I just bought this house and the first snow melt that saturated the ground around house seems to have caused a rank odor in the basement that was not there the day before. There is no carpet or anything for the smell to come from. The basement has clean cement walls with a painted floor. The basement seems dry and I do not have a sump pump. It does not smell musty as with mildew, it is not natural gas, and it doesn't smell like urine. It seems like the snow melt is causing a vapor to be forced in that is really foul. I know that some landscaping was done around the house. Any ideas?