South Sewer Interceptor - West Richland, WA

Overview

This project consisted of constructing a 6-mile long sanitary sewer interceptor for the City of West Richland.  The new interceptor allowed for the abandonment of the City’s South Sewer Lagoon and opened up 2,500 acres to new development.  E

nvironmental issues included elimination of two low-quality wetlands and a mitigation plan including enhancement of nearby existing wetlands.  Planning involved identification of the 2,800 acre drainage basin area.  Portions of the interceptor are over 25-feet in depth and were installed in groundwater conditions.

This project included:  

• Hydraulic modeling.
• Deep trench excavation.
• 70,000 c.y. of roadway excavation and embankment.
• Demolition of existing lift station.
• Dewatering.
• Removal of existing sanitary sewer pipe.
• Construction of sanitary sewer manholes and an irrigation canal under crossing.