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<br />,'~ ~ ".'i .... ::-', ,') <br />J0i."".t,::l>"~ <br /> <br />is wider in some areas than others does not indicate there is a flood hazard, as Mr. <br />McLaughlin well knows, yet, he does not address velocity, nor mention the fact <br />that the design of the structures has accelerated the velocity of the river. Mr. <br />McLaughlin's analysis on this point is meaningless without reference to the <br />velocities in the compared cross-sections. <br /> <br />In support of his conclusion that the RICD structures constrict the channel, Mr. Browning <br />cites an "Attachment D" which consists of a Figure comparing the large cross-section at <br />Station 996941 immediately downstream of the D-Hole, to the apparently smaller cross- <br />section at station 996890 located roughly at the D-Hole. (See Browning at 3.) The <br />apparent implication of this Figure is to imply that the D-Hole structure at station 996890 <br />has constricted the "natural" riverbed at station 996941. This is misleading. The design <br />drawings shown in Appendix 1 of this letter show the design layout for the D-Hole. In <br />these design documents, it is clear that the area downstream of the structure was <br />excavated to create a deep pool and to increase the capacity of the streambed as part of <br />the Boating Park construction at the D-Hole. The increase in flow area shown at <br />station 996941 is due to these excavations. The fact that these excavations occurred is <br />further evidenced by Mr. Browning's own Figures F and G, which clearly show that the <br />current post-construction riverbed at these sections is lower than the channel invert <br />measured by FEMA prior to construction. In other words, Mr. Browning bases his <br />conclusion on constriction by measuring the cross-section at the D-Hole structure against <br />a cross-section that was excavated and enlarged as a part of the Boating Park <br />construction, and then demonstrates with his own recent cross-sections that the structures <br />have lowered the river elevation. <br /> <br />A more appropriate cross-section to measure against the RICD structures would be at the <br />13th St. Bridge. This cross-section has already been established to not affect the 100-year <br />flood as part of its construction approval process, has been approved by FEMA,and was <br />not modified by construction of the RICD structures. Figure 3, shown below, is a cross.;. <br />sectional comparison between the cross-section at the 13th St. Bridge and the cross- <br />section at the D-Hole: <br /> <br />9 <br />