The medals and achievement for gold requires you to go 4 runs on a survival event without dying or rewinding as well as 5 runs in any gear without dying.
Go to Siberia - Kara-oiuk - Critical Mass. Choose the slowest board you have and make sure you have no gear selected. Follow the video, take your time, and you will have the achievement :)
Props to UncannyDoom on the map choice, I decided to also include a video to help with visuals. Hope it helped.