Go to campaign, solo campaign, and complete races #11 through #20 in Down and Dirty Valley, which is part of the White Series. You will need to finish the first ten races in White Canyon to unlock these races, which will get you the Canyon White clear achievement in the process. Took me under 45 minutes to get this at a leisurely pace (starting from race #1), restarting some races for Gold medals, although you can get any medal for the achievement to unlock.