A couple of things:
0. Goblins are NE. Selfish, not chaotic.
1. Remember that goblins are cowards, but maliciously, deliciously evil cowards. They fight only when they have numbers. Consider violating DM code of an EL "fair fight." It's possible that they all gather together in a huge horde for protection. Party breezes through, deals with a few nasty but simplistic traps ... and then comes in to face 35 goblins all with that sharp-toothed smile: "Bugger," says the first PC in.
1a) When the party, hopefully, runs, they now have an incentive to figure out ways to trick the goblins into facing them with smaller sizes... picking off patrols, stealth, looking for hidden entrances, etc.
2. In addition to the other nasty tactics, have the noncombatants fling poo at the PCs. You might rule that the PCs have to make a Fort save DC5 or be nauseated at the first hit.
3. Goblins should be easily distracted. A smart sorceror who throws fistfuls of shinies (copper) or food ought to take 1d6 goblins out of the fight for a few rounds.
4. Second the motion for small sized tunnels if you don't go for the unexpected big swarm of gobbos.
5. Glass jar with a hornet's nest is absolutely perfect.