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12 <br /> impervious soils, steep slopes or previously disturbed areas. Areas <br /> designated as suitable for septic tank nitrification fields may not be used <br /> for stormwater infiltration purposes. <br /> Run-off from roads, parking lots, and/or sidewalks shall be <br /> directed to undisturbed areas through use of berms, grassed diversion <br /> ditches or swales, or other acceptable means to reduce run-off velocity <br /> and filter out pollutants. <br /> b) Structural Measures <br /> Non-structural methods may not adequately control the first inch <br /> of stormwater runoff due to the amount of impervious surface proposed <br /> to be developed, and other factors such as soil type, slope, presence of <br /> floodplains and erodible soils, and/or lack of vegetative cover. In such <br /> cases, structural detention ponds, which capture stormwater for slow <br /> release through an outlet, are required. Where required, detention <br /> ponds shall be constructed in accordance with Appendix A. <br /> c) Impervious Surface and Detention Pond Requirements <br /> For all protected watersheds, there is a absolute limit on the <br /> percentage of lot area which can be covered with impervious surfaces. <br /> In some cases, detention ponds are required when the proposed <br /> impervious surface ratio exceeds a specified percentage, which is <br /> below the absolute limit. <br /> Impervious surface and detention pond requirements are as <br /> follows: <br /> 1. Residential Development <br /> i <br />