Indiana Code Title 16. Health § 16-41-25-7.2

Sec. 7.2. (a) As used in this section, “sinkhole” means a depression or hole in the ground caused by some form of collapse of the surface layer, as when subsurface limestone is dissolved or worn away by the movement of water underground.

(b) A residential onsite sewage system shall not be installed in a site less than twenty-five (25) feet from the edge of a sinkhole, as identified by a professional soil scientist registered under IC 25-31.5-4.