FAA Regulations - Laserfiche WebLink

Home

r 3/21/80 5050. 4 Management and Protection, contains DOT's policies and procedures for implement- ing the executive order. The DOT order further defines the natural and beneficial values served by floodplains as including, but not limited to "natural moderation of floods, water quality maintenance, groundwater recharge, fish, wildlife, plants, open space, natural beauty, scientific study, outdoor recreation, agriculture, aquaculture, and forestry." The executive order and the DOT order establish a policy to avoid taking an action within a 100-year floodplain where practicable. Every effort must be made to minimize the potential risks to human safety and property damage and the adverse impacts on natural and beneficial floodplain values. (c) If the proposed action and reasonable alternatives are not within the limits of a base floodplain (i.e., 100-year flood area) and would not indirectly support secondary development within a base floodplain nor otherwise significantly impact a base floodplain, it may be assumed that there are no floodplain impacts. No further analysis is necessary. 1 To determine the limits of base floodplains, the Federal Insurance Administration (FIA) maps are the primary reference. A Flood Insurance Rate Map or Flood Insurance Study Report shall be consulted first. If neither of these maps is available, a Flood Hazard Boundary Map may be used to determine if the proposed action and alternatives are clearly out of the base floodplain. If the proposed action or any alterna'lve appears to be near or inside the approximate boundaries of the Flood Haze d Boundary Map, more detailed boundary information must either be obtained or developed using the best available method meeting acceptable professions' engineering standards. The delineation of floodplain limits shall take pro] r account of previous alterations to the floodplain by flood retention wo3 s or other elements of the built environment. If a 100-year floodplain de: .gnation is in question, the FIA or the Corps of Engineers shall be contacted for information. 2 To determine whether other impacts are of concern to a base floodplain even though the proposed action is outside the floodplain, the evaluations of other categories of impacts as described in paragraph 47e are to be used with particular attention to potential effects on natural and bene- ficial floodplain values of water pollution, increased runoff from impermeable surfaces, alteration of hydrologic patterns, induced secondary development, and construction impacts. Consideration of impacts shall include proposed methods to minimize harm and to restore and preserve natural and beneficial floodplain values affected. In most cases, conceptual design as opposed to detailed engineering will be sufficient to help establish the adequacy of mitigation measures. Mitigation measures include: a Construction controls to minimize erosion and sedimentation. b Design of the facility to allow adequate flow circulation and preserve free, natural drainage. c Use of pervious surfaces where practicable. Chap 5 Par 47 Page 49