§ 155.116 STORMWATER MANAGEMENT SYSTEM; OVERFLOW ROUTING; FLOODPLAIN COMPENSATORY STORAGE; FLOOD PROTECTION GRADES.
   (A)   Stormwater management system. The stormwater management system (wet ponds, dry ponds, and the like) shall be designed using the methodologies outlined in the town's Stormwater Quantity and Quality Management Ordinance and its Stormwater Technical Standards Manual.
   (B)   Floodplain compensatory storage. All impacts to the floodplain shall be designed using the methodologies outlined in the town's Stormwater Quantity and Quality Management Ordinance and its Stormwater Technical Standards Manual.
   (C)   Overflow general grading.
      (1)   No fences or landscaping can be constructed within the easement areas that may impede the free flow of stormwater. These areas are to be maintained by the property owner or designated as common areas that are to be maintained by the homeowners’ association. The property owner may not materially alter the grade of the property or in any way cause an alteration or re-routing of storm drainage runoff. Overflow routing of all on-site and off-site runoff through the development shall be in compliance with town's Stormwater Quantity and Quality Management Ordinance and its Stormwater Technical Standards Manual.
      (2)   Maximum yard slopes must be no greater than 3:1 where soil has been disturbed during construction processes. Finished floor elevation of the proposed structure (main floor for ranch or two- story homes or entryway for other structures) must be no less than six inches above finished adjacent grade and shall be set 24 inches above the adjacent top of curb elevation as measured from the mid-point of the lot. Finished floor elevations should also be two feet above the maximum design flow elevation of the overland flow route(s) through the development.
   (D)   Flood protection grade.
      (1)   For all structures located in the Special Flood Hazards Area (SFHA) as shown on the FEMA maps, the lowest floor elevations (including basements) of all residential, commercial, or industrial buildings shall be two feet above the 100-year flood elevation.
      (2)   For areas outside a FEMA-designated floodplain, the lowest adjacent grade (including walkout basement floor elevation) for all residential, commercial, or industrial buildings adjacent to storm water management features shall be two feet above the 100-year flood elevation under proposed conditions. Any basement floor must be at least two feet above the permanent water level (normal pool) of a retention facility.
      (3)   Maximum longitudinal driveway slopes shall be one-foot rise to twelve-feet horizontal.
      (4)   Grading plans shall show grades at the edge of pavement, top of curb and gutter, and back of sidewalk at the corners of the lots and at the mid-points of the lots. Grading plans shall show top of foundation grade elevations for each building pad, minimum opening elevations (window wells and walkout basements), proposed lowest adjacent grades at each of the four corners of the building pad, proposed driveway slopes, proposed finished grade elevations at each corner of the lot, and intermediate points along the lot lines as necessary to indicate high and low points.
      (5)   Grading plans shall provide flow arrows indicating the direction of proposed flow across each lot, side yard, and rear yard and shall indicate the direction of flow along streets.
(Ord. 27, §§ 6.70.10 - 6.70.70, passed 4-16-1997; Am. Ord. 85, passed 10-17-2000; Am. Ord. 157, passed 5-29-2007; Am. Ord. 172, passed 6-17-2010; Am. Ord. 210, passed 9-11-2012; Am. Ord. 234, passed 5-13-2014; Am. Ord. 334, passed 5-24-2022)