Dublin Airport Authority

Background to specification
Balfour Beatty Ireland had already overseen the very positive installation of a 4,500 m³ Tubosider tank in Phase 1, and now required a high output project with tight schedules for pipeline and activation. The speed and efficiency with which they had been working was therefore very important for Phase 2, plus achieving all targets in their demanding safety guidelines.

At a capacity of over 550,000 ft³ (15,600 m³), this project called for then the largest single tank ever commissioned from Tubosider, and one specially designed and delivered to make the minimum carbon footprint.

It also called for a 6,500 m³ pollution tank at depths of up to 6 metres and a 900 metre foul sewer at depths of up to 4 metres, all of which must be connected in to one system. The DAA was involved in and co-operated fully on the solution developed by the Tubosider and Balfour Beatty Ireland design teams, and also observed the manufacture of the tanks at the St Helens facility.

Key criteria
The stormwater attenuation tank at the heart of Dublin Airport Authority’s (DAA) Phase 2 Drainage Project was not only a record size, but was to be loaded, delivered to site, handled and installed in a model of environmental and safety planning.

Balfour Beatty is committed to making all its operations as green as possible. This includes all construction activities from manufacture through to installation, all to the highest level of safety. Loading and unloading the nested sections of pipe using forklift trucks and on-site mechanical lifting equipment completely avoided the need for people to work from truck beds or anywhere at height.

Solution & benefits
The tank was composed of a manifold of pipes totalling 5,600 metres in length, half with a diameter of 2 metres and the other half with a diameter of 1.8 metres. The variation in diameters allowed the sections to be nested together before, during and after transportation, and halved the number of truck loads – saving 220 journeys from St Helens to their destination in Dublin airside.

Delivered in nested lightweight sections, the giant tank was fitted together using Tubosider’s gasketed joints (WRc approved to ‘Sewers for Adoption’ standards of watertightness) and installed over a three-month period. It was the sixth commission then by Tubosider completed for DAA at the Airport.