Woodhollow Dam in Austin, Texas, was built between April and December of 1979 to control flash flooding in an Austin, Texas, neighborhood. This first dam constructed of Reinforced Earth MSE Retaining Walls in the United States created a buzz in the community and even had a visit from the inventor of the retaining wall system, Henri Vidal. The dam proved its value early and is still in use more than 40 years later as a flood control measure, as well as a new artistic landmark.
Neighboring apartment buildings and an adjacent roadway created a tight space, preventing the use of a conventional sloped earth dam. Having been introduced in the U.S. only eight years earlier by Vidal, the Reinforced Earth retaining wall system was still relatively unknown in civil engineering markets such as water resources and floodplain management. In addition to the smaller footprint, the cost efficiency compared to a cast-in-place concrete dam convinced the City of Austin Engineering Department to move forward with the Reinforced Earth Co.’s engineers in Arlington, Va., to finalize the design of the dam.
The dam was designed with a tiered wall facing on the downstream side. Initially the plan was for a straight vertical face, but with the proximity to the roadway, the City of Austin preferred the dam to be stepped back to appear smaller. Landscaping helped blend the tiered wall in with the site. The upstream side of the dam was built as a sloped-earth fill, extending 2.5 to 1 down from the back of the soil reinforcements. A clay core keyed into bedrock, a full-height crushed rock drainage blanket, riprap and other typical features of an earth dam are incorporated into the section of the structure.
During construction in November 1979, a resident posed a question in the Austin American-Statesman newspaper:
After completion of the dam’s construction, Vidal and his wife, Elizabeth, traveled from France to observe the structure, and they were guests at Austin’s City Council. From the City of Austin:
“Mr. Davidson, city manager, asked Mr. Charles Graves, director of engineering, to make an important presentation to [the] council on a unique project not only to Austin, but within the United States. He said we are proud to have been associated with it.
“Mr. Graves told council and members of the chamber audience that a new program of flood control had been launched a few years ago. One of the more interesting areas was the Shoal Creek Watershed. Henri Vidal, a French architect, engineer and inventor developed the concept for reinforced earth structures that has been used in the construction of Austin’s first major stormwater retention dam.”
Mayor Carole Mcclellan designated Dec. 13, 1979, Henri Vidal Day in Austin.
The mayor presented a key to the city to Mrs. Vidal. The Texas Society of Professional Engineers then presented a plaque to Mr. Vidal.
Passing the test
Only a couple of years after its construction, on Memorial Day weekend 1981, the dam was tested by a 500-year flood.
A new look
In 2019 the dam’s “pretty face” was given quite an upgrade. Local artist, Bill Tavis, was commissioned by the city to paint a mural on the entire concrete face of the dam, an area of about 3,900 square feet (362 m2). Through TEMPO, part of Austin’s Art in Public Places program, the city is awarding local artists the opportunity to create temporary sculptures and murals on city property, paid for by the city. This particular mural took about four weeks to complete in fall 2019 and will eventually be replaced.
Tavis said he found the wall’s facing panels very useful during the layout phase of his halftone mural. “They wound up being a big part of my process because I used the panels to grid out and transfer my image, it really helped!”
More about Tavis’ work on Woodhollow Dam can be found on his website.
Woodhollow Dam MSE wall
City of Austin
Austin Engineering Co.
City of Austin Engineering Department
This article first appeared on the Reinforced Earth website, www.reinforcedearth.com.