(Mishnah): 'Shoulder stones' may be removed from anywhere and a Kablan (building contractor) may bring stones from anywhere. These are 'shoulder stones' -

(R. Meir): Any stone that cannot be taken with one hand.

(R. Yosi): It's as their name implies - whatever is carried on the shoulder, either two or three at a time.

If a person builds a wall between his property and the public property, he may dig down to the bedrock. What should he do with the dirt?

(R. Yehoshua): He should pile it up in the public domain and then fix it up (by moving it to his own domain).

(R. Akiva): Just as one may not (even temporarily) damage a public domain, so too he should not pile it there. What should he do with the dirt? Pile it in his field in the way of those that fertilize.

They also disagree when digging a well, a trench or a cave.

(Gemara): Shoulder stones may be brought from anywhere - even from his own property; and a Kablan may bring from anywhere - even stones smaller than shoulder stones.

(R. Chiya citing R. Yochanan): When the Mishnah permitted digging down to the bedrock, it referred to a wall between him and the public domain; but between him and his neighbor, it is prohibited in Sheviis, but on Chol HaMoed, even between him and the public domain is prohibited, if the breach is blocked with dirt and thorns that block it; but if it isn't blocked, he may build and close it up in Sheviis.

Support (Baraisa): Any breach that is blocked with dirt may not be built in Sheviis; if it's not blocked, it may be built. This applies when is not disturbing the public, but if it is, even if it's blocked, it may be built in Sheviis.

Question: Why not fix it, if the pasuk states (Tehillim 50:23), "And prepare the way, I will show him the salvation of Hashem''?

Answer: It's different here, because although he might repair, before he does so, he brings a pile of dirt to the public domain and sometimes he even might change his mind and leave it there.

As R. Shimon ben Lakish said (to support the understanding of the pasuk above (g)) - Shaul only merited to be king because his grandfather had lit candles for the public (to be able to walk to the Beis Midrash and learn at night)

One pasuk states (Divrei Hayamim 1:8:33), "Ner begot Kish'' and another pasuk states (Shmuel 1:9:1), "...and Kish son of Aviel''. (Kish was the father of Shaul.) So wasn't Aviel his name (not Ner)? Rather, since he (Shaul's grandfather) would light candles for the public, he was called Ner.

Question (R. Avin): (At the beginning of the Perek, piling up manure was only permitted when the workers who fertilize the fields stop their work at the end of the season). Do we also have this requirement when piling up dirt to later build the wall? (The Gemara leaves this question unanswered.)