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TO: Tina Ndoh, U.S. EPA/OAQPS/SPPD - Minerals and Manufacturing Group

FROM: Eastern Research Group, Inc.

DATE: March 24, 2015

SUBJECT: Notes from Meeting with Florida DEP Regarding Gypsum Dewatering Stack and 

Cooling Pond Management Plan

SUMMARY

The EPA and ERG visited the Florida Department of Environmental Protection (FDEP)

on March 4, 2015. This visit primarily focused on control technique options that were (or could 

be) included in the gypsum dewatering stack and cooling pond management plan proposed in 

subpart AA.

PARTICIPANTS

Tina Ndoh – EPA

Brandon Long – ERG

George Sharrock – FDEP

Syed Arif – FDEP-DARM

Jeff Koerner – FDEP-DARM

Quaid Noor – FDEP-SWD

Jason Waters – EPC HC

TOPICS OF DISCUSSION

The EPA and FDEP discussed various aspects of the gypsum dewatering stack and cooling pond 

management plan proposed in subpart AA. Specifically, the following items applicable to the 

management plan were examined:

 Enforcement options for the management plan: FDEP offered the following question for 

the EPA to consider: how would enforcement officials interpret the control techniques 

and determine if facilities were complying? They suggested that the management plan 

either contain more specificity for each control technique option, or include a review and 

approval process where the specifics would be determined between the facility and 

state/federal agency. The FDEP also requested clarity on if and how the control technique

options and management plan would be implemented into their Title V permit. It was 
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noted that facilities may need the ability to incorporate work practice requirements into 

their permit for compliance.

 Consistency of definitions between Federal and State regulations: FDEP suggested that 

the EPA may consider the use of “gypsum dewatering stack system” versus simply 

“gypsum dewatering stack,” because FDEP rules reference the “gypsum dewatering stack 

system.”

 Discharge pipes: Submerging the discharge pipe may be possible for certain pipes. It is 

probably not practical for the gypsum slurry discharge pipe from a compliance 

perspective (partly because the pipe moves). The EPA may want the control technique 

language to focus on the hot water discharge pipe from the plant.

 Slaked lime: FDEP suggested that the EPA consider using language that stated slaked 

lime does not need to be applied to the entire gypsum dewatering stack.

 Soil caps and vegetation on side slopes: FDEP suggested the EPA allow flexibility with 

“50 feet” language (remove it) and when soil and vegetation could be applied. FDEP 

noted that grassing does not occur at certain or consistent intervals, there is no set 

method. FDEP also explained that facilities define “top” as essentially at bench heights 

and not necessarily the ultimate height, so use of distances from “top” would require 

clarification.

 Rim ditch: FDEP requested clarification on how facilities would show they are 

minimizing the surface area by using the rim ditch technique. Would they need to show 

that area is minimized for each cell? FDEP suggested emphasizing “cells” for 

minimization. An option discussed was that facilities may want to compare the surface 

area from using the rim ditch technique to the surface area that would exist if another 

technique were used (i.e., area if only a single outer dike existed).

 Gypsum Dewatering Stack Ratio Limit: FDEP suggested the ratio of phosphoric acid 

manufacturing capacity versus gypsum dewatering stack area could be used as a control

technique option, rather than requiring facilities to meet the limit.

 Cooling pond area minimization: FDEP and the EPA discussed an option of allowing 

facilities to develop a plan that evaluates their cooling pond area to show it is appropriate 

for the operations and conditions at their facilities. Emergency ponds would be allowed, 

but the evaluation would need to discuss and consider this. The evaluation would need to 

show the cooling pond area is necessary, considering allowances for hurricanes and 

excessive rain, and that excessive ponds are not used. If the cooling pond area is too 

large, this control technique would need to require facilities to create a plan to reduce the 

area.