§ 154.251  GENERAL DESIGN PRINCIPLES.
   (A)   Conservation design subdivisions are subject to all other subdivision design and improvement standards of this chapter unless otherwise expressly stated.
   (B)   Lots and development sites within conservation design subdivisions must, to the maximum extent practical, be located outside of areas containing woodlands, grasslands, surface waters, steep slopes, drainageways, rock outcroppings and other natural resource features. See the figure below. A natural resources inventory report, that includes site specific data, prepared by the Will/South Cook Soil and Water Conservation District shall be submitted to aid in identifying areas that merit conservation.
 
   (C)   Impervious areas must be limited and, to the maximum extent practical, be sited and designed to minimize stormwater runoff impact to the watershed’s receiving waters by:
      (1)   Minimizing concentrated stormwater flow;
      (2)   Minimizing and breaking up or disconnecting large areas of impervious surface into smaller areas;
      (3)   Maximizing the use of sheet flow through vegetated areas;
      (4)   Maximizing the flow length through vegetated areas;
      (5)   Encouraging groundwater recharge; and
      (6)   Providing natural preserve areas where natural soils will remain undisturbed and soil compaction activities are prohibited.
   (D)   Stormwater best management practices (BMPs) shall be used to protect water quality, preserve natural hydrology and minimize overall impacts of development on aquatic resources. BMPs may include, but not be limited to, the following practices:
      (1)   Use of naturalized detention basins designed to maximize removal and transformation of run-on pollutants;
      (2)   Use of wet-bottom detention basins and native, emergent vegetation along their periphery and in bottoms of wetland basins;
      (3)   Use of stilling basins at major detention basin inlets and use of maximum distances between major inlets and outlets;
      (4)   Where detention basins discharge into adjacent or downstream wetlands, use of detention basins outlet structures designed to spread and infiltrate run-off through use of level spreader devices;
      (5)   Use of bio-swales in lieu of stormwater piping;
      (6)   Use of permeable pavers where practical; and
      (7)   Curb and gutter, pavement widths, right-of-way widths and sidewalk requirements will be waived or modified in a conservation design subdivision contingent upon the approval of the appropriate highway authority.
(Ord. passed 7-8-1970; Res. 09-167, passed 6-18-2009)  Penalty, see § 154.999