Al Seeb Wastewater Project – Muscat, Oman

The Al Seeb Wastewater Project involved building the first wastewater management system in Muscat, Oman; and is the primary element of the Muscat Wastewater Master Plan. Its function is to provide the 350,000 residents of the province bordering Muscat (Al Seeb) with a new US$1.1 billion sewer system. The project footprint extends over an area approximately 490km², and required construction of a new comprehensive wastewater network and Wastewater Treatment Plant (WWTP). The system was designed for more than municipal sanitation; it also supplements the region’s water resources by treating 100% of wastewater to the high-quality level required for consumer reuse.

Al Seeb Wastewater System Features

The wastewater management system includes numerous features:

• 700 mi (1,100 km) of gravity collector sewer lines
• 14 mi (22 km) of main collector sewer by micro tunneling
• 170 km of high-density polyethylene pressure line for distribution of recycled water
• 2 large treated-effluent storage and pumping facilities
• 3 sewage lift stations with pump sizes up to 180 horsepower
• Largest vacuum sewage system in the world, with 11 vacuum stations, 140 mi (225 km) of vacuum lines, and 4,500 vacuum interface valves
• 26,500 sewer house connections
• Al Seeb Advanced Wastewater Treatment Plant, designed to conduct tertiary treatment on 21.1 million gallons (81 million liters) per day
• Emergency ocean outfall

Design measures for the project included flood protection for the riverine-like geography with wadis (dry rivers that flood during rain), a vacuum system for areas with a high-water table, and enclosure of the Seeb wastewater treatment plant plus odor control solutions to meet the requirement of no odor at the facility’s boundary.

Remaining Flexible To Accommodate Client Changes

Under a multi-phase program, we were the engineering consultant responsible for the design, project management, design review, construction document preparation, and construction supervision of six separate contracts to deliver this project. With six local and international construction contractors involved, a critical success factor was establishing uniform standards and practices from the start. Another success factor was mobilizing a workforce of over 140 construction management and quality assurance personnel to support the client through each phase of the overall program.

Due to rapid urbanization, the client made significant changes to the original design. These changes included moving the ocean emergency outfall to a different location, expanding the total capacity of the system, and changing the location of the Sewage Treatment Plant (STP) and various sewer mains. Although these design changes extended the design period to 24 months, nine months more than the original design schedule, we completed the design on time.

Our Approach

Our project management approach delivered uniform quality assurance and quality control among the six contractors executing the project. We helped the local and international contractors upgrade and implement quality plans and conducted audits to ensure full implementation of the quality systems throughout the project.

Embodying Parsons Core Values

As on any project, quality, safety and cost are all key considerations. We delivered excellence for each element on this project.

Quality management: We worked with the six construction contractors to ensure uniform quality assurance and quality control throughout.

Health and safety: We helped the contractors develop and implement Health, Safety and Environment (HSE) programs to protect workers and the public. As a result, the project achieved excellent safety performance.Cost. We helped the client address the costs of the changing design by performing cost-benefit scenarios of each change, including lifecycle costs. We also incorporated sustainable features, further reducing costs.