If I remember, the legion that built the ramp was recalled from Britannia to suppress the Bar Kokhbah rebellion. They spent ten years building that ramp by hand, until it was high enough for them to ascend to the summit. Of course, by then the occupants had all died. A pyrrhic victory for both sides.
Different 10th legion. The legion that surrounded Masada in 72 AD was Legion 10 Fretensis. It had been raised in 40 BC and was stationed in the Syria and Judea at the time. The Legion you are thinking of was also the 10th legion. It was raised in 61 BC by Julius Caesar and fought with him in Gaul and Britain. Disbanded 45, it was reconstituted a few years later as Legion 10 Gemina. That 10th Legion served in Spain until 70 AD, then was transferred to Rhine border in Holland. It was there at the time of Masada.
It took the Legion X Fretensis less than 6 months to build the ramp and reduce Masada.