The distinctive landscaped terraces were built in 1938 and 1939 by the Oamaru Beautifying Society between Itchen St and Douglas Tce, part of beautification projects undertaken by the group around Oamaru.
But over time they have deteriorated, becoming unstable and unsafe.
The Waitaki District Council will undertake major work on the terraces, expected to take about three months.
The work was budgeted for the past financial year but carried over into the new financial year.
It is estimated to cost about $400,000, with funding coming from the roading budget subsidised by the New Zealand Transport Agency.
Roading assets manager Gary Woock said yesterday tenders for the work, which he described as a "big, challenging job", had closed and were being evaluated.
A contract was expected to be awarded before the end of next month and work would start as soon as possible after that, depending on the weather and ground conditions.
The bottom retaining wall would be removed in 2m long sections, replaced by reinforced concrete with a facing of Oamaru stone to retain its original appearance.
That will stabilise the top two tiers.
The next two tiers would be restored.
Vegetation would be removed, particularly trees whose roots had gone through the walls and destabilised them, and a new landscaping plan was being developed.
Mr Woock said one of the two southbound lanes up Severn St and the footpath would have to be closed while the work was done.
Work would stop before Christmas to reduce congestion.
The Oamaru Beautifying Society, which no longer exists, was formed in 1908 and carried out a number of projects around Oamaru, including plantings in Thames St.
Under the direction of Dr A. Douglas, it designed and built the Severn St walls.
Douglas Tce, above the walls, is named after Dr Douglas.
The walls are listed as a heritage item in the Waitaki district plan and approval for the work has been given by the New Zealand Historic Places Trust.
