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Local News

Detention basin at Science Hill headache for city leaders

September 3rd, 2011 10:03 pm by Gary B. Gray

The City Commission has asked City Manager Pete Peterson to negotiate with Bluff City’s Baker’s Construction on a plan that could deviate from the current contract to remedy possible drainage problems with a large detention basin being built on the Science Hill High School campus.
Right now, the consensus among commissioners is that reported problems with unsuitable soil may not be as bad as are being reported. Still, they want to make sure alternative fixes will work, that all environmental requirements are met and the city will not be legally liable should repairs not hold.
Commissioners were presented with several options at their Aug. 18 meeting but deferred action until more could be learned about the basin’s condition and costs for properly completing the project. Presented with a nearly $103,000 option Thursday by Eugene Coleman with Johnson City’s Tysinger Hampton & Partners Inc., commissioners again deferred the matter. The option was the least expensive, save from doing nothing at all.
“The contractor is waiting, and we’re here to make things happen,” said Commissioner Clayton Stout. “But I’m not ready to strap taxpayers with an extra $103,000.”
Coleman’s recommendation followed an inspection of the soil by GEO Services LLC which reported to the city that Baker Construction discovered unstable soil at subgrade level which is preventing them from continuing forward with final construction, including the installation of a clay liner.
The construction company was in the process of installing an underground drainage system which was going to be topped with a compacted clay liner. But the contractor found a soggy organic soil in what they reported was about 60 percent to 70 percent of what is called the subgrade — the material underneath the compacted layer at the bottom of the basin.
The suggested remedy included the application of cement and/or lime into the soft portions of the subgrade to provide a stable platform on which 18 inches of clay liner would be placed.
“With what we know, will the law allow us to do nothing?” Vice Mayor Phil Carriger asked Coleman.
He did not have an answer.
“With this option, is there no risk?” Carriger asked.
Coleman initially said no.
“You mean there is no risk? Carriger asked again.
“Well, there’s always a risk,” Coleman answered.
On Friday, four men stood in the middle of the basin in the hot sun. They reassessed the situation and reaffirmed the commissioners’ conclusions.
“After talking with these guys, we’re not going to do any more than is absolutely necessary,” said Mayor Jeff Banyas after consulting with Allan Cantrell, city engineer; Tommy Burleson, the city’s construction agent; and Randy Christiansen, who does building information modeling for Burleson.
The basin is in a Karst region, which means the area is apt to have sinkholes, and in some cases caves.
“You can’t compact pudding,” Christiansen said. “And since this is in a Karst region, it must be compacted and have a liner.”
On Thursday, Banyas said he had been to the site the day before with a steel pole testing the ground. He asked Coleman if radar could be used to search for problems before additional money was spent.
“That’s been there for 35 years, and I feel like we’re being a little over regulated,” Banyas said. “The surface is dry out there; there was only a small amount of soft soil. I think we could probably treat smaller areas. I’m not saying don’t put the liner in, I’m just saying don’t do it right now.”
Burleson said the base contract to construct the basin was about $320,000. However, a $50,000 change to install a drainage system means there is no contingency money left.

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