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2 <br />BACKGROUND: In accordance with NC General Statute 143 Chapter 21, Orange <br />County adopted watershed management standards in the late 1980's early 1990's <br />establishing regulations to prevent significant future water quality deterioration in <br />`existing or potential future drinking water reservoirs'. This included the adoption of <br />impervious surface limits for properties designated as being located within either <br />`protected' or `critical' watershed areas. <br />Impervious surface is defined within Article 10 Definitions of the UDO as: <br />A surface composed of any material that impedes or prevents the natural <br />infiltration of water into the soil. Such surfaces include concrete, asphalt, and <br />gravel surfaces. These include, but are not limited to streets and parking <br />areas, sidewalks, patios, and structures that cover the land. <br />Large amounts of impervious surface on a parcel of property impacts water quality by <br />limiting the availability of undisturbed natural area allowing for the infiltration and <br />treatment of stormwater runoff. To address this issue, the County adopted limits on the <br />total cumulative amount of impervious surface(s) that can be developed thereby <br />encouraging the preservation of natural area and allowing for more on -site infiltration. <br />Impervious surface limits vary based on a properties location within a Watershed <br />Protection Overlay District. Please refer to Attachment 1 for a chart breaking down <br />current impervious surface limits in each district. Please note there are no impervious <br />surface limits on those properties not located within a `protected' or `critical' Watershed <br />Protection Overlay District. This includes areas north of Chapel Hill, around the Town of <br />Hillsborough, and a portion of land area within the Bingham Township. For more <br />information on the location of various overlay districts, please refer to Attachment 2. <br />ISSUE: Staff and Board members have received numerous inquiries related to <br />increasing allowable impervious surface area including: <br />• Increasing allowable impervious surface percentages in Watershed Protection <br />Overlay Districts, <br />• Allow additional impervious surface area on property based on the installation of <br />a stormwater feature, and <br />• Exempt gravel from being considered an `impervious surface area'. <br />The County already has procedures in place, specifically contained Section 4.2.8 of the <br />Unified Development Ordinance (UDO), allowing for a property owner to modify the <br />allowable impervious surface area for a parcel, specifically: <br />a. Applying for a variance <br />STAFF COMMENT: Obtaining a variance from existing impervious <br />surface limits is extremely difficult as the property owner has to <br />demonstrate there is a unique hardship on the property. <br />b. Proposing the establishment of a conservation easement on an <br />adjacent parcel of property. This conservation easement would allow <br />for a defined area to remain in a natural, undeveloped, state while <br />allowing for the transfer of the impervious surface area to the subject <br />parcel to facilitate development. <br />