Currently I'm trying to build some megaprojects on my map but have made zero progress due to sieges. They're not a challenge or anything since I have 50 axedwarves (my fort wound up being named Axeclan so I had to), the issue is the cleanup. I don't have a chasm or other bottomless pit to use so here's my technique and if anyone has a more efficient or time saving solution other than just outright hiding the items let me know.
I send out my army and slaughter everything(I wait till the siege is right outside my fort), and all their items are forbidden. I then send my dwarves back inside and mass dump everything. I then go into the stocks screen and undump corpses and parts (I want those in the refuse pile not my main fort). Everything else is then dumped in a garbage tile that's near but not next to a pit with magma in it. Once it's all dumped I mass designate melt on the pile. Anything that's metal is marked so I unforbid them and let the dwarves haul it to my stockpiles where it later gets melted. Then I move the garbage dump zone to my magma pit and dump everything that's left in there.
I thought this was a good method, but even with a full population it takes so long that before I'm even done dumping everything, another siege comes. This has gone on for like 5 sieges now and I'm not getting anything done so is there a quicker way because this is getting tedious.
First, how far away from your
entrance is your dump? If you put a spot that's near your entrance but safely out of the line of fire, each trip will take a LOT less time than having to haul every sock and loincloth halfway across the fortress.
Second, don't necessarily dump everything. How far away is your trade depot from your entrance? If it's close, put a finished goods stockpile near it and unforbid - but NOT dump - the GCS stuff. That not only shortens the cleanup trip, but saves a trip later when you want to get it near the depot so that it can be traded later. The same goes for weapons and armor stockpiles: you can just have the gear taken to those if they're close by, and have them melted down from there. It'll be a slightly longer melting job, but a much faster cleanup job.
Third, you may have to just have to resign yourself to a cluttered entryway until the sieges die down. Getting that many sieges that close together is very uncommon unless cleanup is taking a VERY long time.
Fourth, if all else fails, you can pump some magma up there to dump on the stuff. The iron gear will be fine and can be picked up afterwards, but all those (narrow gremlin leather codpieces) laying around won't need cleaned up afterwards.
Edit: Just wanted to add a method I used in my last fort.
1) Dig a 1x1 channel next to the usual battlefield. I mean like practically on it.
2) Put a bridge over it, and link the bridge to a lever.
3) Dig a tunnel between the bridge-covered pit and your fort so that you can get to it from underground.
4) Put a deactivated garbage dump zone where your guys will dump things in the pit when it's activated.
5) After a fight, retract the bridge, activate the garbage zone, unforbid the corpses so they're taken to their usual spot, and mark everything else for dumping. Everything will be taken and thrown in the pit after a trip of a half-dozen tiles or so.
6) After everything is cleaned up, pull the lever again to cover the pit with the bridge.
7) Now the crap is where your dwarves can do whatever you want with it, even during a siege.