BOARD: 

Pat1 C. Aughrry, 111 

Chairman 

Edwin H. Cooper, I11 

Vice Chairman 

Steven G. Kisnsr 

Secretarv 

PROMOTE PROTECT PROSPER 

C. Earl Hunter, Commissioner 

P~omoti~!y nridproter,tirzg the l7erilth ofthe pd&c iind ti7c eni~ironrn~izt 

BOARD: 

Henry C. Scott 

M. David Mirchell, MP 

Glenn A. McCall 

Coleman F. Ruckhouse. MD 

December 18,2007 

Ms. Nacosta C. Ward, Environmental Scientist 

U.S. Environmental Protection Agency, Region 4 

Air, Pesticides & Toxics Management Division 

Air Planning BranchRegulatory Development Section 

61 Forsyth Street, SW 

Atlanta, GA 30303-8960 

Re: Regional Haze SIP Comments 

Dear Ms. Ward: 

South Carolina has prepared a draft SIP to address visibility and regional haze issues for the 

State's Class I Federal area, the Cape Romain Wilderness area. The Department submitted a 

notice to the South Carolina State Register in October 2007, soliciting comments on the draft 

SIP. 

On October 23, and December 12,2007, the Department received comments from the US EPA - 

Region 4 staff on the State's per-hearing draft State Implementation Plan (SIP). The October 

comments were summarized in two sections. The portion entitled "General Comments" is 

dedicated to the State's treatment of a variety of substantive issues including the interpretation of 

sea salt in the new IMPROVE equation, and the exemption threshold value selected by the State 

in determining Best Available Retrofit Technology (BART) eligibility. Section I1 entitled "SIP 

Narrative" addresses particular areaslspecific statements in the SIP that Region 4 believes should 

be revised to more accurately describe the particular subject matter. The December comments 

are organized into several sections entitled: (1) Sea Salt and New Improve Equation, (2) Best 

Available Retrofit Technology (BART), (3) SIP Narrative, (4) Appendices, and (5) General 

Comments. 

The Department appreciates the depth and specificity of EPA in its review of the State's SIP. 

The attached documents serve to specifically address both sets of the comments received from 

EPA. Attachment A addresses the October comments, while Attachment B addresses the 

December comments received by the State. 

The Department has considered these comments as well as additional comments submitted by 

other interested parties. In reviewing these comments, the Department has evaluated the 

significance of each in terms of addressing visibility impairment and has revised the SIP 

accordingly. The final SIP package is due to EPA by December 17, 2007. The Department 

hopes that the changes made to the final SIP package serve to address all the comments/concerns 

that were submitted during the public comment period. The Department remains committed to 

SOITTH CAROLINA DEPARTMENT OF HEALTH AND ENlrIRONMENTXL CONTKOI, 

2600 Bull Street Columbia, SC 29201 Phone: (803) 898-3432 www.scdhec.gov 
Ms. Ward 

December 18,2007 

Page 2 

improving air quality in the region and appreciates the opportunity to work with Region 4 to 

produce the best possible SIP. 

Should you have any further questions concerning South Carolina's regional haze SIP 

development, please feel free to contact me at (803) 898-2230 or maso~lmr@dhec.sc.gov. 

Sincerely, 

Robert J: Brown, h., Director 

Division of Air Planning, Development & Outreach 

Bureau of Air Quality 

South Carolina Department of Health and Environmental Control 

cc: Renee Shealy, Assistant Bureau Chief, SCDHEC 

Stacey Gardner, Manager, Regulation Development Section, SCDHEC 

Pat Brewer, VISTAS Technical Advisor 
Ms. Ward 

December 18,2007 

Page 3 

Attachment A: EPA Comments received on October 23,2007 

Section I: General Comments 

Sea Salt Term in the New IMPROVE Equation 

The Department chose to address the bulk of the suggested changes put forth by Region 4 in 

Appendix 0. Appendix 0 includes a letter addressed to EPA as well as several supporting 

documents that together address earlier concerns from the EPA dated March 23,2007. 

