An application by the Department of Corrections for approval to carry out work needed before an extra 150 inmates can be housed at the prison has been filed with the Clutha District Council.
The upgrade includes additions to the eastern and western ends of one building to create more cells; more exercise yards; extra car parking and lighting; a new search facility building; a new inmate employment training building; and a new fence.
Most of the work was regarded as "internal infrastructure works" and would not change the site's external appearance, the department's application document said.
The exceptions to this were the exercise yards, the additions to the separate cells unit, extra car parking and extra training facilities.
Walls for the exercise yards will be a maximum of 3.6m high, while the highest building, at 9m high, will be the new workshop.
No extra landscaping will be done as part of the upgrade.
The document said the only potential effect on traffic flow would be at the Narrowdale Rd intersection with State Highway 1.
Consultants, who originally designed the intersection before the prison opened two years ago, said it was built to safely cope with increased traffic.
The prison's existing infrastructure of water, stormwater and wastewater had enough capacity to cope with the extra demands that would be placed on it by extra prisoners and an estimated extra 67 staff who would be employed there.
Council planning and environment manager Murray Brass, in a report to this week's regulatory services committee, said the construction proposal met the conditions of the prison's existing designation, granted before it opened.
No extra resource consent applications would be needed, although building consents for individual work would still be needed.
"Once more detailed plans are available we will be able to assess what specialist expertise and/or other special arrangements will be required for processing these applications."
