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Seattle, WA


The project in Seattle, WA included an early 20th century 108” diameter wooden formed cast in place concrete pipe that was used to deliver the entirety of South Seattle’s wastewater to the West Point Wastewater Treatment Plant.  An equally old pipe was used to transport the county’s wastewater beneath a 500’ wide shipping canal.  Stellar J was selected to construct the replacement pipelines for this aging system. The scope of work was to replace, where possible and improve, as necessary, the transport pipelines without stopping the flow of sewage waste.

On one side of the canal, Stellar J placed constructed a steel structure to suspend the existing century old 108” diameter reinforced concrete sewer force main pipe in order to build a diversion structure to replace the aging pipeline and provide connections to new work.

On the other side of the canal, Stellar J performed a live By-Pass of the existing 144’ diameter concrete sewer force main while construction of the new pipeline and diversion structure was constructed.

Concurrently, Stellar J built two 80’ deep x 30’ diameter secant pile shafts to launch two micro tunnels under the 500’ wide shipping canal.  Stellar J successfully installed two 84” diameter steel casings by micro tunneling under 500’ wide ship canal; one shaft in an active city park and the other shaft in a university parking lot.  This project successfully replaced the 100-year old system serving the majority of the Sewer for the Seattle Area.

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