When clearing out the various Camps you will find additional collectible items such as Scrap, History Relics, Project Parts and Scrotus Insignia that must be collected (or in the case of the Insignia, destroyed) as part of the optional objectives of the camp. Using
in the camp will display all optional items that must be found. You can return to cleared camps to search for items that you may have missed the first time around, although it is recommended to get these items done when you first clear the camp. Once you have completed all the optional objectives in all camps, the achievement will unlock.