62-672.780. Phosphogypsum Stack System, Operation Plans

The following items shall be included in the operation plan for each phosphogypsum stack system and shall be approved by an engineer experienced in the construction and operation of phosphogypsum stacks:

(1) The method used to raise and operate the stack.

(2) A description of the source and consistency of gypsum used in constructing the gypsum dikes and the method used for shaping and/or rolling the gypsum.

(3) The overall average exterior slope for raising the phosphogypsum stack and the maximum design height of the stack.

(4) The procedures used to assure that pipes used to transport phosphogypsum to the phosphogypsum stack systems and to return process water to the phosphate fertilizer production facilities are operated and maintained in a safe manner.

(5) The procedures used to decant process water from the top of the phosphogypsum stack.

(6) The location of pumps, spillways, and staff gauges.

(7) Provisions that address emergency measures to be taken in the event of mechanical failure of a pump or in the event of a power failure for any portion of a phosphogypsum stack system that relies on pumps or power to operate monitoring equipment or to transfer process water and/or rainfall-runoff from low areas to the main cooling pond. Such emergency provisions may include:

(a) Back-up power (e.g., on-site power; diesel generator, etc.) and/or back-up pump which would be activated in the event of electrical or mechanical failure; or

(b) Sufficient surge storage capacity or emergency surge capacity within the conveyance system to contain the process water stream(s), if applicable, as well as runoff from a storm event generating 12 inches of rainfall in 24 hours; or

(c) Increased inspection frequencies or continuous monitoring (e.g., remote video camera or automatic water level control device tied to a warning system) to provide early warning of an imminent spill prior to its occurrence; and an emergency action plan that would be undertaken to prevent or contain an accidental spill.

(8) A site-specific water management plan updated annually to reflect changes in process watershed area, storm surge, and projected water balances. The updated plan, consistent with water quality based effluent limits applicable to the facility, shall be submitted to the department by February 1 of each year.

(a) Each plan shall specify, at a minimum, a set of specific actions, including minimum process water consumption and transfer rates, that are put into motion when certain “triggers” are exceeded in the cooling/surge pond system. The plan shall specify additional actions that shall be implemented prior to exceeding such triggers in the cooling/surge pond system, where such actions are determined to be necessary based on water balance model results for the rainfall scenarios described in subsection (9) below. For facilities with approval to store process water in an AHP or RHP, such additional actions shall, at a minimum, specify the operational conditions for transferring to or removing process water from each authorized AHP, whether lined or unlined, or any RHP. Each trigger shall correspond to the event or system storage volume or operating water level(s) needed to contain the storm surge (or a fraction of the storm surge) in the system from a specific design storm (e.g., 12 inches in 24 hours, or the 25-year/ 24-hour event). If provisions are made to contain the direct rainfall quantity from a storm event generating 12 inches of rainfall in 24 hours in the settling compartments atop the phosphogypsum stack, then the top area of the stack need not be considered in calculating the process watershed of the cooling/surge pond system and corresponding storm surge capacity.

1. The trigger levels in the cooling/surge pond system shall include:

a. The “action plan” trigger corresponding to the event storage volume or operating water level(s) required to contain the rainfall quantity from a storm event generating 12 inches of rainfall in 24 hours. When this level is exceeded for 72 consecutive hours, the owner of the system shall notify the department in conjunction with the weekly reporting required under paragraph (c) of this subsection and present for the department’s review a site specific action plan (or refer the Department to a previously submitted site-specific action plan) for process water inventory management and/or consumption.

b. The “may treat” trigger corresponding to the event storage volume or operating water level(s) required to contain the 25-year/24-hour storm event. When this trigger is exceeded for 48 consecutive hours, the owner of the system shall notify the department on the next working day and begin implementing activities needed for activating any permitted treatment station(s), or, alternatively, the owner shall undertake actions to increase the available surge storage capacity within the process system which could include reductions in the volume of water reporting to the process water system, transfer of process water within the phosphogypsum stack system, or transfer of process water to one or more AHPs or RHPs. Incorporation of process water treatment and discharge as a specific action in the site-specific water management plan at this level by facilities that have a department permit to discharge is optional.

c. The “must treat” trigger corresponding to the system storage volume or operating water level(s) required to contain one half of the 25-year/24-hour storm event. When this level is reached or exceeded, the owner of the system for which the department has issued a discharge permit shall notify the department in writing, within 24 hours. Whenever the “must treat” trigger is exceeded for 24 consecutive hours or more, the owner or operator of the system shall treat process water for reuse or discharge in accordance with the facility’s site-specific water management plan.

