13.73.080: DRAINAGE:
   A.   Site design shall not change natural drainage patterns. (See section 13.72.080, figure 18 of this title.)
      + 1. All final grading and drainage shall comply with appendix chapter 33, excavation and grading of the Uniform Building Code (1994 edition and as amended from time to time) and best management practices (1977) as set forth in the Salt Lake County erosion-sediment control handbook (1981 and as amended from time to time).
      + 2. To the maximum extent feasible, development shall preserve the natural surface drainage pattern unique to each site as a result of topography and vegetation. Grading shall ensure that drainage flows away from all structures, especially structures that are cut into hillsides. Natural drainage patterns may be modified on site only if the applicant shows that there will be no significant adverse environmental impacts on site or on adjacent properties. If natural drainage patterns are modified, appropriate stabilization techniques shall be employed.
      + 3. Development shall mitigate all negative or adverse drainage impacts on adjacent and surrounding sites.
      + 4. Standard erosion control methods shall be used during construction to protect water quality, control drainage, and reduce soil erosion. Sediment traps, small dams, or barriers of straw bales shall be located wherever there are grade changes to slow the velocity of runoff.
   B.   Locate buildings outside stream corridor buffer zones:
      + 1. Permanent structures shall be located a minimum of one hundred feet (100') horizontally (plan view) from the ordinary high water mark of stream corridors or other bodies of water. (See figure.) At the discretion of the community development director, and based on site specific studies such as soils or vegetation, setback distances may be reduced according to the modification provisions and criteria set forth in subsection 13.72.060B of this title, or greater setback distances may be required. The community development department, and the health department should be consulted in determining appropriate site specific setback requirements. See also subsection 13.72.030J, "Stream Corridor And Wetlands Protection", of this title.
      + 2. To the maximum extent feasible, developments shall not alter natural waterways.
   C.   Bridges for stream crossings are recommended. (See figures.)
      + 1. To the maximum extent feasible, the use of culverts to cross perennial streams shall not be allowed. Culverts may be used on small side drainages, across swales, and on ephemeral or intermittent streams. See subsection 13.72.030J, "Stream Corridor And Wetlands Protection", of this title.
      + 2. Bridges and culverts shall be sized to pass 100-year storm events. Concrete or stone head walls and side walls shall be required to maintain the integrity of the bridge structure. (Ord. 2012-15, 9-20-2012)