Owner
County Sanitation District No. 2 of Los Angeles County
Client
Dragados USA
Cost
$630.5 million USD
Timeframe
May 2019
— December 2025
Services performed
Dr. Sauer & Partners performed temporary work design tasks, signed and sealed by our Engineer of Record.
Description
Construction of a joint water pollution control plant (JWPCP) effluent outfall tunnel. Tunnel dimensions: 8 miles in length, with 18ft i.d. The project features the first use in the USA of post tensioning (PT) of the segmental lining. Up to 40% of the alignment will feature PT in order to maintain integrity as a result of internal pressure during pumping out operations.
Dr. Sauer & Partners designed an unreinforced tremie slab and a crane pad for the JWPCP shaft, a starter and tail tunnel to facilitate the TBM launch, a TBM jacking frame, slurry wall panels for tail tunnel end wall, and risk assessment as well as mitigation measures design for squeezing ground conditions of TBM drive.
Dr. Sauer & Partners designed an unreinforced tremie slab and a crane pad for the JWPCP shaft, a starter and tail tunnel to facilitate the TBM launch, a TBM jacking frame, slurry wall panels for tail tunnel end wall, and risk assessment as well as mitigation measures design for squeezing ground conditions of TBM drive.
Geology
The shaft is located in the Lakewood formation which primarily consists of fine sand with silt. The tunnel crosses various geologic formations including squeezing ground.
Location
Los Angeles, CA, USA
Highlights
- THE FIRST USE IN THE USA OF POST TENSIONING (PT) OF THE SEGMENTAL LINING
- TUNNEL ALIGNMENT PASSES THROUGH THE SEISMICALLY ACTIVE PALOS VERDES FAULT ZONE
- NEW TUNNEL WILL TIE INTO EXISTING MANIFOLD STRUCTURE FOR CONNECTION TO THE FOUR EXISTING OCEAN OUTFALLS
Project area overview - shaft site highlighted (cweawaternews.org/)
Slurry wall reinforcement with tremie slab block-out (Dragados USA)