2. For purposes of establishing the “action plan” and “may treat” triggers, the portion of the storage capacity of a department-approved AHP corresponding to that which would be available during a 24-hour period, through any combination of gravity flow and emergency measures identified in the operation plan, shall be taken into account.

3. For facilities that are authorized to use a department-approved RHP, the storage capacity of the RHP shall not be taken into account in establishing the “action plan,” “may treat,” and “must treat” triggers. However, use of an RHP may be part of a facility’s site-specific water management plan.

4. When process water is to be moved into an AHP or RHP that does not contain process water, the owner of the system shall notify the department, in advance when feasible, but not later than one business day after transfer begins. Whenever process water is stored in an RHP, the owner shall implement all measures needed to consume, remove or treat the water from the RHP as soon as practicable. When an AHP or RHP is emptied of process water, the owner of the system shall notify the department within 7 days. An RHP is required to have either a separate operation and contingency plan, or be included as part of a single facility’s operation and maintenance plan.

5. Whenever the “action plan,” “may treat,” and “must treat” triggers are exceeded, the owner or operator of the system shall implement the applicable specific actions in accordance with the facility’s site-specific water management plan. Where the plan specifies that additional actions are to be implemented prior to exceeding the “action plan,” “may treat,” and “must treat” triggers, the owner or operator of the system shall implement such additional actions in accordance with the facility’s site-specific water management plan.

(b) Each facility’s water management plan shall be site-specific and shall be based on a water balance analysis performed annually which considers the rainfall scenarios described in subsection (9), below.

(c) Each facility must maintain records for at least three years to identify the “trigger” levels. This record should contain as a minimum a site-specific water balance summary sheet which includes the following elements:

1. Water levels in each impoundment area;

2. Operating levels and trigger levels of each impoundment area;

3. Acreage of each impoundment area;

4. Acreage of watershed that contributes to the impoundment area;

5. Available storage capacity at the various operation levels, in inches of rainfall runoff and acre feet;

6. Available event and system storage, in inches of rainfall runoff and acre feet; and

7. Available maximum potential storage, in inches of rainfall runoff and acre feet, where determined in accordance with subsection 62‑672.870(1), F.A.C.

Each facility shall provide the department the water balance summary sheets at the following frequency:

a. Monthly by the 15th of each month when water levels are below the “action plan” trigger. The summary sheet provided shall contain the required information for the last day of the preceding month.

b. Weekly on the Tuesday of each week when the “action plan” trigger is exceeded. The summary sheet provided shall contain the required information for the preceding Friday.

c. Daily (except weekends and holidays) when either the “may treat” or “must treat” triggers are exceeded. The summary sheet provided shall contain the required information for the preceding day.

Each facility shall also regularly monitor water levels as required elsewhere by this rule as well as be able to demonstrate the water levels and available event, system, and maximum potential storage capacity at any time upon the request of the department.

(d) For the purposes of this subsection, information to be provided to the Department, including notifications required herein, may be provided by facsimile, electronic mail, or other electronic means where established by the department.

(9) The adequacy of the facility’s site-specific water management and action plans and emergency measures shall be based on a five-year water balance analysis which shall be updated annually.

(a) The water balance analysis shall use October 1 as the beginning date for the analysis. The analysis shall identify the rates of all water inputs and outputs, any manufacturing production changes, and changes in process watershed area considered in the analysis. A third party engineer shall verify the accuracy of the analysis. A summary of the analysis and the water balance analysis results shall be included in the annual updated site-specific water management plan required in subsection (8) above.

(b) The water balance calculations shall be performed for the 5-year period using input rainfall quantities which shall include either:

1. The 100-year September rainfall occurring during the 100-year Annual Rainfall as defined herein, and multi-year rainfall events that have an equivalent probability for not being exceeded during the 5-year period as that of the 100-year Annual Rainfall Event. Rainfall events other than the 100-year Annual Rainfall shall be determined based on a long‑term rainfall record from a National Oceanic & Atmospheric Administration or equivalent weather station in the vicinity of the facility. For the multi-year rainfall events other than the 100-year annual rainfall, the annual rainfall quantities exceeding or less than the long-term average annual rainfall shall be distributed amongst the various months of the year in proportion to the normal monthly rainfalls determined from the corresponding long‑term record. For the 100-year annual rainfall, the annual rainfall quantities exceeding or less than the long-term average annual rainfall shall be distributed amongst the various months of the year, other than the month for the 100‑year September rainfall, in proportion to the normal monthly rainfalls determined from the corresponding long‑term record; or

2. The input rainfall quantities for each of the 5-year extreme rainfall scenario listed below:

 

