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21 <br /> Undisturbed areas for infiltration of run-off shall also be located downslope from <br /> impervious surfaces and shall not include areas characterized by floodplains, highly <br /> erodible or impervious soils, steep slopes or previously disturbed areas. Areas designated <br /> as suitable for septic tank nitrification fields may not be used for stormwater infiltration <br /> purposes. <br /> Run-off from roads, parking lots, and/or sidewalks shall be directed to undisturbed areas <br /> through use of berms, grassed diversion ditches or swales, or other acceptable means to <br /> reduce run-off velocity and filter out pollutants. <br /> b) Structural Measures <br /> Non-structural methods may not adequately control the first inch of stormwater runoff <br /> due to the amount of impervious surface proposed to be developed, and other factors <br /> such as soil type, slope, presence of floodplains and erodible soils, and/or lack of <br /> vegetative cover. In such cases, structural detention ponds, which capture stormwater <br /> for slow release through an outlet, are required. Where required, detention ponds shall <br /> be constructed in accordance with Appendix <br /> c) Impervious Surface and Detention Pond Requirements <br /> For all protected watersheds, there is a absolute limit on the percentage of lot area which <br /> can be covered with impervious surfaces. In some cases, detention ponds are required <br /> when the proposed impervious surface ratio exceeds a specified percentage, which is <br /> below the absolute limit. <br /> 4 <br />