Highlands and Islands Airports Limited (HIAL) operate 11 airports across the Scottish Mainland, the Islands of Orkney and Shetland and the Inner and Outer Hebrides. With its head office in Inverness, the private limited company is subsidised by the Scottish Government and sponsored by Transport for Scotland.
These connections support economic and social activities by enabling lifeline services to locations with populations from 5,000 people to fewer than 600. Some of these have limited access to surface alternatives and the region’s weather can also mean that ferry services can be disrupted by high winds and rough seas. The airports not only enable connections for people and goods but support critical services such as Emergency NHS passenger transfers, Royal Mail services and the offshore energy industry.
CHEM RESIST EXPERIENCE
For the planes to operate, the runways need to be free from ice; salt-based de-icers cannot be used so ECO-GEN runway de-icer is used instead. ECO-GEN is aqueous potassium-based solution which is not particularly aggressive so won’t damage the aircraft, engines and parts as a salt-based version would.
The challenge really comes from the local weather conditions which can include snow, rain, high winds and temperatures as low as -20°C. Using metal storage tanks in these conditions would see them quickly corrode.
Chem Resist specialise in Thermoplastics, so the material of construction is proven down to -40°C, but the whole de-icer storage system needs to be ice-proofed. The pipework and every component including the valves, seals and ‘O’-rings need to be operational at these low temperatures due to the critical nature of the application.
A Chem Resist De-Icer Storage System project for BAA at Glasgow Airport, completed in November 2011, led to a project at HIAL’s Inverness Airport. The project at Inverness was a large capacity system of 180m3 which was automated using a control panel to fill the agricultural long-armed spray vehicle with the exact amount of de-icer needed for the runway. The project at Inverness was completed in October 2012.
Simon Hewitt, MD at Chem Resist comments, “Word of the De-Icer Systems had spread within the HIAL Group, so we next won the project to work with Wick, but their requirement was different, so we developed a simplified system for the smaller airports and those located on the more remote islands. The de-icer systems are operated by the Airport Fire Service, so the specification was changed to minimise any possibility of damage or future repairs.
“We removed the automation, so these systems are manually operated, with cat and mouse and ultrasonic level indication. To save time on-site we approached the build in a modular way, manufacturing not only the tanks and all the steelwork, but also completing as much work as we could on the pipework, ChemiGuards and pumps in Dewsbury, so the time our installation teams spend on site is absolutely minimal. The systems are installed and up and running in just 1-2 days, so any impact on the critical air services is dramatically reduced.”
Chem Resist successfully used this approach at Wick (completed December 2019) and then went on to complete projects at Kirkwall in Orkney (September 2020), Dundee (February 2021) and Benbecula in the Western Isles (April 2021).
HIAL 2021 TENDER
In September 2021, HIAL issued a tender for the design, manufacture and installation of De-Icer Storage Systems at 5 remaining airports within the group.
The tender covered 5 sites and 7 systems; Stornaway (Lewis) and Sumburgh (Shetlands) required 2 systems (2x 55m3 tanks) due to their size and traffic levels, and Tiree, Islay and Campbeltown each requiring 1 system (1x 30m3 tank). These new systems were to replace the existing rubber lined steel tanks at Stornaway and Sumburgh which were perishing, and the IBC’s being used at some of the smaller airports.
As part of the tender, The Scottish Environmental Protection Agency (SEPA) required that best practise be followed, with operatives no longer manually handling the ECO GEN in IBC’s and the new storage systems providing inherent protection for the environment from any potential loss of containment incidents.
The solution proposed by Chem Resist included Bunded Spiral Wound Chemical Storage Tanks to provide secondary containment and ChemiGuard Pressurised Offload Cabinets to meet SEPA’s requirements. The tender was awarded to Chem Resist in December 2021.
During January 2022, Ian Ward, Project Engineer, surveyed each of the 5 sites. During the visits he met with local customer contacts and liaised with civil contractors and cranage contractors to advise the site-specific requirements.
Ian explains, “Site surveys are a basic part of any project to make sure things run smoothly, but where we have possible infrastructure restrictions such as narrow roads and tight bridges, they are absolutely fundamental to a project’s success. In some cases, we were measuring the width of the roads and there was a humpback bridge just outside Inveraray that could’ve caused real problems with the wrong type of delivery trailer.”
The De-Icer Storage Systems are located ‘airside’ so beyond the passport and security checks travellers usually go through. Working airside involves security checks for the individuals working on the project, but also physically negotiating security fencing and gates.
Ian adds, “Working airside brought in one layer of complexity, but the remote nature of some of the islands brought in another. During my visits in January, I booked the accommodation for the installation teams to make sure they had somewhere to stay.”
MANUFACTURE AND FINAL INSTALL
Manufacture of the 55m3 Spiral Wound Thermoplastic Storage Tanks for Sumburgh began on the 24th March 2022. Based on learnings from the project completed for Orkney, the tanks were manufactured to 3.8m diameter to ensure they would fit on to the ferries.
Not only were the tanks and steelwork manufactured in advance, but preparation work was done for the ChemiGuards, pumps and pipework to save time on-site. Each installation included a ChemiGuard Pressurised Offload Cabinet to protect operatives and the environment as the de-icer transfers from the delivery tanker to the storage tank. The applications demanded that electric pumps were used, so Mono Progressive Cavity Pumps were specified, and Plast-O-Matic Anti-Siphon and Pressure Relief Valves were also included in the pipework configuration.
Neil Williams, Director of Fluid Transfer comments, “The pumps specified for the project were outside our usual fluid transfer technologies, but, as with every project, we make sure our customers have the best pump for their application. Also, as we wanted to ensure any future repairs were minimal, we included the premium Plast-O-Matic valves due the high pressures involved in the system.”
Ian explains, “The project timeline included the ferry timetables and our accommodation bookings, but because ferries can be impacted by the weather, rough seas and also by emergency loads taking priority, confirmations were sometimes to the wire. A large transporter can easily take up the space of 6 cars which meant the crane and tank had to go on separate ferries, which meant the cranes were getting to site a day before. We allowed some waiting time in the timeline for all the elements of the project to arrive in the final locations.
The installation phase began on the 19th May 2022, with 2 systems at Sumburgh being the first to be successfully completed, followed by Stornoway, Tiree, Islay and finally Campbeltown in June. The systems were commissioned by October 2022 in advance of the winter.
There is one final airport in the HIAL Group which Chem Resist won’t be providing a de-icer storage system for. Barra Airport, where the runway is the beach!
Installation pictures at (LtoR): Islay, Stornoway and SumburghBack to Blog