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Control of Discharge° - provision shall. be made for the control, of <br /> a. stora-ter discharges : for the. types of development as speeiEic <br /> m'T cl <br /> below. After development of the site, the Peak discharge of <br /> storirwater runoff resulting from a ten-year st#m shall. be -no <br /> c;re.aLer than that 1.1hi.cn would result from a ten--year storm on the <br /> same site prier to development. This requirement shall. apply to <br /> developments <br /> Commercial., -industrial, officeland institutional. <br /> on tracts larger than 50,000 square feet. <br /> 2xulti--family residential developments of more than 10 units. <br /> Sin'gl.e-familry residential developmerkts on lots 2 acres or <br /> smaller in size wheie iddre than :1.0 lots are to be created. <br /> b. Control of Velocity -- stream banks and channels doxmstream from <br /> any land clisturbi_ng activity shall be protected from increased <br /> deorAdation by accelerated erosion caused by increased velocity <br /> OF runoff from land disturbing activities. The land disturbing <br /> activity shad be planned and conducted such that the velocity <br /> of stormwat.er rurnaff in the receiving watercourse at the menu. <br /> of discharge resulting from a 10 year storm after' develop <br /> sh ll not ex'cee' d the grea.teir of <br /> (i) the velocity as determined from the table in F. of <br /> this rule, or <br /> (ii) the velocity in the receiving Watercourse determined <br /> for the 10 year storm prior to development. <br /> if conditions W or (ii) of this Paragraph cannot be met, the <br /> channel below the discharge Point shall_ be designed and construc- <br /> ted to withstand the expected velocity. lied ,alone <br /> l) Acce tai�le Management Measurements - measures app <br /> or ixt combination to satisfy the. intent of this subchapter <br /> are acceptable if there are no objectionable secondary copse-- <br /> gaeuces. Innovative techniques and ideas will be considered <br /> and may be used when short to have the potential to produce <br /> successful. results. Some alternatives are to_ <br /> (i) avoid increases in surface runoff volume and velocity <br /> by including measures to promote infiltration to <br /> co*_npeusate for increased runoff from areas rendered <br /> impervious; <br /> (ii) avoid increases in stormwater discharge velocities <br /> by using vegetated or roughened swales and water <br /> spays in lieu of closed drains and high velocity <br /> paved. sections; <br /> (ij.i) provide energy' dissipators at outlets of storm <br /> drainage facilities to reduce flog velocities at <br /> the point of discharge; these may range from simple <br /> rip-napped sections to complex structures; <br /> (iv) protect watercourses subject. to accelerated erosion <br /> by improving crow sections and/or ptoviding erosion <br /> - <br /> resistant lining., <br />