The City and County of Honolulu has issued contractors with a Request for Qualification for its 3.2-mile (4.8km) long 10ft-12ft (3m-3.6m) i.d. Kaneohe-Kailua Sewer Tunnel Project, under the Oneawa Hills, in Oahu, Hawaii. The deadline is March 27, with bids due May 30.
The estimated $175 million project, which has been designed by Wilson Okamoto Corporation with Jacobs Associates, is part of the Kaneohe-Kailua Wastewater Conveyance and Treatment Facilities Project that is being constructed by the City and County of Honolulu to replace an existing 42″ force main – presently conveying wastewater from the Kaneohe Wastewater Pre-Treatment Facility (WWPTF) to the Kailua Regional Wastewater Treatment Plant (WWTP) beneath Kaneohe Bay Drive.
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Tunnel construction will be staged from the Kailua Regional WWTP and involve the use of a hard rock TBM. Access and retrieval points for the TBM will be at vertical shafts at either end of the tunnel, with controlled blasting required for construction of the shaft and initial start-up portion of the tunnel at the Kailua Regional WWTP.
Approximately 95% of the route will be excavated through basaltic rock, therefore bolts, wire mesh and steel bands will be used, as necessary, to achieve structural stability for the majority of the tunnel prior to the installation of fiberglass pipe that will result in a finished interior diameter of 10ft-12ft (3m-3.6m). The annular space will be backfilled with grout.
As the finished tunnel will convey wastewater by gravity flow, it will be inclined throughout its length toward the Kailua Regional WWTP – starting at a depth of approximately 44ft (13.5m) below ground level at the Kaneohe WWPTF and ending at a depth of 75ft (23m) below ground level at the Kailua Regional WWTP. A new influent pump station (IPS) will lift the wastewater from the vertical shaft to the surface for treatment. Construction of the new influent pump station will fall under a subsequent construction contract.
A Pre-Bid Meeting will be held on April 25, 2013 at 10.00am in the 2nd Floor Conference Room at the Kailua RWWTP, 95 Kaneohe Bay Drive, Kailua, Hawaii 96734.
The City and County of Honolulu has the contract documents posted on its website at: http://www4.honolulu.gov/bfspurchasingbids/main/vueOpenBids.asp?sType=C
For more information visit the project website: http://kkgravitytunnel.org/