Orange County NC Website
Browse       Search
Proposed Amendments to Section 6.23.3 of the Zoning Ordinance 1 <br /> (additions are underlined, deletions are in strike-through text) <br /> 6.23.3 STORMWATER INFILTRATION AND DETENTION <br /> As a watershed becomes more developed, the amount of impervious <br /> surface increases, causing a decrease in the rate at which stormwater <br /> runoff which can be absorbed into the soil. This results in more stormwater <br /> flowing directly into streams and other water bodies. Because this direct <br /> runoff has not been filtered through the soil, pollutants from the air and land <br /> surface enter streams and increase the potential for pollution of drinking <br /> water supplies. <br /> The effects of stormwater pollution on drinking water supplies can be <br /> minimized by one of two general approaches. First, the amount of <br /> stormwater runoff which reaches drinking water supplies can be controlled <br /> by assuring that there is adequate ground area into which water can be <br /> absorbed. This type of non-structural control is achieved through limitations <br /> on impervious surface. A second approach is to collect stormwater run-off <br /> in engineered ponds so that pollutants may settle. The water is then slowly <br /> released and contains fewer impurities when it reaches the water supply <br /> reservoir. The watershed protection standards adopted by Orange County <br /> utilize a combination of these two approaches. <br /> a) Non-Structural Stormwater Control <br /> The first inch of stormwater run-off shall be controlled to the <br /> extent possible through on-site infiltration and through the use of <br /> methods which rely on natural soil properties for absorption and <br /> treatment. <br /> In order to promote infiltration of stormwater runoff into the soil <br /> and minimize direct and immediate runoff into streams and water supply <br /> impoundments, the maximum percentage of the total lot area which <br /> may be covered with an impervious surface shall be specified. This <br /> limit is referred to as the "impervious surface ratio". <br /> Impervious surface calculations for an individual development <br /> shall be cumulative for original construction and any subsequent <br /> additions. One-half of the width of any of any existing or proposed road <br /> adjacent to an individual lot shall be included as impervious surface for <br /> that lot, except in the case where an existing road was contained within <br /> a dedicated public right-of-way at the time that the watershed <br /> regulations were first applied to the watershed within which the <br /> development is located. <br /> Infiltration techniques not only remove both suspended and <br /> dissolved pollutants, but they require less maintenance, reduce <br /> flooding, promote groundwater recharge and help maintain stream flow <br /> during dry periods. <br /> Where on-site infiltration methods are utilized, areas for such <br /> purposes shall be designated on the plat and shall remain undisturbed <br /> both during and after construction. Undisturbed areas for infiltration of <br /> run-off shall also be located downslope from impervious surfaces and <br /> shall not include areas characterized by floodplains, highly erodible or <br />