Spillway and Outlet Works Design Challenges at Upper Chiquita Dam

摘要

This paper describes spillway and outlet works design challenges for Upper Chiquita Dam. The spillway consists of 1) a covered spillway inlet structure to prevent contamination of the potable water in the reservoir, 2) a closed conduit for conveyance down the abutment to mitigate aesthetic concerns, and 3) a Reclamation Type VI impact-type stilling basin, which doubles as the energy dissipation for the outlet works. Several other potential configurations considered for the spillway components are described in this paper. The outlet works incorporates three intake structures on the 2.5H to 1V reservoir slope with butterfly valves rather than traditional slide gates, and a fixed cone bypass valve on the downstream end for emergency drawdown requirements. This paper describes the design processes for these components, as well as the considerations for the alignment of the inlet works and outlet works across the core trench.