Q. If there was some garbage bags left out in a private parking lot last year containing disposed food and likely chometz leftovers in them such as pieces of chala, and then this harsh winter came by and a huge mound of snow and ice was piled on top of them and it is still mostly there. Is this considered Chometz Shenofal Olov Mapoles and can be ignored after bitul, or do we have to dig it out? How about if we are in doubt if it was removed or not? What happens if the compacted snow and ice melts during Peasach?
Please see if you can find a kula, thanks

Answering your request for further clarification. Yes the garbage bags are mine and so is the property. It is not rented out but I let a neighboring building pile up their snow on that shady corner. Half the snow is gone today but there is still plenty. It could all be gone during Pesach.

A. Shulchan Aruch (O.H. 433: 8) rules that if a wall collapsed on the chometz even if the resulting heap is less than three tefachim (approximately 30 cm.) if there is danger of being bitten by a poisonous scorpion etc. one is not required to remove the pile, it suffices to annul the chometz. If there were no threat, you would be obliged to dig the chometz out unless the mound is more than three tefachim deep.

Mishna Berura (ibid. 38) quotes two dissenting opinions whether the annulment is only a rabbinical requirement since it was covered by accident and not by his intention and the concern is only that it may become uncovered during Pesach (Rashi, Ran, Nahar Shalom mentions that this is the opinion of most Poskim, Shaar Tzion ibid. 43). Other Poskim maintain that the annulment it is a biblical requisite (Mogen Avrohom ibid.)

Horav Shlomo Miller’s Shlit”a opinion is that since temperatures are on the rise you should wait until the day before Erev Pesach to see how much snow and ice are left, it may then already be less than the permitted three tefachim. If the mound is still large, but after considering the weather forecast, there is a reasonable possibility that during Pesach the chometz will become uncovered, you should remove it before Pesach

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a