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C [ T Y o F SUNNY CIVIL ENGINEERING SERVICES TO DESIGN STREET AND DRAINAGE IMPROVEMENTS B E A C H ISLES ) 2. EVALUATE EXISTING DRAINAGE CONDITIONS FOR THE PROJECT AREA y Determine existing drainage patterns of the site. y Determine hydrologic characteristics for the sub-basins, including soil characteristics, groundwater levels, surface area, land use characteristics, slope, flow directions, vegetative cover, times of concentration, existing storage areas, swales and existing drainage structures. y Determine outfall discharges and flood stages of the site under existing conditions. A hydrologic computer model is developed using determined hydrologic/hydraulic parameters. y Prepare maps showing existing drainage conditions and systems. y The existing conditions results will be used to evaluate the effectiveness of proposed alternatives to alleviate the problem. In addition, current permit criteria require that the predevelopment discharge or set limited rates are not exceeded after improvements. 3. PREPARE CONCEPTUAL SURFACE WATER MANAGEMENT PLAN ALTERNATIVES y Work with the City and permitting agencies to identify proposed stormwater management facilities and alternatives while minimizing environmental impacts and construction costs, y Prepare proposed pervious-impervious coverage ratios, stage storage relationships, requirements and design storm flood stages for each sub-basin. y The computer models developed for the existing drainage conditions shall be modified to analyze alternative stormwater management plans, such that it meets regulatory requirements for flood protection. Post development condition runoff hydrographs, peak discharges and stages are calculated based on the proposed and selected development plan. y Preliminary cost estimates will be completed for comparison and evaluation of the effectiveness of the different alternatives, y Prepare a Surface Water Management and Improvements Recommendations Report with documentation and information as may be required by the permitting agencies. The report will include data collected or generated during previous tasks, Comments will be incorporated into the Final Report. ) AL TERNATIVES RJ Behar has evaluated several alternatives that could be studied for this project. A. Implementation of exfiltration (French drains) systems as a closed system. This alternative will consist of constructing a French drain system along the roadway right-of-way possibly connecting new and existing inlets. Some of the roadway and sidewalks are in bad condition, therefore this alternative would be combined with I partial reconstruction of the roadway to raise some low areas and re-establish the pavement conditions. ! In order to avoid impacts at the back of sidewalk profiles, the rest of the street can be milled and resurfaced maintaining existing elevations. [III R.).Behar R. J. BEHAR & COMPANY, INC. I RFQ No. 11-11-02 I 4