Kuahea Street Area Stabilization Project
The City is implementing a project to install stabilization improvements within City and City-acquired parcels to protect the City’s infrastructure from earth movements. While there may be incidental benefits to private properties, area residents and private property owners are advised to take precautionary measures to protect themselves and their own private property. Area residents and private property owners may also wish to seek advice from qualified engineering professionals or other professionals regarding this matter.
The City’s efforts include the stabilizations of City infrastructure in the Kuahea Street area between Kuahea Place and Helo Place and City infrastructure in the Waiomao Road area in the vicinity of 2293, 2301, and 2311 Waiomao Road. In the meantime, City infrastructure in the area is currently being monitored and repairs are being made as needed.
For project-related questions, please contact Scott Ishikawa of Becker Communications, Inc. at (808) 397-5396 or Scott.ishikawa@beckercommunications.com
To report water main leaks, please contact BWS at 748-5000 extension 1.
To report sewage spills or leaks, please contact the City’s 24/7 hotline at 768-7272.
Fact Sheet
Starting in the mid-1950s, areas of Waiomao Road, Kuahea Street, and Kipona Place in Palolo Valley on Oahu have been affected by the natural movement of earth. The earth movements (known as the Waiomao Landslide) have resulted in damages to roadways, underground utilities, sidewalks, and the surface drainage systems. The City & County of Honolulu has initiated monitoring of the earth movements in this area of Palolo Valley since the late 1990s. Since then, the area along Kuahea Street between Kuahea Place and Helo Place has seen an acceleration in earth movement. The City has implemented stabilization improvements to protect its infrastructure and public access in this area along Kuahea Street (Phase 1) and also along Waiomao Road (Phase 2).
A number of repair efforts have been implemented over the years starting with the first remedial repairs of the Waiomao Landslide in 1957. Recent stabilization efforts are focused on the lower portion of Kuahea Street between Kuahea Place and Helo Place with work in this area solely designed to protect public infrastructure. Recent efforts include the following:
- Drainage system revision on Kuahea Street (completed).
- Drainage system upgrade along Waiomao Road from Kuahea Street to 10th Avenue (completed).
- Implementation of Tieback Anchor Test Program (completed).
- Installation of tieback anchoring system (galleries 1, 2, 3, and 4, completed).
- Installation of soldier pile wall and tieback anchoring system (completed).
- Closure and regrading of Kuahea Street between Kuahea Place and 2319 Kuahea Street (completed, closure still in effect with reopening of roadway pending street lighting installation)
- Reconstruction of Kuahea Street, Kuahea Place to Helo Place (completed, reopening of roadway pending street lighting installation).
- Permanent relocation of utilities (completed).
- Grading activities (in progress). Grading activities include earthwork and revegetation of disturbed areas.
- Installation of temporary and permanent fencing (in progress).
- Roadway improvements in vicinity of 2293 and 2301 Waiomao Road (completed).
The work is being performed systematically in phases.
Plans issued for construction for Phase 1 work (PDF)
Plans issued for construction for Phase 2 work (PDF)
Plans issued for construction for the Finish Work phase (PDF)
Phase 1 (Kuahea Street) – Installation of tieback anchoring systems was performed from March 2020 through September 2020.
Phase 2 (Waiomao Road) – Installation of soldier pile wall was performed from August 2021 through October 2021. Installation of additional tieback anchoring systems was performed from September 2021 through January 2022. Observation period of the tieback anchoring systems was completed in March 2022.
Finish Work Phase – Grading activities commenced in April 2022. The reconstruction of Kuahea Street was performed from September 2022 thru February 2023. Roadway improvements in the vicinity of 2293 and 2301 Waiomao Road were also performed in March 2023. Utility relocation was completed in July 2023. Outstanding tasks include the installation of fencing, erosion control, and vegetation.
7 a.m. to 5:30 p.m., Mondays through Fridays
9 a.m. to 6 p.m., Saturdays (as needed)
Project Lead: City & County of Honolulu, Department of Design & Construction, Civil Division
Civil Consultant: AECOM
Geotechnical Consultant and Construction Manager: Geolabs, Inc.
