Agenda - 11-19-1985 - Laserfiche WebLink

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PAGE 5 In order to promote infiltration of stormwater runoff into the soil and to minimize direct and immediate runoff into streams and water supply impoundments, inl ervious surface ratios shall be required as provided the Table of Impervious Surface Ratios Section 6.23.4. Impervious surface calculations for an individual developanent shall be cumulative for original construction and any subsequent additions and calculations of impervious surface coverage for individual lots shall include that portion of a right of-;way between the centerline of the street and the edge the abutting property line of the lot. ORDINANCE AMF,N (S): 6.24.8 _.:r{ o_ •.. - _ ,.t ." •_ 1 1.• _ .• _ t_- - Stor Iter runoff from impervious surfaces generally carry large amounts of oil, nutrients, metals, bacteria and other pollutants. The amount of such pollutants in stormwater runoff is closely associated with the land use from which it originates. An important determinant of water quality is the increase in impervious surfaces which prevent the natural infiltration of water into the soil. Most of the pollutant concentration is carried in the "first flush" of runoff. To control this pollutant load within the Water Quality Critical Area the first one half-inch (1/2") of runoff. from all impervious surfaces in new developments shall be controlled. The purpose of the stormwater control measure is to reduce off site effects by minimizing clearing, motion and overall site disturbance, while maximizing vegetated areas for stormwater infiltration. Methods to accomplish this standards shall include, in order of preference: retention of through the tent a. on-site infiltration g undisturbed, vegetated areas b. structural or engineered infiltration measures, such as ' trenches or retention ponds, which reduce the amount of runoff c. detention structures that reduce the rate of runoff. Areas to which the standard applies shall include individual lots or a new development as a whole. If applied to a develocpent as a whole, the applicant mist provide for installation and maintenance of pry stormwater management facilities. Applicants shall be required to submit documentation which indicates compliance with the specified standard.