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<br />PROPOSED AGENDA ITEMS <br />COORDINATION MEETING 12-14-78 <br /> <br />Item numbers correspond to November :22, 1978 review memo f:rom CWCB <br />regarding Hydraulic Technical Addendum. <br /> <br />Items 3, 4, 18, 24 <br /> <br />See attached tabulation of structures for debris blockage poten- <br />tial assessment. The 0.3 and 0.1 expansion and contraction loss coef- <br />ficients were utilized for the HEC-2 backwater program; not for <br />structure ratings. See attached sample copies of structure rating <br />curves. Cross i ng rat i ngs were determi ned from the I'at i ng data, and <br />ca 1 cul at i on sheets are i ncl uded in the Hydraul i cs Addendum. Overfl ow <br />ca 1 cul at ions were performed by computer, us i ng the ~Iei I' formul a of Q = <br />CwLHl.5, and a weir coefficient of 3.1. <br /> <br />Item 5 <br /> <br />See attached field notes. <br /> <br />Items 7, 8, 10, 11 <br /> <br />The slope area method was employed for rat i ng the city streets and <br />determi ni ng flow depths and vel ocit i es (s ee attached typi ca 1 rat i ng <br />sheets). Flow splitting at the street intersections was determined <br />based on street slope, velocity head, and depth of flow. As flows were <br />routed through the streets, the flow arriving at a particular location <br />from upstream spi 11 age was compared to that deri ved from spi 11 age at <br />that location, and the greater amount was assumed present for purposes <br />of indicating flooding extent. See attached maps for calculations. <br />This mapping supplements calculations shown on worksheet mapping and <br />that contained in Hydraulics Addendum. <br /> <br />Item 9 <br /> <br />Separate mapping is to be provided, per' the contract, for the ini- <br />t i a 1 (5 year) storm, and 100 yea I' storm. Regardi n9 the defi nit 'j on of <br />flood depth "acceptable limits", the term might be broadly defined as <br />depths not resulting in inundation to bui'ldings. For the 5 yeal" storm, <br />neither Cedar Creek nor Montrose Arroyo spi 11, so obviously, sUI"face <br />flow is maintained within acceptable limits. For the 100 year storm, <br />surface flow is not maintained within acceptable limits, as may be seen <br />from the quantities of flow spilling from the main channel areas. <br /> <br />, Pl ease note that re 1 at i ve to urban generated runoff, no analys i s <br />was to be performed with the exception of that dealing with the 16 <br />problem areas. Therefore, "flood hazards" and maintenance of surface <br />flows "within acceptable limits" deals only with the major draina- <br />geways. <br /> <br />1 <br />