Responsa על עבודה זרה 13:10

Vinegar that has been mixed with the yeast of beer must be sold to a Gentile before Passover (in order not to violate the commandment of Ex. 12,19 and 13,7, which prohibits a Jew from possessing leaven during the Passover week). The Gentile may be told that if he holds the vinegar until after Passover, a Jew will buy it from him.
SOURCES: Cr. 68; Pr. 31; L. 340; Rashba I, 850.

On the Sabbath, a Jew is not permitted to pour sewage into a stone-trough, which is situated partly in his yard and partly in the public domain (used to carry off sewage into the street), unless the trough is covered for four cubits length in the public domain.
SOURCES: Cr. 69; Pr. 31; L. 341; Rashba I, 850; Mord. Shabb. 375.