FLOOD04427 - Laserfiche WebLink

Home Browse Search

Memorandum November 22, 1978 Page 2 3. The assumptions for defining debris blockage potential for bridges and culverts were not "identified structure by structure within the Technical ,Addendum" . 4 . Were ( 0 . 3 and reaches? the same expansion and contraction loss 0.1 respectively) for all struct;ures on Please identify these structures. coefficients used the study 5. Field surveys used to "supplement t;he mapping and digitized sections" appear to have been limited too overflow of the left bank of Montrose Arroyo. The location of these sections were not indicated on a map and copies of field notes were not submitted. 6. Not all whole even-'numbered water surface contours of the 100-year flood were indicated by wavey lines dUia to the fact that the lOa-year flood was for many reaches confined to the steep and narrow channel where these intermedia'te contours were omitted from the base maps. However, where the lOa-year flood leaves the channel it would have been possible (and efficient) to delineate the boundary on the work, map as requested. 7. It is not clear as to what method '^'as used to route the initial design storm and the 100-year storm runoff through the existing urban drainage system (i.I~'. streets). 8. Delineation of flow splitting at st;reet intersections v?as not shown on the maps except at isolated spot locations along the left bank of Montrose Arroyo. 9. For the initial and 100-year storm,is the capacity of the street, system sufficient to maintain surface flows within acceptable limits? "Hydro-Triad, Ltd. shall delineate all flood hazard areas along all waterways in and around the City of Montrose..." and "the results shall be shown on separate maps for each storm frequency." The map scale of Figure II used to show the 5-year flooded areas is too small (1" = 1000') to suitably represent the intended level of detail specified in the drainage analysis. This matter will be addressed further in a separate memo. :l0. No "rating of city streets for flood flow capacity" was submitted. :,1. What typical street sections were analyzed "to develop "street storm flow capacity for various street slopes?" :~2. Where is a street classification map showinq local, collector and arterial category streets? 13. What are acceptable depths .of flow for the :Lnital arid 100- year storms for each classification?