Principal Rachel Skelton said the extension at the current campus will encompass a new teaching block, gym extension, all-weather playing court cover, expanded support services storage and parking, and general site landscaping.
The design and build for this had been awarded to construction company Watts and Hughes.
At the same time planning of the second campus was moving into an exciting stage, she said, as the design and build tender was awarded to Christchurch-based construction company Southbase.
Ministry of Education head of property Sam Fowler said the ministry could not yet provide cost details of the two projects.
"This (extension) project is currently at tender with suppliers and as such the anticipated costs are commercially sensitive at this time. We are in the early planning stages for the new campus.
"We'll be able to provide more details of anticipated costs later in the design process," Fowler said.
Expansion of the college's gym would be completed late 2023 and new teaching spaces and other works would be completed 2024. Extension of the current campus would cater for a further 700 students.
In the meantime, the school is relying on short-term teaching spaces to cater for growth. Skelton said two new buildings would be provided for the beginning of next year, to add to others already on site.
"We are very lucky in that these are brand new offsite-manufactured buildings. We have been very happy with them in terms of light, warmth, acoustics and spaciousness." Skelton said.
"They are built for modern teaching practice and were installed with minimum disruption to us, which was appreciated.
"A number of these buildings have been modified specifically to meet our specialist teaching space requirements."
