Note: If you want to complete the watchpoints, I would suggest that you do a run on casual. It will be much easier!
"Deluge" is obtainable in around 30-120min. I had to restart several times but was able to finish a run in 32min.
You are going to
need the C-65111 truck (orange one) . You select the truck before starting the level.
At the beginning you are going to spawn next to a second truck and two trailers. Take the C-65111 and couple the trailer to your back and tow the other truck to your back aswell. It will be very usefull to cross the river. Now you are going to drive up the road (south). Take the first and only path on the right side and drive till the end.
To cross the river you need to start at the "tree trunk" and pass the island on the right.
To reach the other coast, drive up on the right side of the "3 tree trunks".
Untow the other truck and pull the handbreak.
Now just follow the road to the north until it ends, turn left and you will arive at the garage. Deliver the trailer and
equip the LOG CRANE CARRIAGE. The next destination is the gas station which can be found on the other side of the street.
Fill up your truck and drive back to the coast where you came from. Drive to the next Log Station and take 12 short logs with you.
Your truck should look like this.
Drive back to your second truck, swap seats and cross the river just like the last time but without the trailer. After reaching the other coast, untow the truck and swap seats again. Drive down the path and turn left on the solid road. Follow the road until you reach a path on the right side. Follow this path and deliver the logs (4 logs are one delivery, so you have to unload the others, so they do not vanish).
I would suggest you do all other achievements on casual or you are going to drown many times.