Linwood College's lower fields will be turned into a forested wetland area to divert storm waters from neighbouring houses in Woolston.
The forest will be home to native plants and trees and hopefully attract native birds such as Kereru and Tui.
A Christchurch City Council report states the basin will be a way to store flood water in heavy rainfall events and divert it back into a local stream.
The college's lower fields will be dug out and the rain flow will be diverted by a pipeline.
Of the 59 submissions, 46 were in support and 12 had concerns. Some concerns included that it could be a fire hazard or encourage anti-social behaviour.
The forest will be part of the $9 million Council Bells Creek flood mitigation scheme.
Linwood College Principal Richard Edmundson said the school fields hadn't been used since the 2011 Canterbury earthquake.
He said the fields couldn't be used for sports anyway because the fields were too wet as they did not have a free draining area.
Edmundson said teachers at the school were already in talks with the council about how the students could be involved.
Construction will start in the next few months.