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URS Greiner Woodward Clyde <br /> floodway analyses and the significant effort that would be required to establish the <br /> continuity between the previous and new FIS studies. <br /> A3 Channel and Greenhill Tributary Floodplain and Floodwav Study <br /> The A3 Channel and Greenhill Tributary are two major tributaries that discharge to the <br /> Lower Amazon Creek. Due to increasing new developments occurring adjacent to the <br /> A3 Channel and Greenhill Tributary from Terry Street to the confluence with the Lower <br /> Amazon Creek, URS proposes to include the A3 Channel and Greenhill Tributary from <br /> Terry Street to their confluences with the Lower Amazon Creek in this detailed FEMA <br /> i ~ hydraulic study. <br /> Most portions of the A3 Channel, from upstream to Terry Street were studied using <br /> detailed hydraulic methods in the 1979-1986 FIS study. However, the Greenhill <br /> Tributary was not included in previous flood insurance studies. <br /> The procedures involved in the detailed hydraulic study for the A-3 Channel and <br /> Greenhill Tributary are similar to those for the Lower Amazon Creek. HEC-RAS is <br /> recommended to perform the required hydraulic analyses. <br /> Procedures and Cost Estimate for the Lower Amazon Creek Floodalain and <br /> Floodwav Study <br /> <br /> ~r ' To complete the Lower Amazon Creek LOMR study based on FEMA requirements, the <br /> following tasks are defined and presented below. Table 2 provides a summary of the cost <br /> estimate for each of the tasks. <br /> Task 1: Data Collection <br /> URS will collect the required hydrologic and hydraulic information for the Lower <br /> Amazon Creek, the A3 Channel, and the Greenhill Tributary: <br /> • URS will obtain the HEC-1 and HEC-2 input data and work maps from the previous <br /> Amazon Creek and A3 Channel FIS study from FEMA library; <br /> • URS will gather and organize the existing study site related hydrologic and hydraulic <br /> information from Corps of Engineers and the City; <br /> • URS will obtain a complete set of FEMA LOMR application forms. <br /> Task 2: Hydrologic Analysis <br /> URS will review the hydrologic information from the previous FIS study and generate <br /> hydrologic input data for the Lower Amazon Creek model, including portions of the A3 <br /> Channel and Greenhill Tributary downstream of Terry Street. The peak discharge values <br /> for different recurrence design storms from the Lower Amazon Creek basins will be <br /> either obtained from existing XP-SWMM models or generated by a new runoff model, if <br /> r necessary. Since the existing XP-SWMM models for Amazon Creek and A-3 Channel <br /> \U'or2\PROI-WC1945(W2na\TASK03W\AMAZOMFEMA\I'cma.duc 4:08 PM 02/25HM) Page 4 <br /> <br />