x Abu Dhabi, UAESaturday 22 July 2017

New sewers will be built 'over period of time'

Work to improve the capital's severely overloaded sewer system will continue, as the city works to repair old and damaged pipes.

Work on the Dh5.7 billion Strategic Tunnel Enhancement Programme is under way next to the Armed Forces Officers Club in the capital. It will be one of the longest gravity-driven wastewater tunnels in the world. Ravindranath K / The National
Work on the Dh5.7 billion Strategic Tunnel Enhancement Programme is under way next to the Armed Forces Officers Club in the capital. It will be one of the longest gravity-driven wastewater tunnels in the world. Ravindranath K / The National

ABU DHABI // Sewer works that began last year in the capital will continue long-term as the Government works to update and repair the city's severely overloaded system.

Five contractors, using up to four teams each, are working on pipe replacement and refurbishment projects. Excavation works are expected to last no more than four weeks, and digging is designed not to disturb residents or traffic.

The sewage system dates to the early 1970s, but a rapidly expanding population has caused extreme strain on the city's aging pipes, said Alan Thomson, the managing director of Abu Dhabi Sewerage Services Company.

"A lot of our sewers are between five and 10 metres below ground, but if you lift a manhole lid on the road, at peak flow times, you would probably see sewage just below the lid," Mr Thomson said.

A 41-kilometre-long, deep sewer tunnel that should be complete in 2015 will relieve some of the pressure, but the company will have to prioritise repairing existing infrastructure - including leaking pipes and overworked pumping stations - until it opens.

In addition to renewing or relining pipes, the company has also built four new treatment plants and is "over pumping", or transferring capacity from a heavily loaded part of the system to one less heavily loaded.

"These are all temporary arrangements, just to get over the hurdle," Mr Thomson said. "To put new sewage systems in a city like Abu Dhabi, you can't do it very quickly. You've got to plan it, and you've got to build it over a period of time."

Locations for pipe refurbishment or replacement are selected by the contractors who are continually surveying the sewerage system and pinpointing trouble spots.

Work is specifically designed to be of minimal disturbance to residents living in what Mr Thomson calls "poor condition areas".

"If people notice something about us, we're doing it wrong," he said. "The nice thing is that we're an invisible service."

Sewer overflow is still a real danger, however. That threat will disappear once the Dh5.7 billion Strategic Tunnel Enhancement Programme (Step), one of the longest gravity-driven wastewater tunnels in the world, is completed in four years.

When Step comes online, 35 pumping stations on the island will be closed and a new treatment facility in Al Wathba, 40km from Abu Dhabi Island, will be opened.

"The decommission of the pumping stations will have a huge impact on our carbon footprint," Omar Al Hashimi, head of the sewerage company's asset management division, said last year.

"These stations are powered by electricity and when they come offline we can save energy."

Step is expected to have a 90-year lifespan.

 

jthomas@thenational.ae