"This will give us a clear understanding of the cost of undertaking this aspect of the works," he told Radio New Zealand.
Work needing to be done would include upgrading huts and track surfacing, as well as legal access for sections of the track crossing private land.
"Other work to deliver the project is tracking well with final approval set for completion in mid- to late March."
"Some of the construction works will be delivered this financial year, however the bulk of the works, specifically the track works, will be completed next summer."
Last year Fleming said the scoping of the on-the-ground work had finished.
The total budget is expected to reach around $7 million, following the extra year's delay.
The main construction phase will happen in 2022 and into 2023.
Hump Ridge Track
The Hump Ridge Track from Tuatapere has been in place as a multi-day hike for over two decades. Currently operated by the Tuatapere Hump Ridge Track Charitable Trust, it was first proposed following the closure of forestry on the edge of Fiordland.
It crosses land belonging to DOC, Southland District Council and a range of private owners including Ngāi Tahu.
Work identified as needing to be done to cope with increased Great Walk visitors includes increased parking, hut upgrades and track drainage.
Announced with the goal of bringing increased tourism to area, DoC says there has already been an increase in usage of the Tuatapere Hump Ridge Track since the 2019 Great Walk announcement.
The Trust will continue to manage the walk after DoC's upgrades in 2023.