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Task 1. Data Collection <br /> The following additional work is anticipated to complete this task: <br /> • Collect the final design information from the City on the Greenhill Tributary <br /> Improvements project and obtain a good understanding of when the project is going to be <br /> started and completed in order to determine whether it should be included in the model. <br /> • Collect the final design information, and if possible, as-built information, for the proposed <br /> bike path and pedestrian bridges in the 1135 project area. <br /> • Work with the Corps and the City to make sure that the bike path design meets the Corps' <br /> requirements with respect to levee certification. <br /> The estimated cost to complete the additional work listed above is $3,800. A detailed <br /> breakdown of the estimated costs is also presented in Table 2. <br /> Task 2. Hydrologic Analysis <br /> The following work is anticipated to complete the hydrologic analysis: <br /> • Convert the XP-SWMM model for the Greenhill Tributary developed for the City's <br /> comprehensive stormwater master plan to the EPA-SWMM model and use the results <br /> from the EPA SWMM model to obtain peak flow information for the Greenhill Tributary; <br /> • Compare the 100-year peak flow at SPRR generated by the HEC-1 model with the peak <br /> flow at SPRR from the existing FIS to check the required effective tie-in. <br /> The estimated cost to complete the additional work listed above is $5,500. A detailed <br /> breakdown on the estimated costs is also summarized in Table 2. <br /> Task 3. Hydraulic Analysis <br /> Due to the complexity of split flow and storage in the Lower Amazon Creek and the need to <br /> perform a floodway analysis, we propose a different approach for the hydraulic analyses in <br /> this area. Since the approach is unlike most of the methods used in flood insurance studies, <br /> we anticipate frequent communications with FEMA officials during the course of the <br /> hydraulic analyses. The City also requested that we discuss the approach with FEMA and its <br /> technical review contractors to obtain their consent before further proceeding with the <br /> analyses. The approach that we propose for the hydraulic analyses is summarized below. <br /> We will use the HEC-RAS program to perform the floodplain and floodway analyses for the <br /> f A Channel, the Diversion Channel and the Greenhill Tributary downstream of the 1135 <br /> <br /> ~1r? s:~proj94~945042°d~amazonFEMA~contractaddendum.doc <br /> 07/ 13/01 <br /> 3 <br /> <br />