Inspections indicate weakness in some dams

Inspections of four dams in South Texas showed them to be from marginally safe to conditionally and potentially unsafe, according to a report from the U.S. Army Corps of Engineers.

However, International Boundary & Water Commission officials said Thursday that the structures are operating normally.

Dams are inspected every five years and in 2007 the U.S. Army Corp. of Engineers inspected Amistad Dam near Del Rio, Anzalduas Dam near McAllen, Falcon Dam near Roma and Retamal Dam near Donna, public records show.

“It is important to point out that inspectors noted that they (Amistad Dam and Falcon Dam) are able to operate under normal and flood conditions,” IBWC spokeswoman Sally Spener said.

She said that staff is “closely monitoring the dams and have not noticed anything that would be considered abnormal or problematic.”

However, county officials throughout the Rio Grande Valley expressed concern.

“IBWC needs to take a serious look at the inspections and provide the infrastructure needed,” Cameron County Judge Carlos Cascos said.

Hidalgo County Judge Rene A. Ramirez said that inspections needed to continue “without a doubt. Without inspections we don’t know the quality or integrity of the structures.”

In Starr County where residents are experiencing extensive flooding, County Judge Eloy Vera noted that “the livelihood of more than 3,000,000 people depend on Falcon (Dam).”

Inspection reports noted the following concerns in 2007:

>Amistad Dam: The dam’s entire foundation needed evaluation due to potential impact of seepage from naturally-occurring sinkholes, and the high risk to potential loss of life and economic damages. The dam was evaluated in 2008 and a project plan was finalized in November 2009. Improvements, depending on funds, were to begin this year with foundation and embankment studies. The dam has a hazard potential classification of “High.”

>Anzalduas Dam: Electrical/mechanical and geotechnical/structural recommendations were made. Other recommendations included the removal of sand bars, sedimentation, and vegetation growth. The dam has a hazard potential classification of “High.” Projects completed in 2008 were the removal and installation of an emergency backup power generator and switchgear and upgrading control panels on a pier.

>Falcon Dam: The inspection report called for an evaluation and repair or replacement of the seepage collection and pressure relief systems. The dam’s entire foundation also was in need of further investigation, evaluation, and study. The dam has a hazard potential classification of “High.” The replacement of “dam crest roadway guard rails” was completed in 2008.

>Retamal: The primary concern is the design of the center gate mechanism, which makes the radial gate oscillate during high flow conditions. The radial gate mechanism needs re-designing. The dam has a hazard potential classification of “Significant.” Recommendations are scheduled to be addressed this year.

Spencer would not elaborate on the exact meaning and ramifications of the individual safety action classes. She explained that she would have to research the information before interpreting what they mean.