DESCRIPTION:

Trinity PUD and the USBR intend to boost the power generating capacity at Lewiston Dam, California from the existing 350 kW. Sunrise Engineering was selected to optimize the power generating capacity (determined to be 2.2 MW) while also attending to important Trinity River fisheries issues.

Sunrise performed pre-design studies to determine project feasibility, evaluated impact to the environment though NEPA studies, developed design plans and specifications, and will perform construction administration and testing in full compliance with USBR requirements. The design effort involved geotechnical, hydraulics, structural, powerhouse and electrical/instrumentation components. Design challenges included a new intake structure to be constructed and anchored underwater, a new 96-inch diameter siphon penstock around the left abutment of the dam, fractured rock excavation, limited area of construction at the new powerhouse location, and interconnection of the bypass system with the existing 48-inch penstock.