A'Seeb Wastewater Project

Comprehensive New Wastewater Management System

The Sultanate of Oman has experienced significant development and population growth in the past 40 years under the leadership of His Majesty Sultan Qaboos bin Said. Haya Water, responsible for wastewater management in the Sultanate’s capital, is supporting this development by implementing the Muscat Wastewater Master Plan in the Governorate of Muscat—the country’s most populous region, with expected population growth from 740,000 in 2010 to 1 million by 2025.

The A’Seeb Wastewater Project is a primary element of the Muscat Wastewater Master Plan. With a project area of 490 km², it will provide a new, comprehensive wastewater network for all residents of the Seeb catchment area. In addition to wastewater treatment, the system will supplement the region’s water resources by treating wastewater to the high degree necessary for beneficial reuse, then distributing the water for irrigation.

Parsons is providing design, project management, design review, and construction supervision for the project, which is being executed under six contracts, each with a different contractor.

Project Highlights

The collection system includes a new main sewer, three main pumping stations, 1,452 km of gravity sewer, and 212 km of vacuum sewer. The vacuum sewer network will be one of the largest in the world—and the largest ever constructed in a single project. This solution is being implemented along the coastline where flat terrain, sandy soil, and a high underground water table are design considerations.

The main collector sewer runs along 21 km of the Sultan Qaboos Highway, Muscat’s primary traffic corridor. Closing the highway for construction was not an option, so Parsons is using microtunneling to install pipes in this portion of the project. This technique bores a tunnel and inserts the pipe in a single operation, avoiding the disruption of open trenches.

The new Seeb advanced wastewater treatment plant (AWTP) is designed for water reuse. It will conduct tertiary treatment on 100% of the flow in a process that involves pretreatment of incoming wastewater, sequential batch reactors, ultrafiltration, and chlorination. Aerobic digesters will provide sludge processing. All processes will take place in an enclosed environment and will use strict odor control measures, monitored by electronic nose technology, to meet the requirement of no odor at the facility’s boundary. The AWTP will also have an emergency sea outfall with an offshore design length of 1.8 km.

The project scope includes installing a fiber optic duct network along the sewage and recycled water lines, taking advantage of this construction opportunity to bring fiber-to-the-home connections to Seeb residents.

Uniform Guidelines for Multiple Contractors

Parsons prepared standardized specifications for Haya Water based on the sixth edition of Civil Engineering Specification for the Water Industry (CESWI) and on local practices. Specifications address materials, construction, equipment, testing, and commissioning requirements. Standard materials include Haya Water’s selection of factory-manufactured high-density polyethylene (HDPE) manholes and chambers, as well as some pipe sizes. Polycrete manholes and pipes were introduced for the first time in Oman to address specific requirements of the main collector sewer. A design manual catalogues standard details implemented on all Seeb projects so they can be used for other Haya Water contracts.

As part of the overall project management, Parsons worked with the six contractors responsible for executing the contracts to ensure uniformly high quality assurance and quality control (QA/QC) throughout the project. Contractors include both local and international companies. We helped local contractors upgrade and implement quality plans, and we conduct quality audits together with Haya Water’s quality team to ensure full implementation of quality systems throughout the project.

Parsons also helped the contractors develop and implement health, safety, and environment (HSE) programs to protect workers and the public. This project includes deep excavations, work adjacent to public roads, traffic diversions, and tunneling. HSE programs address pretask planning, daily inspection criteria for performance evaluation, near-miss reporting, and root-cause analysis of near-miss cases before they become accidents. As a result, the project has achieved several milestones: Contracts 1 and 2 have achieved 5 million work hours with no lost-time incidents, and Parsons’ supervision team of more than 100 staff has completed 500,000 work hours with no lost-time incidents.