The Kaneohe/Kailua Sewer Tunnel increased the reliability of the aging Windward Oahu sewerage system by conveying flows by gravity from the Kaneohe Wastewater Treatment Plant to the Kailua Regional Wastewater Treatment Plant, replacing an existing pump station and force main system. Additionally, the tunnel will store wet weather flows during heavy rain storms.
JWF was the microtunnel subcontractor for the Southland/Mole, JV and will install 1,540 feet of 60-inch sewer pipe and steel casing in four drives of 177, 360, 425 and 578 feet.
Flows from the existing Kailua Regional Wastewater Treatment Plant were diverted to a new pump station by a new near-surface pipeline installed via microtunneling. The microtunneled pipeline was located under/near an existing DAFT Control building supported by shallow spread footings, existing 24-inch and 36-inch force mains and an existing diversion structure.
The soil conditions included highly variable ground consisting of primarily squeezing and flowing ground conditions. The soils include fill, alluvium, lagoonal deposits consisting mainly of saturated, highly compressible, soft to medium stiff clays and very loose to medium dense clayey coralline sands and gravel with extremely weathered basalt gravel and basalt.