Sinkhole appears in Roosevelt neighborhood not far from another historic site
May 3, 2016, 2:20 PM | Updated: 3:16 pm
A massive sinkhole that opened up in north Seattle's Ravenna neighborhood in 1957 was the nation's largest sewer failure at the time. (Seattle Municipal Archives image)
(Seattle Municipal Archives image)
A recent tunneling project may be to blame for a sinkhole that developed in the Roosevelt neighborhood last weekend, causing three households to evacuate their homes as an investigation into the matter continues.
A sinkhole developed in Seattle’s Roosevelt neighborhood at 12th Avenue NE and 62nd Street NE on May 1 — about 50 feet above the recently bored southbound light rail tunnel, according to Kimberly Reason with Sound Transit.
Related: Boring machine is tunneling underneath Seattle’s canal
The sinkhole is about 3 feet wide and 6 feet long and is located on the border of the sidewalk and a home. The hole has since been filled with concrete. The residents of the home are staying at a hotel while Sound Transit crews inspect the area for other underground spaces that could develop into additional sinkholes. Two other households are also staying at a hotel as a precaution and are expected to be away from their houses for another day.
The contractor that is inspecting the ground is working under the assumption that the tunneling likely caused the sinkhole the develop, Reason said, and is now working to prove or disprove that theory. It is “likely” because the hole developed directly above the tunnel. The southbound tunnel underneath the area was constructed last summer and completed in March. The tunnel will connect the existing line to Northgate from the University of Washington at Husky Stadium.
A sinkhole developed 50 feet above a new light rail tunnel in Seattle’s Roosevelt neighborhood on May 1. It is not far from another historic sinkhole in the Ravenna neighborhood. (Dyer Oxley, MyNorthwest)
The area is no stranger to sinkholes. While the recent sinkhole is located in the Roosevelt neighborhood, it is not far from the site of another sinkhole — the historic Ravenna sinkhole of 1957. That massive hole was the result of a failed sewer line and caused a cavity measuring 60 feet deep, 120 feet wide and 200 feet long. The Ravenna hole took two years to repair.
The recent sinkhole in Roosevelt is much smaller than its historic counterpart. The two sites are about .3 miles apart and are separated by Cowen Park — the entrance to Ravenna Park.
This is the second time light rail tunneling has caused sinkholes in Seattle. The Seattle Times reports that seven “underground voids” became an issue in 2009 near the Beacon Hill station. One of those voids was near the surface and threatened a house.
An unrelated project, the Alaskan Way Viaduct Replacement Project with the world’s largest tunnel-boring machine Bertha, also experienced a sinkhole along the waterfront in January. That was of concern as that machine is going to tunnel underneath the viaduct and downtown Seattle.
Follow @https://twitter.com/DyerOxley
