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Proposed Amendments to Section 6.23.3 of the Zoning Ordinance <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 />5 <br />