The Floodplain (FP) District is defined and established to include the following land areas:
A. Areas subject to inundation by waters of the one-hundred-year flood (one-hundred-year-flood boundary and approximate one-hundred-year-flood boundary) as delineated on the Flood Boundary and Floodway Map, Township of Marshall, Allegheny County, Pennsylvania, Community Panel Number 421080-0010B, prepared by the Federal Emergency Management Agency, Federal Insurance Administration (FIA) and the Flood Insurance Study, on which said map is based. Said map and study are hereby adopted by reference and declared to be part of this chapter.
B. The Floodplain(FP)District shall be comprised of three (3) subdistricts as follows:
1. Floodway (FW). That portion of the Floodplain (FP) District including the watercourse itself and any adjacent land area that must be kept open in order to carry the water of a ONE-HUNDRED-YEAR FLOOD without causing an increase of more than one (1) foot in the elevation of that flood at any point. These areas are shown on the FIA maps.
2. Floodway Fringe (FF). The remaining portion of the Floodplain (FP) District lying beyond the Floodway in areas where detailed study data and profiles are available. These areas are shown on the FIA maps.
3. General Floodplain (FA). Those areas of land within the Floodplain (FP) District subject to inundation by the ONE-HUNDRED-YEAR FLOOD, where a detailed study has not been performed but where a one-hundred-year-flood boundary has been approximated. These areas are shown on the FIA maps. In determining the necessary elevations for the General Floodplain, other sources of data may be used, such as:
(a) Corps of Engineers: Floodplain Information Reports.
(b) United States Geological Survey: Flood-Prone Quadrangles.
(c) United States Department of Agriculture, Soil Conservation Service: County Soil Survey (Alluvial Soils).
(d) Known high-water marks from past floods.
(e) Other sources.
C. Where the specific one-hundred-year-flood elevation cannot be determined for this area using other sources of data as listed above, then the applicant for the proposed USE, DEVELOPMENT or activity shall determine this elevation in accordance with hydrologic and hydraulic engineering techniques. Hydrologic and hydraulic analyses shall be undertaken only by professional engineers or others of demonstrated qualifications who shall certify that the technical methods used correctly reflect currently accepted technical concepts. All studies, analyses, computations, etc., shall be submitted in sufficient detail to allow a thorough technical review by the Township Engineer.
D. Studies used to establish boundaries shall be available to the public in the Township Municipal Building for reference.
E. All subsequent changes made in the boundaries shall be indicated on the Floodplain District Map (a part of the Zoning Map of Marshall Township).
