The next least costly option is “Eastern Growth”, with houses built in the fields to the east of Kaiti, medium density housing in Wainui, higher density housing in and around the CBD, and mixed use and higher density development-medium density intensification based on accessibility to the CBD.
An immediate issue in weighing these two options is that one relies on reticulating Wainui and the other doesn't, but the beach-side suburb needs to be reticulated irrespective of this strategy. There should not be any consideration that Wainui not be reticulated for wastewater (at least) in the near to medium future.
A “Dispersed Growth” option that includes a CBD focus for higher-density housing, intensification in existing areas and building on some fields to both the east and west of the city sounds appealing, but is the most costly option due to infrastructure costs across the city.
The second most costly option, due to the infrastructure upgrades required, is “Intensification”. This involves keeping the existing city footprint and encouraging CBD revitalisation, medium-density housing throughout the city centre and higher density in the CBD, plus significant medium-density housing in Kaiti.
Like reticulating Wainui, efforts to revitalise the CBD should be non-negotiable as part of this planning for future development.