My initial thought is that candidates deliver quicker in the ‘real’ assessment than they do in preparation. Mainly due to stress! I would be worried that you will probably finish it in 6 to 7 minutes.
So… I would see if you could develop some more into it. Often spending 30 seconds to a minute explaining the project in question and your role (with the aid of photos and plans,if available) is of huge benefit to your assessors and an invaluable way of setting the scene.
Also take a watch with you on the day, to pop on the table in front of you, and time your presentation so you can effectively manage the 10 minutes.
If you are near any of my RTA Surgeries, come and deliver it to me for FREE. I can give you some direct pointers then… http://www.delever.com/rta
Also I provide mock interviews: http://www.delever.com/mocks (new dates for session 2, 2013 will be published soon)
Also Also, see my Online Masterclasses on APC Process and Presentation http://www.delever.com/masterclass (there are some free Masterclasses there too)
I hope this helps