Watching the Slopes: Landslide Mitigation and Response


Landslides are a real public safety hazard in many areas of the United States. They can have devastating effects on people and property, but because they often occur in less populated areas, the risks and causes of landslides are sometimes overlooked. I have spent most of my 40-year geotechnical career working in the Pacific Northwest and Alaska—two regions where landslides are common. While at GeoEngineers for the last 33 of those years, I have had the opportunity to work on hundreds of geologically hazardous area and landslide projects. We help agencies and communities reduce landslide risks and respond to emergencies when the ground does give way. It is challenging and intense work, but some of the most rewarding of my career.

Landslides occur because of steep terrain, geology, climate influences (rain, freezes or thaws), and many other factors. Most landslides are strongly influenced by changes in groundwater conditions like saturation from rain events or a rise in shallow aquifers and/or the local groundwater table. Landslides can be small, shallow events, or massive, deep-seated failures. Shallow landslides can peel off veneers of soil and vegetation and crash into homes. Deep-seated slides can destroy homes, pipelines and roads, dam rivers, and dump soil and vegetation debris into nearby bodies of water.

Landslides sometimes cause heavy casualties and economic losses. Fortunately, in the U.S., most landslides damage property or infrastructure without loss of life. This is partly thanks to the local geotechnical and geologic practitioners doing their part, and geologically hazardous-area regulations that many states use to proactively identify properties and projects within landslide areas. Geohazard studies and regulations require a geoprofessional to evaluate any landslide risks for a proposed action (a new development or roadway construction for example), and incorporate mitigation strategies when necessary to protect human health, environment and property.

Public agencies are typically responsible for maintaining safe and open roads for emergency services and community access. When their infrastructure is threatened or damaged, GeoEngineers can essentially act as an extension of public works departments. We can perform a full range of services. Our landslide professionals can complete rapid safety assessments, advise public officials on decisions to close roads or evacuate areas, evaluate post-slide conditions, and provide repair scenarios or complete landslide repair designs.

Landslide projects are typically interdisciplinary, including geotechnical engineers, geologists, and hydrogeologists. I love being part of the experienced team that we can bring to geohazard and landslide projects. We help local jurisdictions, state agencies, and developers evaluate geohazards and develop mitigation strategies for their projects. When landslides occur, we respond to assess life safety and emergency response, and often guide these projects all the way through repair and construction. The team evaluates the cause of a landslide, explores a range of stabilizing measures, and prepares appropriate mitigation designs—anything from improved drainage, buttresses, soil reinforcement or retaining walls.

GeoEngineers responded to the Adams Mountain landslide near Hunters, Washington. It was just above a logging road and the South Fork of Hunters Creek and threatened to damage both if not stabilized.

Landslide projects are opportunities to really collaborate with our clients, regulatory agencies and sometimes entire communities. As technical experts, we sometimes provide education regarding the many nuances of landslide response, assessment and repair. These situations are always very fluid and take a lot of strategic thinking. Not only are we doing the technical analyses required to figure out what the problem was and now is, we need to determine the if there are safety, technical, economic, regulatory, or other concerns associated with the various response and repair options. (If all that doesn’t scare the crap out of you, come work for us. It’s really a lot of fun.)

I like working on landslides because I get to work outside, visit unusual locations, and play in the mud. What more could a geotechnical engineer ask for? It requires a good understanding of the complex interaction between steep terrain, geology, hydrogeology, and human influences. The technical side of our work is always challenging, but nothing beats bringing that technical expertise and collaborative team to a tough situation—and helping a community or client fix it. It is one of the most rewarding parts of this job.

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