MEMORANDUM

To: File

From: Environmental Protection Agency (EPA) Region 9, Air Planning Office

Subject: Cost effectiveness of SO2 Best Available Retrofit Technology (BART) controls for 

converters at Miami Smelter using cost data from Freeport McMoRan Miami, Inc.

(FMMI)

Date: June 24, 2014

In our February 18, 2014 Federal Register Notice (79 FR 9318) we relied on cost information provided by 

ASARCO for its Hayden Smelter to evaluate proposed BART controls for FMMI’s Miami Smelter. We 

did this because the cost information provided by FMMI was claimed as confidential business 

information (CBI).

1 Accordingly, we were constrained in our ability to incorporate this information into 

our BART analysis.

2

On May 7, 2014, FMMI released its claim of confidentiality on the cost information previously 

submitted.

3 Accordingly, we are now able to consider cost effectiveness of SO2 controls for the converter 

aisle using cost information provided by FMMI.

Control Costs Provided by FMMI

As an attachment to its May 7, 2014 letter, FMMI provided the cost information that appears in Table 1. 

Because this information was provided after the end of the public comment period and only weeks before 

our court-ordered deadline for promulgation of the final rule, we have not had time to review the cost 

information in detail for accuracy or to determine if inappropriate coasts have been included. Nonetheless, 

in order to evaluate whether this information, if accurate, would alter our BART determination for the 

Miami Smelter, we conducted a supplemental cost analysis based upon the cost data provided by FMMI. 

The equipment upgrades and new construction that appear in Table 1 were originally proposed by FMMI 

to address the one-hour SO2 NAAQS.4 These projects have been designed to control emissions from both 

subject-to-BART and not subject-to-BART equipment.

5 For example, according to FMMI, 55 percent of 

the SO2 controlled as a result of upgrades to the tailstack scrubber is emitted by the primary smelter

 

1 Letter from Derek Cooke, FMMI, to Thomas Webb, US EPA (July 12, 2013). These costs were determined by 

FMMI for a smelter expansion and voluntary emission limit project.

2 See CAA section 307(d)(7)(A), 40 U.S.C. 7607(d)(7)(A) (rule may not be based on any information or data which 

has not been placed in public docket); 40 CFR § 2.301(g)(2)(criteria and procedures for disclosure of CBI in 

connection with a rulemaking under the CAA).

3 Letter from Jay Spehar, FMMI, to Geoffrey Glass, US EPA (May 7, 2014)

4 See generally, ADEQ Significant Permit Revision Application, ADEQ Class I Permit Number 53592, Smelter 

Expansion & Enhanced Controls; (July 2013) (FMMI Permit Application),

5

Id. 
(a.k.a. the IsaSmelt).

6 The IsaSmelt was installed in 1991 and is not subject-to-BART. Therefore, we 

expect the overall costs provided by FMMI to be higher than if FMMI planned to control emissions only

from subject-to-BART equipment.

Table 1: Control Costs Provided by FMMI

EPA Item 

No.

Proposed Improvement/Upgrades Proposed Costs

Equipment Installation O&M ($/yr)

1 New Converter Mouth Covers $1,367,000 $5,244,000 $165,000

2 Reconfigured Roofline Above Converters $2,806,000 $27,423,000 $1,353,000

3 New Aisle Scrubber $25,046,000 $63,292,000 $3,719,000

4 Upgraded Acid Plant Tail Scrubber $2,407,000 $11,986,000 $1,079,000

5 Upgraded Hood System $180,000 $1,028,000 $42,000

6 Upgraded Vent Fume Scrubber $2,335,000 $17,778,000 $2,622,000

Item number 5, the upgraded hood system, will improve emissions capture from the electric furnace and 

not the converters. Item number 6, the upgraded vent fume scrubber, will improve the control efficiency 

of emissions from the electric furnace and the smelter, not the converters. Thus we only considered items 

number 1-4 in our cost calculations. Because the equipment in items 1-4 were designed together (e.g. the 

new aisle scrubber was sized for use with the converter mouth covers, etc.), we only consider them 

together as part of a unified control strategy.

Baseline Emissions

In the Technical Support Document for our proposed rulemaking we calculated the following baseline 

SO2 emissions from the converters in tons per year (tpy). Converter emissions from the acid plant 

tailstack were calculated assuming that 35 percent of SO2 ducted to the acid plant originated in the 

converter aisle.7 The range of uncollected emissions was calculated based on a collection efficiency of 95 

to 98 percent for the existing side flue vent on the Hoboken converters.8

Table 2: Baseline SO2 Emissions from the Converters

Source Acid Plant Tailstack Emissions (tpy) Uncollected Emissions (tpy)

Converters 495 3,231 - 8,078

 

6 Letter from Derek Cooke, FMMI, to Thomas Webb, US EPA (July 12, 2013), Table 4-1

7

Id.

