The bill was paid to a caterer on March 11, a week after Jack's resignation was announced, and about 660 employees had been invited to the gathering at the Municipal Theatre, but not the councillors.
"It was considered appropriate to invite all staff, given his length of service in his role as chief executive," a statement said, adding it was "very well attended".
While it was not normal for the council to provide gifts for departing staff, which would usually be funded by staff contributions, the council did provide a $600 patu pounamu which was presented to Jack, who had been CEO since 2013, returning to his hometown Napier after several years working in local government in Australia.
The statement said the provision of the gift was due to the short departure timeframe and that Jack's length of service "… a gift of a patu pounamu that cost around $600 felt appropriate".
"While it is not normal practice to provide catering at council events, due to the nature of this event catering was again considered appropriate," the statement said.
Mayor Kirsten Wise told Radio New Zealand she was not even aware of the farewell party until RNZ drew her attention to the item in the report.
"It was a little bit of a surprise to me," she said, adding it was disappointing that none of the councillors were invited.
While Wise had initial concerns about whether the spending had been signed off appropriately, she had since confirmed that "all the correct delegation processes were followed".
"I was advised it was based on a full complement of staff being at the morning tea shout, and at a cost of $6.50 per head," she said. "I wouldn't say it's excessive. But I'm unaware of how many staff members turned up."