Plans for the development of St Eunan's college in Letterkenny are in jeopardy following an objection lodged by a local residents association.
The plans include the demolishing the 1979 annexe to the rear of the school and to demolish the existing gymnasium and to construct a new 900 pupil school building on three floors alongside and to the rear of the existing school building
The plans also include the construction of a new site entrance to the college road.
But aspects of the plans have been objected to by the Hawthorn Heights Residents Association.
The council had granted permission to the college for the development but the residents association has appealed that decision to An Bord Pleanala.
In a submission they expressed their shock that permission was granted for the development on a number of grounds.
The group has expressed concern that no report had been compiled to determine what impact the development would have on the remaining protected structure.
Other concerns include the over-development of what is described as a restricted area - the residents are concerned that the new building would have a detrimental impact on residential amenities and the value of their properties.
They also say the development would have an adverse visual and flooding impact.
The residents say their concerns have been exacerbated by both the applicant and architects and the approach they have adopted.
The association says that no meaningful consultation has taken place and that their concerns have been ignored, dismissed and undermined.
An Bord Pleanala is due to make a decision in the case by the end of April next year.