62-672.670. Inspection and Maintenance Requirements for Perimeter Earthen Dikes

(1) Personnel or agents of the department may accompany inspectors on any inspection required by this rule, or inspect perimeter earthen dikes at any other time which is reasonable under the circumstances involved. They may also examine any inspection reports and be furnished copies thereof upon request.

(2) A completed new perimeter earthen dike shall be thoroughly inspected prior to the placement of process water behind it. Spillways and water level control structures shall be certified by the design third-party engineer as meeting all specifications of the design, and degree of compaction of the fill shall also be certified. Legible photographs, either aerial or ground, may be used to document this initial inspection, but shall not in themselves constitute certification. A complete file describing the items inspected and their condition shall be maintained by the owner, and a copy shall be furnished to the department for approval prior to the deposition of process water behind the dike.

(3) All perimeter earthen dikes and water control structures shall be inspected weekly unless a critical condition listed in subsection 62-672.670(6), F.A.C., has been disclosed, in which event the defective area of the dike shall be inspected daily until corrective maintenance has cured such defect. Water level elevations and freeboard compliance shall be determined at least every 12 hours. Piezometric water levels within the dike shall be measured quarterly if piezometers have been installed. The inspections shall be made by a qualified company employee or contractor employed or retained by the owner of the dike which employee or contractor has been trained in accordance with Rule 62-672.800, F.A.C. The findings of each inspection shall be recorded in a log which log shall be made available to the department upon request.

(4) When a critical condition listed in subsection 62-672.670(6), F.A.C., is suspected during an inspection, the inspector shall ensure that a technical representative of the dike owner is made aware of the condition immediately. If the existence of the critical condition is confirmed, the department shall be notified immediately. A written report of the condition and the actions proposed for its correction shall be made to the department within seven (7) days from the time existence of the critical condition is confirmed.

(5) Each perimeter earthen dike shall be inspected annually by a third-party engineer with experience in the field of construction and operation of perimeter earthen dikes. One copy of the report pertaining to such an inspection shall be furnished to the department, and the original report shall be retained by the owner. These inspections shall include:

(a) Analyses of seepage or other significant items shown on all aerial photographs of the dike which have been taken for any reason since the date of the last annual inspection.

(b) Condition of soil surfaces and top and slopes of the dike and in areas for fifty feet (50') downstream from the outside toe.

(c) Review of all periodic inspection reports to evaluate the effectiveness of maintenance which was done to the dike during the period since the last annual inspection.

(d) Examination and interpretation of data obtained from any instrumentation installed in the mass of the dike.

(e) Condition of spillway and water level control structures, including all conduits exiting the dike.

The annual inspection report shall include recommendations and corrective measures taken. If corrective measures are not completed by the time of annual submittal, then follow up inspection shall be conducted by the third-party engineer with quarterly project reports submitted until completion of all corrective measures.

(6) Any of the following items shall be considered as indicating a critical condition which requires immediate investigation and may require emergency maintenance action:

(a) Concentrated seepage on the downstream slope, at the toe of slope, or downstream from the toe of slope (e.g., boils, soil cones, springs or deltas).

(b) Evidence of slope instability including sloughing, bulging or heaving of the downstream slope, or subsidence of the dike slope or crest.

(c) Cracking of surface on crest or either face of the dike.

(d) General or concentrated seepage in the vicinity of or around any conduit through the dike.

(e) Observed or suspected damage to the liner system.

(7) The following items shall be considered as indicating potential trouble areas which should be closely checked on subsequent inspections and repaired as necessary:

(a) Abnormal dead vegetation or damp areas on the downstream slope, at the toe of slope, or downstream from the toe of slope that could be indicative of pond water seepage.

(b) Surface erosion, gullying or wave erosion on the upstream slope of the dike.

(c) Surface erosion or gullying on the downstream slope of the dike.

(d) Erosion below any conduit through the dike near or at the toe of slope of the dike.

(8) All logs and reports required under this section shall be retained by the owner of the phosphogypsum stack system for a period of not less than three years from the date of the last entry in the log or from the date of the report.

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