Agenda - 02-25-1991 - Laserfiche WebLink

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calculated. according to procedures-10 the United States D artment of Agdculture Soil Conservation Service's National En neering Field Manual for Conservation Practices or according to Rrocedures ado ted -bL any other a Mc of s state r the United States or any generally reeognized organization or association. COMMENTARY- The purpose of the change in the above paragraph is to require a higher level of sediment-trapping efficiency in High Quality Waters (refer to the definition in Section 3). For a number of reasons, however, this change has little practical impact in Orange County. (1) the amendment specifies improved performance for sediment ponds only,and, because of the type of development that usually occurs in these rural HQW, it would be unlikely that a sediment pond would be used; (2) existing standards in the Erosion Control Manual require both sediment ponds and sediment traps (which are most often used in these areas) to be designed and constructed to a greater efficiency than this amendment requires;and (3) the standards in the Manual apply not only to HQW but to all of Orange County and Chapel Hill. i ewly constructed open chani�Ls-in HQW zones shall be designed and constructed with side slopes no steeper than 2 horizonta_L to l vertical if a vegetative cover is used for stabilization unless soil conditions grmit a s r slo a or where the lo es are stabilized b win mechanical devices structural devices or other igMtable devices.jn-any event the angle for side slopes shall be sufficient to restrain accelerated erosion. e. Ground cover sufficient to restrain erosion must be Rrovided for an R2rtion of a land- disturbing activity ctivity in_a_HQW___zone within 15 working days or 60 calendardays, whichever period is shorter, following_coWletion of construction or development. COMMENTARK These amendments were adopted by the Legislature to provide additional'protection for High Quality Waters. The revision concerning sediment ponds in Section 8 (d) (1) is a change proposed by the staff`. "Sediment pond"is used instead of'sediment basin"because it is the term used in the Erosion Control Manual. Section 9 Stormwater Outlet Protection Protection aw Stream. Channels COMMEN!ARY.- To clarify the intent of this section, the title has been changed. 10 year storm after developumt 9WI no' Stentu of- or (ii) the velocity in the receiving wateremrse dekwmiwA for the '() YeN Ste'M F"01 to development` COIfldFIVTARY.- The text above will be deleted and replaced by the text below. b. Control of Velocity. Persons shall plan and conduct land-disturbing activity so that the post-construction velocity of the 10- 5 1-15-91