“The high winds that damaged the tank resulted in uplift on the tank dome,” Steve Hewitt, a structural engineer with McKim & Creed, an Atlanta-based firm, wrote to City Manager Pat Crook. “It also exerted significant positive force on the windward side of the tank, resulting in bending at the tank’s base, more uplift on the dome, and increased tension on the walls.”
Hewitt said only the downward pressure of the water in the tank kept it from being completely blown away, but that also contributed to the likelihood of cracking now or in the form of micro cracks in the future. He also said repairs would require doweling in and epoxy grouting rebar in the existing tank, effective only if the rebar is embedded deep enough — a difficult task due to the thin walls of the dome.
“While it may be possible to repair the tank,” he wrote, “it is unlikely that the tank can be restored to its condition prior to the damage.”
Hewitt also noted that the repair estimate omitted about $60,000, including:
• $5,000 for site cleanup;
• $33,000 for recoating the tank exterior;
• $5,000 to reconstruct a gravel access road; and
• $18,500 to replace fencing around the tank site.
Crook noted that Crom Corporation, the tank’s builder, proposed repairing the tank for $545,124 or replacing it for $789,500.
“Crom estimates the service life of their tanks to be 50 years minimum and up to 100 years with proper maintenance,” she said. “On the other hand, the existing tank had been in service nearly 20 years, or 27 percent of its life expectancy. Even if the tank was properly repaired and leak-free, I believe it would have a diminished service life.”
The council voted unanimously to replace the tank.
Adairsville City Council will meet next on Tuesday, May 7, at 7 p.m.