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ORDINANCE NO..~_,~~],- AN ORDINANCE TO AMEND CHAPTER 11 OF THE CODE OF THE CITY OF PORTSMOUTH, VIRGINIA (2006) BY AMENDING SECTIONS 11-2,11-3, AND 11-4 THEREOF PERTAINING TO EROSION AND SEDIMENT CONTROL. BE IT ORDAINED by the Council of the City of Portsmouth, Virginia: 1. That Section 11-2 of the Code of the City of Portsmouth, Virginia (2006) be amended by the adoption of the definitions "Natural channel design concepts," "Peak flow rate," Runoff volume," and "Water quality volume" to read as follows: Sec. 11-2. Definitions. Natural channel design concepts means the utilization of engineering analysis and fluvial geomorphic processes to create, rehabilitate, restore, or stabilize an open conveyance system for the purpose of creating or recreating a stream that conveys its bankfull storm event within its banks and allows larger flows to access its bankfull bench and its floodplain. Peakflow rate means the maximum instantaneous flow from a given storm condition at a particular location. Runoff volume means the volume of water that runs off the land development project from a prescribed storm event. Water quality volume means the volume equal to the first one-half inch of runoff multiplied by the impervious surface of the land development project. 2. That Section 11-3 of the Code of the City of Portsmouth, Virginia (2006) be amended by the adoption of new subsections (f) and (g) to read as follows: Sec. 11-3. Erosion and sediment control program. (f) In accordance with, Section 10.1-561 of the Code of Virginia, stream restoration and relocation projects that incorporate natural channel design concepts are not man-made channels and shall be exempt from any flow rate capacity and velocity requirements for natural or man-made channels." (g) In accordance with Section 10.1-561 of the Code of Virginia, any land- disturbing activity that provides for storm water management intended to address any How rate capacity and velocity requirements for natural or manmade channels shall satisfy the flow rate capacity and velocity requirements for natural or manmade channels if the practices are designed to (i) detain the water quality volume and to release it over 48 hours; (ii) detain and release over a 24-hour period the expected rainfall resulting from the one year, 24-hour storm; and (iii) reduce the allowable peak flow rate resulting from the 1.5, 2, and 10-year 24-hour storms to a level that is less than or equal to the peak flow rate from the site assuming it was in a good forested condition, achieved through