Waste disposal is always a problem in any civilization. Goblins, though only nominally civilized share that concern. Their solution is clever. First they seperate the night soil from the rest of the trash and take it to be processed to into fertilizer. Say a prayer for the goblins that work that detail. It is hard work and they have few friends.
The rest of the trash goes into the silver bin for 30 nights. It is not really silver as if it was it would be nicked in less than half a night. While in the the silver bin any citizen of Goblin town may pick at it to their heart's content. This is a primative but very effective form of recycling.
From there it is dumped into the Smelly hole. Goblins COULD go into the Smelly hole, but few would. Not only is the stench strong as popeye after a spinach bender, but the hole is rife with magically augmented vermin. A six foot long rat will ruin anyone's day.
After collecting for a year the Goblins send the collection team in. Six mages and sixty soldiers. The soldiers are there to keep the mages safe. They arrange themselves around the pit armed with burning spears.
The first mage is the most senior and powerful. He will chant for hours and use extremely expensive ingredients to create a spell of rarification. He doesn't transform the garbage so much as to purify it to pure information. The "soul" of the waste if you will.
The next two mages then start to take this information and weave it to words, and then bind it to the pages of a book. The final three mages are in a state of magically enhanced perception. The quickly scan the pages as the words are bound to them. If there is anything of interest they can stop the process and take it back. It is an expensive process but it has been proven worth it.
Finally, all the waste is now in a book. The mages retire to scented baths and unnameable pleasures. The soldiers press the book between two heavy iron plates and wrap it in silver wire. They then place it in a steel box that has been hexed to resist magic. It is then riveted and sealed with bronze and taken to the Midden Library. So a whole year of waste has been reduced to a book. Hopefully nothing will dismiss the spells or it would be quite a mess.