One who builds a wall between his [property] and the public domain is permitted to dig down to the bedrock. What should he do with the dirt? He should pile it in the public domain and repair it; [these are] the words of R’ Yehoshua. R’ Akiva says: Just as one may not cause damage to the public domain, so too one should not [even] repair it. What [then] should he do with the dirt? He should pile it inside his field in the manner of stored dung. So too, one who digs a pit, a ditch, or a vault.