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### DIVISION OFAIR QUALITY Permit Application Analysis, NSR-AP-C92 April :4,2002

BlackHills Corporation WYGEN2 FACILITY LOCATION:

TYPE OFFACILITY: 13 151 Highway 51 Gillette, WY Section 27. T50N. R71W Campbell County, Wyoming Coal Fired Stearn Electric Generating Plant RESPONSIBLE OFFICIAL: TomOhlmacher SeniorV.P. Power Supply and Operations**-----~._--------------** 

### COMPANY REPRESENTATIVE:

MAILING ADDRESS:

REVIEWED BY:

PURPOSE OFAPPLICATION: Fred Carl Environmental Coordinator P.O. Box 1400 Rapid City, SD 57709-1400 Stewart Griner, Air Quality Engineer Ken Rairigh. Air Quality EngineerlModeler

BlackHills Corporation submitted an application to construct a 500 megawatt (MW) pulverized coal (PC) fired electric generating facility to beknown as WYGEN 2. The proposed facility consists ofone PC boilerburning coal from the nearby Wyodakcoal mine with associated coal and lime handling and flue gas desulfurization (FGD) wasteproducthandling. Parameters used for design values, based on coal from theWyodakmine, include a designheatcontent of7,950 Btullb and amaximum sulfur content of 1.2%. The maximum design heat inputto the facility willbe 5,145.7 MMBtu/hr. The applicant identifiedthe following emission sources in the permit application:



### TB002538Black Hills Corporation ( JYGEN 2) Permit Application Ana!ys:s, NSR-AP-C92 Page 2 

### So rce No. Source ?2-O01 C.)C-OOI C:'>C-002 C::>C-003 CDC-004 LDC-OOIA LDC-OOIB RDC-OOI RDC-002A RDC-002B 500 MWPC Boiler Coal Storage Silo Dust Collector (top) Coal Storage Silo Dust Collector (bottom) Coal TransferBuilding Dust Collector UnitTransfer and Silos Dust Collector Lime Unloading Silo Dust Collector Lime Unloading Silo Dust Collector FGD Waste Recycle Storage BinDust Collector FGD Waste Loadout Silo Dust Collector FGD Waste Loadout Silo Dust Collector



### SUMMARY OFPOTENTIALEMISSIONS: .Potential emissions for this facility are based on proposed limits with the exception ofammonia and hazardous airpollutants (HAPs). Ammonia emissions are calculated in an April 16, 2002 memo to file NSR-AP-C92. HAP emissions are detailed inthe following section on HAP emissions and maximum available control technology 

### (MACD. Potential emissions are estimated in 

### the following table:

Source

### # Potential Emissions (tpy) NOx S02 PMlPM,o CO VOC NH3 

### HAPs PC-OOI 1578 3381 270 3381 225 97.4 110 CDC-OOI 8 CDC-002 2.5 CDC-003 2.5 CDC-004 11 LDC-OOIA 0.5 LDC-OOIB 0.5 RDC-OOI 1 RDC-002A/B* 2



## *TOTAL 1578 3381 298 3381 225 97.4 Only one ofthese units (RDC-002A orRDC-002B) will be in service at anyone time. 110



### TB002539Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 3



### CHAPTER 6, SECTION 4 - PSD APPLICABILITY: The proposed WYGEN 2 facility is subject to Prevention ofSignificant Deterioration (PSD) review underChapter 6, Section 4 ofthe Wyoming Air Quality Standards and Regulations

## C'NAQSR) because it is classified as a "major emitting facility." Fossil-fuel fired steam electric plants ofmore than two hundred and fifty million Btulhourheat inputwiththe potential to emit one hundred tons peryear or more ofany regulated pollutant are considered "majoremitting facilities" under Chapter 6, Section 4(a)(i) ofthe WAQSR. Potential emission rates from the WYGEN 2 facility and the PSD significance levels are shown in the following table:

Pollutant PC Boiler Potential PSD Significant PSD Review EmissionLevel Emission Rate • Emission Rate Required?

(LblMMBtu) (fPY) (fPY) NOx 0.07 1578 40 Yes S02 0.15 3381 40 Yes

--**-----~ -----~**  "---- 

### PMJPM 10 

### 0.012 298 b 

### 25/15 Yes CO 0.15 3,381 100 Yes VOC 0.01 225 40 Yes H2 SO4 

### 4.62 x 

### 10') 104 7 Yes Lead 2.53 x 

### 10.5 

### 0.57 0.6 No Fluorides 3.69 x**10~** 

### 8.3 3 Yes Total Reduced Sulfur Negligible Negligtble 10 No (including H2

### S) Mercury' 1.24 x 

### 10.5 

### 0.28 0.1 Yes BerylliumC 

### 7.54 x 

### 10-6 0.17 0.0004 Yes

• Based on 5,145.711MBtu/hr and 8760 hours peryear. b 

### Includes 28 tpy from material handling based on 6.4 lblhrperthe August 2001 supplement.

C 

### Mercury andBeryllium are excluded from federal PSD regulations since 1990per Section 112(b)(6) of

the Clean Air 

### Actbut still included in WAQSR, Chapter 6, Section 4(a)(xxi). The proposed WYGEN 2 facility is subjectto aPrevention ofSignificantDeterioration (PSD) review consisting ofthe following: 1) A BestAvailable Control Technology (BACT) analysis is required for all regulated pollutant emitted in significant amounts. 2) An 

### ambient airquality impact determination is required for all regulatedpollutants emitted in significant amounts and any otherpollutants required by the Administrator.



### TB002540Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 4
3) An increment consumption analysis is required for regulated pollutants based on allowable emission rates as well as increment consuming emissions from other sources in the region. The total deterioration determined from this analysis must comply with the allowable increments established for PM 1o, S02' and NO. for the classification ofthe area (i.e. Class I or Class II) in which the increment consumption is predicted. 4) An analysis is required to assess the impairment to visibility, soils, and vegetation resulting from the facility and general commercial, residential, industrial, and othergrowth associated with the facility. BEST AVAlLABLE CONTROL TECHNOLOGY (BACT): A best available control technology (BACf) analysis for NOx, S02' PMJPM1o, CO, VOC, H2 

### S04, and fluoride is required because each ofthese pollutants is emitted above PSD significantemission rates. Additionally, a BACT analysis is required forberyllium and mercury under Chapter 6, Section 4(a)(xxi) ofthe WAQSR. The BACT analysis for each emission source is presented in the following sections: I. 500 MW PC Boiler

- NO. Control BlackHills Corporation proposed low NOx burners and SCR with an emission limit ofO.09lblMMBtu as BACT. The Divisionreviewed the RACTIBA(.lfLAERClearinghouse (RBLC) and information from EPA Regional offices to find permined orproposed PC utility boilers with NO. emissions equal or lower than 0.09**1~lMMBtu** as shown in the following table:

Facility
Kansas City Power & Light Co.

- Hawthorne Station State Size (MW) MO 570 Control Device SCR NOx Emissions (IblMMBtu) 0.08 (30 day)· Status Operational May 2001

0.121blMMBtu(30day) limitforfirst 3years, then0.081blMMBtu ifdemonstrated feasible. According to Missouri DNR., Hawthorne Station is currentlymeeting the 0.08 IblMMBtu limit. 

## •Great Plains Power

- Weston Bend

Generating Station MO 820 SCR 0.08 (30 day) Proposed

Emission Control Technologies BlackHills Corporation considered the following controls forNOx reduction: 

### Combustion Controls

- Low NOx burners (LNB), overfire air (OFA), and advanced gas reburn (AGR) all serve to reduce peakcombustion temperatures thus lowering NOx emissions. Although none ofthese controls can achieve emission levels comparable to postcombustion controls, they do prevent some of the initial formation ofNOx. BlackHills Corporation selected low NOx burners in combination with post-eombustion controls because the lower emissions generated result in lowercapital cost and reagent use.



### TB002541Black Hills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 5 

### Selective CatalyticReduction (SCR)

- SCR is apost combustion control teclmique in**whi.:~** the flue gas is combined with vaporized ammonia in the presence ofa catalyst and NO. is reduced to nitrogen and water. BlackHills Corporation evaluated SCR at emission levels of0.06, 0.08, and 0.09 :o,'MMBtu. 

### Selective Non-Catalytic Reduction (SNCR)

- SNCR is similar to SCR in that it involves t::e injection ofa reducing agent such as ammonia or urea into the flue gas stream. The reduction chemistr:!, however, takes place withoutthe aid ofa catalyst. SNCR systems rely on appropriate injection tem:;eratures, proper reagent/gas mixing and prolonged retention time in place ofthe catalyst. SNCR s;'stems are very sensitive to temperature changes and typicallyhave lower emissions reduction (up to. fifr! or sixty percent) and higher ammonia slip. BlackHills Corporation did not further consider SNC';' because ofthe lower emissions reduction and the lack ofany operational advantage over SCR. 

### HybridSNCRJCatalyst System

- These systems were developed to combine the relatively 'ow capital cost and high ammonia slip associated with SNCRwith the high reduction potential and low ammonia slip inherent to SCR. The first part ofthe system is a typical SNCR system with increased re:::.:ent flow for additional NOx reduction. A small catalyst follows to reduce ammonia slip and possibly :chieve additional NOx reduction. This systemrequires more ammonia but uses a smaller cataly:.. Black Hills

_____**-----'C'-'orporation-did-not-furtheHlensidef"~ybrid_systern-becauseofpussfule** l'toolems**aclile'.'~'g** adequate distribution ofammonia and because there is no operational or emission reduction advanLge over SCR. Energy and Environmental Evaluation Black Hills Corporation evaluated the energy and environmental considerations for SCR. An SCR systemconsumes electrical energy for ammonia transport and vaporization and for incremental fan demand to overcome pressure drop across the catalyst. Environmental considerations include ammonia slip, a slight increase in SO) emissions, a possible slight increase in PM10 emissions, and ammonia handling and storage. Ammonia slip emissions of2 to 5 ppm and a 1 to 2 percent increase in SO) emissions are expected. Unreacted ammonia and SO) can react to form ammoniabisulfate and ammonia sulfate salts in the form ofPM 1o emissions. Ammonia is a hazardous material and adequate design precautions are necessary for handling and storage. Economic Evaluation ofAlternatives BlackHills Corporation evaluated the combination ofLow NOx burners and SCR at emission levels of 0.06, 0.08, and 0.09 IblMMBtu. An economizerbypass is required to keep temperatures in the optimum range in orderto meet the 0.06 or 0.08 Ib/MMBtu emission limits at 50% load. Consequently, the incremental cost is higherfrom 0.09IbtM:MBtu to 0.08 IblMMBtu than from 0.09 Ib/MMBtu to levels lowerthan 0.08 IblMMBtu. The results are shown in the following table:



### TB002542Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 6

Annual Emissions Emissions Reduction Total Annualized Cost Total CostEffectiveness Incremental Reduction· Incremental Annualized Cost Incremental Cost Effectiveness Baseline 0.25 IblMMBtu 5,635 tpy Baseline Baseline Baseline LNB/SCR LNB/SCR LNB/SCR r.09lblMMBtu 0.08 IblMMBtu 0.06 Ib/MMBtu 2,028 tpy 1,803 tpy 1.352 tpy 3,606 tpy 3,832 tpy 4,283 tpy $12,563,000 SI5,582,000 $17,798,000 $3,484/ton $4,067/ton $4,156/ton

Baseline 225 tpy 676 tpy Baseline $3,019,000 $5,235,000
Baseline $13.395/ton $7,742/ton

• The Division calculated incremental costs based on a 0.09 IblMMBtu baseline for both 0.08 and 0.06 IblMMBtu because an economizerbypass is required to achieve either**~rJL06** IblMMB**tu~** - - BlackHills Corporation chose 0.09 IblMMBtu as BACTbecause they considered the incremental cost effectiveness to be unreasonable for the lower emission levels and because they were unable to find an issued permitwith a limit less than 0.12 IblMMBtu for a PC boiler. (Note that the Hawthorne Station boiler in Missouri has a limit ofO.12lblMMBtu for 3 years and then a limit ofO.08lblM:MBtu unless the permittee can demonstrate that 0.08 IblMMBtu is not feasible.) According to Missouri DNR, Hawthorne Station is meeting the 0.08 IblMMBtu limit. Missouri DNR is also working on a permit for Great Plains Power with aproposed limit of0.08 IblMMBtu. Although Great Plains Powerrequested 3 years to determine ifthey can comply with the limit as allowed in the Hawthorne Station permit, Missouri DNR indicated thatthey do notplan to issue the permitwith any exceptions to the 0.08 IblM:MBtu limit. The Division evaluated the control efficiencyrequired to meet limits of0.09,0.08, and 0.06 Ib/MMBtu using a baseline of0.25 IblMMBtu as shown in the following table:
Emission Level

(lbt1vfMBtu) 0.09 0.08 0.06 Control Efficiency (%) 64 68 76

These efficiencies seem low based on information that vendors are designing and providing guarantees for SCR systems with at least 90% control efficiencies. Forexample, Montour Steam Electric Station in Allentown, PAretrofitted two 750 MW coal fired boilers with SCR systems designed for 90% control efficiency and 0.04 IblMMBtu using eastern bituminous coal. It should be noted that these are design levels to meet acid rain requirements and there are no permit limits requiring this level ofreduction.



### TB002543Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 7 The BACfanalysis indicates that 0.06 IblMMBtu is technically feasible and the Division considers the total and incremental cost effectiveness to be reasonable. Note that the incremental cost effectiveness is much lower when considering emission limits less than 0.08 IblMMBtu because an economizerbypass is required to achieve emission limits of0.08 IblMMBtu or less. Although the BACT analysis indicates an emission level of0.06 IblMMBtu, BlackHills Corporation has expressed uncertainty about meeting 0.06 Ibl1v1MBtu on a cO:ltinuous basis. The Division and Black Hills Corporation discussed various options for dealing with t;;;5 uncertainty while setting an appropriate BACT level. One option discussed was 0.06 Ibl1v1MBtu a::::ual average and 0.08 IblMMBtu 30 day average. This option still left Black Hills Corporation with:. :neasure ofuncertainty in regards to meeting the annual limit and they requested that the 0.06IbIMMB:t:.limit notbecome effective until issuance ofthe Title V operating permit in order to allow additional :....eto demonstrate compliance. Even with the additional time for compliance, Black Hills Corporation expressed concern about meeting a0.061blMMBtu limit and discussed options ifthey could notmeet the :imit. Upon further discussion, the Division and BlackHills Corporation agreed that a 30 day limit ofO.C7lblMMBtu wouldbe more stringent than any existing limit for an operating PC boiler and could**C~** met without'additional time to demonstrate compliance. The Division concludes that Low NOx burners <:'l1d SCR with an emission limit ofO.07lblMMBtu (30 day rolling average) represent BACf. II. 500 MW PC :-"'Jiler

- 

### S02 Control**~----** ---- --- --------

- --_.-

BlackHills Corporation proposed a semi-dry lime spray dryer absorber with emission limits of0.15 IblMMBtu (30 day average) and 0.17 IblMMBtu (2 hourblock). The Division reviewed the RACfIBACfILAER Clearinghouse (RBLC) and information from EPA Regional offices to find permitted orproposed PC utilityboilers with S02 emissions lower than 0.15 Ib/MMBtu as shown in the following table:



### TB002544Black Hills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 8



### Facility State Size- Control S02 Status Device -- Emissions (lblMMBtu) Deseret Generation and 

### UT 500MW Wet Lime 0.0976 Permit Issued Transmission Company FGD (12 month) 3/16/98 SEI Birchwood, Inc. VA 2200 Semi-Dry 0.1 Permit Issued MMBtuIhr Lime FGD (30 day) 8/23/93 Kansas City Power & 

### Light Co. MO 570MW Semi-Dry 0.12 Startup May

- Hawthorne Station Lime FGD (30 day) 2001 Great Plains Power

-Weston MO 820MW Semi-Dry 0.12 Proposed Bend Generating Station Lime FGD (30 day) Maple StreetPowerhouse

- MA 30MW Semi-Dry 0.12 PermitIssued Unit 2 -Ware Lime FGD 12/2191 -----Semi**~-Dry-** 

### PermitIssued ----Platte-River-PWR--="Rawhide--

- 

### --CO 250

### ~- Lime FGD 0.13 5/22180 375 Semi

- Dry PermitIssued Cogentrix ofRichmond VA MMBtulhr 0.13 each LimeFGD 1/2191 375 Semi

- Dry Permit Issued Cogentrix ofDinwiddie VA MMBtuIhr 0.13 each Lime FGD 4/16/92
HCC Chemical Company

- 312.5 Permit Issued 

### LA MMBtuIhr FGD 0.14 Convent each 11/6/80

- For comparison, WYGEN 2 is 5145.7 

### MMBtuIhr and 500 MW. 

## ** Semi-Dry Lime Flue Gas Desulfurization (FGD) includes Lime Spray Dryer/Absorbers and Dry Lime Scrubbers. A Lime Spray Dryer/Absorber is proposed for WYGEN 2. Emission Control Technologies BlackHills Corporation considered the following controls for S02 reduction: 

### WetLime andLimestoneBasedFlue Gas Desulfurization (FGD)

- In wet lime FGD, S02 is reacted with a lime slurry to produce calcium sulfite or calcium sulfate (gypsum). Wet lime FGD can achieve high removal efficiencies (>95%) whenburning high orlow sulfur coals. Itcan achieve higherremoval efficiencies than 

### semi-dry FGD whenburning high sulfur coals butthere is no advantage with low sulfur coals. WetFGD uses more waterthan serni-dry FGD and has 

### a visible moisture plume. 

### Semi-DryLimeBasedFGD

- Semi-dry FGD processes include lime spray dryer/absorbers and dry lime scrubbers. In these processes, S02 is reacted with Ca(OH)2 as either a slurry or a drypowder to produce



### TB002545Black Hills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 9 calcium sulfite or calcium sulfate (gypsum). Significantly less water is used in these processes compared to wet lime FGD and there is typicallyno visible moisture plume. Semi-dry FGD can achieve removal efficiencies comparable to wet FGD with the low sulfur coal proposed for this plant. Energy and Environmental Evaluation Black Hills Corporation evaluated the energy and environmental considerations forthe processes described above. The majority ofenergy consumption for the wet FGD process is attributed to reagent preparation (grinding limestone) and the high pumping power due to a high liquid to gas ratio. The lime spray dryer has the lowest energy demand. Environmental considerations include visible moisture plumes, H2SO. formation, waste disposal, and waterconsumption. As discussed above, wet lime FGD produces a visible moisture plume but semi-dry FGD typically does nol. H2SO. can be formed by the reaction ofSO) from the combustion process with moisture in the flue gas. The H2SO. can also condense resulting 

### in increased PM 10 emissions and opacity. These concerns are less ofan issue with semi-dry FGD because this process is more effective at removing SO) and there is less moisture in the flue gas. Waste disposal is an issue with either the wet or dry process. The wetprocess has an advantage In tlUlt fly ash is collectedpriorto the FGD process allowing the sale offly ash rather than disposal at a landfill. However, the semi-dryprocess has the advantage ofdrybyproducts allowing easier handling and transport. The mixture offly ash and unreacted lime that results from the semi-dryprocess can be conditioned with waterto produce a cementatious product with low permeabilityresulting 

### in lower leachate and fewer handling problems at the landf!ll. Waterconsumption rates for the sem-dry process are about 20 to 30 percent less than the wetprocess which is important for areas with low water availability. Economic Evaluation ofAlternatives An economic evaluation was performed for semi-dry FGD at emission levels of0.15 and 0.131blMMBtu and for wetFGD at emission levels of0.13 and 0.10 Ib/MMBtu as shown 

### in the following table:



### TB002546Black Hills COllloration (WYGEN 2) Permit Application Analysis, NSR-AP·C92 Page 10
Baseline SDFGD· SDFGD· WFGD

.... WFGD** 2.13 0.15 0.13 0.13 0.10 IbfMMBtu IblMMBtu IblMMBtu IblMMB:'" lblMMBtu Annual Emissions 48,147 tpy 3,382 tpy 2,932 tpy 2,932 tpy 2,250 tpy EmIssions Reduction Baseline 44,765 tpy 45,215 tpy 45,215 tpy 45,897 tpy Total Annualized Baseline $21,080,000 $21,271,000 $26,567,000 $26,952,000 Cost Total Cost Baseline $471/ton $4701ton $588/ton $587/ton Effectiveness Incremental Baseline 450 tpy 450 tpy 1,132 tpy Reduction Incremental Baseline $191,000 $5,487,000 $5,872,000 Annualized Cost ."--------

---- -----mcremental Cost Effectiveness

• Semi-Dry Flue Gas Desulfurization

.. Wet Flue Gas Desulfurization Baseline $424/ton $12,193 $5,1 87/ton

Due to the considerations discussed above and the fact that semi-dry FGD can achieve removal efficiencies comparable to wet FGD with low sulfur coal, Black Hills Corporation chose semi-dry FGD (lime spray dryer/absorber) with an emission level of0.15 IblMMBtu. The above data suggests that BACT shouldbe closer to 0.10 IbIMMBtu without consideration ofthe removal efficiency necessary to achieve 0.10 Ib/MMBtu. The design heating value ofthe coal for WYGEN 2 is 7,950 Btullb and the design sulfurcontent is 1.2%. This equates to uncontrolled emissions of

### JUSt over 3 Ib S02IMMBtu as shown in the following calculation:
lbeaal 7,950Btu x 12lbS 100lbeaal x 106 Btu MMBtu 64lbS02 x 32lbS 3.02 lbS02 MMBtu An emission limit of0.1 0 Ib/MMBtu equates to a 97% removal efficiency as follows:
3.02

- 0.10 x 100 

## = 97% 3.02 The proposed limit ofO.15lblMMBtu results in a 95% removal efficiency. BlackHills Corporation claims that 95% removal efficiency on a continuous basis is higher than the proven performance for lime spray dryer/absorbers. The Division compared coal properties and removal efficiencies for several ofthe facilities listed above as follows: 1) The SEI Birchwood facility 

### in Virginia is permitted at 0.1 IblMMBtu (30 day average) using semidry FGD butthe coal has differentproperties. Although the sulfurcontent is approximately the same


### TB002547Black Hills Corpcration (WYGEN 2) PennitApplicalloil Analysis, NSR-AP-C92 Page II (limited to 1.2% maximum and 1% annual average), the heating value is higher (average of approximately 12,500 Btullb according to the Virginia Department ofEnvironmental Quality). Using ahe::::ng value of 12,500 Btullb and a sulfurcontent of 1.2% in the above equations results In a 94.8% rcr:-.oval efficiency to achieve O.I IbIMMBtu. The permit for the SEI Birchwood facility also cont.,:::: a minimum efficiency limitof90% for the semi-dry FGD. 2) Kansas**Ci~'** ?ower 

### & Light's Hawthorne Station is permitted at 0.12 IblMMBtu using semi-dry FGD.**Acc:~ding** to Missouri DNR, this facility uses low sulfur, sub-bituminous, Wyoming coal (pRB coal) with sulfur contents ranging from 0.5 to I percent. Assuming aheat value of8,000 Btullb and a sulfur content ofI% in the above equations results in a 95% removal efficiency to achieve 0.12IblMMBtu. 3) Platte River Power's Rawhide Station is permitted at 0.13 IblMMBtu (30 day average) using semidry FGD. According to the Colorado Department ofPublic Health and Environment, the actual properties ofcoal used during the year 2000 averaged 8,850 Ib/MMBtu and 0.2% sulfur. This equates to 

### a71% removal efficiency to achieve 0.13 IblMMBtu. However, the operating permit for this facility contains aminimum efficiency limit of80% for the semi-dry FGD

.

.

## _. -_

.. 

# - ._--.'.-



### ----------- Note that the above calculations use the upper end ofthe sulfurrange. Ifaverage sulfur contents were used, the resulting removal efficiencies wouldbe lowerthan the above values. These average sulfur removal efficiencies would 

### be less than 95% which supports the claim by Black Hills Corporation that a 95% control level has notbeen proven on a continuous basis. An emission limit of0.15 IblMMBtu for design case coal (7,950 BtuIlb, 1.2% sulfur) results in aremoval efficiency of95% which is at least as stringent as otherrecent BACT determinations. However, 0.15 IblMMBtu could be achieved at a much lower efficiency when burning coal with a higherheating value and/or lower sulfurcontent. Requiring a minimum removal efficiency of90% as required for the SEI Birchwood facility in Virginia will ensure that the control device is operated to achieve agood control efficiency regardless ofcoal properties. The requested 2hour limit ofO.17lblMMBtu is to allow for short term spikes in the coal sulfur content and time to adjust scrubber operating parameters. The Division concludes that a semi-dry lime spray dryer absorber with an emission limit of0.15 IblMMBtu (30 day average), 0.171blMMBtu (2 hour block), and aminimumremoval efficiency of90% represents BACT. 

### Ill. 500 MW 

### PC Boiler

- PMJPM,o Control BlackHills Corporation proposed fabric filters (Ryton Bags) with an emission limit of0.018 IblMMBtu as BACT. The Division reviewed the 

### RACTIBACTILAER Clearinghouse (RBLC) and information from EPA Regional offices to fmd permitted orproposed PC boilers with PMlPM,o emissions lower than 0.018 IblMMBtu as shown in the following table:



### TB002548Black Hills Corporation (WYGEN 2) PennitApplication Analysis, NSR-AP-C92 Page 12

Facility State Size Control PMlPM\o Status Device Emissions (IbIMMBtu) Firestone Tire & Rubber· Permit Decatur (pC Industrial Boiler) IL 178 MMBtu/hr Fabric Filter 0.01 Issued 7/1/85 Saginaw Steering Gear

- Permit AL 121.4 MMBtulhr Fabric Filter 0.013 Issued Athens (pC Industrial Boiler) 10/15/80 Central Power and Lime, Inc. Permit

- Brooksville (PC Industrial FL 1850 MMBtu/hr Fabric Filter 0.0135 Issued Boiler) 8/15/95 HCC Chemical Company

- Permit Convent (PC Industrial LA 312.5 MMBtu/hr Fabric Filter 0.014 Issued Boiler)

-**-~** _ ..--- ----- 1116/80

___ -- .----- .------ Mon Valley Energy Limited Permit Partnership

- PolandMines PA 966 MMBtu/hr Fabric Filter 0.015 Issued (PC Electric Utility Boiler) 8/8/95 B.F. Goodrich Chemical Permit Group

- Convent (pC LA 338 MMBtu/hr Fabric Filter 0.015 Issued Industrial Boiler) 11124/80

Emission Control Technologies Black Hills Corporation considered the following controls for PMlPM,o reduction: 

### ElectrostaticPrecipitators

- Electrostatic precipitatorsremove particulate matter from the flue gas stream by charging the particulate matterwith a DC electrode and attracting the charged particles to grounded collecting plates. A layer ofcollectedparticles forms on the plates and is removed periodically by rapping the electrodes. Precipitatorperformance and sizing is dependent on the quantity and chemical composition oftheparticulate matter and flue gas. 

### Fabric Filters

- Fabric Filters use fabric bags in compartments to collectparticulate matter. As the thickness ofthe collectedparticulate matter (dustcake) increases, the pressure drop across the bags increases proportionally. The bags are cleanedperiodically by dislodging a large portion ofthe dustcake with a pulse ofairpressure. Fabric filters are well suited for use with a lime spray dryer systembecause the flue gas passes through a dustcake ofunreactedreagent and reaction products on the filter surface resulting 

### in additional removal ofS02 and air toxics. BlackHills Corporation chose Fabric Filters as the top control option because they aremore effective than electrostatic precipitators at controlling PM\o and airtoxics.



### TB002549Black Hills Corporation (WYGEN 2) Pemut Application Analysis, NSR-A.P-C92 Page J3 Energy and Environmental Evaluation Black Hills Corporation evaluated fabric filters at emission levels of0.0 18,0.0I

### S, and 0.012 IbIMMBtu. There are no significant energy orenvironmental differences between these options other than the emission levels. Economic Evaluation ofAlternatives Black Hills Corporation evaluated Ryton filter bags at an emission level of0.018 IblMMBtu and membrane filter bags (e.g. Gore Tex) at emission levels of0.015 and 0.012 IbIMMBtu. The results are shown in the following table: Baseline Ryton Bags Membrane Bags Membrane Bags 10.2 0.018 0.015 0.012 IblMMBtu IblMMBtu IblMMBtu IblMMBtu Annual Emissions 231,032 tpy 406 tpy 338 tpy 270 tpy

---- -**~-** --

--------- EnusslOns Reduction Baseline 230,626 tpy 230,694 tpy 230,762 tpy Total Annualized Cost Baseline $536,000 $1,331,000 $1,331,000 Total Cost Effectiveness Baseline $2.3/ton $5.8/ton $5.8110n Incremental Reduction Baseline 68 tpy 136 tpy Incremental Annualized Baseline $795,000 $795,000 Cost Incremental Cost Baseline $11,691/ton $5,846/ton Effectiveness

BlackHills Corporation chose 0.018 IblMMBtu as 

### BACTbecause they considered the incremental cost effectiveness to be unreasonable for the loweremission levels. Note that the incremental cost is higher for 0.015 IbfMMBtu because membrane bags are required to achieve either0.015 or 0.012 IblMMBtu. The Division considers the total and incremental cost effectiveness to be reasonable for 0.012 IblMMBtu and the RBLC shows other facilities with pennitted emission levels in this vicinity. Additionally, fabric filters with an emission limit of0.012 IblMMBtu represent maximum available control technology (MAC!) in the following 

### MACTanalysis. The Division concludes that fabric filters with an emission limit ofO.012lblMMBtu represent

### BACT. IV. 500 MW PC Boiler

- CO and VOC Control BlackHills Corporation proposed good combustion controls with an emissions limit of0.09 Ib NOxIMMBtu as BACT. Measures taken to minimize the formation ofNOx during combustion inhibit complete combustion and increase emissions ofCO and VOe. (post combustion NOx controls such as SCRdo not increase emissions ofCO and

## voe.) To ensure avalid comparison, the Division reviewed



### TB002550Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 14 

### CO and VOC limits for the facilities previously listed under the NOx control section with emissions equal or lowerthan 0.09 Ib NOxIMMBtu. The CO and VOC limits for these facilities are shown in the following table:

Facility

Kansas City Power & 

### Light Co.

- Hawthorne Station Great Plains Power

- Weston Bend Generating Station State Size Control CO VC: Status Device Emissions Emis2:ons (MW) (IblMMBtu)**(lbMy.~3tu)**


### MO 570 Combustion 0.16 0.0;;}6 Operational Controls May 2001

MO 820 Combustion 0.16 0.0036 Proposed Controls

------ - -----
--- ---- --------- 

### Emission Control Technologies 

### --_.. -- ._-

---


### BlackHills Corporation considered the following controls for CO and VOC reduction: Oxidation Catalyst

- 

### A catalytic oxidation method is available for gas and oil fueled combustion sources. Theprocess is a straight catalytic oxidation/reduction reaction requiring no reagent. The required operating temperature forthese catalysts is approximately 650 to 750 

### OF and emission reductions are on the order of80 percent for CO and 20 percentfor VQC. An 

### oxidation catalysthas never been applied to a coal fired source and application ofthis technology presents substantial challenges. The oxidation catalystwill not only oxidize CO and VOC butalso apredominate portion ofS02 to SO), Combination of this SO) with ammonia from the SCR systemmay result in fouling ofthe airheater. Plugging and erosion ofthe catalyst would also occur due to fly ash and abrasive combustion products. Finally, the acid gases and trace metals in the flue 

### gas would poison the catalyst. Forthese reasons, BlackHills Corporation considered catalytic oxidation technically infeasible. Good Combustion Controls

- 

### The RBLC does not show any BACTdeterminations using post combustion controls for CO and VOC from PC boilers. Therefore, BlackHills Corporation selected good combustion controls to achieve emissionrates of0.15 Ib COlMMBtu and 0.01 Ib VOClMMBtu as BACT for CO and VOC, respectively. The proposed limits correspond to 3381 tpy CO and 225 tpy VOC. Energy and Environmental Evaluation There are no energy or environmental considerations for good combustion controls. Economic Evaluation ofAlternatives An 

### economic evaluation is notrequired since good combustion controls is the only feasible option. The proposed emission limit of0.15 IblM:MBtu for CO is lower than the determinations listed above. Although the proposed limit of0.01 IblM:MBtu for VOC is higher than the determinations listed

### above,



### TB002551Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 

### 15 the method ofcontrol is the same. Requiring an emission limit of0.0036 IblMMBtu would have no effect on actual emissions. The Division concurs that good combustion controls with an emission limit of0.15 IblMMBtu for CO and an emission limit of0.0I IblMMBtu for VOC represents BACT. V. 500 MW PC Boiler

- Sulfuric Acid Mist Control BlackHills Corpora::on proposed a semi-dry lime spray dryer/absorber as BACT for sulfuric acid (H2 S04) 

### mist. Apercentage ofthe S02 in the flue gas will be oxidized to SO), This SO) can combine with moisture in the**_~ue** 

### gas to form H2 S04, 

### The semi-dry lime spray dryer/absorber proposed for S02 control removes S02 Lhat couldbe oxidized to SO) and also removes SO) and H2

### S04 

### in the flue gas by reacting condensed**~cid** 

### with the alkaline reagent. BlackHills Corporation estimates that the lime spray dryer/absorber will**r~move** 

### approximately 95% ofpotential H2 S04 

### emissions for apotential emissions rate of 104 tpy. As c-'plained in the previous discussion on S02 control, the semi-dry process does not typically result in a**v~sible** 

### moistureplume because there is less moi!>ture in the flue gas and the semi-dry process is more effec:ive atremoving SO)as compared to wet flue gas desulfurization. The Division concurs that a semi-<:.} lime spray dryer/absorberrepresents BACT for H2 S04,

----- _.- 

### -----

______**VI~OO_MW_PC**

### --Be::**~p--Fluoride-Control-** 

### -- Fluorides are regulatt:d under the PSD program and the more specific pollutanthydrogen fluoride (hydrofluoric acid) is regulated as ahazardous airpollutant. They are the same, for all practical purposes, for this analysis because hydrogen fluoride is the expected form offluoride emissions. A more detailed discussion on fluoride emissions is included in the subsequentMACT section. Black Hills Corporationproposed a semi-dry lime spray dryer/absorber and a fabric filter as BACT (and MACf) for hydrogen fluoride and the Division concurs. VII. 500 MW PC Boiler

- Beryllium Control Berylliumis excluded from federal PSD regulations since 1990per Section 112(b)(6) ofthe Clean Air Act but still included in Chapter 6, Section 4(a)(xxi) ofthe WAQSR. Berylliumis regulated as a hazardous airpollutant. A more detailed discussion onberyllium emissions is included in the subsequent MACT section. BlackHills Corporationproposed a fabric filter as BACT (and MACf) forberyllium and the Division concurs. VITI. 500 MW PC Boiler

- Mercury Control Mercury is excluded from federal PSD regulations since 1990per Section 112(b)(6) ofthe Clean Air Act but still included in Chapter 6. Section 4(a)(xxi) ofthe WAQSR. Mercury is regulated as ahazardous air pollutant. Amore detailed discussion on mercury emissions is included in the subsequentMACT section. BlackHills Corporationproposed good combustion controls, SCR, a semi-dry lime spray dryer/absorber, and afabric filter as BACT (and MACf) for mercury and the Division concurs. IX. 500 MW PC Boiler

- Ammonia Control (Chapter 6, Section 2) BACT is required for ammonia emissions underWAQSR, Chapter 

### 6. Section 2(c)(v). BlackHills Corporation stated that ammonia slip emissions of2 to 5 pprIly are expected and thatcatalyst



### TB002552Black HiJls Corporation (WYGEN 2) 

### Permit Application Analysis, NSR-AP·C92 Page 16 

### manufacturers will guarantee ammonia slip emissions of5 pplTly or less. The Division concurs that ammonia slip emissions of5 ppm, or less (dry basis, corrected to 3% OJrepresent BACT. 

### X. Material Handling

- PMlPM 10 

### Control Black Hills Corporation proposed fabric filters with an emission limit of0.009 gr/dscfas BACffor coal handling and fabric filters with an emission limit of0.0I gr/dscfas BACT for othermaterial handling. Fabric filters have the highest control efficiency ofany ofthe particulate matter control options and BlackHills Corporation chose them as the top option. The Division concurs that fabric filters with an emission limit of0.009 gr/dscfrepresent BACffor coal handling and fabric filters with an emission limit of0.01 gr/dscfrepresent BACT for other material handling. XI. Miscellaneous Sources

- PMJPM 10 

### Control The Division evaluated BACT for fugitive PMlPM 10 

### emissions from unpaved haul roads, coal conveying, unloading lime trucks, loading FGD Waste, and trucktransport. The haul roads at the Wyodak coal mine are treated with suitable chemical dust suppressants in addition to water to control fugitive dust.**_~**

______**~em** .........**iS''''''s'"'jons.._1"he_same_method~be_used_fonmpaved** 

### roads at WYGE1'r2 andthe Division considers this BACT for unpaved haul roads. The application indicates that coal is transferred from the Wyodak coal mine through the coal storage silo fill systemand plant feed systems, both ofwhich are covered to the maximum extentpractical withbolted metal shrouds. The Division considers covered conveying systems to represent BACf. The application shows lime unloading will be accomplished with a pneumatic transfer systemcontrolled with the lime unloading silo baghouses (LDC-OO 1A and LDC00IB). The Division considers this BACT for lime unloading. The FGD Waste Loadout Silos are controlled withbaghouses and these baghouses can also be used to control fugitive dust from loading FGD Waste. The Division considers loading spouts with an outer sleeve for dust withdrawal or equivalentconnected to the silo baghouses (RDC-002A, RDC-002B) to represent BACffor loading FGD Waste. The Division considers enclosingthe loads to represent BACT for truck transport emissions. CHAPTER 6, SECTION 6 - HAZARDOUS AIR POLLUTANT 

