Project Location:

The project is located in Boucher Phase·2 (previously known as AI Ghubrah Allanubiyya Phase-3) located In Gala adjacent to Muscat Expressway in Muscat Governorate.

Project Overview & Scope of Work

The link road from Ghala Street adjacent to the American School in Muscat is a dual carriageway terminating at a roundabout. To complete the link across the Wadi and gas pipeline a suitable structure would be required. The Wadi crossings upstream (Expressway) and downstream (23rd July Street) are by bridges. This would initially indicate a bridge would be required at this location also from the hydraulic point of view. Also a bridge could be feasibly be designed to span over the existing 20" gas pipeline valve housing. Subsequent discussions with Oman Gas Company revealed opposition to the bridge solution as it would interfere with maintenance access to the valve housing from above for which a crane would need maneuvering space. Furthermore, the preliminary hydrology study model demonstrated that the bridge approaches would be inundated in the 50-year return period Wadi flow event. This would negate the usability of the bridge and such an investment would be unwarranted for a local access. The bridge option was therefore dismissed in favour of the lower cost floodway solution from the existing roundabout connecting to the internal roads of Bousher residential area, Phase 2, without affecting the gas pipeline valve housing. The problems associated with crossing the gas pipeline and other utilities will have to be addressed in close consultation with the various owners to ensure their satisfaction.

To carry out the project the following main steps will be implemented:

• Carry out detailed topographic survey by our in-house survey team to cover the project area and margins beyond including upstream and downstream of the wadi.
• Review satellite and regional topographic information to determine the wadi catchment area.
• Collect rainfall and wadi gauge data from MRM&WR and any available hydrology reports associated with this wadi
• Carry out detailed hydrology study led by our principal hydrologist/ hydraulic engineer; culminating in a report and recommendations for the structure assuming a 100-year return period and scour checking for 500-year return period.
• Obtain utility information from survey and from utility owners.
• Create base mapping with accurate representation of existing features, utilities and terrain.
• Prepare concept alignments for the road link with the Wadi crossing structure according to the hydraulic design recommendations and spanning major utilities (especially the 20” gas pipeline)
• Coordinate with Ministry of Oil & Gas and individual utility owners to understand their requirements and constraints - the letters to the individual utility authorities are appended with this report.
• Obtain Ministry of Housing planning information to confirm “right-of-way” (ROW) limits.
• Review design concept with Muscat Municipality. Alternatives, if practicable, will also be considered; particularly in consideration of the skew angle of the Wadi crossing. Studies already concluded have closed this step with the decision to implement a floodway.
• Establish locations for the geotechnical investigation by boreholes and trial pits to establish a soil profile and data for scour calculations.
• Implement the geotechnical investigation.
• Review of geotechnical report by our geotechnical engineer to requirements and protection against scouring as well as other basic design parameters.
• Prepare preliminary design of access road with floodway for review with Muscat Municipality.
• Prepare traffic management plan for guidance during construction.
• Carry out the detailed design and cost estimate.
• Finally prepare tender drawings and documents