First, you need to turn on the respective special event.

1. Go to Settings and select the "Game" options.
   
2. Make sure "Allow Christmas" and "Allow Halloween" are both set to "On".
   
3. Select "Christmas" or "Halloween" under the "Force Special Event" option.

If you did activate the event while being in the workshop, go back to the main menu to trigger the event and return to the workshop.

Now, you need to start the extraction which you will get offered via email.

1. Check the computer for new emails.
   
2. Select the special event email and accept the offer.
   
3. Start the extraction via the Organizer.
   
4. Find the tank, clean it and extract it.

Once the tank has been loaded onto the trailer, you will get the achievement.