Surpluses in council accounts would be used to boost the reserve, but councillors were warned that the cost of the new track together with possible leaky home claims could put the reserve under "severe stress".
Smith said the section of track was a slip waiting to happen because it was sited on a relic slip.
The base track was currently closed because of a major slip on the same section of track that the council wanted to bypass. A temporary $20,000 track along higher ground was due to be built within six weeks, but it would be unsuitable for wheelchairs and pushchairs.
He said the benefit of permanently bypassing the unstable land was that future slips falling on the new beachfront section of the base track would be simple to remove, meaning the track could be reopened quickly.
"This happened on other locations on Mauao after the recent ex-cyclone events where slips settled on existing tracks."
Smith said staff were aiming to get the work done as soon as possible. Tauranga was hosting its first international marathon in October and the base track was included in the route.
Councillor Catherine Stewart opposed, saying building a new 250m track for a 14m to 20m slip seemed to be over-scoping. People would not get the same views lower down.
The $2.2m cost led to councillors asking whether the trust which administered Mauao on behalf of its Maori owners should use its status to seek funding that was not available to the council.
The council dismissed the idea of donation boxes at both ends of the base track, but Cr Bill Grainger suggested ways that people could donate to support the maintenance of
Mauao be put on carved information panels telling the history of the maunga.
It was agreed that the trust be asked to consider opportunities for alternative community funding to maintain Mauao.
Councillor Rick Curach opposed spending $2.2m, saying he knew the maunga and preferred the approach of taking a little risk and addressing slips as they happened.
"A lot of the tracks on Mauao are unstable . . . reinstate the track and deal with the issues as they arise."
Councillor Steve Morris said the base track was being used more than a million times a year and the council should be able to tap into public goodwill for Mauao.
He said the part of the track where the slip occurred was much more technically difficult to fix and he believed the $2.2 million would pay for itself in 10 years from savings on other slips.
Timeline to relocate section of base track
Evaluations, designs and consents: Up to 25 days
Tender process: 20 to 30 days
Construction: Two to three months
Base track opens: Summer 2017-18
