FOLLOWUP: City finds ‘defect’ in sewer line near Alki slide site

| Safety | Utilities | West Seattle news

(WSB photo, June 1st)

Two and a half weeks after a slide and water leak on the slope in the 1200 block of Alki SW – at which time Seattle Public Utilities told us the leak appeared to be on private property – an update from SPU spokesperson Sabrina Register:

On May 31, Seattle Public Utilities and Seattle Parks and Recreation responded to reports of a landslide from City property that affected private property at 1200 and 1210 Alki Ave SW. Staff have been working to assess whether the slide was the result of natural causes or caused by water. As moving water was found at the site, the City has been trying to determine the source of that water since the slide occurred.

Shortly after the slide occurred, SPU began checking upslope pipelines and systems for leaks and other damage and SPR evaluated the site for hazard trees. SPR will return to remove hazard trees when the site is made available. During its testing, SPU discovered a broken water service at one home above the slide zone, which was shut down. No other water leaks were discovered.

When the water outflow did not diminish, SPU continued to look for leak sources, including examining development patterns and their potential impact on drainage, and possible subsurface groundwater movement. SPU also conducted tests on water samples which showed elevated fecal coliform levels, indicating a possible sewer leak or another source such as animal waste.

Based on the fecal coliform levels, SPU had all upslope sewer mains inspected by CCTV. The inspection turned up a defect in a nearby 8- inch combined sewer line. While It is not currently known whether that defect is related to the landslide, SPU is planning for prompt repair of that sewer defect.

The Seattle Department of Construction and Inspections has dispatched Building inspectors to the site to evaluate the slope stability and the impacts to existing buildings and adjoining properties. No visible damage was observed.

We’ll be checking on the timeline for the promised repairs, as well as the building impacts.

mok4315 June 18, 2020 (7:00 pm)

Holy crap, time is moving weird. I could’ve sworn that slide was a year ago.

Pete June 18, 2020 (7:13 pm)

Our infrastructure continues to crumble, either by lack of maintenance, population growth that can’t manage the demands or both.i will be the first to admit I don’t have the answers, but our bridges, electrical grid, sewers , road repairs etc are something with the high taxes we pay I would think would be in better shape

WSB June 18, 2020 (7:30 pm)

Datapoint, you’e only highly taxed if you’re low-income.
https://www.seattletimes.com/seattle-news/data/seattle-taxes-among-nations-kindest-to-the-rich-and-harshest-to-the-poor/
- Jon June 19, 2020 (2:10 pm)
  
  That’s a bit dismissive of Pete’s valid point. The local government collects a lot of tax revenue with a disproportionate amount of infrastructure maintenance to show for it.
- TM7302 June 20, 2020 (12:02 pm)
  
  Datapoint, the numbers from the $25,000 household from the EOI don’t add up. For example, the article uses $1,390 for rent per month ($16,680/yr) which leaves only $8,320 in income to spend on food (not taxed) and everything else. With a 10.1% sales tax in Seattle, collecting $824 in sales tax essentially means that family is not purchasing any food. The Seattle Times relies on too many assumptions so it’s no wonder their math is wonky.

Flo B June 18, 2020 (7:34 pm)

If memory serves me years ago there were quite a few slides in that area.

john June 18, 2020 (8:24 pm)

Interesting info from Seattle DCI Sewer and Drainage GIS (DSOResearch_Ext) indicates the SPU 8″ ‘sanitary sewer’ pipe was installed 1988 and constructed of PVC, might be interesting to see the video of the “defect?” That hillside like many others along Puget Sound bluffs has a history of slides and soil instability (some of it since 1988). The map indicates the top end of the sewer branch to be above the slide area on 1200 block of Alki with just one home sewer connected at that point. Nevertheless, we all know what flows downhill…

Resident June 20, 2020 (12:42 pm)

Those maps also show an 8″ combined sewer in Sunset Ave just above the location you mention. It was installed in 1913 and is in the same location where a water main leak had a 2 or 3″ spout of water coming up through the joint in concrete panels in the street just a couple weeks ago. SPU told me that main has been a chronic problem for them and is being considered for replacement.Unfortunately, there are no specifics on the location of the combined sewer failure. But I bet it serves a LOT more customers than the one connection to the sanitary sewer in California Place. AND it is a combined sewer not a sanitary which would carry MUCH more flow during rainy weather like the record rainfall the day before the slide occurred. Initially, SPU said their inspections did not show any leaks in sewers or water mains. Just the water service to one home which is the homeowner’s responsibility. It is not clear when SPU found the failure in the combined sewer. How long the failure existed is a critical piece of information and we may never know that. But when SPU discovered it is also very important. Much more information is needed to determine the cause.

Hammer in Hand June 18, 2020 (8:55 pm)

Sdot should take a lesson quick, prompt are action words Sdot knows nothing about

Jon Wright June 18, 2020 (11:07 pm)

Sick burn!

Shadowtripper June 19, 2020 (7:28 pm)

Can’t remember the year that the Seattle Land Use was changed to allow 6 story construction replacing the 3 story limit along Alki Avenue. I do remember that the change was made stipulating that the Condo builders would be required to shore up the hillside due to unstable soil and slides that were happening at the time. Walking in back of these Condos there is very little evidence of any money spent on containing the unstable hillside. Probably just got overlooked when the final inspection passed.

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