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Portland Bureau of Transportation

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

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Landslide Prevention

The Portland Bureau of Transportation is prepared for winter weather from October through March and the spring rains that follow each year. When storms bring snow, wind and heavy rains, transportation crews are prepared and take action as needed. Downed trees and power lines, mudslides, debris flows and a rising Johnson Creek and Fanno Creek can all close city streets.

We’ve all seen that roaring rivers and landslides can turn deadly in an instant. What’s most helpful is for the public to support Portland’s first responders by following their direction, including signs they’ve put up on roads, and staying away from active work zones. If there is a call for public assistance – such as to build up the seawall during the 1996 flood – it will be widely heard. People interested in participating in volunteer assistance efforts in emergencies are encouraged to contact the Portland Bureau of Emergency Management and see how they might connect with their neighborhood NET (Neighborhood Emergency Teams).

The Bureau of Transportation's stormwater management services are an integral part of maintaining a safe transportation system and preventing slides that push water, mud, and debris onto city streets. Some streets in the West Hills have been settling over the years due to loose fill and groundwater under the street. Crews regularly monitor the West Hills - and higher elevations on the east side as well - to make sure that ditches, culverts, and trash racks are clear of limbs and debris that could negatively impact stormwater runoff.

If you live in a landslide-prone area, be alert, particularly during periods of heavy rain or snowmelt. If you see signs of a landslide or suspect a landslide may occur, you yourself must make the decision to evacuate.

To report a life-threatening landslide - evacuate the property and call 911. To report landslides that do not threaten public safety, call 503-823-1700.


How you can help prevent landslides and neighborhood drainage problems

Water is the most common cause of unstable slopes, landslides, and erosion. Check your home's drainage system. Maintaining the drainage system on private property is the owner's responsibility. Make sure your drainage system directs water away from your foundation and not on to your neighbor's property.

Never discharge water over the side of a steep hill.

Clean your gutters and downspouts. Check your gutters once a week during fall and winter. Just one wind or rainstorm can clog a well-flowing drainage system.

Check your property for signs of earth movement and water below ground; i.e. a cracked foundation, new cracks or bulges in the ground or pavement, a leaning structure or tree, a broken water line, or a soggy or spongy patch of ground that doesn't dry out. If you have a problem, contact a soils engineer (see the Yellow Pages, under "Engineers-Geotechnical-Soils") to evaluate the situation.

In general, trees and plants with strong root structures help prevent soil erosion but do not prevent landslides.

Never block any part of the city's drainage system. Do not put leaves, dirt, grass clippings, or any materials in ditches, culverts, or drains. Doing so can cause flooding. It is against the law to dump any material into the drainage system. To report illegal dumping, call 503-823-1700.


When a landslide occurs

The City conducts a geotechnical study to determine risks and solutions to stabilize the slope and street and protect public safety. Street Maintenance crews clear landslide debris from streets and bridges and oversee repairs to protect them in the future. Some landslide locations require continual maintenance and closures of streets and sidewalks.

In the event that a landslide causes damage on your property, a Development Services inspector, when notified of the event, can assess the hazard and its impact to structures in the area of the slide. Due to safety considerations, inspections will be limited to daylight hours. 

In most cases, you will need to hire a geotechnical and/or structural engineer (see the Yellow Pages, under "Engineers-Geotechnical-Soils") to provide a report to Development Services describing the level of hazard for the building and any repairs needed.

As is the case in all emergency response, the initial evaluation is preliminary in nature and a final resolution and status will be deferred until such time as additional site-specific detailed information becomes available.

Contact the Bureau of Development Services Site Development program at 503-823-6892 for information about how the City works with private property owners on issues of landslide assessment and mitigation. If you have an immediate concern with a landslide impacting private property, please call the Bureau of Development Services enforcement program at 503-823-CODE (2633).