Episode 2: The Cavalry
Scenario 6: Under Construction
At the Bone Shaker rollercoaster site, you will need power for the ride. Press LT and choose the left location with a bunch of wood panels. Nima will send Jess to look for the power generator. Have Jess interact with the left wood panel (the one with the X button prompt). That one will be the sign that will unlock this achievement. Were you tall enough to ride? ;p
NOTE: Be sure to choose the left one first. Choosing the one that uncovers the electric panel (in the middle, Y prompt) will result in bypassing the wood panels entirely when you come back.
Thanks to xXDobleEquisXx for the heads up on that!