The following performance standards shall be applicable to all design, construction, implementation and maintenance of stormwater management systems as required by this subchapter:
A. Treatment System: All stormwater from impervious areas shall be directed to a stormwater management system identified in the handbook of best management practices for stormwater management and erosion and sedimentation control, and the stormwater management plan criteria and engineering standards, prepared for the Panhandle health district and the interagency stormwater committee by Kennedy Engineers, Spokane, WA, April 1992, or by implementation of measures shown by a design professional to have an effective design capability which equals or exceeds the standards of this subchapter. Stormwater treatment systems shall be sized to hold and treat the first one-half inch (1/2") of stormwater from impervious surfaces.
B. Collection And Conveyance System: No stormwater shall be collected or concentrated, except within a channel or artificial watercourse protected against erosion and containing energy dissipation measures to prevent erosion on adjoining lands. Existing watercourses and streams shall be protected from disturbance and erosion during site development. Any site development shall preserve installed components of a stormwater management system if they exist. All disturbed soils shall be protected from erosion during the course of construction.
C. Disposal System: The disposal component of a stormwater management system shall have the capacity to collect, convey and provide detention for a twenty five (25) year design storm, without damage to the stormwater management system or adjacent land and improvements.
D. For new subdivisions, planned unit developments, commercial and industrial development and public projects, as set forth at section 12-720.2 of this subchapter, there shall be no increase in the peak rate of runoff from the site when compared with the dissipation of stormwater from the site prior to the start of any construction, for the first one-half inch (1/2") of runoff. Within project boundaries, sufficient retention capacity shall be constructed to retain stormwater flow from the first one-half inch (1/2").
E. Certification: Certification in the Panhandle stormwater and erosion education program is encouraged for all contractors, developers, and excavators involved in site disturbance activities within two hundred feet (200') of the shoreline.
F. Weed, Pesticide Free Materials: Use of weed free and pesticide free materials is encouraged when natural materials are called for in stormwater/erosion control plans. (Ord. 501, 11-18-2008)