"The principal, Mrs Carolyn Pentecost, continues to have full management responsibilities for all day to day operations of the school," Casey said.
"The aim of any intervention is always to return the school to full self-management as soon as the recommendations of the intervention have been met.
"We will formally review the intervention in 12 months' time."
College board of trustees chairman John Schnackenberg earlier confirmed the board had sought governance support from the ministry for "some complex employment matters".
Schnackenberg would not elaborate on the details of those matters but he said the board welcomed Gielen's appointment to work alongside it to help it address these matters.
"Shawn has extensive governance and leadership experience across a wide range of schooling contexts, and he will take responsibility from the board for all functions, powers and duties as an employer and across finance operations," he said.
Schnackenberg said Gielen may also advise the board on its communications, policies and procedures.
"Shawn has begun the scoping phase of the intervention, focusing on some complex employment issues and understanding the school's finances.
"This will continue on into the 2020 school year. An action plan will then be developed for taking the school forward."
Schnackenberg said college staff and the school community had been informed.
"The board will update our school community following the completion of the scoping exercise."
