A landslide early Sunday morning, Oct. 27, covered a stretch of Interstate 5 in Bellingham between Iowa and Sunset with 2,000 cubic yards of debris, closing the northbound lanes for nine hours.
The slide was caused by a blocked culvert that resulted in water buildup during a heavy period of rainfall, and doesn’t appear to indicate slope instability, representatives from the Department of Transportation (WSDOT) and City of Bellingham Public Works said.
A roll of wind-blown carpet padding from an unknown location blocked the 2.5-foot culvert opening and led to water buildup, which saturated the soil and destabilized the slope on the east side of the freeway, Bellingham Public Works communications manager Riley Grant confirmed on Monday.
Rick Moore, a developer turned real estate agent, lives around the corner from the landslide site and built many of the houses in the neighborhood. He told Cascadia Daily News that he’d always thought it was only a matter of time until the open drainage ditches on the block caused an issue — he expected an errant basketball or deep leaf pile to plug one of the pipes and cause water to overflow onto the freeway, although he didn’t foresee a landslide.
On the other hand, Moore has never seen as much water pour down the street from the retention pond a few blocks up the hill as he did on Sunday morning. In a post on X, the National Weather Service in Seattle noted Bellingham International Airport hit a new Oct. 27 rainfall record, accumulating 1.75 inches within two hours Sunday morning. With 2.12 inches total, Sunday ended up as BLI’s second wettest October day ever, NWS said, the first being Oct. 16, 2003, which saw 2.46 inches of rain.
No one was injured when mud and debris from the hillside sloughed onto the interstate a little after 6 a.m., but a semi-truck did become stranded. A tow operator from Heston Hauling responded and extracted the semi on Sunday afternoon as spectators on the pedestrian bridge cheered from above.
If the slide had happened at a different time of day, the outcome could have been more consequential. On I-5 between Iowa and Sunset, based on data collected by WSDOT this spring, around 36,400 vehicles travel northbound on Sundays each week; in 2023 the annual average daily traffic (both directions over the course of a year) on that stretch of interstate was 81,000 trips.
Engineers with the City of Bellingham assessed the area and determined there was no immediate risk to the surrounding streets and buildings, including those adjacent to the slide on the end of Maryland Street. The city’s engineering and maintenance teams are now working with WSDOT to repair the damaged embankment and will continue to monitor the slope.
Landslides are among the most common natural hazards in Washington. In the western part of the state, unstable slopes are especially prone to slides during heavy precipitation and snow-melt cycles in the high country.
In 2020, the state Department of Natural Resources published a landslide inventory of western Whatcom County. The map doesn’t show future risk but includes information on historic slide areas. The absence of a landslide in the inventory, however, does not indicate the absence of risk.
WSDOT spokesperson RB McKeon said the small vegetated bank above the interstate is not on the agency’s unstable slope list. WSDOT is generally more concerned with the Samish corridor, where 17 unstable slopes are in the 8-mile stretch of interstate between south Bellingham and Burlington. Atmospheric rivers have caused slides there that closed lanes of travel as recently as February 2020 and November 2021.
McKeon said WSDOT monitors unstable slopes during weather events in order to respond quickly to any incidents, like the landslide on State Route 20 this summer. In Western Washington, debris flows after wildfires are of increasing concern, like on US 2 near Skykomish, where the burn scar from the 2022 Bolt Creek Fire necessitated new infrastructure to protect the highway.
WSDOT prepares for geological hazards through specific road crew training, seismic retrofitting, and structural inspections, monitoring and mitigation, McKeon added.
But for more isolated incidents like Sunday’s slide, the Bellingham Public Works department has one reminder: Help prevent future flooding by keeping storm drains and ditches clear of debris.
If you see a clogged drain, remove the debris safely if possible or report it at cob.org/fix, through the SeeClickFix app, or by calling 360-778-7700.
A previous version of this story misstated the size of the culvert. The story was updated to reflect this change at 5:30 p.m. on Oct. 28, 2024.
Julia Tellman writes about civic issues and anything else that happens to cross her desk; contact her at juliatellman@cascadiadaily.com.
