Environmental resource permitting rules have certain exemptions, limitations or requirements that are based on the amount of impervious surface either proposed or existing for a project. Longstanding District practice has been to include semi-impervious materials with impervious materials when addressing such provisions. Recently, the District adopted a specific definition of “semi-impervious,” which made the continued inclusion of semi-impervious material in requirements for impervious material unclear in some rules. The amendments proposed in this rulemaking will eliminate any uncertainty concerning how semi-impervious material is to be addressed. Subsection 40D-4.051(3), F.A.C., which sets forth an exemption from environmental resource permitting for surface water management systems for agricultural or silvicultural activities, is amended to clarify that the area of impervious and semi-impervious surface must not equal or exceed 2 acres in order to be exempt under this provision. Subsection 40D-4.091(1), F.A.C., is amended to incorporate by reference a revised Environmental Resource Permitting Information Manual Part B, Basis of Review, various sections of which are amended to include the word “semi-impervious” in provisions relating to impervious surface materials. The definition of “impervious” is also amended to eliminate overlap with the definition of “semi-impervious.” The Joint Application for Environmental Resource Permit/Authorization to Use State-Owned Submerged Lands/Federal Dredge and Fill Permit, Form No. 547.27/ERP, is revised to include the term, “semi-impervious” in application information requirements relating to impervious surface material. Rule 40D-4.101, F.A.C., is amended to incorporate by reference the revised form, with an effective date of 6/2010.