I find it amazing that people are even allowed to hire one and play with it without any training. Presumably building sites wouldn't allow it, people could get killed.
Clay is different, most people don't want it. Mine was fluffy black topsoil and a bit of sand. Even so, you may be able to get the digger driver to relay it to where a grab lorry could take it from. Alternatively a self-drive dumper truck or powered wheelbarrow would do it. Just be prepared to pay for longer for the digger if he ends up waiting for you to come back.
Clay is different, most people don't want it. Mine was fluffy black topsoil and a bit of sand. Even so, you may be able to get the digger driver to relay it to where a grab lorry could take it from. Alternatively a self-drive dumper truck or powered wheelbarrow would do it. Just be prepared to pay for longer for the digger if he ends up waiting for you to come back.