The achievement "Drained" has not been achieved by any player since the 19th of October in 2018 during beta, according to exophase.com's steam achievement tracking. The achievement's description states that it is earned through "destroying or disabling an enemy fuel truck", but no such truck appears on any map in-game. A friend who did get the achievement during beta says he did so by destroying the enemy team's cache in Skirmish mode, but this no longer works.
@luri In Skirmish, both teams used to have their own Fuel Truck. If the truck was destroyed, the enemy team could no longer gain resupply waves from capturing objectives, but on top of that they also no longer got Technical respawns.
They could be destroyed by either explosives or lots of gunfire. It was similar to how the oil barrels in Day of Infamy worked, but Sandstorm included the ability to manually drain out all of the fuel in the tank similar to rigging a weapon cache.
At some point, though, NWI just replaced the fuel trucks with supply caches, and when destroyed they do the same things a destroyed fuel truck would do. The achievement for disabling/destroying a fuel truck still remains, though lmao. I got the achievement back when the fuel trucks were in-game.