capacity available at the time. With Pump 2 unavailable, the station was operating on its standby pump, creating significant operational pressure to restore full resilience quickly.
If the issue could not be resolved promptly, Scottish Water would have needed to install temporary over-pumping, a costly and time-consuming mitigation that also carried environmental, operational and reputational risks, as well as local disruption. The station also pumps through the historic St Andrews golf course - any failures not picked up promptly could have serious repercussions to land in and around the courses.
Working closely with Scottish Water, Xylem’s engineering team quickly devised an alternative solution to control incoming flows without the need for over-pumping. The agreed approach was to temporarily manage and restrict flows from the five upstream pumping stations, using their available storage capacity while the rising main was drained and the NRV replaced.
This required careful coordination and real-time monitoring of the five stations to avoid spillages elsewhere in the network. Crucially, two of the five upstream pumping stations were equipped with Xylem’s Xylem Vue Secure Connect (Avensor) monitoring system, providing live data on wastewater levels and asset health.
The solution
Xylem Vue Secure Connect (Avensor) is a digital service that provides alerts and data-driven insights from a device connected to pump stations or other water infrastructure assets. Once a modem is installed to connect all the assets, Xylem Vue Secure Connect (Avensor) collects and analyses data to give a complete overview of all connected operations, including trends and alerts, via the web and a mobile app.
Insights from Xylem Vue Secure Connect (Avensor) allowed Scottish Water and Xylem engineers to remotely monitor conditions via mobile devices and attend sites only when necessary to pump water in a controlled manner.
The remaining three stations were monitored through periodic site checks. With this intelligence in place, the St Nicholas SPS was safely shut down, the rising main fully drained and the NRV replaced.
Throughout the operation, Xylem engineers worked collaboratively onsite with Scottish Water, adapting plans in real-time to ensure the work could proceed safely and efficiently. As a result, Scottish Water asked Xylem to quote for additional work onsite.
Results
- St Nicholas Pumping Station was returned to 100% operational status without the need for temporary over-pumping
- Significant cost and time savings achieved by avoiding additional mitigation measures
- Environmental risk reduced, with controlled flows preventing pollution events across the network
- Minimal disruption to Scottish Water operations despite the complexity of the site
- Demonstrated value of Xylem Vue Secure Connect (Avensor), providing real-time intelligence at a critical moment. Scottish Water has continued to deploy Xylem Vue Secure Connect (Avensor) across its assets.
This project highlights how Xylem’s engineering expertise, rapid problem solving and digital monitoring technology can resolve unexpected issues on complex assets. It also demonstrates the wider value of Xylem Vue Secure Connect (Avensor), enabling operators to make informed, timely decisions that mitigate pollution risk and deliver better outcomes.
Mike Kelly, Scottish Water’s wastewater networks team leader, said: “This was a complex job on a busy terminal pumping station. Having live information available allowed our team to manage incoming flows safely, respond quickly and keep the wider environment protected while the work was completed. Working closely with Xylem, we were able to restore the station to full operation, avoiding the cost and disruption associated with temporary over-pumping.”