The row of golden elms were axed by PowerNet contractors in Coutts Rd, near the school’s rugby field.
A PowerNet spokesperson said the trees, which were next to a footpath, were dangerously close to overhead power lines.
"Trees are one of the most significant risks to the overhead electricity network," the spokesperson said.
"Managing vegetation around power lines is essential for public safety, and the security and reliability of the electricity network."
Trees too close to power lines could cause fire and power outages, and could electrocute people nearby, particularly in severe weather.
When trees were identified as a risk to power lines, PowerNet issued notices and contractors were dispatched to trim or cut them down.
Trimming the trees to keep them a safe distance from the power lines would have come with ongoing costs, the spokesperson said.
St Peter’s College principal Kieran Udy said the school would fill the gap.
"We’re planning on replacing them, and planting predominantly natives … so we can maintain them ourselves and … keep them trimmed and under control," Mr Udy said.
The school’s gardener, Beth Campbell, teacher John Ryan and caretaker Ray Shanks were part of a committee formed to manage the school’s trees, he said.
PowerNet did not disclose the cost of chopping down the Coutts Rd trees.
St Peter’s College had also removed poplars in Kakapo St, after some of them fell down during the storm in October last year, Mr Udy said.
At the time, arborists had told the school the roots of the almost 10m-high trees were compromised, meaning they were at risk of falling at any time, he said.
