Engineering report: Barton Springs Dam urgently needs repairs

A structural condition assessment of Barton Springs Dam released last week shows large cracks in the lower dam that need to be repaired “as soon as possible.”

 

The Parks and Recreation Board and Environmental Board Joint Committee heard a summary of the study, which was started last September. Though Datum Engineers found the dams to be in relatively good condition overall, repairs to the horizontal cracks at the lower dam are estimated to cost $129,937.50.

 

“If you read it, you may get to a point where you get kind of alarmed at their language,” said Gary Gregson, a Parks and Recreation Department employee.

 

According to the summary of the study, “The horizontal cracks are approximately 15 feet long and actively leaking water. It is recommended that these horizontal cracks be repaired as soon as possible.”

 

“They don’t know if the cracks will cause the dams to fail in the next five years or the next 50 years, but they recommend it is better to err on the side of caution,” said Gregson.

 

The repairs would require building a cofferdam around the repairs, and injecting something like an epoxy grout to seal the cracks. Engineers estimate that this will increase the dam’s service life by 20 years. A cofferdam is an enclosure within a body of water to allow water to be pumped out to create a dry work environment.

 

“I think they low-balled the cofferdams, considering the flood debris project we just did, I think it was $245,000 to cofferdam that area. This would be a smaller area, but still,” Gregson told In Fact Daily. “I think $45,000 is probably a little low on that.”

 

Subcommittee member Carol Lee remarked that the repairs would cost “less than what it took to think about it,” upon hearing that the assessment alone cost $140,000.

 

Gregson reassured Lee that $130,000 would only cover the cost of the immediate repairs necessary. The assessment also includes gate improvements that could improve water flow and widened walkways over the dam remain an unknown cost for the future, though these repairs are less pressing.

 

Repairing Barton Springs Pool is not an easy process, as it requires going through US Fish and Wildlife, the Army Corps of Engineers, the Texas Commission on Environmental Quality, the Watershed Protection Department, and the Texas Historical Commission before it gets anywhere near City Council.

 

Gregson compared the current situation to the repairs that are currently needed on the bypass culvert that runs along the pool, for context.

 

“2008 is when the holes first developed and we felt it was almost an emergency situation, and here we are and we’re not even started yet,” said Gregson.

 

Despite the Datum Engineers’ determination that the north side of the downstream dam is in “unsatisfactory condition” due to the cracks, Gregson remained saying, “Besides the cracks, the dams are in good shape.”

 

The full report was not available online on Monday due to its 80 megabyte size, which has delayed its online publication. The summary is expected to be available on the Parks and Recreation Department’s website (www.ci.austin.tx.us/parks/) sometime today.