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streams. Carrboro also has standards for intermittent�streas _ irhereas the Couaty does not _ F t m. Retention o6 Runo55 6itom Indua.tAi,aZ Sit" - On aitee deveeoped A-13 ! Son -in t+iiaZ punpoaea .i.e., uaea invotv.ing the manuSactun.utig, p,%ocesa.ing, cneuti.ng, %epziAi.ng, renovating, leg, cteani.ng, on assembling os goods, muchandi.ee, on equipment), tetenti.on o% deteation [Uteri meeting the a.tandatda set South in subaection J. i ahael be u4ed to inaune that nunoss .ca retained on the a.ite beSoae being ne2eaaed. The purpose os this %equixement is to .ensure that, not only w.iZZ the atandand set South in subsection 9a, be met, I but atao a mechanism will be pnov.ided to saseguand the watershed against the apZ2.tage o6 toxic on dangeh.oub substance.. !I = Section 9 Permanent Downstream Protection of Stream Banks and Channels I : Provision shall be made for permanent protection of off-site stream banks i and channels from the erosive effects of increased velocity 1 ty and vplume of . stormwater runoff resulting from land-disturbing activities. a, Contnot os Vize- ange -.pnovi.aona shall be made San the controt os ,1 stoAuutzt'eA dt4c"ea Son the types o6 development as 6pec.i6ied below. .Aster development os the site, the peak d+ischange os !' stOA wlaten nunoss ke6utting from a ten-year atonm ehatZ be no l greater than that which wowed xeauZt Snom a ten-yeah atonm on the t same a.ite phioh. to development. _This hequitement shall apply to: ' 1. Commene.ial, .in dceatic,iat, 055.i.ce, and .i.na.titwti.anal deveeopmenta i 2. Mutti.-Samiey widentiat devetgpment6 os mane than 10 unit& 3. S bigte-SamiZy'detached ned.ident ia.0 developments where mane than 3 .iota ake to be cheated. b. ' Control of Velocity - stream banks and channels downstream from any and- istur ing activity shall be protected from increased degradation by accelerated erosion caused by increased velocity of runoff from a land-disturbing activity.. The land-disturbing activity shall be planned and conducted such that the velocity of stormwater runoff in the receiving watercourse at the point of discharge resulting from a.10-year storm after development shall not exceed the greater of: ' r r (i)) the velocity as determined from the table in (F) of' this rule, or f ' (ii) the velocity, in the receiving watercourse determined for the 1' 10-year storm prior to development. t I, �. If conditions (i) and (ii) of this paragraph cannot be met, the channel f below the discharge point shall be designed and constructed to withstand the expected velocity. 1 1) Acce table Management Measures - measures applied alone or in combination to satisfy the intent of this subchapter are acceptable if there are no objectionable secondary consequences. Innovative techniques and ideas will be considered and may be used when shown to have the.potential to produce successful results. Some alternatives are to: (i) avoid increases in surface runoff volume and velocity by including measures to promote infiltration to compensate for increased runoff from areas rendered impervious; (ii) avoid increases in stormwater discharge velocities by using vegetated or roughened swales and waterways in lieu of closed' drains and high velocity paved sections; (iii) provide energy dissipaters at outlets of storm drainage facilities to reduce flow velocities at the point of discharge; these may range from simple rip rapped sections to complex la structures; iv) protec* eiatercourses subject to accelerated erosion by improving cross sections and/or providing erosion-resistant lining.