Mr Hewitson, who first raised his concerns in November, expressed frustration the issue had not been resolved, and suggested the delay might be a tactic to avoid action.
The hens lost their appetite and their condition, egg production dropped and his income was down.
When he talked to a council staff member in November he was told the project complied with the Resource Management Act (RMA).
"It is quite ratshit how they’re just dragging it all out," Mr Hewitson said.
He was disappointed the construction was not suspended immediately after he reported the problem.
If human remains or buried petrol tanks were found, the work would have stopped immediately, he said.
His situation should be a warning to other farmers about what could happen if changes proposed to the RMA that were fast-tracked went through.
"There are going to be other people who have the same issues."
The Invercargill City Council is investigating the matter.
Council consenting and environment group manager Jonathan Shaw is leading the investigation but has said it was too early to comment on the findings.
He promised to report back to Mr Hewitson in two weeks and prepare an update for the next community wellbeing and regulatory committee meeting.
At a meeting on Tuesday, committee chairman Darren Ludlow confirmed councillors received a verbal update on the investigation’s progress.
However, he did not provide specifics, saying only that a full report would be made public at next month’s meeting.
In his presentation to the council last month, Mr Hewitson said the noise from the development had disturbed his hens since September, and he was perplexed about how the consent could have been approved without considering the impact on his farm.
