The owners of the Binghamton-Johnson City Joint Sewage Treatment Plant, site of a 100-ft wall collapse in May, are eager to begin repairs but they first must determine if Hurricane Irene-related flooding undermined the structure's foundation.
The two south-central New York state cities, which own and operate the plant, are also dealing with a pair of engineering reports that blame construction errors and changes for the wall failure and that limit use of parts of the plant. The flooding has added to the cost of repairs but the amount can’t be estimated until they know if the building support was undermined after flooding forced the plant offline Sept. 8-11. The utility has since returned to limited operation.
“We’re getting prepared to go out for bids on the collapsed wall,” said George Kolba, chairman of the Joint Sewage Board that runs the plant.
The cost hinges upon the results of an exploratory dig for damage underneath the buildings, he said.
Flood cleanup will be in the $8-million range, he said.
However, plant manager Cathy Aingworth has estimated the flood damage at $10 million to $25 million, according to published reports. She has not returned ENR's e-mails and calls for comment.The board has authorized $250,000 for the electrical lighting system and another $250,000 to rebuild switch gears, Kolba said.
Water treatment has resumed on a limited basis and the three digester tanks should be repaired in about six months, he said.
The engineering reports follow a construction audit, completed before the wall collapse, that found more than 150 construction deficiencies in a $67 million plant upgrade completed in 2006.
“The cause of the wall failure appears to have been the result of an insufficient lap splice of the main reinforcing at the base of the wall,” Edgar C. Eslinger, structural engineer with EFI Global Inc. of Fall River, Mass., said in his report.
His other findings include:
- The main wall reinforcement lap splice location “was changed during construction,” and lap lengths shortened. • The splice lengths in construction documents were not in compliance with code and lengths required where most of the main reinforcing is spliced at a single section.
- The wall that fell apparently was designed as a cantilevered wall but did not have safety factors required by code. • Modifications were made during construction and structure was not what construction documents specified, “including wall intersection reinforcement and waterstops”.
- The 144-ft wall was designed and built without expansion or contraction joints “which may have caused or aggravated the observed wall cracking.”
- Wall deflection, modifications to seal the wall joints and cracks in the wall “should have alerted the owner and design team that issues existed with the integrity of the wall.” “Based on an uncracked wall section, the anticipated deflection at the top of the cantilevered wall section would have been over 1 inch,” Eslinger wrote. “This is likely why angles and sealant were applied to the joints between the west wall and interior perpendicular walls of the tank in order to seal the large separation at the top of the tank wall.”
- Tests conducted on concrete did not “indicate any intrinsic material issues.”
- “It is apparent from the observed termination of the horizontal reinforcing at the interior dividing walls of the tanks that they were not constructed per the construction documents,” he said. “The horizontal reinforcing was terminated in short straight terminations rather than a properly detailed hook.”
