From: Chuck French/RTP/USEPA/US 

 

To: "King, Heidi R." <Heidi_R._King@omb.eop.gov> 

 

Cc: "Raymond, Gabrielle" <graymond@rti.org>; 

VanLare.Paula@epamail.epa.gov; "Marinshaw, Richard" <rjmarinshaw@rti.org>; 

 

 

Date: 12/15/2010 12:57 PM

 

Subject: RE: EO 12866 Interagency Review comments on Gold Mine Draft Final

Hi Heidi,

 Attached is a slightly revised document to address the one remaining 

question.

Thanks.

Chuck

(See attached file: Summary of Interagency Working Comments_Gold Mines

Final_2010_12_8-EPA-responses-revised.doc)
Summary of Interagency Working Comments on Draft Language under EO12866 Interagency Review. 

Subject to Further Policy Review.

1. The Cost Analysis page 13 mentions an increase in electricity consumption and an 

increase in carbon generation. Can we be more specific?

Response: The additional electricity consumption and increase in carbon generation is from 

facilities that will have to add a carbon adsorber to their units to meet the MACT standards. We 

have added this description to the impacts document.

2. The Cost Analysis lists the facilities by name and number, the MACT Floor document 

uses names but the preamble uses A-Z lettering. Could the preamble switch to numbers that are 

consistent with the support documents, or simply, to be most transparent use the facility names 

(at most only 9 facilities are presented in each table)? The goal is to allow a reader to crosswalk the documents.

Response: We added the letters used in the preamble/rule to the MACT floor document to keep 

consistent. The numbers in the impacts document are not used as facility identifiers, but just as a 

listing the number of facilities. 

3. MACT Floor TSD page 2 states that there are 10 facilities for carbon processes with 

mercury retorts. This is consistent with table 2 in the document. However in the preamble (table 

3) only lists 9 facilities.

Response: We clarified this in the preamble.

4. MACT Floor TSD: Could EPA provide the number of tests used to calculate the average 

for each source in Tables 1, 2, 3, and 4?

Response: Yes, we will add the number of tests or runs used for each facility used in those tables 

in the MACT floor document.

5. What comments did EPA receive (formally or informally) regarding the cost of emissions 

reductions? In particular, on the capital cost for additional controls in the MACT Floor TSD?

Response: Industry said that we underestimated the capital and total annualized costs of the 

carbon adsorbers on the autoclaves. Barrick provided new estimates of capital and TAC that we 

used in our analysis. We will send you a separate document that described these.

6. MACT Floor TSD Page 8 mentions invalidated emissions tests from 2007 and 2008 but 

the reationale for invalidation is very vague. It would be helpful if EPA could provide more 

details on this. In addition, the preamble should then reference this discussion in the TSD.

Response: The document showing all of NDEP’s invalidations is in the docket as EPA-HQOAR-2010-0239-0061, can add this to the preamble. Some of the rationale are: failure to 

comply with federal reference method, failure to comply with established test protocol, possible 

sample contamination, etc. We will add more rationale to the MACT document.
Summary of Interagency Working Comments on Draft Language under EO12866 Interagency Review. 

Subject to Further Policy Review.

7. MACT Floor TSD. Regarding variance calculation, could EPA provide reference for the 

adopted method, assumed distribution of the variance, etc? In particular, is the adopted method 

appropriate for small sample size (n=2 or n=10)

Here is a reference for the UPL method: 

Neter, J, Wasserman W. and Kutner M. H. 1989. Applied Linear Regression Models, 

Second Edition. Richard D. Irwin, Inc. p.246.

As for the appropriateness of using it for small sample sizes, we believe it is fine for small 

sample sizes if the distribution is normal.

8. MACT Floor TSD page 13, table 5 shows results for a 70% reduction. Why 70%? S ome 

text to explain this, for the beyond the floor analysis, would be helpful.

Response: We used 70% reductions from carbon adsorbers on autoclaves because that was what 

Twin Creeks proposed in their Phase 2 applications. We used 70% reductions for the carbon 

adsorbers on the ore preheaters/dryers to be consistent with percent reductions we said that the 

carbon adsorbers on the autoclaves were getting. We will add some text to the MACT floor 

document to clarify this.