	Rainfall, inches
	Year 1	Year 2	Year 3	Year 4	Year 5	Total
Scenario 1	76	60	56	56	52	300
Scenario 2	60	76	56	56	52	300
Scenario 3	56	60	76	56	52	300
Scenario 4	52	56	60	76	56	300
Scenario 5	52	56	56	60	76	300

 

For the 100-year annual rainfall and the multi-year rainfall events, the annual rainfall quantities shall be distributed amongst the various months of the year proportionally based on the values shown for each month as listed below:

 

	Portion of Annual Rainfall Amount, Percent
	100-Year Annual Rainfall	Other Multiyear Rainfall Events
January	3.2	4.5
February	3.7	5.2
March	4.1	5.8
April	3.4	4.8
May	5.7	8.0
June	15.2	14.8
July	15.9	15.4
August	14.5	14.1
September	24.8	13.9
October	4.1	5.8
November	2.5	3.5
December	2.9	4.2

 

(c) The water balance analysis for any phosphogypsum stack system shall indicate whether the system storage will be less than any of the following water balance targets:

1. 16.25 inches of rainfall run-off on June 1 of any year,

2. 12 inches of rainfall run-off on October 1 of any year; and

3. Water levels that exceed impoundment maximum design levels at any time during a year.

If the water balance for any phosphogypsum stack system indicates that system storage is less than the water balance targets, the owner must provide reasonable assurance that additional process water consumption or management items, not already included as outputs in the water balance analysis, are readily available and capable of maintaining these water balance targets. Use of available storage within an AHP or RHP, up to their maximum design levels, may be used to provide this assurance. For a period not to exceed three years following July 19, 2006, a company may utilize water levels corresponding to maximum potential storage to provide reasonable assurance that water balance targets will be met. In subsequent years, if the modeling results of the annual water balance analysis provide reasonable assurance that the water balance targets will be met utilizing only system storage on or after June 1, 2011, a company may continue, at its discretion, to utilize water levels corresponding to maximum potential storage for modeled periods prior to June 1, 2011. Whenever a company relies on the use of maximum potential storage, the water balance analysis must specify the assumptions that were used to determine the temporary use of the design freeboards.

(d) If the water balance indicates that at any time during the five-year period that process water levels, in conjunction with additional available process water consumption or management items as described in paragraph (c) of this subsection, will not meet the water balance targets, the owner must provide additional process water consumption or management items, and submit an alternatives plan and implementation schedule for department approval for the additional consumption or management measures within 90 days of submittal of the water balance analysis. The plan and schedule shall include, at a minimum, the following elements:

1.  A listing and description of the additional process water consumption or management items to be evaluated, including the identification of items that can be rapidly implemented to achieve the water balance targets.

2. A listing of interim measures that can be implemented to prevent an unpermitted release of process water in the event that actual rainfall events contribute to process water levels exceeding maximum design levels.

3. A proposed schedule for the evaluation, selection, engineering, design, and construction, installation or implementation for the items and interim measures needed to increase water consumption, reduce inventories, or any combination of such actions that will result in achievement of the water balance targets.

4. Where such alternatives or interim steps may include a new or increased discharge to surface waters of the state, the evaluation of the new or increased discharge shall include:

a. Identification of any impaired waters and parameters included on a verified list, determined in accordance with chapter 62-303, F.A.C., for any water body or water body segment existing at or downstream of the proposed new or increased discharge;

b. Identification of any Total Maximum Daily Load, adopted in Chapter 62-304, F.A.C., for any water body or water body segment existing at or downstream of the proposed new or increased discharge;

c. Preliminary estimates of any proposed new or increased loading and concentrations, expressed on an annual average basis, and a description of the expected frequency and duration of discharge events that would be needed to meet the water balance targets and terms of this paragraph for each of the identified impaired parameters;

d. A description of and estimated quantity for potential pollutant loading offsets that may be available for any proposed receiving water body or water body segments, if needed to implement any alternative including a proposed new or increased discharge to impaired surface waters of the state.

The department shall approve the plan upon a demonstration that implementation of the plan will result in achievement of the water balance targets. Upon receipt of an alternatives plan, the department shall approve or deny the alternatives plan following the procedural steps outlined in Section 120.60, F.S. Any such additional process water consumption capacity or other management items necessary to meet the terms of this paragraph shall be installed in accordance with the approved plan or within 18 months of receipt by the owner of all necessary permits or other prior approvals whichever occurs later. 

(10) The site-specific water management plan and action plans, based on an updated water balance analysis performed in accordance with subsection (9) herein for each phosphogypsum stack system and complying with all of the provisions of this section, shall be submitted to the department by no later than February 1, 2007 and annually thereafter.

Specific Authority 403.4155 FS. Law Implemented 403.4155 FS. History–New 6-28-99, Amended 7-19-06.