62B-33.024. Thirty-Year Erosion Projection Procedures

(1) A 30-year erosion projection (30-YEP) is the projection of long-term shoreline recession occurring over a period of 30 years based on shoreline change information obtained from historical measurements. A 30-YEP of the location of the seasonal high water line (SHWL) shall be made by the Department on a site specific basis upon receipt of an application with the required topographic survey, pursuant to rules 62B-33.008 and 62B-33.0081, F.A.C., for any activity affected by the requirements of section 161.053(5), F.S., except applications for those structures located landward of a General Permit Line established under chapter 62B-34, F.A.C. An applicant may submit a proposed 30-YEP for a property, certified by a professional engineer licensed in the state of Florida, to the Department for consideration.

(2) A 30-YEP shall be determined using one or more of the following procedures:

(a) The Department shall determine the 30-YEP for beaches where there is no beach nourishment or restoration project, and no coastal armoring, and the beaches that are not adjacent to an inlet, as follows: An average annual shoreline change rate (SCR) in the location of the MHWL at a Department reference survey monument shall be determined as set forth in subparagraphs 62B-33.024(2)(a)1. through 3., F.A.C., and multiplied by 30 years (Calculated Erosion Distance). The location of the 30-YEP is determined by projecting the location of the existing SHWL, as depicted on the application survey, landward by the Calculated Erosion Distance (SCR x 30 years). (see Figures 1 and 3):

1. The SCR shall be derived from historical shoreline data obtained from coastal topographic surveys and maps, controlled aerial photography, and similar sources approved by the Department. Data from periods of time that clearly do not represent current prevailing coastal processes acting on or likely to act on the site shall not be used.

2. The SCR shall include the zone spanned by three adjacent Department reference monuments on each side of the site. A lesser or greater number of reference monuments can be used as necessary to obtain a rate representative of the site, and a rationale for such use shall be provided.

3. In areas that the Department determines to be either stable or accreting, a minus one-foot per year SCR shall be applied as a conservative estimate.

(b) If coastal armoring is present at the site, the Department shall determine whether or not the 30-YEP shall stop at the armoring. The applicant shall provide scientific and engineering evidence, including a report with data and supporting analysis certified by a professional engineer licensed in the state of Florida, which verifies that the armoring has been designed, constructed, and maintained to survive the effects of a 30-year storm and has the ability to stop erosion of the MHWL for 30 years. The Department shall waive the requirement for the applicant to provide scientific and engineering evidence if the Department determines the information is not necessary in order to make the erosion projection determination.

(c) Some shoreline areas, such as those adjacent to or in the vicinity of inlets without jetty structures, can experience large-scale beach-width fluctuations with or without net erosional losses. Other beach areas can fluctuate greatly due to the observed longshore movement of large masses of sand, sometimes referred to as sand waves. In these areas, a 30-YEP shall be estimated from the available data at the SHWL landward limit of the large beach-width fluctuations within the last 100 years.

(d) Beach nourishment or restoration projects shall be considered as follows:

1. Future beach nourishment or restoration projects shall be considered as existing if all funding arrangements have been made and all permits have been issued at the time the application is submitted.

2. Existing beach nourishment or restoration projects shall be considered to be either a one-time beach construction event or a long-term series of related sand placement events along a given length of shoreline provided such projects have resulted in and will continue to result in the presence of sand seaward of the ECL. The Department shall make a determination of remaining project life for such existing beach nourishment or restoration projects based on the project performance, the likelihood of continuing nourishments, the funding arrangements, and consistency with the Strategic Beach Management Plan adopted by the Department for managing the state’s critically eroded shoreline and the related coastal system.

3. The pre-project SCR shall be calculated as set forth in subparagraphs 62B-33.024(2)(a)1. through 3., F.A.C., derived from historical shoreline data for the time period before the first restoration occured. The Department will use the following stepwise procedure to determine the 30-YEP on a beach with a beach restoration or nourishment project. (see Figures 2 and 3):

a. The Department shall determine the distance between the MHWL and the SHWL, using either a pre-project survey or current locations of these lines, as appropriate. That distance will be added landward to the location of either an established ECL or pre-project surveyed MHWL, as appropriate, to establish the pre-project SHWL (PSHWL).

b. The difference between 30 years and the expected remaining life (in years) of the existing beach nourishment project will be multiplied by the pre-project SCR to determine the projected distance of erosion. The projected distance of erosion will be added landward to the location of the PSHWL calculated under subparagraphs 62B-33.024(2)(a)1. through 3., F.A.C., and will represent the 30-YEP.

4. If the Department is unable to scientifically determine a pre-project erosion rate due to a lack of pre-project data, the Department shall set the 30-YEP along an existing, reasonably continuous, and uniform line of construction that has been shown to be not unduly affected by erosion.

FIGURE 1: 30-YEP Calculation for a Non-restored Beach

30-YEP = (Historical Erosion Rate feet/year) X (30 years) landward of the existing SHWL

FIGURE 2: 30-YEP for a Restored/Nourished Beach

30-YEP = (30 Project Credit years) X (Historical Erosion Rate feet/year) landward of the Pre-Project SHWL

FIGURE 3: Cross-Section of Figures 1 and 2.

(e) The 30-YEP shall extend no farther landward than the CCCL. In the event that the plane of the seasonal high water elevation does not intercept the upland terrain on the site, the 30-YEP shall stop at the CCCL, unless it is determined to be stopped by armoring as described in paragraph 62B-33.024(2)(b), F.A.C.

(f) When the Department approves a permit for new, repaired, or significantly modified coastal structures or activities that affect the lateral movement of sand along the shore, the change in site conditions can significantly affect the future shoreline location. In these areas, if the Department is unable to use historic data to determine a 30-YEP, the Department shall make a 30-YEP assessment based on the best available information and shall provide the rationale to all interested parties.

(g) If a specific SRC for a 30-YEP has not yet been determined for a given area, but the Department can determine that a proposed structure is sufficiently landward such that it will not likely be affected by a worst case erosion projection estimate, then the proposed structure shall be considered as being landward of the 30-YEP. Such an estimate shall be based on the topography, geomorphology, the erosion experienced at the site thus far, the sand supply situation, ongoing coastal processes and coastal management, and any other applicable coastal engineering factors.

(h) In the event the Department is unable to make a site specific 30-YEP following the procedures in this rule section, the Department shall make an assessment based on the best available information and shall provide the rationale to all interested parties.

(3) The Department shall continue to develop, maintain, and update a database of shoreline data for assistance in making 30-YEPs.

Rulemaking Authority 161.053(20) FS. Law Implemented 161.053(5) FS. History–New 11-10-85, Formerly 16B-33.24, 16B-33.024, Amended 1-26-98, 6-13-04, 5-31-07, 10-4-18.