Lebanon Water Treatment Plant Intake
The City of Lebanon required consulting support for conceptual and final design of a new raw water intake as a component of a larger project including a new water treatment plant. The City decided to construct their own water diversion and treatment system to supply water to the City’s residents.
Kleinschmidt provided an alternatives analysis and conceptual and final design of the new raw water intake designed for flows up to 10 MGD. The design included a steel cofferdam layout, foundation, reinforced concrete structures, integrated fish screen and baffle panels, backwash piping layout and supports, and all ancillary features. The primary structure consists of cast-in-place concrete and uses post-tensioned rock anchors for sliding resistance. Kleinschmidt analyzed the stability of the structure for several different load combinations including design low and high-water levels along with static and seismic loading conditions. Due to the vulnerable on-river location, the exposed concrete structure, screen supports, and bulkhead panels were design for significant debris impacts. Innovative systems were designed to clean the fish screens and intake. The fish screens are cleaned with a backwash system that progresses from the upstream end to downstream end in zones to effective remove debris and pass it beyond the intake. At the toe of the screens is water jet manifold that is used to clear sediment in the river at the base of the structure. A sediment sparging system suspends sediment within the intake and allows the sediment to be transported with the water and out of the intake. The system utilizes 10 electronically actuated valves that are programmed to operate in sequence to automate operation of the cleaning system.
The City of Lebanon has been pleased with the ease of operation and reliability of the intake due to automated and adjustable cleaning systems. All three cleaning systems are integrated with the control system and level sensors so they can be adjusted to meet seasonal variations in water demand and sediment loads and reduce maintenance requirements and associated costs while maintaining reliability of the intake. This project received a Pacific Northwest Section of the American Water Works Association Excellence in Engineering Award and the 2020 Excellence in Concrete Award.