S.C. Code Regs. § § 61-62.7.I
The purpose of this regulation is to prevent the use of tall stacks or other dispersion techniques from affecting the emissions limitations required to meet National Ambient Air Quality Standards (NAAQS) or Prevention of Significant Deterioration (PSD) increments. This Regulation does not, in any manner, restrict the actual physical stack height nor the actual use of dispersion techniques at any source. Rather, it sets limits on the maximum credit for stack height and other dispersion techniques which can be used in ambient air quality modeling for the purpose of setting an emission limitation and calculating the air quality impact of a source. Sources requiring modeling must use Good Engineering Practice (GEP) Stack Height. Credit for dispersion techniques is prohibited.
S.C. Code Regs. § 61-62.7.I