Beachwalk Wastewater Pump Station to Ala Moana Park Sewer, Phase I: Force Main System

Location: Oahu, Hawaii
Client Name: City and County of Honolulu, Department of Design and Construction
Date Completed: 2008
Construction Cost: $37,000,000
Disciplines Applied: Water & Wastewater EngineeringPlanning & Permitting

Project Description:

This unique project involved the construction of approximately 7,000 lineal feet (lf) of new pipelines to convey wastewater from the Waikiki / Moiliili area to the gravity sewer at Ala Moana Park. The initial 1,250-lf segment consists of twin 33.8” linear diameter (lD) microtunnelled lines. The remaining 5,800 lineal will be a large-diameter, approximately 72”-lD, microtunnelled pipeline.

In the initial years of the project, the system will be utilized as a force main from the Beachwalk Wastewater Pump Station and provide redundancy to the existing force main. In the future the pipelines are to be converted to deep-gravity sewers.

One of the unique features of this project is the use of curved microtunnelling for the first time in the United States. The curved microtunnelling will eliminate the need for one shaft and save more than a million dollars. Work also included the connection of the system to the existing WWPS which included a major valve box and construction under challenging conditions.