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We are assessing the stability of a section of sewer pipe in Lakeridge Park / Deadhorse Canyon.
Prior to 1946, sewage from homes above and around Deadhorse Canyon was managed by an on-site sewage treatment plant in the canyon. At this time, the homes were part of unincorporated King County. Between 1946 and 1947, the City of Seattle annexed the park and surrounding homes. During this time, the City of Seattle built a sanitary sewer line through the park on the east side of Deadhorse Canyon. The sewer line relies on gravity to move sewage downhill through the canyon to a sewer main along Rainier Avenue.
Between 1995 and 1997, the City of Seattle replaced the sewer line on the east side of the Canyon with the existing sewer line on the west side of the canyon after a number of small slope failures and required repairs. When the sewer line was relocated to the less steep west side of the canyon, a trench was dug for the sewer line and the trail was added on top of it as part of the project.