On the way back to the Tower you hear from Alfie - that they just lost gas at the Tower - and it seems the rest of the city as well.
You need to talk to Jeff - and fortunately he is nearby. In fact when you approach he will actually start warning you that he will shoot you. When you approach he tells you that he is Commander Jeff and he is in charge here.
He admits that he shut off the gas - then he tells you that you will have to turn the gas back on because he is not going to do it. Well, looks like you have another chore to do!
Head to the marker on the map to open the valves - if you have trouble finding a way to the marker, look closely at the map. Yes, you do need to go inside the Tunnel. Sorry mates.
Once you make your way to the Valve and open it you will then need to head to the next marker and Valve - which unfortunately is guarded by a heavy infected. On the plus side though you should be pretty good at dealing with these guys by now!
Before you go after the heavy you should kill the Toad on the overpass as otherwise he will make your life miserable.
With the Train Bridge Valve now open, you need to head to the third and final one, which is located under the overpass.
On the way there you run into a hit chick a the Safe Zone who is a major fan of Jade - the crazy girl actually came to this shithole to see Jade. She asks you to tell Jade she is her biggest fan. Say what?!
When you get to the overpass there will be a Toad and some regular infected there to be killed, after which you can use the Valve.
After that you just need to head over to open the Primary Distribution Gate.
Be warned at this final location there are some dangerous infected. There is a Toad and some of the Tank ones - plus normal ones. It would be an idea to clear them all out before you try to complete the mission.
Once you have all of those cleared away you need to deal with the Heavy that is down int he cage - so pick the Hard Lock on the door to the building then head over to the other side of the road and dive into the pond. Swim through the tunnel there and you enter the cage where you have to take out the Heavy.
With him eliminated, turn the last Valve and then you will have restored the main gas flow - you need to get away from that Valve.
Unfortunately after you do that Jeff tells you that you made a small error - it seems you need to close the Blue Lines Valves in order to keep the gas from leaking. Well that is reasonably close by so head there, clear out the infected then get those valves closed!
With that done Commander Jeff calls you back to the “base” and you get thanked - sort of - then he tells you he will open the main controls - and you have ten seconds to get away from that disaster area!
Jeff pretty much got what he deserved, right? Right!
Collectibles
Statue - in the Train Car on the way to the Primary Distribution Gate.
Note #20 - Inside the building at the Primary Distribution Gate.
Filthy Blade Blueprint - Inside the building at the Primary Distribution Gate.