If you want to recover your gear, and I'm sure you want to. Plus not to mention how hard it is going to be without it, if your not good at full stealth.
Make your way toward the marker. Until you reach the refinery area. Inside it looks like your completely lost, you can't climb or even blink your way out of the place.
In the same area, you may see a boat with some oil tanks. they are all empty, you can take one of those are one from one of the dispensers.
Right around that area there will also be an oil dispenser to fill up the oil tank. Do so and place it in the holder, THEN you can flip the switch to activate the staircase.
The next problem is the same idea, but easier. Another empty oil tank. This time, just jump over the gate blocked by some breakable planks. Pick up the empty can and fill it nearby. SAVE your game, because this will cause a chain that we must go down to appear. There are also tons of weepers here.
Finally deal with the weepers or not, and turn the wheel valve to open the door, after retriving your gear of course. Then blink back to Daud marker.
Only problem here is the riverkrust at the bottom of the pit, if you fall. If not turn the nearby wheel to open the nearby gate. on mid floor level.
Finally there will be a sole assassin with a key kill him and loot his corpse for the key to the entrance to Daud.
Kill Daud, do it quick or he will probably end up killing you. Best to blink then quick strike.
After killing him take his key, use his key at the marker.
Begin your escape into the sewers. Once your in the sewers you will need the sewer master key.
Make your way to the sewer master key. Help granny rags and she will give you the key.
Head back through the sewer drain, it is near the furnance and under some planks. break the planks to enter the sewer drain.
It will take you directly back to the sewer gate area where you needed the key. use it. Dodge the weepers and espeically the river krust, blow them up with a grenade, then blink past them. Finally enter the door to hound pits pub to complete this long and challenging mission.