Deciview Threshold and Modeling Exemption 

The exemption threshold selected by the State in determining whether a BART-eligible source 

can reasonably be anticipated to cause or contribute to visibility impairment is included in 

Appendix H, Section 7.4. The appropriateness of the threshold chosen by the State (0.5 delta 

deciview) while addressed in Appendix H, is also referenced in Chapter 7 of the SIP narrative. 

Referencing Websites 

The Department acknowledges the comments from Region 4 related to the potential future 

inaccessibility of data and websites used to support the State's final SIP submittal. As such, 

references to websites within the SIP narrative and Appendices produced by the State have been 

removed. Supporting documentation for those remaining websites will be provided by the State 

in its final SIP submittal. 

Section 11: SIP Narrative 

Several of the suggested changes in this section were primarily related to verbiage andor word 

choice, the Department chose to adopt nearly all of the suggested changes put forth by Region 4, 

including: Comments number l,2,4, 5, 6,9 - 16, 18, 19,21- 23,26. 

Comment number 7 addresses portions of Appendix F as not being included in the SIP submittal. 

Appendix F.2 refers to Appendix F, Chapter 2. These references have been clarified throughout 

the SIP. 

Comment number 8 is addressed in Appendix D of Appendix F. 

Comment number 17 has been addressed. Specifically, Appendix H.4 addresses 17.q and 

updates to Tables 7.8.2 and 7.8.2-1 have been made. 

Comment number 24 has been addressed. Table 8.0-2 depicts the visibility impacts and cost 

analyses for potential controls for those sources included in a four factor analysis. Appendix H.6 

incorporates the BART modeling reports. 

SC DHEC appreciates comment number 25 and its reference to the importance of a case-by-case 

analysis. This is echoed in SC DHEC's 4 factor analysis addressed in Chapter 8 of the SIP 

narrative. 
Ms. Ward 

December 18,2007 

Page 4 

Appendices H, K, and I have been updated according to the comments received. 

Attachment B: EPA Comments received on December 12,2007. 

Several comments presented in ths correspondence were echoed in the earlier document 

submitted by EPA Region 4. 

Sea Salt and the New IMPROVE Equation 

The Department chose to address the bulk of the suggested changes put forth by Region 4 in 

Appendix 0. A lead-in discussion has been incorporated in the SIP narrative on page 84 that 

addresses the State's use of the sea salt term in the new IMPROVE equation. 

Best Available Retrofit Techdorrv (BART) 

TRC Environmental was contracted by VISTAS in April, 2006 to conduct BART exemption 

modeling for several sources in South Carolina. Specifically, ten sources were analyzed, 

including (among others) Solutia, Inc., Honeywell: Clemson, and Shaw Industries. 

Comment 1 : The Department appreciates Region 4's opinion related to the discrepancies in the 

use of sea salt in the new IMPROVE equation. As noted in the SIP narrative, SC DHEC has 

decided that compliance with CAIR satisfies sources' requirements under the Regional Haze 

Rule for this first planning period. As indicated in the SC DHEC's response to EPA's comments 

(Appendix 0.3), the Department remains confident that the end result for all the facilities 

required to submit a four factor analysis will be the same as if these facilities were required to 

submit a BART determination analysis for consideration of controls. 

Comment 2.a.: A subsequent evaluation by SC DHEC in the summer of 2006 clarified that the 

three aforementioned sources were non BART-eligible based on the boiler source. This has been 

addressed on page 8 1 of the final SIP narrative. 

Comment 2.b.: Correspondence between EPA and SC DHEC in June of 2006 (M. Notarianni to 

C. Bedenbaugh) clarified that sources determined to be VOC exempt, but that have been 

determined to emit other visibility impairing pollutants under the 250 tonslyear threshold, can be 

found to be exempt from further BART determinations. This has been addressed on page 91 of 

the SIP narrative. 

Comments 2.c. and 3: Discrepancies between emission units located in Appendix H.4 and H.6 

exist because the information is presented differently. More specifically Appendix H.4 

(produced by SC DHEC) refers to stack ID numbers, while Appendix H.6 (produced by TRC) 

refers to unit ID numbers. 

