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Williamson County will fill fifth chamber of cave at Cambria Drive, officials say

According to WilCo, the approved plan includes boring two holes from the road surface into the upper level and lower level of the fifth chamber and filling both with flowable concrete.

WILLIAMSON COUNTY, Texas — A new void discovered in an underground cave underneath a Williamson County neighborhood is the cavern's fifth chamber, county officials said on Aug. 3.

Environmental officials halted remediation efforts at the Cambria Drive cave on Aug. 2 after the contractors discovered the new void. Officials said after they removed some of the loose soil material, county environmental consultants and the Texas Commission on Environmental Quality were able to gain access into the chamber and explore it.

Credit: Trejo, Rebeca
Credit: Trejo, Rebeca

Maps of the cavern show the fifth chamber has a irregular shape.

It has a long narrow, crawl space before reaching the 9-foot high upper level. The lower level of the chamber is 3 feet high. Officials said they don't believe this latest void is related to the one that was discovered during core sampling. Consultants did not find the material used to fill the core hole in the new void, officials said.

Williamson County officials said Aug. 8 they do not feel there is any immediate danger for vehicles passing over the road due to the depth of the cave.

The Texas Commission on Environmental Quality requires all construction to stop near sensitive features -- like cave formations -- until a geologic assessment is completed.

Williamson County submitted an amendment to the previously approved Encountered Feature Mitigation Plan the TCEQ on Thursday Aug. 9 and was approved on Friday Aug. 10. According to WilCo, the plan includes boring two holes from the road surface into the upper level and lower level of the fifth chamber and filling both with flowable concrete. This will provide stability for the roadway and utilities, as well as protect the aquifer from potential contamination associated with utility reconstruction, officials said.

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The county originally said construction would finish in late October or early November.

Neighbors like Tim Kelley may have to wait longer for Cambria Drive to reopen.

"If this continues like this, how many more delays will there be," asked Kelley.

Kelley said he suspected the cave to be larger than originally thought.

"Basically, it was confirming what I always thought to be true," he said.

Williamson County said their environmental consultants may go back into the fifth chamber to explore the cave further.

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