Austin is proceeding with a $14 million project to modernize the Old Lampasas Dam, according to a recent update by city officials. The project to ensure the safety of nearby residents and improve water quality is currently in the permitting phase, with construction expected in the fall of 2024. The city will ask contractors to submit bids in the spring.
Built in 1984, the facility safeguards nearly 30 structures and two roads downstream from the dam on a Bull Creek tributary. Tropical Storm Hermine damaged the dam’s primary outlet pipe in 2010. That, in combination with “poor construction” materials has resulted in erosion and the formation of “numerous holes” on the upstream slope of the dam, described by the city as “unsafe.”
Construction plans include replacing the existing 60-incue diameter spillway with a 42-inch diameter pipe and installing a new intake structure and low flow riser upstream of the dam. The project also calls for installation of a new Flood Early Warning System and replacing the existing wastewater line upstream of the dam’s centerline.
The scope of the project also includes installing a concrete headwall for the principal spillway, armoring of the existing plunge pool, building an auxiliary spillway and a new maintenance drive to give the city of Austin employees access to maintain the dam. Plans call for removing existing trees and boulders on the dam’s footprint, grading and resurfacing of embankment slopes and raising the dam to contain a worst-case scenario flood.
Photo by the city of Austin