app1-Low Impact Development and Sustainable Stormwater Management-给排水参考资料.pdf

APPENDIX A THE STORMWATER CALCULATION PROCESS Flowchart A is provided to guide the user through the first steps of the stormwater calculation process and can be thought of as a series of steps executed through a series of worksheets. Step 1. Provide general site information (Worksheet 1). Step 2. Identify sensitive natural resources, and if applicable, identify which areas will be protected (Worksheet 2). Step 3. Identify the area of the site contributing to a capture–reuse system (Work- sheet 3). Identify the area of the site for which stormwater runoff must be managed, or the stormwater management area (Worksheet 3). (Note: Steps 10 and 11 discuss the procedure for taking stormwater credit for capture–reuse strategies.) Step 4. Incorporate nonstructural best management practices (BMPs) into the stormwater design. Quantify the benefits of nonstructural BMPs (Worksheet 3). For nonstructural BMPs being proposed, provide nonstructural BMP checklists to demonstrate that these BMPs are appropriate. Step 5. Estimate the target volume of runoff associated with the design storm event (e.g., the 85th percentile storm runoff volume, the net increase in a 2-year storm), using the runoff curve number or small storm hydrology method. The use of weighted curve numbers for pervious and impervious areas is not acceptable. Runoff volume should be calculated based on major land use types and soil types (Worksheet 4). Low Impact Development and Sustainable Stormwater Management, First Edition. Thomas H. Cahill.  2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 193 194 THE STORMWATER CALCULATION PROCESS Step 6. Design and incorporate structural