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Ws. <br /> i __ i ' <br /> i <br /> I _ <br /> 9 <br /> itical area. Note. One method to determine the buffer size <br /> take the minimum 50 foot buffer and add 4 times the slope <br /> 100 (for further details of this method refer to Orange <br /> - Soil Erosion and Sedimentation Control Ordinance, see <br /> t person listed in Appendix D. <br /> e critical area concept evolved from the idea that the . <br /> st water quality protection is needed in this area. A zone <br /> ing from 1/2 to 1 mile from the reservoir 's high water mark <br /> ake point was originally defined as the time needed for <br /> ncy personnel to respond to a spill and contain it . This <br /> as converted into distance water. would. travel in the . i <br /> aries over this time period . Therefore, the average <br /> =e traveled by the water courses during this period was <br /> from the reservoir 's backwaters upstream to a certain <br /> The Falls of Neuse and B. Everett Jordan Reservoirs were <br /> ed for this purpose and the average distance upstream was <br /> to be approximately l mile. From this determination it was <br /> nat water supply watersheds less than 100 square miles <br /> . only need a 1/2 mile critical area due to their smaller <br /> size. . <br /> ntrol measures for the remainder of a watershed (outside of <br /> itical. ar.ea) may include: 1 ) . density limits on new i- <br /> oment of 12%, impervious surfaces or 1 dwelling/1 acre with <br /> tank only or 30% impervious surfaces or 3 to 4 dwelling/1 <br /> ith sewer connections (the 30% impervious surfaces only <br /> s to a WS-II and WS-III watershed) ; 2) natural vegetative <br /> s adjacent (both sides) to all perennial tributaries <br /> g to the reservoir or direct intake ranging in width from <br /> 150 feet depending on slope, soil , and land-use <br /> ter i st i cs; 3) control of the first one-half inch of runoff <br /> ew development if the impervious surface is greater than <br /> Structural means of controlling the first one-half inch of <br /> may include the use of wet detention basins. Methods for <br /> and designing wet detention basins can be found in the EPA-- <br /> nt "Methodology for Analysis of Detention Basins for <br /> 1 of Urban Runoff Quality" , (September 1986) and the State <br /> yland document "Feasibility and Design of Wet Ponds to <br /> ; -e Water Quality Control" , (July, 1996) [both documents are <br /> -ble from DEM]; and 4) hazardous materials inventoried and <br /> i n restrictions be placed on their use, storage and <br /> ortation. _ - <br /> _._ 4 pecific strategies for WS-I , WS-II and WS-III watersheds _ <br /> t een put together in the form of program outlines. These <br /> les are given in Tables 2 to 4. <br /> 1 <br /> 4. <br /> 1 <br /> 1 <br />