Is it legal (chicago) to have your yard raised 6ft higher than ur neighbors and since then our yard floods?

Ever since they reconstructed the building next door about 2 1\2 yrs ago our yard floods because their yard is leveled 6 feet higher then ours Also they made their (side) sidewalk slanted so the water when it rains leans on our house and theres is dry... is this legal in chicago, IL ? They our causing alot of damage to our property that did not happen before they reconstructed.