For all projects with proposed placement of fill within the 100-year floodplain, the applicant shall provide the following with the application:

1. (a) The following information on the grading plans:

   1. (1) The 100-year floodplain boundary, determined using one of the following methods:

      1. a. In Zone AE, where FEMA has performed detailed studies, the 100-year floodplain boundary shall be determined using FEMA’s 100-year floodplain elevations in combination with detailed topography for the site;
      2. b. In Zone A, along riverine flooding sources, where FEMA has mapped the floodplain by approximate methods, a study to determine the 100-year floodplain shall be performed in accordance with (c) below; or
      3. c. In Zone A, along lacustrine flooding sources, where FEMA has mapped the floodplain by approximate methods, a study to determine the 100-year floodplain shall be performed in accordance with FEMA-265: Managing Floodplain Development in Approximate Zone A Areas, 1995, available as noted in Appendix B.

   2. (2) Compensatory storage locations and volumes necessary to meet all of the following criteria:

      1. a. Located at equal or lower elevations than the fill being placed;
      2. b. Located on the same site;
      3. c. Hydraulically connected to the floodplain; and
      4. d. Within the 100-year floodplain, the total volume of the fill that is proposed to be placed is no greater than the total volume of material that will be removed.

2. (b) A supplementary report that includes the following:

   1. (1) The total volume of fill in acre-feet that is proposed to be placed within the 100-year floodplain between existing grades and the 100-year flood elevations;
   2. (2) The supporting information used to determine the 100-year floodplain elevations, in accordance with (a)(1), above;
   3. (3) The supporting information used to determine the compensatory storage, in accordance with (a)(2), above; and

   4. (4) For any project where the total fill volume is greater than 0.5 acre-feet or where a bridge or culvert crossing is proposed, the following:

      1. a. The size of the river’s watershed above the project’s furthest downstream boundary;
      2. b. Photographs of the right and left stream banks; and
      3. c. Supporting information used to analyze the impacts of the placement of fill in the floodplain, in accordance with (c), below.

3. (c) Subject to (d), below, a HEC-RAS analysis and cHECK-RAS analysis check, stamped by a qualified engineer, that includes cross-sections and profiles for the pre- and post-development conditions, completed according to the following:

   1. (1) A minimum of 6 cross-sections that span the entire river and 100-year floodplain shall be surveyed to analyze the project’s effect on flood elevations through the affected reach, where:

      1. a. At least 2 cross-sections are surveyed at the project site in those areas where floodplain encroachment are greatest;
      2. b. At least 2 cross-sections are surveyed upstream of the proposed floodplain fill area with one being located at the upstream property line; and
      3. c. At least 2 cross-sections are surveyed downstream of the proposed floodplain fill area with one being located at the downstream property line;

   2. (2) For projects involving bridges or culverts, or both, a minimum of 6 cross-sections shall be required as follows:

      1. a. At least 3 cross-sections shall be surveyed above each proposed bridge or culvert; and
      2. b. At least 3 cross-sections shall be surveyed below each proposed bridge or culvert; and
   3. (3) The GPS coordinates of the beginning and end points of each of the cross-sections required by (1) and (2), above, in units of degrees, minutes, and seconds of latitude and longitude, with at least 3 decimal places of precision (DDMMSS.sss) and referenced to the North American Datum of 1983 (NAD 83) or its successor;

   4. (4) Flood discharges shall be estimated using the first available method listed below:

      1. a. FEMA Flood Insurance Studies (FIS) covering the proposed project site;
      2. b. Stream gauge data collected by the USGS; or
      3. c. USGS National Flood Frequency (NFF) program for the state of New Hampshire; and
   5. (5) A cHECK-RAS analysis to verify the parameters used in the HEC-RAS hydraulic model;

4. (d) If the hydraulic model results indicate that the proposed project will raise flood stages on abutting properties or alter flow and sediment transport characteristics in a manner that could adversely affect channel stability and surface water quality, a proposal for compensatory flood storage or conveyance, or both, that is designed to ensure that:

   1. (1) There is no increase in flood stages on abutting properties; and
   2. (2) Flow and sediment transport characteristics will not be affected in a manner which could adversely affect channel stability.

Source. #9343, eff 1-1-09; ss by #12342, eff 8-15-17; ss by #14472, eff 1-19-26, EXPIRES: 1-19-36