The United Arab Emirates (UAE) has a long history of problems with sewage. Some estimates report that sewage output in the emirate of Dubai is growing as quickly as 25 percent every year. The emirate’s rapid growth has officially outpaced the only national plant for treating sewage, which is many decades old.
In 2008, Dubai’s International City was flooded with sewage after its system was overwhelmed. In 2009, The New York Times reported that the emirate’s sewage plant was handling more than 15 million cubic meters of sewage every day, double its intended capacity.
Approximately 4,000 trucks were lining up daily at the three entrances to the facility. Some of the trucks were forced to wait as long as a full day before offloading their cargo. Because of the long wait, some of the truck drivers choose to dispose of their sewage in rain gutters, where it then traveled to the ocean, sullying the emirate’s pristine beaches.
Solving the Problem
Dubai recently announced a new project to address its water treatment needs: a deep-tunnel sewer system.
The project will be completed in two phases at two locations: the Deira District and the Bur Dubai. It is expected to cost more than $3 billion.
The deep tunnels will stretch more than 46 miles and be supported by nearly 93 additional miles of sewage pipeline.
The tunnel that initiates at Bur Dubai will be approximately 31 miles in length. It will transfer sewage beneath the new Dubai area to a treatment plant and two pumping stations in Jebel Ali.
The Deira tunnel will transport sewage underneath the emirate’s airport to be deposited at a treatment plant in Al Warsan. This tunnel will be the shorter of the two, at just over 15 miles.
Some of the tunnels will be more than 30 feet in width and buried as deeply as 98 yards below the surface. The large size of the tunnels will allow for future installation of an underground train network for transporting cargo.
American engineering firm Parsons has been awarded the contract for the deep tunnel project. Designs will be submitted next year and construction will begin the following year.
Benefits of the Deep Tunnel Sewer System
Intended to last a century, the deep tunnel sewer system is meant to replace more than 120 pumping stations in the emirate.
The tunnels, which transfer sewage using the power of gravity, will be an improvement on the pumping stations, which require significant electric power and maintenance to function properly. The emirate is expecting the project to cut carbon emissions by more than 25 percent.
This decrease in carbon emissions and power consumption will reduce costs and help prepare for the dramatic population growth that the small country is expecting in the coming years.
Microtunneling
In order to avoid as much disruption of daily life as possible during construction of the deep tunnel sewer system, the deep tunnel project will use the micro-tunneling technique.
In this technique, a large shaft is dug and reinforced with steel and concrete. A small boring device is then placed in the bottom of the shaft to dig the tunnel. This device, called a microtunnel boring machine (MTBM), is operated remotely by a professional located above ground.
The MTBM drills through the soil and ejects the excess slurry through a pipe. Microtunneling eliminates the need for a large, open trench in which to lay pipe and allows for a less invasive construction process.
Expanding Jebel Ali Sewage Treatment Plant
In conjunction with the deep tunnel sewer system, the existing Jebel Ali Sewage Treatment Plant (STP) is undergoing an expansion.
The expansion will more than double the plant’s capacity, meaning it will be able to process almost 700,000 cubic meters of sewage daily. This expansion will serve almost 1.5 million Dubai citizens and the cost is estimated at nearly $3 billion.
This expansion will relieve some of the pressure on the Al Warsan STP, which is currently operating at almost 30 percent over its capacity.
The newly-expanded plant will have many sustainability features. Compost will be created from the solid waste collected at the plant and resold to the public and methane emissions will be used to produce electricity.
The treated wastewater will be used to irrigate parks and green spaces throughout the city, reduce dust on dirt roads, and cool off hot parts of the community. The water will also be used to supplement firefighting water resources. Sewage treatment plants provide as much as 35 percent of the water used for fire safety in Dubai.
Other UAE Sewer Projects
Dubai is not the only city-state in the UAE that is rebuilding and expanding its sewage and wastewater infrastructure.
The Sharjah district in the north of the UAE just opened two new STPs in 2012, one underground and one located in the Al Sajaa area.
Abu Dhabi is has initiated a Strategic Tunnel Enhancement Program (STEP) to expand its wastewater management capacity. Much like the Dubai project, the $1.6-billion STEP will include the development of a long sewer tunnel and numerous smaller tunnels with the hopes of eliminating more than 30 pump stations in the emirate.
This is just a few of the country’s many efforts to solve its wastewater problem in a sustainable, eco-friendly manner.