In-Conduit Hydroelectric Generation Sustains Pressure, Produces 300kW of Electricity

This in-conduit hydroelectric generation project is part of the larger Placer County Water Agency (PCWA) Gold Run Pipeline project. The pipeline project includes construction of 5,000 feet of 36-inch ductile iron pipe (DIP), an intake structure with screens, and a new pressure sustaining valve building with in-conduit hydro. The project impacts a portion of the PCWA Boardman Canal system, which is a critical portion of the agency’s raw water system. During annual PG&E outages, the Gold Run system provides all of the raw water for PCWA customers.

The Bennett Engineering Services team provided design and permitting for an in-conduit hydroelectric generation plant that replaces the function of a pressure sustaining valve and produces 300kW of electricity. Since flows vary from 8 to 26 CFS over a year, a cross-flow turbine was selected as it maintains efficiency over a large flow range. The team provided permit acquisition services including PG&E approval, CEC approval, and FERC licensing assistance.

The project also required design of more than 1,800 LF of 12kV power line extension to connect to the existing PG&E system. The team sought and obtained PG&E approval for a Rule 15 line extension, which saved PCWA more than $60,000 in PG&E connection costs. Another innovation was the use of a small pump-as-a-turbine generator placed in series with the bypass valve that provides backup power for an unlimited power outage.

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