Haines Beach Road Landslide – Geotechnical Investigation and Analysis
November 22, 2021
In December 2020, record-breaking rainfall triggered a large landslide on Beach Road in the Southeast Alaska community of Haines. This slide was about 600’ wide and resulted in about 1-16’ of landslide debris and trees covering the area. Several homes were destroyed and numerous others damaged. Gov. Mike Dunleavy. Declared a state of disaster.
As initial mitigation activities were being conducted, they were temporarily halted due to concerns about the stability of the site. Geotechnical services were needed to assess the landslide area so search and rescue operations, recovery efforts and property access could be safely resumed.
R&M subcontracted Landslide Technologies to provide subject matter expertise. The project team began working with the Haines Borough and the Alaska Department of Transportation & Public Facilities (DOT&PF) to provide the necessary geotechnical services to achieve these goals, as well as a greater understanding of slide hazards affecting the community. R&M and Landslide Technologies are monitoring the landslide area and working to develop solutions to mitigate future landslide risks and minimize further damage. The work includes geotechnical investigations and assessments; risk assessments; monitoring changing landslide conditions and detecting accelerated and/or expanding conditions; and developing landslide models and mitigation options.
Due to the existing hazards at the project site, the work was time critical and completed on an expediated schedule. The most immediate concern was monitoring the slide area so local emergency operations could resume search and rescue (SAR) activities. It was critical for SAR operators to be aware of potential hazards and predict movement risks to safely conduct their operations. Other pressing needs included identifying how and when residents could access their homes and when utilities could be reconnected.
To address these concerns, winter reconnaissance was conducted in February 2021 to identify current conditions at the project site. Six surface extensometers were installed to monitor any crack movement and serve as an initial early warning system for any landslide activity.
R&M then conducted further geotechnical investigations and analyses in summer 2021 to increase understanding of the initial winter reconnaissance conclusions and recommendations. This work is critical to assessing short-term and long-term stability concerns, and developing mitigation measures for future landslides. To help with this effort, 12 subsurface monitoring instrument arrays were installed to detect and measure subsurface movements, and groundwater pressures.
In addition, R&M’s Land Survey Group worked with all stakeholders to establish and build a remote total station monitoring system. The site runs autonomously and uploads data every 15 minutes 24 hours a day to a server located in the Anchorage office. The station is another tool used to monitor the existing slide path for any potential hazards, helping to keep the road open and the residents safe.
Extensive coordination was required between multiple federal, state and private entities during this process. Stakeholder agencies include DOT&PF, Haines Borough, Alaska Division of Geological and Geophysical Surveys (DGGS), and the Haines Emergency Operations Center (EOC). These agencies, along with R&M, the University of Alaska Fairbanks, Landslide Technology, Siemens & Associates and Discovery Drilling, worked together to provide emergency services to Haines residents and provide resources so the community can monitor potential landslide activity and prepare for any reoccurrences, limiting future damage and minimizing risk to residents.
R&M Project Manager: Aaron Banks, CPG
R&M Project Team: Bob Pintner, PE; Bill Preston, PLS; Emery Schramm; Ryan McCormick; Brian Meyers, PLS, CFedS; Chris Fell, CPG; Tucker Brinker; Vincent Carlos, LSIT; Alex Brown; AJ Griffin, PLS; Aaron Comstock, LSIT; Vanessa Crandell-Beck; Michael Montuya; Katherine Jarupakorn
Teaming Partner: Landslide Technologies