17 MARCH 2018: Salem Alzahrani is a man on a mission: to help deliver on ADA objectives to minimize the environmental impact of the Metro during construction and operation, with the overarching goal to improve the quality of life and health of the city’s population.
The overall objectives may be ambitious but it is exactly the sheer scale of the challenge, and the potential for making a positive difference to the lives of people in Riyadh, which fuels Alzahrani’s passion for his job. Having joined FAST as an Environmental Consultant in 2015, he has been the Environmental Manager for Package 3 - covering Lines 4, 5 and 6 - since 2016. It is a job requiring not only technical dexterity, innovation and the foresight to remain aligned with ADA directives, but also an ability to work with, and for, diverse stakeholder groups.
“We’re effectively minimising the environmental impacts of the project for the benefit of millions of residents and their communities. It’s a huge job,” Alzahrani explains.
As he reels off the scope of his work during construction phases, the scale of the task becomes clear.
“Take the challenge of managing solid waste, for example. To date, more than eight million cubic metres of soil and one million cubic metres of construction waste has been generated from the project to date. For example, during the construction of Line 5, two TBMs generated 1.2 million cubic metres of excavation material in slurry form that had to be treated. However, Riyadh as a city did not have the necessary sites to carry out the required treatment, which made the management of these materials a challenge. The only option available for managing these materials was their disposal in solid waste landfills, even if this meant significantly increasing the volume of waste sent to the landfill and decreasing its capacity,” he explains.
The most sustainable option was, Alzahrani points out, to treat the excavated material as reusable soil.
“Therefore, it was proposed that the material extracted from the tunnel be reused in domestic waste landfill as a daily or final covering layer instead of imported and excavated soil from natural resources for the covering process. FAST and ADA collaborated with Riyadh Municipality, as part of its social responsibility towards the city, and transferred tunnel boring machine (TBM) excavation material to Al-Sulay landfill where it is dried, compacted and reused. The transfer process was controlled using a unique tracking and ticketing system to manage transferring trips which reached up to 1,000 round-trips per day.Subscribe to continue reading...