Work on the Katea Rd bridge near Owaka resumed this week after being delayed by the discovery concrete in the abutments and wing walls of the bridge was of poor quality.
Clutha District Council service delivery manager Jules Witt said engineers found the structure was worse than anticipated.
‘‘There's big voids and holes in [the concrete], which means it wasn't compacted properly when it was made.''
The estimated cost to renew the 1930s bridge was $500,000.
The council was investigating options as it could not change the budget by half a million dollars ‘‘at the drop of a hat'', Mr Witt said.
‘‘We're looking at a bit of re-strengthening in the interim to keep it going while we work through the other options for long-term renewal.''
The bridge, originally planned to be opened on May 8, would now reopen on June 14.
It will have a lowered speed and weight limit ‘‘for an undetermined length of time''.
Mr Witt said the council was consulting those most likely to be affected by the changes.
Another bridge in the Catlins also undergoing scheduled maintenance has had its time-frame extended.
When the ODT visited Papatowai last week, most residents believed the work on the Papatowai bridge was going to be completed at the start of May.
However, this time-frame was extended until May 23 due to the original scheduled starting date for work being pushed back three weeks.
A 19km detour around the Papatowai bridge via Tahakopa added about 30 minutes' travel time for motorists.
One business owner in Papatowai, who did not want to be identified, said it was a ‘‘pain'' having to travel the extra distance multiple times each day.
He used the road about three to six times a day.
He had not noticed any change in the amount of traffic using the main highway despite the detour.
He observed there was still ‘‘quite a bit'' of work to be done on the bridge.
‘‘I don't know if it will be finished on time,'' he said.
‘‘They've already moved the date.''
Mr Witt said two-thirds of the deck replacement was completed and contractors were waiting on two pier sections to be fabricated.
He believed it would be reopened on time.
Mr Witt said that unlike with the work on the Katea Rd bridge, the Papatowai bridge would not incur any extra cost as a funding contingency had been built into the contract.