8 See Letter from Derek Cooke, FMMI to Tom Webb, EPA (January 25, 2013) at 5 (reporting a range of values of 

87 percent to 98 percent). We used the high end of this range to ensure that our cost per ton estimates were 

conservative. That is, we assumed the baseline level of uncaptured emissions was lower and that there were 

therefore fewer emission reductions available, resulting in higher cost per ton values
Capture and Control Efficiencies

In its application for a permit revision submitted to ADEQ, dated July, 20139and proposed BART 

analysis10, FMMI reported the following capture and control efficiencies from the equipment proposed in 

Table 1:

 New converter mouth covers: 80 percent capture (page 2-4, proposed BART analysis)

 Reconfigured roofline above converters: 84 percent capture (Section 4.1.3, ADEQ permit 

application)

 Upgraded acid plant tailstack scrubber: 98 percent control (Section 4.1.1, ADEQ permit 

application)

 New aisle scrubber: 90 percent control (Section 4.1.4, ADEQ permit application)

We used these capture and control efficiency numbers to calculate the cost effectiveness of SO2 control 

for items 1-4 in Table 1 as applied to emissions from the converters.

Cost Effectiveness of Proposed Converter SO2 Controls

Based on the cost information, baseline emissions, and capture and control efficiencies outlined above, 

we determined that the cost effectiveness of the proposed controls varies from $2,386 to $5,478 per ton of 

SO2 on an annual basis. We assumed an interest rate of 7 percent and a 20 year payback period to 

annualize equipment and installation costs. The calculations are included in the docket11 and the results 

summarized in Table 3.

Although these cost effectiveness values are higher than those that we calculated in our February 18, 2014 

proposed rulemaking, we still consider these values to be reasonable. In particular, the low-end estimate 

($2,386/ton) is well within the range what we have considered to be cost-effective for BART 

determinations.12 The high-end estimate ($5,478/ton) would be higher than we have previously required 

for purposes of BART. However, we consider this estimate to be conservative (i.e. tending to 

overestimate rather than underestimate costs) for several reasons. First, as noted above, the costs

provided by FMMI are not limited to control of emissions from units that are subject-to-BART. Second, 

the cost values provided by FMMI are not supported by documentation sufficient to verify their accuracy. 

Finally, the cost values provided by FMMI include costs that are not permitted by the Control Cost 

Manual and that EPA has excluded from other BART analyses (e.g. owners cost). Therefore, we consider 

it very unlikely that the actual cost effectiveness of the controls would be as high as $5,478/ton. For these 

reasons, we have no basis to alter our BART determination based on the cost information provided by 

FMMI.

 

9 ADEQ Significant Permit Revision Application, ADEQ Class I Permit Number 53592, Smelter Expansion & 

Enhanced Controls (July 2013) 

10 Best Available Retrofit Technology (BART) Analysis, Freeport McMoRan Miami, Inc. (March, 2014)

11 Miami Smelter Converters SO2 BART Supplemental Cost Calculations

12 See, e.g. BART EGU FIP Summary.
Table 3: Cost Effectiveness of Proposed Controls (High and Low Estimates of Uncaptured Emissions)

High baseline 

emissions

estimate

Low baseline 

emissions

estimate

Pre-project uncaptured SO2 emissions from converters (tpy) 8,078 3,231

Post-project SO2 emissions from converters captured by primary capture system as 

a result of new mouth covers (tpy)a

6,462 2,585

Post-project SO2 emissions from converters captured by primary capture system as 

a result of new mouth covers and controlled by acid plant and upgraded tailstack 

scrubber (tpy)b

6,462 2,585

Post-project SO2 emissions from converters captured at roofline (tpy)c 1,357 543

Post-project SO2 converter emissions captured at roofline and controlled by new 

aisle scrubber (tpy)d

1,221 489

Pre-project acid plant tailstack SO2 emissions from converters (tpy)e 495 495

Post-project SO2 emissions controlled by upgraded acid plant tailstack scrubber 

originating from converters (tpy)f

485 485

Total SO2 emissions from converters controlled by proposed project (tpy) 8,169 3,558

Annualized cost $19,490,515 $19,490,515

Cost effectiveness (dollars per ton) $2,386 $5,478

a Assumes 80% of previously uncaptured converter emissions captured because of new mouth covers

b Assumes 99.69% control by acid plant and 98% control by tailstack scrubber, rounded to nearest ton

c Assumes 84% capture efficiency as provided by FMMI

d Assumes all post-project captured emissions reduced by 90% in new aisle scrubber

e Measured by SO2 CEMS and reported by FMMI to ADEQ in 2010 emission inventory

f Assumes 98% control from upgraded scrubber