The project consisted of building a new cooling water discharge system to support a 1200 MW energy center being constructed at the existing Moss Landing Power Plant site. This new system consisted of three underground structures that were built in sequence, the disengaging basin, the discharge channel and the drop tube structure. The disengaging basin receives hot water from the new energy center through two 120" diameter pipes. The inlet end of the basin a 35' deep by 25' wide by 50' long irregular shaped structure had an internal concrete weir and heavy reinforced 2' thick concrete walls. The weir was designed to reduce flow of the water and transition the flow into the next structure, which consisted of a 500' long, 17' deep, by 17' wide channel. The channel alignment was adjacent to and followed the footprint of the existing power plant that was in full operation. Differential settlement along this alignment was a major concern due to the potential to shut down the existing plants. Watts Constructors developed a plan and methods for stabilizing the excavation and eliminating this concern. As the channels' floor and walls were poured, a second crew followed behind forming and pouring a dividing wall and roof cap. This dividing wall and roof cap turned the channel into its final product, twin 14' deep by 6' wide box culverts. The twin tubes directed the water flow into the drop tube structure that was 35' deep by 14' wide by 30' long. The floor of this structure was the roof of the existing discharge tunnel for the operating power plant. Working around planned outages two 9' diameter, by 3' thick concrete cores where cut and removed from the existing tunnel roof. Two fabricated steel drop tubes were set over the cored holes and the annual space was filled with concrete. The twin tunnel structure was tied into the drop tubes to complete the system.
Solicitation Number:
Completion Date: 2001-11-01

Clientele: Retail
Owner: owner_6
Specialty: Utility

Contract Value: $10,876,781.00

Project Recognitions: