59-C-18.242. Regulations.

   (a)   Applicability.  All development or subdivisions requiring a building or sediment control permit (except as noted below) and served by community sewer will be subject to these regulations.  All public projects are subject to the provisions of this overlay zone, however, these provisions are not intended to preclude the development of public facilities.  Such facilities must conform to the water quality plan submission and review requirements established in the Montgomery County Code, Chapter 19, Article V, and keep imperviousness to the minimum needed to accomplish the public purpose intended.

   (b)   Exemptions.  The following are exempted from the provisions of this overlay zone:

      i.   Any property expressly exempt by the applicable approved and adopted master plan.

      ii.   An addition or accessory structure to an existing one-family residential dwelling.

      iii.   Any use in an industrial or commercial zone.

      iv.   Development associated with a private institutional facility that has an approved preliminary plan as of November 15, 2004, provided that the development is consistent with the preliminary plan (or a landscaping plan approved as a condition of the preliminary plan) or with section v. below, and that every effort is made to minimize imperiousness and/or mitigate the impacts of runoff.

      v.   Development on private institutional facilities that contains no more than 5 percent greater total imperviousness than shown on a preliminary plan (or a landscaping plan approved as a condition of the preliminary plan) approved as of November 15, 2004.

   (c)   Development standards.  The development standards of the underlying zone apply except as modified by the requirements of this overlay zone.

      (1)   Restriction on Impervious Surface.  No development may result in more than 8 percent impervious surface of the total area under application for development, except as noted below.

         (A)   Any impervious surface lawfully existing pursuant to a building permit or sediment control permit issued before November 15, 2004 that exceeds the 8 percent restriction, may continue or be reconstructed (provided that overall imperviousness does not increase).

         (B)   Any impervious surface which results from construction pursuant to a building or sediment control permit application filed with the Department of Permitting Services as of November 15, 2004, may continue or be reconstructed (provided that overall imperviousness does not increase).

         (C)   No expansion of an impervious surface above the 8 percent restriction is allowed, except in accordance with the waiver provision of Subsection (c)(2).

      2.   Waiver.  The Planning Board, or if no Planning Board action is required, the Director, may grant a waiver from the 8 percent impervious surface restriction subject to the following standards and procedures:

         (A)   Written request.  The request and basis for a waiver from the 8 percent impervious surface restriction must be made in writing to the Planning Board or Director.

         (B)   Review and action.  The Planning Board or Director may grant a waiver from the 8 percent impervious surface restriction if the applicant shows by clear and convincing evidence that:

            (i)   the 8 percent impervious surface restriction would result in undue hardship to the applicant because of events or circumstances not caused or facilitated by the applicant, or the applicant can demonstrate that the impervious surface restriction would prevent the applicant from building the maximum number of affordable housing units otherwise allowed by the zone

            (ii)   the applicant complies with all applicable federal, state, and county water quality standards; and

            (iii)   the relief sought is the minimum needed to prevent the hardship and the applicant has applied all appropriate alternative techniques to minimize imperviousness.

         (C)   Limit on imperviousness for affordable housing waiver.  If the Planning Board grants a waiver for affordable housing, it must approve the minimum increase necessary to allow the affordable housing.  In no event may the waiver result in development with more than 10 percent impervious surface area.

(Legislative History: Ord. No. 15-32, § 1.)