Waimalu Sewer Rehabilitation/Reconstruction Phase I project includes the installation and construction of the following:
Site specific erosion and pollution control
1,791 linear feet of 8-inch diameter PVC sewer line
3,010 linear feet of 10-inch diameter PVC sewer line
522 linear feet of 16-inch diameter PVC sewer line
Slip lining of approximately 273 linear feet of 8-inch diameter sewer line
Sewer lateral reconnection
Temporary bypass system
Receiving and Jacking Pits
Ground settlement monitoring devices
Special and standard manholes
Existing utilities relocation
Concrete curb and sidewalk reconstruction and restoration
Removal of monitoring wells
Asphalt pavement restoration and reconstruction
Pavement striping
Improving Long-Term Support of Pipes and Manholes
Jet grout columns will be constructed in subsurface areas that have been determined to be unstable, and creating a low permeability barrier for groundwater control/cutoff
Jet grout columns are produced by injecting high-energy jets of cementitious slurry into the soil
Methods of Sewerline Installation & Construction
Pilot Tube
Majority of the 8-inch and 10-inch sewer lines will be installed by "Pilot Tube" method of construction. The ground under the new sewer line alignment will be jet grouted for ground water control and to strengthen the soil prior to the horizontal drilling operation and jacking of the "pilot tube".
Open-Trench
Open trench method of construction will be used on sections of the new sewer system that can not be constructed using the "pilot tube" method. Sections that are too "short", making the construction of a jacking and receiving pits too costly will be constructed using the open trench method of construction. Sheet piles will be driven into the ground and the trench limits jet grouted prior to the trench excavation work.
Microtunneling
The 16-inch diameter sewer line that crosses Kamehameha Highway and onto Hekaha Street /Pahemo Street intersection will be installed using this method of construction so as to minimize the impact on traffic. Jet grout columns, jacking and receiving pits will be constructed in preparation for the microtunneling operation (installation of the steel casing, sewer line, annulus pipe grouting).
Sliplining
Approximately 273 linear feet of existing 8-inch diameter sewer line will be properly cleaned, and lined