The debris surround a kiln is not limited to ash and firebox residues (as seen here). Even after the hard work of preparing the clay, shaping the forms, drying them, and loading and firing the kiln, thing can go wrong. In the heat of the furnace, vessels can shatter, slump, burn, or warp. Once fired, these "wasters" cannot be reshaped. The potter must wait for the kiln to cool, removed the casualties, and pitch them outside. It is possible that this debris could be ground up into bits (or "grog") and mixed into a future clay batch. Tiny inclusions of fired pottery can enrich fresh clay and help it expand and contract. They may even prevent some form down the line from suffering the same fate.
Note the deformed ebreek in the center of the shot. It also looks like a plastic successor of this traditional liquid container has found its way into the rubbish pile as well. These too can be recycled in a conscientious world!
This pile of wasters accumulated outside of Abu Ali's kiln in Aqabat Jeber.