In my previous H3 maps, you will see the arena slowly get covered in unused equipment and grenades over time. It will begin to really pile up! The only way to clean these items up was to start another round and lose all of your deployed AI. This button allows you to clean up the arena, without deleting all the AI with a new round start. This switch is located at the map center, sitting at an angle on the central pillar near the cliffside.

To use it properly, press the switch to turn it YELLOW. Continue looking at it for a few seconds until it automatically turns GREEN. The garbage cleanup is now complete and you can walk away. The reason you should not look away during this time is due to the fact Halo 3 does not recycle anything that is too close to a player, or in view being looked at by the player. Keeping your back to the map allows for a thorough, effective clean up.