Waste storage structure. A new waste storage structure may not be located within 350 feet of a property line, or within 350 feet from a property boundary. If any portion of an existing structure is closer than 350 feet from a property boundary line, such structure may be expanded, provided the expansion is not located any closer to the property boundary line than the existing structure. A single new livestock waste storage structure may be constructed closer than 350 feet if such structure 1) is located on the same tax parcel as a livestock waste storage structure in existence before May 1, 2006, 2) is not larger than the existing structure, 3) is no further than 50 feet from the existing structure, and 4) is no closer to the property boundary line than the existing structure. This setback requirement does not apply to existing waste storage structures, except that an existing structure within 30 feet of a property line or road may not expand toward the property line or road.