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