All sites in Myplace take part in a systematic rollover process ahead of the start of the academic year.
This takes place in June preceding the start of the year. A full description of the rollover can be found at Rollover Explained.
Some classes may have a "None" rollover action, meaning that absolutely no action will be performed during the rollover processes.
Sometimes however it is desirable "rollover" a site at a later date
When a site is rolled over a new Turnitin class is created, along with new Turnitin Activities. This means that the submissions for the forthcoming academic year do not conflict with the previous year's submissions.
Where a site does not rollover (move and none rollovers) this does not happen, and the forthcoming year's submissions are added to the existing Turnitin class & activity.
For "move" sites this is normally the desired behaviour: there is only ever a single site available.
If you use Turnitin and you require content to be segregated from previous Turnitin activities, you must perform a class reset on the site and include reset user-submissions