Filling of the land in the floodplain of a regulated drain or any natural stream or watercourse, that has a contributing drainage area of 25 acres or more, located within the City of Carmel is prohibited. The use of the floodplain area for detention/retention ponds or lakes is also prohibited. Floodplain boundaries are to be determined by using the 100-year base flood elevation (BFE) as shown on the flood insurance rate maps (FIRM) of the Federal Emergency Management Agency (FEMA) and the Hamilton County one-foot topographic data available on the Hamilton County GIS webpage.
(a) If during the process of using the BFE and the one-foot topographic data it is determined that the FIRM is incorrect, then a letter of map revision (LOMR) to correct the FIRM is to be filed with FEMA. No filling of the floodplain, either the floodplain shown on the FIRM or the floodplain determined by the floodplain study, whichever is more conservative, will be allowed until an approved copy of the LOMR is provided to the City of Carmel.
(b) If a FIRM does not establish a 100-year BFE for a regulated drain, natural stream, or natural watercourse, the 100-year BFE shall be established through a site specific floodplain study performed by a professional engineer registered in the State of Indiana in accordance with the IDNR Hydraulic Modeling Guidelines.
(1) If the drainage area for the floodplain study is greater then one square mile at the farthest downstream point of the study, then the floodplain study must be submitted to IDNR - Division of Water for approval and to the City of Carmel for review and comment. A copy of the final study, approved by IDNR - Division of Water, must be submitted to the City of Carmel as part of the project requiring the study to be completed.
(2) If the drainage area for the floodplain study is less then one square mile at the farthest downstream point of the study, then the floodplain study must be submitted to the City of Carmel for review and approval. The City of Carmel will have the option to send the floodplain study to a consulting engineering firm for review and comment, should the accuracy of the floodplain study be in question. The cost of the consulting engineering firm's time will be the responsibility of the owner of the project and will need to be consented to in a written agreement prior to any review of the floodplain study by the consulting engineer.
(c) The requirements of the section do not apply to the following:
(1) Agricultural uses such as crop production, pastures, orchards, tree farms, planting nurseries, vineyards, and general farming.
(2) Forestry, wildlife areas and nature preserves.
(3) County, city, or township parks.
(4) Public streets, bridges, and roadways, as long as the crossing structure are properly sized to convey the natural stream or watercourse and not raise the 100-year BFE.
(5) Regional detention basins approved by the City of Carmel.
(Ord. D-1794-06, 2-6-06)