The middle section of Fallout 3: The Pitt features a mixture of gladiator combat and treasure hunting in the steelyard. If you having any problems with The Hole, The Steelyard, or The Unsafe Working Conditions quest in general, then look here for a complete guide.
Unsafe Work Conditions
No matter how you got into town, you'll have to walk to Midea's house. Just follow the marker. You need to go along the pit with the slaves working on the bus. Then move into the big square. Midea's house is opposite the slop table. Go inside to get your instructions. If she's not here yet, then just use the wait command. You'll have to gather 10 steel ingots from the steelyard. Sounds easy, right?
It's not too bad once you get some weapons. Go back to the main pit you passed. Walk by it to find the marked entrance to the mill. Go inside and follow the path around the mill. Ignore the entrance to the steelyard and go a bit further around to find the control room first. Marco is inside. Talk to him to get an auto axe. It's better than nothing and pretty good against the trogs.
Go to the marked entrance to the steelyard and follow Everett to the entrance. There are 100 ingots out here. I'm not going to list them all here for the sake of organization. There's a full list of all 27 stashes under the separate quest labeled Mill Worker. I suggest that you get at least 50 ingots now, so you can get the Metal Blaster and a bunch of Microfusion Cells to power it. This reward will make the rest of The Pitt easy. You only “have” to get 10 though, so I'll just cover that for now.
Into the Steelyard
Go outside and grab the assault rifle from the dead slave by the door. This should last you for most of the steelyard if you are even a half decent shot. Try to save some of it for the upcoming fights though, especially if you aren't going to collect the ingots and get the better weapons from the Mill Worker quest. Also, if you have 75 points in Science, hack the terminal by the supply plant and activate the four protectrons. They will kill a lot of the trogs and establish a safe zone in the train yard. You can find this turret right around the first corner near the entrance to the supply plant. You should be able to easily see the Protectrons. 
I personally suggest you just go ahead and raid the supply plant. It's next to the entrance, lightly guarded, and there are 18 ingots inside. They are fairly concentrated too. Just go in, kill the few trogs and wildmen, hack the few turrets to your advantage, and come back out. You can also just collect the few easy stashes by the train cars. There are 4 in the dumpsters, 2 in the right corner past the supply plant, 2 in the little storage house at the top of the stairs, and 2 in the alley near that storage house. Easy enough if you can kill the first batch of trogs without wasting too much ammo. If any of this confusing, then just skip ahead to my guide for the "Mill Worker" quest. I'll have full details for every stash in there.
Once you have 10 ingots, backtrack out of the steelyard. The abandoned area isn't as safe, since the first trog you saw on the walkway into the steelyard has broken through the cage. Just shoot him. If you want, you can grab another 3 ingots in a mining cart located off of the main path. Give Everett the ingots to get a new slave outfit and report back to Midea. Collecting 10 steel ingots also earns you the “Auto Axpert” perk, even if you didn't use one the entire time.
Fallout 3: The Pitt - Walkthrough
Fallout 3: The Pitt offers a lot of content, a rich two-sided plotline, and a side quest that will have you searching for 100 steel ingots. This walkthrough will cover all of the things that you can do in The Pitt. If you want to get the most out of this expansion to Fallout 3, then look inside.