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EXHIBIT A: EXISTING CHAPTER 927 927.06 STREETS UTILITIES AND PUBLIC SERVICES CODE 66L (N) If the inspection reveals that a control practice has not been implemented in the time required by this chapter, it must be installed within ten (10) days from the date of inspection. (0) If the inspection reveals that a planned control practice is not needed, the record must contain a statement of explanation as to why the control practice is not needed. (Ord. 2012-76. Passed 10-23-12.) 927.06 STORMWATER CHANNEL EROSION CONTROL STANDARDS. (a) In order to control channel erosion caused by increased stormwater runoff rates and volumes, stormwater runoff from development areas shall be restricted. This provision shall apply to all new construction and redevelopment on lots larger than 8,000 square feet, and for all additions on lots larger than one-half acre. (b) The peak rates of runoff after development shall be no greater than ninety percent (90%) of the peak rates of runoff occurring before any development for all twenty-four hour storms from one to one hundred year frequency. If this requirement is satisfied for the one, two, five, ten, twenty-five, fifty and one hundred year frequency storms, all storms from one to one hundred year frequency may be assumed to satisfy this requirement. (c) The run-off coefficients shall be as follows: Before development or redevelopment, Flat slope, less than 2 percent 0.01 to 0.05 Average slope, 2 to 7 percent 0.05 to 0.12 Steep slope, greater than 7 percent 0.12 to 0.18 After development or redevelopment, Roofsurface0.85 to 0.95 Asphalt surface 0.85 to 0.95 Concrete surface 0.80 to 0.90 Gravel roadway surface 0.65 to 0.75 Grassed area 0.60 to 0.70 Other surfaces As approved by City Engineer Each type of area shall be calculated separately and the individual runoff quantities added together to give the total storm water runoff. The runoff coefficient used for each site within each given range shall be subject to the approval of the City Engineer. (d) The time of concentration shall be determined as follows: (1) Residential areas: The concentration times to the critical inlet varies between 12 and 20 minutes with 15 minutes to be used as the general case based upon full development of the land. (2) Industrial/commercial, multi -family and school areas: The concentration time to the critical inlet varies between 10 and 15 minutes with 12.5 minutes to be used as the general case based upon full development of the land. (3) Major urban business areas and shopping centers: The concentration time to the critical inlet varies between 5 and 12 minutes with 10 minutes used as the general case based upon full development of the land. Runoff characteristics which vary from the expected for either residential, commercial, or industrial development will be supported by data submitted for approval by the City Engineer.