Palm Deira
The breakwater crescent of Palm Deira will be 21 km long, the largest breakwater in the world. The crescent will be divided into 12 districts, and will have 6 openings for water circulation. The special feature to Palm Deira is that each of the districts will have land sticking out to create more beach land for investors. These are referred to as "fingers," and will be 250 m long. It is located in the internal part of the crescent 350 m from the fronds.
Sub-Sea drilled directional crossings
The sub-sea vehicular tunnel and monorail connect the spine tip to the crescent and help facilitate utility services to hotel and leisure developments on the crescent. Six sub-sea HDD crossings are built at the eastern and western ends of the sites. The eastern crossing from Frond D to the crescent is 580m in length at water line, with an average boring length of 680m, while the western crossing is 700m long at the water line with an average boring length of 800m. In order to gain experience, Al Naboodah Engineering Services, the company in charge of installing 12 HDD crossings and 2 micro tunnels for electricity cable installation decided to first build the shorter eastern crossing. The pipes, located at a depth of 13m to 16m below the seabed in water depth ranging from 7m to 14m, provide for drinking water, telecommunications, wastewater and the discharge of treated sewage.
The main challenges of the installation of sub-sea horizontal directional drillings on Palm Jumeirah specifically, was that there were close spacing between the bores (holes), changing soil conditions along the drilling alignment (fill/rock) and brackish (slightly salty) groundwater. To resolve the second problem, vibrocompaction technologies were used just like in the case with sand in the palm's fronds themselves.
​
​
​
​
The islands themselves, the fronds were made out of an obscene amount of sand - 94 million cubic meters of it! That is enough to cover the whole of Manhattan 1 m deep! One would assume that acquiring even that huge amount of sand would not be difficult for a country with sand as their biggest resource (deserts). However, sand from the desert is not the most suitable type for construction of the Palm Islands because it is too fine and "flaky". Instead, sand was obtained from 60 nautical miles out of sea, from the bottom of the Persian Gulf. This is sand was superior because it was coarse, dense and resistant to wave impact. The sand was dredged by the Belgian company Jan De Nul and the Dutch company Van Oord, and was sprayed using dredging ships. Sand placement was guided by Differential Global Positioning Systems (DGPS) allowing for an error of less than 0.39 of an inch beyond imagined boundaries (since there are no rigid mold to hold it in place). The way this works is that five men walk around the entire island daily in the hot temperature and high humidity levels, carrying these cumbersome gadgets behind their backs, and receive signals from the Prince's own satellite system, located 676 km up in space.
​
​
​
​
​
​
​
Another challenge was that since the sand was rainbowed or sprayed, the sand is loose and uncompacted even though sea bed fine material is already cleansed, since it is from great ocean depths. Usually sand compaction would happen naturally over time, but there is no time as the Prince rushes the completion of this project due to declining oil banks, Dubai's main source of revenue. Also, road rolling is not an option in this project because the sand is too deep - 12 m deep. Another potential challenge is the fact that Dubai lie on the edge of an earthquake zone. If sand has low cohesiveness, and there is an earthquake, a process known as liquefaction can develop. This process entails that as the earthquake shakes the Earth's surface, sand particles will move. The sand particles will compact, pushing the water between the particles up, as a result, liquifying the ground. This will ultimately cause the island to sink in the sea, which is not supposed to happen considering all the people and money invested in this project. To resolve the problem, constructors used vibro compaction technologies which made loose sand denser by saturating it with high-pressured water an air, and vibrating it with probes). In January 2004, two thousand holes were drilled into the ground as a result. These efforts helped secure sand in place. Then, additional sand was dumped to fill the remaining space. The process of stabilizing the fronds took approximately 8 months. Although a time-consuming process, it is absolutely critical that a firm sand foundation is established because the city is supposed to support an urban population of 120,000 people.