The purpose of this rulemaking is to add the term, "semi-imperviousa" to the conditions for issuance of general environmental resource permits that are based upon the amount of impervious material proposed for a project. The effect will be to clarify that any such provisions concerning impervious surfaces are intended to include semi-impervious material. Historically, impervious and semi-impervious materials have been treated the same in District rules. However, recent rulemaking that included adoption of a separate definition of "semi-impervious" made the continued inclusion of semi-impervious materials in these rule provisions unclear.