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, Stormwater Modeling It is often necessary to model existing and/or proposed conditions as part of a drainage project during the design phase of the project. CMA is familiar with various modeling programs and software. Typical software and programs implemented include: AutoCAD Civil 3D ICPR by Streamline Technologies Storm CAD Microsoft Excel SWMM Cascade GIS analysis and tools CMA first uses GIS analysis to create a three dimensional model of the existing ground surface within the project area to identify the points of high elevation that create the drainage basins and the low-lying areas where ponding could occur during rainfall events. StormCAD is used to estimate the flow conditions within utility pipe networks and to size the utility components to handle the existing and/or future flows. We can utilize the three dimensional model of the existing ground surface to calculate proper cover for utility pipes and to create utility profiles based on slope and minimum invert requirements. StormCAD is also used to calculate friction losses and size pipes for various flow scenarios. As such, the plan and profiles for underground utilities can be designed and laid out with the assistance of our modeling software. CMA also utilizes our software for an additional check of possible utility conflicts and to determine where pipes must be offset. Due to our extensive experience with projects similar to NE 174th Street, we are the best prepared firm for this project. CMA has conducted a preliminary three dimensional modeling to analyze the NE 174th Street project area. The project area has elevations ranging from 3.75' to 7.75' (NGVD 29). As shown in Figure 1: Drainage Basin with UDAR Data to the right, there are low-lying areas susceptible to ponding during rainfall events near the eastern side of the complex curve and on the western boundary of the project area near North Bay Road. Based on our preliminary review, CMA would propose additional drainage structures along with exfiltration trench for water quality treatment and an outfall to the existing canal located south of the project area to provide drainage improvements to meet the City's Level of Service standard in this area. This will require coordination of a Class I Permit with Miami-Dade PERA, an Environmental Resource Permit (ERP) through South Florida Water Management District (SFWMD) and construction along North Bay Road. :' , II ' , , i /' I. I.-Il1! 't '.' .~ ~ ,a\, ",. l~\, .~ ~P, '_ ._ I _ b 'i! l '" \ Jl >'.. I:^,", ' - ~ "-~-;.' City of Sunny Isles Beach NE 174 Street Drainage Analysis Figure 1: Drainage Basin with lIDAR Data CK!:M From our preliminary information, there is an existing outfall located along North Bay Road. The size and condition of this outfall is unknown. Upon approval and further research, connection to the existing outfall may be a possible design alternative if there is adequate available capacity within the existing outfall system. The existing system including the outfall will need to be retrofitted with current design standards including pollution retardant baffles and manatee grates. If further evaluation supports utilizing the existing outfall system, a simplified regulatory permitting process can be expected resulting in time savings to the project.