(WSB photo from February)

From Councilmember Lisa Herbold‘s newest e-mail update, word that the City Council is considering “supplemental budget” funding for landslide mitigation including three problem sites in West Seattle. One (above) is at the site of last February’s Highland Park Way-closing slide: $60,000 “to install a rock buttress between West Marginal Way SW and SW Holden Street.” Herbold’s update says this will “minimize longterm erosion and sloughing.” This was also discussed during the Highland Park Find It Fix It Walk back in May, which followed Herbold “rais(ing) questions about the Seattle Department of Transportation’s (SDOT’s) practices for managing landslide risks and whether SDOT should be doing more proactive work to minimize the risk of slides rather than responding with repair work after slides occur.” She continues:

What I found is that 17 years ago, in 2000, SDOT performed a risk assessment for slope hazards for landslides on arterial streets in the City. This evaluation was based on a set scoring matrix, and SDOT uses that ranking to prioritize our proactive landslide mitigation program.

The assessment used eight design factors to determine the priority of 73 known potential landslide locations along arterial streets. The criteria were:

Hazard condition of slope
Traffic volume
Street, pavement, and adjacent retaining facility condition
Street or sidewalk access impacts, including Metro, primary emergency routes, and ability to implement detours
Adjacent to community centers, schools, city utilities
Slope modification history that may decrease slope stability
Partnership opportunities with other planned projects to decrease costs
Adjacent to private facilities
Of the 73 locations, 24 were rated a high priority. Since 2000, SDOT has budgeted approximately $500K per year for landslide mitigation. With those funds we have been slowly moving through mitigation efforts for those locations. In 17 years, only seven of twenty-four high priority location have had proactive mitigation work done, because the majority of the allocated funds each year end up being needed for responding to slides after they have occurred in other lower priority locations.

The City Budget Office agreed with me that this a significant problem. I worked with SDOT and the City Budget Office to identify 2017 funds as well as a spending plan over the six-year Capital Improvement Program (CIP) to complete the work. Longer-term funding will be addressed during the 2018 budget process beginning in September.

In the short term, the 2nd quarter supplemental budget proposed by the City Budget Office, and discussed by the Affordable Housing, Neighborhoods, and Finance Committee this week, increases funding for addressing landslides by $1.37 million.

The aforementioned Highland Park site is one of three West Seattle sites; another is at Cambridge and California, $540,000 for a retaining wall at the site of a slide we covered back in January.

(WSB photo from January)

Herbold quotes SDOT:

This slide impacts access for thirteen homes along California Ave SW, north of SW Cambridge St. The slide also damaged two homes below. There is no alternative access point for the properties. SPU completed the initial stabilization and cleanup efforts, since there was also a water main break. We are currently monitoring the slide, and have limited the access to one lane only. If there is additional movement, we may need to eliminate vehicle access to the homes, and limit access to pedestrian only. The responsibility of the initial response and restoration is likely split between SPU and SDOT, since there was both a slide and water main break, and it is impossible to tell which caused which.

The current proposal for repair is to install a wall and pedestrian connection between Cambridge and California. There was an informal trail / path that existing prior to the slide.

And the third site is the 10200 block of 47th SW, where $350,000 would be spent to stabilize a slope hit by a slide. Herbold’s update quotes SDOT:

There continues to be soil movement undermining the roadway at this location. The current solution would be a 50′ long 8′ high permanent soldier pile wall consistent with the adjacent wall. If not completed we will likely need to close the roadway for safety and prevent access to approximately 20 residences. There is no alternative access point for the properties. The closure would affect 20 homes including those on Maplewood Place SW, with potential impact to the apartments block at 10203 47th Ave SW.

Outside West Seattle, the supplemental-budget item also proposes $400,000 for a slope along Rainier Avenue S. and $20,000 for a “rock buttress” along Perkins Lane W.