Contractor (Design-Build): Schnabel Foundation Company
Contractor’s Design Consultant: WSP
Civil Subcontractor: Rons Construction Corporation
Scott Ishikawa
Becker Communications, Inc.
(808) 397-5396
Scott.ishikawa@beckercommunications.com
Background
This area of Palolo Valley where the original Waiomao Landslide occurred was once a basalt rock quarry. The land was purchased by a developer in 1951, who subsequently built a 200-home subdivision. Landslide activity began almost immediately after the subdivision was built, with signs of trouble noted as early as 1952. Significant damage occurred following a heavy rainstorm in 1954 that resulted in several feet of earth movements. From this time on, there is a record of continuous movements leading to difficulties with the utilities, streets, and residences in the area.
A number of geological surveys and studies have been conducted over the years. From 1958 to 1969, Dr. Ralph Peck, a world renowned geotechnical engineer and professor at the University of Illinois at Urbana-Champaign, studied the landslide using tiltmeters and piezometers to monitor subsurface movements and hydrologic conditions over time. He concluded that the earth movements are directly related to rainfall events.
The City has been monitoring the movements in this area of Palolo Valley since 1999. Monitoring of the earth movements in the Kuahea Street Area between Kuahea Place and Helo Place showed slow earth movements averaging about 0.5 to 0.75 inches of movement per year for the first 15 years. The earth movements have accelerated appreciably in times of heavy and/or extended rainfall events, such as the one in 2006. Another episode of accelerated movements was noted in 2016 and 2017 with earth movements of about 20 inches of movement per year. The monitoring progress reports are available to the public through the City’s DocuShare database found on the Municipal Reference Center webpage. Monitoring Progress Reports Nos. 1 to 33 for the monitoring periods from February 2000 to July 31, 2020 are currently available. Future monitoring progress reports should be made available approximately six months after completion of the monitoring period. It should be noted the monitoring progress reports and recommendations contained within have been prepared exclusively for the City to inform, not direct, the City of the area earth movements and conditions of its infrastructure to plan and program improvements in the study area, and not for any other purpose.
A virtual meeting for interested residents and community members was held on September 24, 2020, to discuss project updates. Councilmember Kobayashi and Director Mark Yonamine were in attendance: View Presentation (PDF).
Various concerns in the vicinity of the project have been identified by the Palolo Neighborhood Board and the City for investigation. View the City’s responses.
Project Updates
| Date | Description |
|---|---|
| August 9, 2023 | Project status is available here. |
| July 31, 2023 | The installation of permanent pole and stringing of overhead electrical lines by HECO along Kuahea St were completed. The installation of permanent fencing, instrumented tieback anchor monitoring system, and vegetation are continuing to be performed. |
| July 17, 2023 | The installation of temporary irrigation system was completed. The installation of temporary and permanent fencing is continuing to be performed. |
| July 3, 2023 | Installation of permanent fencing and erosion control matting are continuing to be performed. Installation of temporary irrigation in advance of vegetation efforts has commenced. |
| June 19, 2023 | Installation of permanent fencing and erosion control matting are continuing to be performed. |
| June 5, 2023 | HECO pole work along Kuahea St and the installation of instrumented tieback anchor monitoring system are continuing to be performed. Installation of permanent fencing and erosion control matting has commenced. Site-specific BMPs were also maintained. |
| May 22, 2023 | Installation of permanent pole by HECO along Kuahea St has commenced. Site-specific BMPs were also maintained. |
| May 8, 2023 | Installation of instrumented tieback anchor monitoring system is continuing to be performed. Site-specific BMPs were also maintained. |
Frequently Asked Questions
A: Requestors are asked to complete the Request to Access a Government Record form and submit the completed form to the government agency. Contact information for the DDC and its different divisions can be found on the DDC home page.
A: The City will respond based on severity, available resources and priority. Repairs will be considered equitably with those of any other community within Oahu. Emergencies that affect safety, sanitation and security will be prioritized.