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(a) Basic Impervious Coverage.
The Commission shall establish, by regulation, an Impervious Coverage Map designating land areas within the /WWO overlay district as one of five categories of impervious coverage in order to prevent and control floods of the Wissahickon Creek. No building, paving, street, or other impervious ground cover may be constructed or placed on any property within the watershed in excess of the requirements of the following table:
(b) Category 5 Requirements.
There is no percentage limitation of impervious ground coverage on land deemed to be developed or otherwise disturbed from its natural state, provided that lots larger than one-half acre may be further developed only as follows:
(.1) The increased surface water runoff leaving the site must not adversely affect adjacent property.
(.2) The method of handling runoff on the site must be in accord with sound engineering practices and must not significantly accelerate on-site erosion.
(.3) Such development must not significantly diminish the infiltration capacity of the site.
(c) Additional Impervious Coverage.
(.1) Stormwater leaving the property shall be substantially similar in effect to that under the basic impervious coverage limitation under § 14-510(6)(a) (Basic Impervious Coverage).
(.2) Stormwater countermeasures shall not require excessive or significant maintenance.
(.3) Design of stormwater countermeasures must take account of stormwater runoff that enters the property from adjacent land.
(.4) The method of handling runoff on the site must be in accord with sound engineering practices and must not significantly accelerate on-site erosion.
(.5) Such development must not significantly diminish the infiltration capacity of the site.
(d) Aggregate of Impervious Coverage in Subdivisions.
Coverage may be aggregated to any section of a subdivision provided that an equal amount is withdrawn from remaining sections and provided further that such aggregation will not cause any significant additional erosion or channel enlargement to any portion of a surface water body greater than that allowed prior to aggregation. Any such aggregation provisions must be included within the approved plan of subdivision (see § 14-304(7) (Subdivisions and Subdivision Plats).
Amended, Bill No. 150264 (approved June 16, 2015).