No provision of this chapter shall be construed or deemed to prohibit or declare a nuisance the taking of residual coal from deep mine workings which deep mine workings, because of their proximity to the surface, have removed subjacent support from the surface to the extent that actual subsidence damage has been caused to the land in its natural state, provided that such removal of residual coal from deep mine workings is taken in connection with site preparation and grading preparatory to construction of improvements of the site for building purposes.
(Ord. 727. Passed 1-16-68.)