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Last year, the figure plunged to just over $3 million.
Mayor Vanessa Van Uden said since the 2008-09 financial year the council had taken on more engineering staff - ''and I know that seems a bit strange given the organisational review'' - but their combined salaries were nowhere near the $14 million difference.
The figures were obtained by the Otago Daily Times under the Local Government Official Information and Meetings Act.
A subsequent request for information asking the additional amount the council paid in salaries to the extra engineering staff, employed since the 2008-09 financial year, revealed the ''total additional amount paid to engineers employed by the council in the period 2009-10 until 2012-13 is $4,437,384''.
When asked why the amount spent on consultants had dropped so significantly, Ms van Uden said, five years ago there had been far too many consultants used when they were not needed.
Consultants were being asked to ''come up with solutions that an engineer on staff should have been able to do''.
However, she stressed it was not a case of ''consultants ripping off the council'', it was about how the council was using consultants.
The ''big drops'' during the 2008-09 and 2009-10 years for engineering consultants reflected the employment of more engineering staff.
''My take on it ... [is] we are a whole lot more careful about what goes to consultants now.''
The council was using consultants for roading and water projects, the district plan review and the proposed convention centre, along with other matters.
Ms van Uden said there was ''a place for consultants'', adding it did not make sense to have people with extreme expertise in-house on a permanent salary.
An organisational review announced at the end of 2012 resulted in the council slimming down to 195 fulltime equivalent staff positions from 265.
Ms van Uden, in her second term as mayor, had campaigned to reduce spending on consultants ahead of the 2010 election.
Contemplating the savings, she said, ''I can't pretend I'm not happy'', but added the situation required ongoing effort to maintain.