Safeguarding Communities and Agriculture: Tule River Spillway Enlargement

ABSTRACT ONLY - For decades, the Tule River Basin has depended on Success Lake (Schafer Dam) to mitigate flooding and support irrigation. Originally constructed in 1961 by the U.S. Army Corps of Engineers, the dam provides critical flood reduction and irrigation benefits to the surrounding region. The Tule River Spillway Enlargement Project, located five miles east of Porterville, California, was designed to expand flood control capacity thereby safeguarding agricultural lands downstream. The project raised the reservoir's capacity by 30,628 acre-feet through a series of modifications, including the widening of the spillway and the construction of a new mass concrete ogee weir. The project was conducted in two phases: Phase 1, completed in 2022, involved widening the right abutment of the spillway and relocating the access road, while Phase 2 focuses on excavating the left abutment, constructing the ogee weir, downstream erosion protection apron, training walls, and reinforcing surrounding infrastructure. The ogee weir was constructed using 3-inch aggregate mass concrete and 1.5-inch aggregate mass concrete under strict temperature controls to reduce cracking. Beyond technical elements, this presentation will cover the design aspects and challenges of the project, including the spillway physical model, rock blasting, ogee weir construction, infrastructure relocation, and floodproofing of facilities. We will also share lessons learned from managing such a complex project, focusing on proactive problem-solving, rigorous review processes, and adapting to evolving construction conditions. Understanding these challenges and solutions will provide valuable insights for engineers, water resource managers, and infrastructure planners. The presentation will conclude with a discussion on the project's future impact on flood control and agricultural protection.