A structural engineer and his company have been convicted and fined a combined $480,000 for work failings that contributed to a dangerous land collapse at a Mount Waverley building site.

The 15-metre deep hole on Mount Waverley's Highbury Road, being dug for a medical and childcare centre with a double-storey basement car park, collapsed in 2015 following heavy rain.

Townhouses on the edge of the excavation collapse in Mount Waverley. Credit:Simon O'Dwyer

Residents in neighbouring townhouses were told to get out, amid fears the rock and earth at the edge of the building site would collapse further.

Engineer Aldo DiTonto was fined $100,000 on Friday over the collapse.