You remove the wrenches from the sack to try on the grate below. It would be risky to try and carry the wrenches and lantern in one hand as you climb down the ladder. You need to find a way to get the wrenches and the light down to the grate. How are you going to do this? Remember to take the rope with you too or you'll be stuck.
You can tie the rope around the last ladder rung, thing... and tie the lantern to the excess liek you did to get up the ladder, then go back up and get the wrenches, or just tie the lantern and wrenches to the rope in the first place, then climb down and tie it to the ladder so you can climb back up and you have light. Alao what are the grey and blue objects in the back left of the room, doors? And what are the things in the top of the left wall, mind taking a look real quick?
You've figured out a way to get the lantern and wrenches down the sewer but you are curious about a few things you see in the shadows. There's something high on the wall to your left and two objects down at the far end. Let's look at the items on our left first.