Scottish Water TWS & SPMA Programmes

Client: Scottish Water

Project value: £50M

Location: Pan-Scotland

Timeframe: 2018-present

As a framework contractor, Scottish Water invited Mackenzie Construction to collaborate on its major tank repair programmes following several years working on more minor service reservoir repairs. It was clear from initial meetings that the Treated Water Storage (TWS) Point Repairs Programme and SPMA Programme were going to be more intense and focused projects involving:

  • Over 400 Treated Water Storage Tanks
  • Pan-Scotland locations, both mainland and island
  • Intense programme of works

The driver for the projects is to bring improvements to the quality of water being stored within the assets by carrying out internal and external refurbishment works to prevent ingress and egress into the tanks.


The biggest challenge to overcome is asset availability as Scottish Water must ensure a consistent supply to their customers making it difficult to take these assets offline for repair. Whilst water demand is usually dependent on the time of year, there were several other seasonal factors which proved challenging when working on a pan-Scotland programme of delivery:

Seasonal Tourists on Scottish Islands - given that we were still in the pandemic and many people were still enjoying ‘staycations’, this created a perfect storm where both accommodation availability for our squads was both in short supply and increasingly expensive due to supply and demand

Climate – many structural repair products are challenging to work with during the Scottish winter where rain, ice and low temperatures are common


To accommodate this, we worked in close collaboration with our client to create a suite of procedures that would allow us to work on assets while they were still live, negating the need to take tanks offline. This was a first for Scottish Water and will benefit all contractors working for them in the future. The allowable works include procedures to:


  • Repair, remove and refurbish security hatches and upstands under live conditions
  • Repair external movement joints on live tanks
  • ROV Inspection Works on live assets


A further innovation that we introduced as a first for Scottish Water was the use of an intelligent roof membrane on Clean Water Tanks. The intelligent membrane is a multi-layered waterproof sheeting connected to an electronic geogrid which highlights the exact location of any defects as they occur.

“I am immensely proud of what our team has achieved on both the TWS and SPMA Repairs Programme. During peak delivery, we had more than 35 squads working on this project in every corner of Scotland and a team of over 20 staff supporting delivery. We overcame the challenges of COVID-19, brought new and innovative ways of working to our client which they have now adopted as best practice and formed collaborative working relationships which truly inspired success.”

Mark Brown, Contracts Manager | Contracts Manager


The TWS Point Repairs Programme and SPMA Repairs Programme have contributed significantly to the repair and refurbishment of treated water storage structures across Scotland which in turn will improve and protect water quality. With the scale of this project there was an intense level of collaboration required between all project stakeholders and we are proud of the close chains of communication that were maintained between teams across the country ensuring the project was met with success.


The skills and expertise deployed by Mackenzie Construction and its dedicated supply chain has brought new life to old structures which has maximised the lifetime of the assets. This in turn reduces the need for new construction projects which can have a greater environmental impact than refurbishment works. As a result, this programme is supporting Scottish Water in reducing carbon emissions and supporting society on its journey towards Net Zero.