A faulty weld caused the April collapse of the largest water storage tank in Muscogee County, according to documents released by the Columbus Water Works Tuesday afternoon.
The steel tank that held river water awaiting treatment failed in the early morning, sending a 6-million-gallon flood onto J.R. Allen Parkway and River Road. There was property damage to homes, Lake Oliver marina and power transmission poles, but no serious injuries.
The Water Works had two engineering firms — Krebs Architecture and Engineering and Jordan, Jones and Goulding Engineers — investigate the collapse.
“Both independently found that the collapse was due to a failure in a welded seam which triggered a full top to bottom split of the tank,” a Water Works release stated.
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The split came at an 8-by-8-foot door plate installed in 1993, Water Works President Bob Tant said. The seam had held for 16 years before it gave way about 4 a.m. on April 25. The instant release of the water turned the tank’s 32-foot-high steel wall into a veritable bulldozer blade that cleared off the pine trees and growth on the hill between the tank and the parkway.
“The door was cut into the side of the tank to facilitate the cleaning,” Tant said.
The weld was done by an outside firm and not the Water Works, Tant said.
The Jordan, Jones and Goulding report was completed by Donald A. Sawyer, a nationally recognized authority on steel storage facilities.
“Both independent reports indicate the insufficient welds as the probable cause of the failure,” the Water Works release stated. “The Sawyer report, however, noted that ‘although the welds around the door sheet were not installed correctly, ... it is obvious the welds had enough strength to resist the water load for 16 years.’”
There were no visible signs of weakening around the door, according to the Water Works release.
The Water Works disclosed the cause of the collapse one day after it agreed to settle a $3 million insurance claim with Trident Insurance.
In early June, Tant refused to release the findings of the investigations on the advice of the utility’s attorney, Jorge Vega. The Ledger-Enquirer had requested the information under Georgia’s Open Records Act.
Water Works officials had planned to announce the findings of the investigation at a news conference next week, but instead complied with the Open Records Act when the newspaper requested the information again Tuesday morning.
The settlement does not include about $350,000 in claims from the Water Works, nearby residents, the city of Columbus and Georgia Power, Tant said.
The Water Works is seeking about $150,000 from Trident to cover the cost of cleaning and repairing nearby property. The morning of the collapse, the Water Works facilitated the cleaning of homes that were impacted.
Georgia Power had about $125,000 in damages to transmission poles, Tant said. The city reported about $40,000 in water damage to Lake Oliver marina, where most of the water went back into the river. The rest of the damage is to private residences, and those homeowners are working directly with the insurance company, Tant said.
The Water Works will replace the tank that was built in 1965 with two 4-million-gallon concrete tanks. The insurance settlement money and additional $1 million from the utility’s capital improvement fund will pay for the new tanks.