BOARD: Pat1C.Aughrry, 111 Chairman Edwin H. Cooper, I11 Vice Chairman Steven G. Kisnsr Secretarv PROMOTE PROTECT PROSPER C. Earl Hunter, Commissioner P~omoti~!y nridproter,tirzgthel7erilth ofthe pd&c iind ti7ceni~ironrn~izt BOARD: Henry C. Scott
M. David Mirchell, MP
GlennA. 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 PlanningBranchRegulatory 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.

OnOctober 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 dedicatedto the State's treatment of a variety of substantive issues includingthe interpretation of
sea salt in the new IMPROVE equation, and the exemptionthreshold value selected by the State in determining Best Available Retrofit Technology (BART) eligibility. Section I1 entitled "SIP Narrative" addresses particular areaslspecific statementsin 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 serveto address all the comments/concerns that were submitted during the public comment period. The Department remains committed to

SOITTH CAROLINA DEPARTMENT OFHEALTHANDENlrIRONMENTXL CONTKOI, 2600BullStreet Columbia,SC29201 Phone:(803)898-3432 www.scdhec.govMs. 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 ormaso~lmr@dhec.sc.gov. Sincerely,

Robert 

### J: Brown,h.,Director Division ofAir Planning, Development & Outreach Bureau ofAir 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 AdvisorMs. Ward December 18,2007 Page 3
Attachment A: EPA Comments received on October23,2007

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 ofthe 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: SIPNarrative

Several of the suggested changes in this section were primarily related to verbiage andor word choice, the Department chose to adopt nearly all ofthe suggested changesput forth by Region 4, including: Commentsnumber l,2,4,5,6,9- 16, 18, 19,21-23,26.

Comment number 7 addresses portions ofAppendix 

### F asnot 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 8is 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 itsreference to the importance ofa 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 AppendicesH, 

### K, and Ihave been updated according to the comments received. Attachment 

### B: EPA Comments received onDecember 12,2007. Several comments presented in ths correspondence were echoed in the earlier document submitted by EPA Region 4.

Sea Saltand 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 ofthe 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 ShawIndustries.

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 SCDHEC'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 analysisfor consideration ofcontrols.

Comment 2.a.: A subsequent evaluation by SC DHEC in the summer of 2006 clarified that the three aforementioned sourceswere non BART-eligible based on theboiler source. Thishas been addressed on page 8

### 1ofthe 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 SIPnarrative.

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 exemptionmodeling. This has been addressed on page 92 ofthe 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 100percent 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 of4.0 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 SO2emissions to determine Milliken's combined allowable emissions (tonslyear). Thetable below illustrates this evaluation.



# I Milliken 

## 1 21 

# 1 21*4 = 84 

## 1 408 

# 1 492 

# 1

Source

Comment 7: SeveralAppendices 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 ofthe 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 ofthis in the cover letter of the final SIP submittal. Potential PM Emissions

Deciview Threshold and ModelingExemption 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 # ofthe SIP narrative.
SIP Narrative Extinction Efficiency Calculation Potential NOx 

### + SO2 Emission Total Combined Allowable EmissionMs. Ward December 18,2007 Page 

### 6

1. Estimated Natural Conditions: Addressed in Appendix 

### F, Chapter 4 (cited inNarrative). 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 ofthe 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 statisticaltables 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 asa whole.



### In Appendix C, Section 2.3.11,time series line graphs in Figure C-57 compare modeled components ofPM25to IMPROVE measured vales for the annual 2002 modeling period. The model captured the temporal patterns for SO4;however, the model significantly under predicted SO4on four summer dayswith high (>8 pg/m3)measured SO4peaks and significantly over predicted SO4on several consecutive fall days with low (<4 pg/m3) Soil values. NO3 model performance is poor; over predicting NO3 values in the cold months (lStand 4"' quarters) and under predicting NO3in the warm months (2ndand 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 arepresented in scatter plots and bugle plots for the 20% Best and 20% Worst days in Figures C-53-C56. Forthe 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 SO4and OC than onthe 20% Best days, while bugle plots indicate that EC, soil, and coarse mass meet the goal, SO4and OC meet the criteriabut not the goal, and onlyN03,with very lowobserved values, doesnot 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 forboth the 20% Worst andthe 20% Best days and that there is somewhat more confidence inmodel projections for the 20% Worst than the 20% Best days.

3. Section 7.7, Step 4: Addressed on page 79 ofthe SIP narrative. 4. Title of Table 8.0-2: Addressed.December 18,2007 Page 7


### 5. Referencing Websites: Addressed within SCDHEC-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 ofthe SIP narrative. 7. Addressed onpage 

### 99 and 100ofthe SIP narrative. 

### 8. Addressed onpage 

### 53 ofthe SIP narrative and page 

### 6ofAppendix H. 

### 9. Addressed onpage 78 ofthe SIP narrative. Appendices Appendix F: Appendix D has been addressed. Appendix H: All ofthe 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 10percent. 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.