By Alison Luke
How do you design and build an entire city on an island within less than ten years? Alison Luke finds out at Shams Abu Dhabi.
Fresh on the design map only a few years ago, the concept of offshore developments has quickly grown in popularity. Islands of ever more elaborate designs are being created around the Middle East's coastline, but some developments currently underway in Abu Dhabi are being approached differently.
Rather than create a new land mass for its latest landmark venture, Sorouh Real Estate has opted to develop a city on an existing island. The firm's Shams Abu Dhabi project will be built on Reem Island, which is located a few hundred metres north-east of the capital city. Separated from the mainland by an area of natural mangrove, the development is being designed with respect for the natural environment. "We are taking extra measures to maintain and safeguard the mangroves, which need a lot of maintenance because the area was deserted for a lot of years," explains Mohammad Meerza, MEP manager, Sorouh. In addition, energy efficiency and sustainability are high on the agenda for the MEP services. One of the biggest challenges facing the project team involved is that of co-ordination.
Shams Abu Dhabi stretches across a 1.74 million m2 area of the island and is entered via the landmark Gate District. With a site footprint that is shaped like a fish, the mixed-use development will comprise several hundred buildings including commercial, retail and residential properties. These will be built and operated by several different firms to an overall masterplan. A network of canals and waterways is intended to help maintain the water flow into the mangroves as well as provide a transport network and signature feature of the project. These canals have also provided one of the biggest challenges for the distribution of MEP services.
"Getting the utilities to cross the canals was one of the major achievements," stresses Meerza. "It was quite an engineering feat because you have to go below the canal level." Depending on the services involved, distribution in these areas will be either through a duct bank or culverts. This work will be completed then the canal and bridges constructed on top.
The utilities infrastructure was by necessity one of the first jobs to begin on site, starting in early 2006, and is now well underway. Part of bridge contractor Nurol's contract is to install the facilities for the canal crossing points on the distribution network. The earthworks plus deep and shallow sewer networks are complete and installation of the other utilities is beginning.
Before this work could begin, a major challenge for the utilities distribution network was to ensure that each service can be accessed at every point where it is needed and no clashes arise during the construction period. A difficult task on any project, this has been increased significantly due to the sheer scale of the area to be covered and the number of individual projects being constructed within Shams. Overcoming this challenge has involved the use of three-dimensional computer modelling and considerable time in the design stage to ensure minimal problems will occur on site.
"Because every service is underground you have to locate a particular design depth for them and all these depths have to be maintained at this particular level at every point of this development," stresses Meerza, "If during design you miss something, once on site it is going to be very difficult to resolve this.
"Making sure that everything is in the assigned design area is one of the most challenging things. In some projects people have installed underground services and have had to go back and redo it. This is a time cost, financial cost and [the final system] doesn't look good."
The assignment of specific depths for each service will enable the vast amount of services to fit into the limited available space, plus it will ease the connection to buildings once they are complete. After the deep and shallow sewers the district cooling network will be installed, with the remainder of the services such as electrical power and telecommunications cabling positioned at a higher level.
It is not only the MEP utilities that have required such close co-ordination, logistics is a major challenge for the overall development. The entire project is scheduled for completion in 2011, making it a fast-track development. With multiple large-scale projects to construct and a relatively small access point to the mainland, decisions had to be taken early to ensure that the masterplan could be created both in time and to the standards planned.
"This is a single-phase development," explains Meerza, "we have done a logistics plan and are building in different areas depending on our particular requirement for that area." Individual developers are being allocated access for construction on plots strictly according to the overall logistics plan, with 29 sub-developers already on site.
"One of the most important things for us was the pre-planning - not only of the services but also the logistics," stresses Meerza, "We are not only building the infrastructure, we are also doing the buildings and this is a big logistics exercise." To ensure the construction programme is maintained, a system has been developed to determine the status of every plot on the development at all times. "We have allocated numbers from zero up to five so that we can monitor every plot here to see exactly which stage of development it is at and that also determines our logistics," Meerza adds.
The information will be compiled using an electronics package and displayed on a ftp site that can be accessed by the main contractors, consultants and overall project manager. This will also act as a record management system for correspondence and the meetings reports. In addition, weekly programme meetings will be held throughout the project's development.
To minimise co-ordination issues on site, the main contractor package tendered includes subsections for each other service involved in their works, such as electricity and water. "The idea was to not get involved in the co-ordination between the different services and let the main contractor employ their own resources to do this," explains Meerza. Packaging the work in this way will also aid the speed of construction, as all subcontractors will be approved as part of the initial main contract tender stage. Once a main contractor is appointed the entire team involved will be able to mobilise to site immediately.
