Kachess Dam Modification Phase 3 Yakima Project, Washington, Bureau of Reclama   4

Background
The Bureau of Reclamation, Columbia-Pacific Northwest Region, Columbia-Cascades Area Office has a need for construction services for Kachess Dam Modification Phase 3. The work is located at Kachess Dam, approximately 45 miles northwest of Ellensburg, Washington, in Kittitas County. The principal components of the work include various construction tasks such as:
- Excavating downstream face of Kachess Dam and foundation in the area of outlet works conduit
- Constructing cofferdam within the existing outlet works channel
- Installing and maintaining unwatering systems for removal and control of water within excavations during construction
- Installing government-furnished steel liner inside the existing conduit and installing government-furnished bypass pipe between steel liner and existing conduit
- Extending existing concrete outlet works conduit downstream and constructing new portal structure
- Placing and compacting zoned earthfill embankment materials within outlet works conduit excavation and new stability berm over outlet works conduit extension
- Excavating trench for new auxiliary drain, placing and compacting new zoned earthfill materials, and furnishing and installing auxiliary drain, two auxiliary drain inspection wells, including all mechanical and electrical equipment, and concrete outlet structure, among other tasks.

Work Details
The work includes mobilization to site and demobilization from site; excavation of downstream face of Kachess Dam and foundation in the area of outlet works conduit; demolition of current outlet works portal structure; construction of cofferdam within existing outlet works channel; installation and maintenance of unwatering systems for removal and control of water within excavations during construction; installation of government-furnished steel liner inside existing conduit and installation of government-furnished bypass pipe between steel liner and existing conduit; installation of new government-furnished plunger valve near upstream end of steel liner; furnishing and installing new transition structure near upstream end of steel liner; extension of existing concrete outlet works conduit downstream and construction of new portal structure; re-construction portion of outlet works channel downstream of new portal structure; placement and compaction of zoned earthfill embankment materials within outlet works conduit excavation and new stability berm over outlet works conduit extension; furnishing and installing filter drain and filter drain inspection well, including all mechanical and electrical equipment; excavation trench for new auxiliary drain, placement and compaction new zoned earthfill materials, furnishing and installing auxiliary drain, two auxiliary drain inspection wells, including all mechanical and electrical equipment, and concrete outlet structure; excavation of electrical trenches and furnishing and installing new electrical conduit; construction of new downstream toe approach road; installation erosion control measures; completion restoration activities.

Place of Performance
The work is located at Kachess Dam, approximately 45 miles northwest of Ellensburg, Washington, in Kittitas County.