The former Raincliffe School site currently houses the Year 7s and 8s after the two schools merged in 2010.
Headteacher of Graham, Helen McEvoy, set a letter to parents this week stating that the pupils would all be housed in the upper site in Woodlands Drive from the next school year.
She said the reasons were due to a drop in student numbers and also to save on “wear and tear” on staff moving between the two sites.
At the time of the merger there were 1,579 pupils across the two sites, today that figure stands at just 1,065.
The upper site can house 1,300 students.
The letter stated: “Operating on two sites has had its challenges over the years; one impact has been the wear and tear on staff who have to transfer across sites during the day; another aspect is the difficulty of timetabling to minimise the number of transfers that colleagues have to undertake, this can result in more split groups than we would like to have in school and the impact to the school budget of running two sites is also a significant issue.
“The school has been in discussion with the Local Authority for the last 18 months seeking a positive resolution to the site issues and the LA have been very supportive in looking for a positive way forward and will work closely with the school to achieve a positive transition to a single site from September 2017.”
The school has not indicated publicly what impact it could on staff levels and if there will be any redundancies as a result of the closure.
Last week, Ofsted called for “urgent action” at the school following a visit.