Nakheel's tunnel vision gains international recognition

A technical paper entitled 'Design and Construction Challenges of Sub-sea Directional Drilled Crossings on The Palm Jumeirah, Dubai' prepared by Jack Gahir, Richard Radwanski and Tamer Al Hafez has been accepted by the International Tunnelling Association. The Congress is a showcase for the state-of-the-art and brings together eminent experts and delegates from around the globe. Nakheel's Geotechnical Lead at The Palm Jumeirah, Jack Gahir, has also been invited to make an oral presentation to the Congress.

The paper presents a case history of installing 12 sub-sea horizontal directionally drilled (HDD) crossings - a trenchless construction technique, which uses guided drilling for creating an arc profile - on The Palm Jumeirah. This is the first time that multiple undersea crossings of this length and type have been undertaken in the United Arab Emirates. The crossings will provide water, gas and telecommunications to the 22 hotel and leisure developments located on the 200m wide crescent.

Jack Gahir said:

'The success of the HDD technology on The Palm Jumeirah required careful planning and co-ordination, and we are proud to take our achievements to Seoul where the world's leading experts in the tunnelling industry will be present. The demonstrated success is an asset not only to Nakheel, but to Dubai and the general region where other water front developments are planned.'

Six of the crossings are installed at the eastern end and 6 at the western end of The Palm Jumeirah. Each crossing comprises of a 500mm diameter high density polyethylene sleeve through which a utility carrier pipe is installed. The maximum crossing length is about 800m and the pipe sleeve is located at a depth of 13m to 16m below the seabed.

Jack Gahir added: 'The major design and construction challenges on the HDD crossings were close spacing between the bores, changing ground conditions along the drilling alignment, high salinity of the groundwater and confined plots for entry and exit holes. These were successfully overcome by amending the methodology as the initial pipe sleeves were installed.'

Lessons learnt from the eastern crossing, which was completed last year, have been successfully applied on the western side, where the last two HDD crossings will be completed in early April.