Comment 2.d.: Voridian Eastman Chemical was found to be VOC exempt. However, prior to 

this determination, TRC, in its BART modeling report provided to VISTAS, evaluated this 

facility's sources for BART exemption modeling. This has been addressed on page 92 of the SIP 

narrative. 
Ms. Ward 

December 18,2007 

Page 5 

Comment 4: Based on Department calculations, Albemarle should be included in the list of 

BART-eligible facilities, but was found to be VOC exempt. 

Comment 5 : Addressed. 

Comment 6: The Department determined that Owens Corning and Milliken Chemical met the 

requirement of the BART model plant exemption. This determination took into account all of 

the visibility impairing pollutants (SO2, NOx, and PM). As noted in the VISTAS Procedures for 

Speciation of Emissions for VISTAS BART Modeling dated July 18, 2006, in many cased the 

speciation of particulate matter required for BART analysis will not be known. This is the case 

for Milliken Chemical. As such, consistent with the VISTAS BART exemption modeling, the 

Department has determined that it is overly conservative to assume that 100 percent of PM is 

elemental carbon. Therefore, the Department has chosen to defer to the default assumption; that 

the organics (OC) category with an extinction efficiency of 4.0 is the most reasonable extinction 

category in which to characterize unknown PM. With this in mind, the Department multiplied 

the potential PM emissions for each model plant source by a coefficient of 4.0 and then added it 

to the potential NOx and SO2 emissions to determine Milliken's combined allowable emissions 

(tonslyear). The table below illustrates this evaluation. 

I Milliken 1 21 1 21*4 = 84 1 408 1 492 1 

Source 

Comment 7: Several Appendices found within the SIP narrative do not specify which section of 

these Appendices is being referenced. This request has been addressed throughout the narrative 

by noting chapters wherever possible (see "SIP Narrative" comment 2.a). However, certain 

references (e.g., Appendix H) refer to the actual text of Appendices themselves, and as a result 

remain unchanged. 

Comment 8: Documentation of the meteorological files (e.g., hard copies of the CALMET input 

and output files) were requested to accompany the final SIP. This seems to contradict a latter 

statement by Region 4 that explains that the Region will accept electronic versions of paper 

copies of documents that another state in Region 4 has already officially submitted with its final 

SIP ("SIP Narrative," comment 4). The Department has made a note of this in the cover letter of 

the final SIP submittal. 

Potential 

PM 

Emissions 

Deciview Threshold and Modeling Exemption 

The exemption threshold selected by the State in determining whether a BART-eligible source 

can reasonably be anticipated to cause or contribute to visibility impairment is included in 

Appendix H, Section 7.4. The appropriateness of the threshold chosen by the State (0.5 delta 

deciview) is also addressed in Chapter # of the SIP narrative. 

SIP Narrative 

Extinction 

Efficiency 

Calculation 

Potential 

NOx + SO2 

Emission 

Total Combined 

Allowable 

Emission 
Ms. Ward 

December 18,2007 

Page 6 

1. Estimated Natural Conditions: Addressed in Appendix F, Chapter 4 (cited in Narrative). 

2. Model Performance Documentation: Chapter 3 of the Emissions and Air Quality 

Technical Support Document (Appendix F in SC SIP) includes a detailed model 

performance evaluation for the VISTAS region. In Appendix B of the Technical Support 

Document, additional graphics and statistics are discussed for each component of PM2.5 

for the VISTAS region. Appendix C of the Technical Support Document provides 

statistical tables for several model performance criteria, scatter plots, and bugle plots that 

demonstrate performance for each Class I area for the 20% Best and 20% Worst visibility 

days. Performance statistics for Cape Romain are very similar to those discussed for the 

region as a whole. 

In Appendix C, Section 2.3.1 1, time series line graphs in Figure C-57 compare modeled 

components of PM2 5 to IMPROVE measured vales for the annual 2002 modeling period. 

