The largest of two recent contracts is for the purchase of WPL Hybrid-SAF technology to be installed initially on the Winchburgh expansion project.

The flexible, modular units are required for a minimum of three years at this fast-growing residential development in West Lothian, but could remain in use for up to ten. They are required to treat excess flow and load whilst the site is in the construction phase.

The units will run in parallel with the existing plant serving Winchburgh, taking the total capacity of the works to 5,800 population equivalent (PE) and providing intermediate capacity of 2,800 PE, which will be sufficient up to June 2022. The village’s original 3,000-strong population is expected to grow to 8,243 by 2023, so Scottish Water needs to reduce loading on the trickling filters already in place.

A new larger wastewater treatment works is planned for a site next to the existing one and will start operating by the end of 2022. It will be sized for the 16,389 PE required by 2032.

Scottish Water says the current site has come to the end of its life and the utility wants to build the new works to support the local community as it continues to grow and flourish. In the longer term the WPL Hybrid-SAF units can be transferred to other sites where extra capacity is required to ensure environmental compliance during refurbishment or due to population growth.

The need for flexible assets was also behind a second contract with Ross-shire Engineering for the purchase of conical tanks for a Scottish Water project in Aberchirder, Aberdeenshire. The units will initially provide temporary settlement above-ground during refurbishment of the existing activated sludge plant serving the village.

After completion, the assets will be moved offsite for potential future use. It was decided to acquire the assets by purchase because they can be moved from site-to-site for temporary or permanent applications.

Scottish Water has a number of smaller sites where upgrades are being carried out and the transferability of the tanks will ensure the utility optimises its investment over the long-term.

Andrew Haywood, utility sales manager at WPL, said: “Our success in winning these contracts demonstrates the versatility and flexibility of WPL’s wastewater treatment systems and we look forward to continuing our close relationship with Scottish Water. The modular nature of our equipment means it can fit into the most constrained site footprints, whether on new developments or at remote rural works.

“The WPL Hybrid-SAF units can be transferred offsite for use elsewhere at a later date, ensuring there will be no stranded assets once a permanent system is put in place. This fits with Scottish Water’s plans for a rolling investment strategy which will take a much more long-term perspective on the country’s water and wastewater needs.”