Turriff Water Treatment Works (WTW) is a strategic water treatment works in the Northeast of Scotland for Scottish Water. It not only serves the direct catchment, but also provides resilience to supplement adjacent treatment plant supplies. The Turriff WTW is an ageing asset, with much of the equipment exceeding its design life expectancy, presenting operational challenges in maintaining the demand and quality of water supply required.
To address the asset upgrade and safeguard for future requirements, Scottish Water engaged RSE (Ross-shire Engineering) in mid-2020 to design, refurbish and upgrade several key process and control equipment assets at Turriff WTW. RSE were tasked with installing a new Motor Control Centre (MCC) with SCADA, telemetry and a new standby generator with uninterruptable power supplies, to maintain treatment even during power outages. RSE were further commissioned to complete the refurbishment of all 10 No. Rapid Gravity Filters (RGFs), including new media and upgraded control valves linked to the new control centre. Scottish Water has given a commitment to the Drinking Water Quality Regulator for Scotland (DWQR) that all the work will be completed and operational by June 2022.
The Turriff WTW dates back 40 years and had been significantly modified over the years to accommodate changing operational needs. Working with the ageing equipment provided some significant design challenges, as many of the changes had not been fully documented. To overcome this, RSE undertook a detailed investigation of the software code, to fully understand the required functionality of the existing control system, so that it could be accurately replicated in the new Programmable Logic Controllers (PLC). The entire upgrade is to be completed whilst the existing works remains fully operational to meet supply demands, which will provide a challenge to both the RSE Delivery and Scottish Water Operational teams. Collaboration, strong communication and flexibility are all critical to accommodate regular operational needs while still maintaining a complex capital delivery programme.
The new MCC was manufactured by RSE subsidiary and panel design experts, Saftronics, and installed within the units prior to the modular building being transported to site and lifted onto a newly prepared concrete base. The new MCC was unable to be accommodated within the current building as the existing MCCs were essential to maintain the WTW operation whilst the improvement works took place. As the upgraded MCC will produce approximately 57kW of heat energy when running at maximum capacity, RSE have been tasked with designing a new building ventilation system to utilise the excess heat energy during the colder months. The ventilation system installed on the roof of the upper units, combined with air intake louvres on the base units, will provide sufficient air flow to regulate the room temperature and protect the switchgear from overheating.
The new dedicated MCC Building includes a subbase area for the new cables, consisting of 2 No. 4.1m x 18m modular units, constructed from hollow section steel with a protective paint coating. The complete MCC Building design, fabrication, protective coating application, cabling and assembly were carried out offsite by RSE, at our state-of-the-art Modular facility in Muir of Ord, to minimise disruption to normal site activities.
With the Modular MCC Building being constructed offsite, RSE are always adopting new methods and techniques to minimise our carbon footprint. For example, temporary steel wire ropes were installed within the units for lifting and transportation. These wire ropes will be removed onsite to minimise the amount of steel required in the units, overall enhancing the green credentials of the modular build offering.
RGF refurbishments were also ongoing in advance of the MCC delivery, and all 10 No. filters have had existing sand replaced with upgraded Filtralite media and nozzles. All existing pneumatic control valves have been replaced with modern electrically actuated units, which will be integrated into the new control centre to provide enhanced control over the operations of the RGF’s.
The offsite modular building has significant advantages to the overall management of the health and safety, efficiency and environmental impacts of the project. Less onsite Mechanical & Electrical (M&E) teams reduces the requirement for different trades and personnel to be present on site, resulting in a safer working environment and eliminating unnecessary travel, overall lowering the carbon emission output of the project. Programme savings are also achieved by undertaking offsite M&E build, in parallel with site construction works.
Through our lean manufacturing-based techniques on this project, RSE has had the capacity to deliver certainty and savings in time, costs, client resources, logistics and carbon footprint whilst achieving enhanced quality of build and health, safety and well-being performance.
Craig Watt, RSE Delivery Manager, commented:
RSE’s collaborative approach with Scottish Water on the design and managed delivery at Turriff WTW has enabled the construction of the plant’s upgrades to develop, despite current working restrictions and fixed timeframes. With the support of Scottish Water, and the willingness of all project collaborators to progress, RSE teams have been proactively working to guarantee a safe delivery of the MCC unit to site.
Jim Gordon, Scottish Water Project Manager, said:
The challenges presented by delivering a project with so much live intrusive work, while ensuring such a strategic water treatment works continues to operate normally, cannot be understated. These known challenges have been further compounded by unexpected issues, including dealing with unrecorded asbestos and yet all the while having to maintain the guaranteed output date to the DWQR. We have much still to do, but what we have done so far could not have been achieved without the open and honest cooperation exhibited by all the people involved, from initial concept design through to ongoing delivery operations.
Darren Still, Scottish Water Operational Team Leader, added:
The scale and scope of the work was initially daunting but together as a team, we have managed to overcome many challenges that we have encountered, with little to no impact on water quality. With work still ongoing we continue to work closely with all involved, to plan and implement changes required to complete the project on time and within budget.
