Buyer’s Assessment (Alderney Airport/ASI Solutions)

posted on 2nd October 2019
Buyer’s Assessment (Alderney Airport/ASI Solutions)

In 2018, Alderney Airport benefited from a runway refurbishment carried out with ASI Solutions’ Rhinophalt and Rhino-Dust products

Alderney is the northernmost of the Channel Islands, the small island chain that while being a British dependency actually lies not far from the French coast.

Alderney lies in the bailiwick of Guernsey, another of the Channel Islands, which has control over many of the services and facilities on Alderney – such as health, policing and airport operations – as per an arrangement between the islands reached in the late 1940s.

Alderney was almost completely evacuated prior to the German invasion in mid-1940, with only some camps housing forced labour and other prisoners there during the time of occupation, and when the Germans left in 1945 it was felt that the island needed help getting back on its feet. The 1948 agreement that sees many of Alderney’s functions administered by the States of Guernsey includes the island’s airport.

The airport, built in the 1930s, represented the first air gateway in the Channel Islands. Serving scheduled flights both to Guernsey and Southampton on the southern English coast, it is a vital element not only in Alderney’s transport infrastructure but in its very existence – for Alderney is connected to the rest of the world primarily by air. By sea there are only limited cargo vessel connections and a passenger ferry that does not operate in winter months.

Alderney Airport has three runways, but only one of them is surfaced; the other two are grass. The main 880m-long runway is of asphalt and had, prior to last year, suffered from some serious degradation due to loss of surface aggregate. Colin Le Ray, general manager of ports for States of Guernsey, recalls that it was clear that something had to be done to rehabilitate the runway, with the surface breaking up and creating significant quantities of foreign object debris (FOD).

A number of options were considered, including a project that would have seen the runway lengthened. This option was eventually set aside but it was agreed that a major renewal of the airport’s paved areas would be undertaken; this project will include runway shoulders being widened, new airfield ground lighting (including some new centre line lights) and a complete full-depth reconstruction of the runway. Work is scheduled to start in summer next year and may take up to 18 months at a cost of about £12 million (US$15 million).

However, the runway surface had been deteriorating at a rate significantly faster than expected, largely due to some harsh winter weather in the years around 2015, and something – says Le Ray – needed to be done sooner rather than later to at least halt the rate of degradation before the situation became unmanageable.

Milton Keynes, UK-headquartered ASI Solutions had the answer: its Rhinophalt treatment product. Rhinophalt is a sealant applied by spray that penetrates just far enough into the asphalt mortar at the runway surface to provide a durable seal that prevents water ingress and slows down oxidisation due to weathering and ultra-violet light. Of particular interest to the team at Alderney was the fact that the treatment also seals in loose aggregate at the surface, thereby reducing the risk of FOD.

Rhinophalt is best used as a preventative maintenance measure, extending the operational life of the pavement and delaying the large costs of resurfacing and repair works, says ASI, and for Alderney it was the answer to extend the life of its runway up to the complete reconstruction planned for 2020-21.

Rehabilitation

The Rhinophalt rehabilitation of the heavily oxidised, disintegrating surface of the main runway took place in September 2018. A total of 28,000 square metres of asphalt surface (runway, taxiway and apron) was treated with Rhinophalt and Rhino-Dust, the latter helping to ensure a high level of surface grip/friction.

A specialised combination-truck was used to apply the Rhinophalt and fine Rhino-Dust at a calibrated rate. The truck was operated by ASI’s airfield contractor, Allied Infrastructure.

The procedure was carried out at night to ensure that operations at the airport were not affected. One night’s work had to be suspended due to rain during the day preventing effective application of the treatment that night, but otherwise the task was completed as expected and as scheduled.

Repainting of the surface with the relevant lines and landing markers could then take place. The treated surface was grip tested and found to have a higher level of friction than it had prior to treatment, while the runway is also now suffering from significantly less surface degradation, with less stone loss and less FOD.

The team at Alderney Airport has carried out routine sweeps of the asphalt surface for many years and a record is kept of the amount of loose stone swept up. In the nine months since the Rhinophalt treatment, the average monthly stone loss has reduced dramatically. The following table shows the FOD problem over recent years, and how the asphalt treatment has had a significant positive effect:

Year                                   FOD mass (kg)

2013                                  2,105

2014                                  2,197

2015                                  3,155

2016                                  4,342

2017                                  3,227

2018                                  3,014

2019*                                177

* Up to and including June 2019.

“The results in reduction of FOD mass are evident from our continued monitoring and maintenance of the runway, taxiway and apron surfaces,” says LeRay.

“To date we have seen a near 90% reduction in material being shed from the surface and this is a very visible measure of the effectiveness of the product,” he adds.