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Customer: Solomon Islands Water Authority Contract: Construct Location: Honiara, Solomon Islands   |
Fast Facts:
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We're deliveing the new Kukum Highway Sewer Pipeline Project for the Solomon Island’s Water Authority, dealing with traffic, hard ground and unexploded World War II ordinance in the process.
The project is the first stage in a long-term plan to improve sanitation in Honiara, the nation's capital, which is located on the largest island, Guadalcanal.
Sometimes referred to as the ‘Telekom to Fisheries’ project, the new pipeline alignment runs from the Ministry of Fisheries building through the Ranadi Roundabout to the Telekom building.
One kilometre of gravity-fed pipeline and half a kilometre of pressure main, manholes and lateral connections are being installed in the Kukum Highway. The highway is a main arterial road to Honiara, so extensive traffic management is in place along the alignment. This ensures the safety of the team working in one lane, while enabling the other lane to remain open to traffic.
Our trenching methodology includes a combination of trench shields and sheet piles. At the Western end of the project, the 710 mm diameter gravity pipeline has been installed up to 7.0 m deep; in this section, a sheet piled trench has been used to provide safe shoring. The shallower sections of pipe, where the excavation is less than 4.5 m, are being excavated using a trench shield shoring system.
Challenges
The project has provided many challenges for the team. The crew successfully managed hard ground conditions, deep excavations, and a high-water table, which added complexity to the job. But the most unique and significant complication was the high risk of uncovering Unidentified Explosive Objects (UXO) leftover from World War Two during excavation.
The team uncovered many UXOs during excavation in the first stages of work and adapted their methodology to identify UXOs earlier during excavation. The change in methodology requires full-time attendance from a qualified UXO Surveyor at every trench location; the Surveyor scanning each layer of excavation in 1m depths. The Solomon Islands Explosive Ordinance Department then removes any UXOs identified. This has affected the pace of excavation but is the safest way for work to continue.
Stages 6, 5, and 2 were completed at the end of 2024, and the team is on target to complete Stages 1, 3 and 4 in early 2025.
The next stage of the Project includes building a new wastewater screening plant and pump station, an outfall, and installing connections from private properties to this trunk sewer.
