(A) Requirements.
(1) Except as provided in division (B), encroachments, including fill, new construction, substantial improvements, fences, or other development are prohibited in the regulatory floodway unless certification by a registered professional civil engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that such encroachment will not result in any increase in flood levels during the occurrence of the base flood discharge.
(2) If division (A)(1) is met, any fill permitted to be placed in the regulatory floodway shall be designed to be stable under conditions of flooding, including rapid rise and rapid drawdown of flood waters, prolonged inundation, and flood-related erosion and scour.
(3) Upon demonstration of no other alternative, applicants shall obtain a conditional letter of map revision (CLOMR) from FEMA before an encroachment, including fill, new construction, substantial improvement, fences, or other development, in the regulatory floodway is permitted that will cause any increase in the base flood elevation unless the development causes a temporary encroachment and the conditions in division (B)(1) below are satisfied. Upon completion of the project, but not later than six months after the project completion, a letter of map revision shall be submitted to FEMA to reflect the changes on the FIRM and/or FIS.
(B) Exceptions.
(1) Temporary encroachments in the regulatory floodway for the purposes of capital improvement projects (including bridge construction/repair) must have a development permit issued. This includes ensuring that all other required permits and permissions are obtained from federal, state, and local agencies.
(a) The permit should stipulate the days and dates the structure or other development will be on site. If a longer period is required, a new permit should be issued.
(b) A flood warning system for the project should be in place to allow equipment to be evacuated from the site and placed outside the floodplain.
(c) Placement of equipment in the floodway should be restricted to only that equipment which is absolutely necessary for the purposes of the project. All other accessory equipment and temporary structures (for example, construction trailers) shall be restricted from the floodway. Structures should be placed on site so that flood damages are minimized. The community may want to consider such things as anchoring construction trailers in case evacuation isn’t practical.
(d) The following conditions shall be included in the permit:
1. Identification of the temporary changes to the floodplain under a 1% chance flood event (100-year flood);
2. Identification of all insurable structures affected by any increase in BFE during a 1% chance flood event (100-year flood);
3. Written notification to the applicant that they may be liable for any flood damages resulting from the temporary structure; and
4. The length of time the structure or encroachment will be allowed.
(e) No CLOMR/LOMR will be required because there is no need to modify the FIRM due to the temporary condition of the encroachment, but the community should disclose to all owners of insurable structures and all applicants for permits in the affected area that there is an increased risk of flooding for the duration of the temporary encroachment.
(2) If the temporary encroachment results in an increase in flood levels during the occurrence of the base flood discharge, a CLOMR is not required to be obtained when:
(a) The project is limited as to duration with the days and dates that the structure or other development will be on site specified in the development permit. If a longer period is required, a new permit should be issued;
(b) All other accessory equipment and temporary structures (for example, construction trailers) are restricted from the regulatory floodway;
(c) The project limits placement of equipment and material in the regulatory floodway to that which is absolutely necessary for the purposes of the project;
(d) Structures shall be placed on site so the flood damages are minimized;
(e) The project includes a flood warning system sufficient to allow equipment to be evacuated from the regulatory floodway and placed outside the area of special flood hazard in the event of imminent flood;
(f) The project applicant identifies insurable structures affected by any increase in base flood elevation. The community should disclose to all owners of insurable structures and all applicants for permits in the affected area that there is an increased risk of flooding for the duration of the temporary encroachment; and
(g) The project applicant is provided with written notification that they may be liable for any flood damages resulting from the temporary encroachment.
(3) Projects for stream habitat restoration may be allowed without certification by a registered professional civil engineer provided:
(a) A development permit is obtained prior to initiating development activities;
(b) The project qualifies for a Department of the Army, Portland District Regional General Permit for Stream Habitat Restoration (NWP-2007-1023);
(c) A qualified professional (a registered professional engineer; staff of NRCS; the county; or fisheries, natural resources, or water resources agencies) has provided a feasibility analysis and certification that the project was designed to keep any rise in 100-year flood levels as close to zero as practically possible given the goals of the project;
(d) No structures would be impacted by a potential rise in flood elevation; and
(e) An agreement to monitor the project, correct problems, and ensure that flood carrying capacity remains unchanged is included as part of the local approval.
(Ord. 527, passed 1-14-2013)