After the Head Against the Wall quest, head upstairs and talk to Josh to begin this one. Talk to the poilceman downstairs, to start the Guard On Duty side quest. Once you get past the guard, it's back to the sewers. Stay out of the poison water. Also try to bring some sort of incendiary weapon because enemies with fart clouds around them are flammable.
Once you get to the main section of the grocery store, there will be a big fire fight, so make sure you pick up all the ammo for your gun that you can. After the punks go out, you'll have to go an alternate way and you'll come across a Ram, just skip him.
There will be another firefight with the Punks. After everyone is dead load the supplies into the truck and that will trigger a cutscene that will finish the quest and start the quest Bitter Return.
ID Card #049 - In the first big room you enter, there is a ladder on the left side. Up it the card is on a tool box.
Barbed Wire Mod - Once you're out of the sewers, after you fight the floater, there is a room on the left with a repair bench. The mod is on the table next to the bench.
Banoi Herald Excerpt #27 - After the puck locks the door to the room you're going to it's in the next room on the table.