In general, the mains MEP services will follow the same basic route. A main loop runs around the outer edge of the development, with a grid network stretching from this into the centre of the project to serve each of the buildings.
Guidelines determine how the buildings must be serviced to ensure that Sorouh's goal of a sustainable development can be met. "Generally the building guidelines are clear on what [developers] have to achieve, for example they have to use district cooling and will be supplied by a 22kV electricity network developed according to ADWEA/ADDC standards and specifications. Potable water will be supplied by ADDC and Abu Dhabi Rules and Regulations must be met," explains Meerza.
In addition, several design aspects and technologies have been considered according to their suitability for the individual buildings. "We've been discussing using solar energy as much as possible or using glass facades with a very low co-efficient of performance so that you get light, but you don't lose the cold air...we are trying to design the buildings in such a way that they are energy efficient," confirms Meerza.
The insistence on district cooling rather than individual chiller systems was made in an effort to reduce both electricity and water consumption on the development. "It is mandatory to use district cooling; with this you can reduce the power usage by up to 30%, therefore the design of the electrical network is based on a district cooling system and not conventional packaged air conditioning," explains Meerza.
Four district cooling plants will be constructed for the project, with a total capacity of 200,000TR. The southern end of the development will be fed from one 80,000TR plant; the northern area will be served by three plants of 40,000TR through a linked network. The distribution network ensures that a connection is available at every plot.
The division of the district cooling provision was made for operational reasons: "We didn't want to have such a huge area interconnected - after looking at the hydraulic calculations and the hydraulic model it was decided that we'd have this southern sector fed from one plant and the northern sector fed from three plants of 40,000TR," explains Meerza. A further reason for dividing the total capacity is the size of the pipes that would be needed to distribute the chilled water from one plant. "If it becomes too big, then your outgoing pipes become huge," states Meerza, "for example, the 80,000TR plant will have pipes of approximately 1200mm diameter, which means two outgoing and two incoming pipes of this size."
To further increase the sustainability of the district cooling system the amount of potable water used will be minimised, instead treated sewage effluent (TSE) will be used as make-up water. A sewage treatment plant (STP) will be built on the island and the TSE from this used in the district cooling system and for irrigation.
Two further methods of reducing the consumption of potable water have been proposed. The first involves the collection of condensate water from the fan coil units (fcu) installed in buildings throughout the development. This system is proposed for all buildings where it will be economically viable, which Sorouh has calculated to be those requiring 800TR or more cooling. "People don't believe [that the use of fcu condenste is viable], but on a development like this I can have a four inch (101.6mm) pipe running full every day - that's a lot of water," he stresses.
The second option being considered is the use of a reverse osmosis (RO) plant to provide grade two water for the district cooling and irrigation networks. "We are doing a water balance and depending on the results of this we will [make a decision]," states Meerza. Potable mains water is being supplied via a 1200mm diameter pipe directly from the mains system in Abu Dhabi. The same pipeline will eventually feed the neighbouring Saadiyat Island also.
A 22kV open loop electricity network will serve the Shams development based on Abu Dhabi standards. One 400/132/22kV grid station and four 132/22kV primary substations will be built on Reem Island, with two of these located on Shams property. This will also be one of the first developments in the region to include a fibre-to-home network. "The conventional connections used to be vertical fibre and horizontal copper, but we are taking the fibre to every apartment so [residents] can connect to the fastest available system," explains Meerza.
A further unusual aspect of the services being provided to homes in Shams is the network availability of natural gas for cooking. Again one of the first developments to do this, ADNOC-Distribution has committed in principle to providing natural gas for Reem Island.
"The reason for using natural gas is because we have high-rise buildings and lpg is complex in buildings of more than 20 stories," states Meerza. Most kitchens will be designed to offer the options of both electricity and gas. The gas pipeline is due to be complete by 2010, however as some of the residential properties are scheduled to be let to residents in 2009 a temporary solution has been created.
"A substitute natural gas (SNG) plant within Shams will be developed and tenants who are living there [before the gas pipeline is complete] will have this facility. When the mains natural gas supply line is connected it would then be simply a matter of removing our connection and putting it onto the mains supply and user won't have to do any adjustments to their cookers or appliances," explains Meerza.
Sorouh estimates that the planned design measures for the MEP systems will result in savings of 30%-35 electricity and up to 65-70% of potable water supplies.