1. (1) All perimeter earthen dikes shall be operated so as to maintain the design freeboard in accordance with paragraph 62-672.600(1)(c), F.A.C., unless temporary incursions into the freeboard are demonstrated to be safe pursuant to subsection 62-672.650(2), or Rule 62-672.870, F.A.C. Each perimeter earthen dike shall be inspected as prescribed in Rule 62-672.670, F.A.C. Vegetative cover adequate to inhibit wind and water erosion shall be established and maintained on the outside slope of the dike. Such vegetation shall be maintained sufficiently low to permit visual inspection of the soil surfaces and critical areas outlined in Rule 62-672.670, F.A.C.

2. (2) Temporary Nonemergency Use of Design Freeboard.

   1. (a) To assure system safety and integrity or to reduce the probability of discharge, the department shall approve temporary use of the design freeboard of a perimeter earthen dike upon justification by the owner and review of written documentation prepared by a third-party engineer demonstrating that such use can occur while maintaining the safety and stability of the dike. Any department approval shall include as conditions any specific limitations or other requirements recommended by the third-party engineer as necessary to maintain dike integrity and shall establish a specific time limit for such use. The third-party engineer shall base their recommendations on:

      1. An inspection of the facility,

      2. Dike design and construction information,

      3. Results of seepage and stability analyses (including monitoring of seepage pressures within the dike if such monitoring is deemed necessary); and,

      4. Wind surge and wave run-up analyses.

   2. (b) The report by the third-party engineer shall specify conditions under which such use may be authorized, such as:

      1. Acceptable wind speeds in forecast,

      2. Acceptable rainfall levels in the forecast,

      3. Increased inspection frequencies; and,

      4. Weekly monitoring of piezometric levels within the mass of the dike, if and as needed.

   3. (c) No temporary use of the design freeboard pursuant to this section may be authorized unless the facility either:

      1. Prior to initiation of such temporary use has storage capacity adequate to contain a storm event generating twelve (12'') inches of rainfall in 24 hours below the design freeboard fluid level, or

      2. Such action has been approved by the department under an action plan submitted pursuant to subsection 62-672.780(8), F.A.C.

   4. (d) Fluctuation in freeboard shall not result in activation of emergency overflow spillways.
   5. (e) Changes in water levels during such temporary use shall not be deemed to reach any of the triggers established under Rule 62-672.780, F.A.C.

Rulemaking Authority 403.4155 FS. Law Implemented 403.4155 FS. History–New 6-28-99.