Prado Dam Spillway

Nestled along California’s Santa Ana River, the Prado Dam stands as both a testament to engineering prowess and a guardian of Riverside and San Bernardino Counties. Dating back to its construction in 1941, this unassuming structure has tirelessly regulated the river’s flow, ensuring the safety of the surrounding communities. However, as the years passed, it became clear that the Prado Dam required a significant upgrade to bolster its flood risk management capabilities.

The ambitious Prado Dam Spillway Modifications Project was conceived as a transformative endeavor. The project sought to replace the dam’s existing 15-foot-tall linear ogee weir with a towering 35-foot+ labyrinth spillway, revamp approach walls, chute walls, slabs, and underdrains, all while introducing rock anchors for added stability. But such grand ambitions came with their share of complexities. The sequencing of construction activities had to be meticulously choreographed to minimize disruptions, seasonal restrictions cast shadows on productivity, and the use of roller compacted concrete added both challenges and costs.

Enter the Value Team, a cadre of innovative thinkers tasked with unraveling these quandaries. Their ingenuity bore fruit as they proposed bold solutions. To reduce failure risk, they envisioned replacing all RCC work with mass concrete. To enable work, they advocated for early contractor involvement and the use of existing chute slabs instead of mud slabs and RCC leveling sections. Their crowning achievement was a proposal to construct a massive cofferdam upstream of the labyrinth weir, allowing construction even during the wet season and potentially shortening the project timeline.

The Value Study estimated a maximum potential cost avoidance of nearly 25% of the project cost, a windfall that promised not only cost savings but enhanced safety for the community.