The model captured the temporal patterns for SO4; however, the model significantly 

under predicted SO4 on four summer days with high (>8 pg/m3) measured SO4 peaks and 

significantly over predicted SO4 on several consecutive fall days with low (<4 pg/m3) 

Soil values. NO3 model performance is poor; over predicting NO3 values in the cold 

months (lSt and 4"' quarters) and under predicting NO3 in the warm months (2nd and 3rd 

quarters). The NO3 under prediction is not of concern because observed values are 

generally less than 0.5 and so NO3 does not contribute significantly to visibility 

impairment on these days. The NO3 over prediction in winter months is of greater 

concern because the relative reduction factors for NO3 may be affected by model 

performance. Over prediction of winter time ammonia values may be the reason for the 

over prediction. The model captures temporal trends for organic carbon and elemental 

carbon, including winter peaks, although some summer time peaks were over predicted. 

Soil was generally over predicted while coarse mass was generally under predicted. In 

composite, PM2.5 mass was generally under predicted. 

These same trends are presented in scatter plots and bugle plots for the 20% Best and 

20% Worst days in Figures C-53-C56. For the 20% Best days, scatter plots show general 

under prediction for all components except soil. Bugle plots for the 20% Best days show 

that EC and soil meet the goal, SO4, N03, and coarse mass meet the criteria but not the 

goal, and OC is slightly greater than the criteria. For the 20% Worst days, scatter plots 

show some what better performance for SO4 and OC than on the 20% Best days, while 

bugle plots indicate that EC, soil, and coarse mass meet the goal, SO4 and OC meet the 

criteria but not the goal, and only N03, with very low observed values, does not meet the 

criteria. Plots for sea salt are inconsistent among the figures and suggest that there were 

some problems with the plotting program that need to be resolved. 

These performance results suggest that model performance is acceptable for both the 20% 

Worst and the 20% Best days and that there is somewhat more confidence in model 

projections for the 20% Worst than the 20% Best days. 

3. Section 7.7, Step 4: Addressed on page 79 of the SIP narrative. 

4. Title of Table 8.0-2: Addressed. 
December 18,2007 

Page 7 

5. Referencing Websites: Addressed within SC DHEC-produced documentation. 

6. Interstate Consultation: SC DHEC appreciates this comment and its reference to the 

importance of a case-by-case analysis. This is echoed in SC DHEC's 4 factor analysis 

addressed in Chapter 8 of the SIP narrative. 

7. Addressed on page 99 and 100 of the SIP narrative. 

8. Addressed on page 53 of the SIP narrative and page 6 of Appendix H. 

9. Addressed on page 78 of the SIP narrative. 

Appendices 

Appendix F: Appendix D has been addressed. 

Appendix H: All of the items in Appendix H have been addressed. 

The "miscellaneous" category referenced in Figure 1-1 refers to EPA Tier I categories. The 

miscellaneous category includes area sources not identified in previous categories. For example, 

agricultural emissions and fire emissions fall into this category. Agricultural emissions, both 

from fertilizer and livestock, are major sources of NH3. Fire emissions (wild fire, prescribed 

fire) may be a major contributor of primary carbon (PM2.5 and PMlo). 

Appendix I: This appendix has been updated to include instruction for the archival and access of 

each BART exemption and determination modeling demonstration (see Appendix 1.2). 

Appendix J: Addressed. 

Appendix L: The Department appreciates Region 4's opinion when it comes to the necessity of 

including WIN HAZE images for each of the VISTAS Class 1 areas. These images were 

included at the request of another commenter. The Department also chose to include all of the 

images in order to present a clear view of projected visibility improvement in the entire VISTAS 

region. 

Appendix 0: Comment 1 has been addressed. Comment 2 questions the Department's decision 

not to request a four factor analysis from Santee Cooper Winyah. Based on the four factor 

discussion from the SIP narrative (Section 8.1) it is evident that Sairtee Cooper Winyah was not 

among those sources identified as having a Q/d greater than or equal to five and an RTmax 

greater than or equal to 10 percent. As indicated in the SC DHEC's response to EPA comments 

(Appendix 0.3) (see also Comment 1 above), the Department remains confident that the that the 

end result for all these facilities required to submit a four factor analysis will be the same as if 

these facilities were required to submit a BART determination analysis for consideration of 

controls.