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SECTION ! <br /> <br />1-01 General: <br /> a) <br /> <br />STO~ DRAIN SYSTEMS <br /> <br /> Storm waters shall generally be carried in underground <br /> systems designed on the basis of criteria established in <br /> this section and subject to final determinations and <br /> approval of the City Engineer. <br /> b) At points of convergence of pipes of various sizes the <br /> crown elevations shall normally match. If not, the design <br /> shall take into account the increased hydraulic grade <br /> upstream. <br /> <br />1-02 Design Storms: <br /> <br /> a) Hillside areas (average slope exceeds five percent) Minor <br /> Systems Only. <br /> <br /> 1. The runoff, computed as specified below, for <br /> a "five year storm" shall be totally carried in <br /> the underground system with the design water <br /> surface in curb inlets maintained at least one <br /> foot below top of curb. <br /> <br /> b) Flat areas (average slope less than five percent) Minor <br /> Systems enly. <br /> <br /> 1. The runoff, computed as specified below, for a <br /> "ten year storm" shall be totally carried in the <br /> underground system with the design water surface in <br /> curb inlets maintained at least one foot below top <br /> of curb. <br /> <br /> c) Sump areas - Outfall lines from sump areas shall be <br /> designed on the basis of runoff from a minimum "fifty <br /> year storm" with the design water surface maintained one <br /> foot below the top of curbs. <br /> <br /> d) Major collector or outfall lines shall be designed on <br /> the basis of runoff from a minimum "fifteen year storm" <br /> when serving an area up to 10 square miles. From 10 <br /> square miles to '].5 square miles a "fifty year storm" <br /> shall be used. Over 15 square miles a "100 year storm" <br /> shall be used. <br /> <br /> e) The City Engineer shall have specific authority to modify <br /> any of the above criteria. <br /> <br />1-03 Runoff Calculations: Runoff shall be computed using the <br /> "Rational Formula", Q = CIA, with the following definitions of <br /> terms and arbitrary values: <br /> <br /> a) "Q" is the quantity of runoff in cubic feet per second <br /> and is used as the basis for design of the storm drain <br /> system. <br /> <br /> <br />