USBR Patillas Dam Seismic Retrofit Design Update and Industry Outreach

Description: Construction of a zoned earthfill berm (~600,000 cubic yards) to enhance seismic stability. Commercially sourced materials from nearby quarries for engineered zones. Engineered drainage systems including sand/gravel filters and a 24" hdpe toe drain. Key trench excavation (~35 ft) with foundation dewatering. Installation of advanced instrumentation (in-place inclinometers, piezometers, pressure transducers, settlement points). Demolition and reconstruction of reinforced concrete downstream discharge facilities, canal overflow, forebays, and former power building. Installation of a new 54-inch concrete-encased steel conduit with a 36-inch bifurcation. Outlet works reconstruction inside 20-foot-wide existing horseshoe tunnel (~330 F long) and backfill with clsm. Outlet works extension of approx. 200 F, which also requires diver-installed temporary bulkheads through a 24-inch by 24-inch square manhole at 90+ ft depth. Construction of two new concrete control buildings for gates and valves.