"That combined with ageing buildings and weather-tightness issues has made this one of the most complex school redevelopments undertaken in New Zealand," she said.
"This is reflected in the investment announced today, which is the equivalent of the cost of building two new secondary schools."
The redevelopment would involve two brand new teaching blocks built, comprising a total 64 teaching spaces.
One of the blocks, containing 12 teaching spaces, would be for Nga Puna o Waiorea, the college's Maori immersion-Rumaki unit.
The two new blocks would take the total number of teaching spaces at the college to 81, including the 17 existing teaching spaces that will be upgraded.
Depending on the final design, more of these upgraded teaching spaces may be replaced.
Ms Kaye said the work would increase teaching space capacity by roughly 25 per cent, and allow the roll to rise from over 1300 to around 1700 students in what was a high-growth area of the city.
"Work at Western Springs is expected to start in late 2016 and be completed by the end of 2018," she said.
"Due to the complexity of site issues and the scale of the project, the Ministry has advised me that health and safety specialists and additional project support will be used to complete the rebuild."
About the project
Why Western Springs College?
Western Springs College is a co-educational secondary school (years 9-13) in Auckland.
It opened in 1903, has a Maori immersion-Rumaki unit, and a current roll of more than 1300 students.
In 2014, the school was announced as one of the priority schools for redevelopment, alongside Koru and Southern Cross schools, due to high growth in the surrounding area and a range of property-related issues.
The school's roll is projected to grow to 1700 students in the medium term, including the Rumaki which is projected to grow from the current 215 students to 340 by 2020.
The college has an impressive history of academic achievement of both mainstream and Rumaki classes.
What's the process from here?
A detailed timeline is being developed with the school. Final design, procurement, consenting and review are expected to be completed by mid 2017.
Based on current information available, the redevelopment will be completed by late 2018, Ms Kaye said in a statement.
The final cost of the project will be determined once procurement processes are complete, but is expected to be approximately $75 million for the school redevelopment, and approximately $4 million for TAPAC.
Why has the decision on Western Springs College taken longer than expected?
This is the largest single investment in a school in New Zealand.
It is the equivalent of two new secondary schools and reflects the significant complexities and challenges of the site and buildings.
The ministry "wanted to get it right" for the school and address its property challenges in a way that would get the best outcomes for students, Ms Kaye said.
The extent of site issues has required extensive specialist reviews and resulted in a long planning process.
Western Springs College will be rebuilt on its existing site. What investigations/reports have been carried out regarding site stabilisation and safety?
There have been extensive geotechnical, engineering and environmental investigations carried out by experts since 2010, and a Health, Safety and Environment report was released in December 2014 addressing issues at the school.
Since 2009/2010 around $4.6 million has been spent on property at Westerns Springs, including an investment in roll growth, maintenance and seismic work.
The school also has a Health and Safety Policy to ensure a high level of attention to health and safety matters.
The Ministry is putting in place additional specialist health and safety expertise and additional project support to complete the rebuild.
What options were considered?
Five options were included in the business case considered by Cabinet.
These options ranged from the upgrade of existing facilities through to co-location on the Pasadena Intermediate site.
Why was the option announced today chosen?
The option chosen provides for a rebuild of most of the current school, with at least 80 per cent of the existing teaching spaces replaced entirely, a new gymnasium built and the existing hall and administration areas upgraded.
It also provides for a rebuild of the school's Maori immersion-Rumaki unit and will allow for a future roll of 1700 students.
This option represents an enhanced version to one presented to the school community in June.
There was a streetscape option, but this would have cost around $120 million - an additional $45 million approximately, enough to build two new primary schools - and was not recommended by the ministry.
The option chosen was recommended by the Ministry from the business case analysis and was compared with business cases of other school redevelopments.
Has the location of the new buildings on the site been decided?
There is a preliminary view of the location of the new buildings on the site based on the master planning undertaken to date and understanding of the ground conditions.
Final decisions will be made as part of the design work that will carried out with the school.
Will the Rumaki still retain its own separate identity on the site?
The Rumaki will maintain its own identity on the site. Twelve new teaching spaces will be provided for the Rumaki in the redevelopment including some specialist facilities.
The redevelopment will also allow for the existing wharenui to be retained and upgraded.
What's happening with the Auckland Performing Arts Centre?
Investment of approximately $4 million is now confirmed to upgrade TAPAC, the Auckland Performing Arts Centre.
It is expected that this work will be carried out at the same time as the redevelopment.
How confident are you this timeline can be met?
Additional support is being provided by the Ministry for the project to ensure it is successfully delivered by the completion date of the end of 2018.
The ministry will work closely with consultants and the school to ensure the timetable is met.
School representatives and the project team will continue to meet and discuss issues relating to the work programme through Project Design Group meetings.
Why is the cost of Western Springs College a lot more than the other recent redevelopment announcements?
Western Springs College has a range of site-related issues due to being on a former quarry and landfill.
A portion of the costs, which may vary, has been put aside to remediate site-specific issues.