### (HAP) EMISSIONS AND**~AVAllABLECONTROLTECHNOLOGY~cn:** 

### This facility is subjectto a case·by-case MACfreview under the requirements ofWAQSR Chapter 6, Section 6 and Section 112(g) ofthe 1990 CleanAiiActAmendments (40 CFR 63, SubpartB) because it is a major source ofhazardous airpollutants and the specific MACT standard for this source category has notbeen promulgatedyet. The exclusion for electric utility steam generating units in Chapter 6, Section 6(c) is no longer 

### in effectbecause electric utility steamgenerating units were added to the source category listonDecember20,2000 [Federal RegisterNotice, Volume 65, Number245, Pages 79825- 79831] pursuantto section 112(c)(5) ofthe Clean 

### AirAct. WAQSR, Chapter6, Section 6(h)(iii)(A) requires the MACT limit to be no less stringent than achieved inpracticeby the bestcontrolled similar source. WAQSR, Chapter 6, Section 6(h)(iii)(B) requires the MACTlimitto achieve the maximumdegree ofreduction which can be achieved utilizing the control technologies identified from "available information."



### TB002553Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 17 "Available infonnation" is defined in Chapter 6, Section 6(£)(iii) and includes: (A) A relevant proposed regulation, including all supporting information; (B) Background information documents for a 

### draft or proposed regulation; (C) Data and information available from the EPA Control Technology Center developed pursuant to Section 113 ofthe Act; (D) Data and information contained in the EPA Aerometric Information Retrieval System including infonnation in the MACT data base; (E) Any additional information that can be expeditiously provided by EPA; and (F) For the purpose ofdeterminations by the Division, any additional information provided by the applicant or others, and any additional infonnation considered available by the Division. According to EPA, a regulation will be proposed for coal fired utility boilers but a draft is not available yet. The Division reviewed EPA's Aerometric Information Retrieval System and was unable to find a MACT data base. The available information that the Division could locate is RACTIBACTILAER Clearinghouse (RBLC) data from the EPA Control Technology Center, EPA's Electric Utility AirToxics Study, information from the August 2001 U.S. EPA-DOE-EPRl Combined PowerPlant Air Pollution ---------jContruI-Symposium. 

### TheMegcrSymposnlm, and informatIon from {lie August 2001 AIr**~aste---~** Management Association Specialty Conference on Mercury Emissions: 

### Fate, Effects, and Control. The information reviewed discussed general control concepts but provided little infonnation on emission rates for specific HAPs. Black Hills Corporation estimated HAP emissions from this facility using AP-42 and 1991 Wyodak coal analysis data. A summary ofHAP emissions is shown in the following table: HAP Emissions Pollutant Emission Factor Unconll"Olled Controlled Emission lUte Emission IUle (1bIlon) (lblhr)' (lb/hr)' 2.4-DinilTOlolueneA**2.80E~7 9.06E~5**  2-ehloroacetophenone'**7.00E~6 2.27E~3**  Acetaldehyde' S.70E4I**1.84E~1** Acctophenonc'**I.S0E~S 4.8SE~3**  Acrolein' 2.9OE4I**9.38E~2** Antimony"**2.S9E~1 2.59E~2** **~ic"** 1.94E+OO**1.94E~1** Benzenc'**1.30E~3 4.2IE~1**  Benzyl Chloride' 7.00E4I**2.27E~1** Beryllium'**3.88E~1 3.88E~2**  Biphcnyr**1.70E~** 5.50E4I Bis(2-ethylhexyl)phthalate'**7.30E~S 2.36E~2**  Bromoform'**3.9OE~S 1.26E~2**  Cadmium!**S.10E~5 1.65E~1** **1.65E~2** Carbon Disulfidc' 1.30E4I**4.21E~2** Chlorinc Chlorobenzene"**2.20E~S 7.l2E~3**  Chlorofonn'**S.9OE~S 1.91E~2**  Chromium' 7.77E+OO**7.77E~1** Cobalt' 1.29E+OO**1.29E~1** Cumene'**5.30E~6 1.72E~3**  Cyanide"**2.50E~3** 8.09E-Ol Control Efficiency ("/.)

90 90

90

90

90 90 Potential Emissions

(tpy)' 3.97E4I**9.92E~3 8.08E~1** **2.13E~2 4.IIE~1** **1.13E~1 8.S0E~1**  1.84E+OO**9.92E~1 1.70E~1** **2.4IE~3** 1.03E-Ol**5.53E~2 7.23E~2** **1.84E~1 3.l2E~2**  8.36E-02 3.40E+OO 5.67E-Ol**7.5IE~3** 3.54E+OO



### TB002554Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 18
HAP Emissions (Continued)

Pollul2nl EmIssion Factor Uncontrolled Controlled Control Potential Emission lUte Emission lUte ::.•::iency Emissions (lblton)**(lbIh~** (lblhr)' (%) (tpy)' Dimethyl Sulfale· 480E..()S I.SSE-02 6.80E"()2 Ethyl Chloride· 4.20E-oS 1.36E-02 S.9SE-02 Ethylbenzene" 9.40E-oS 3.04E"()2 1.33E"()1 Ethylene Dibromide· 1.20E-Q6 3.8SE..()4 \.70E-03 Ethylene Dichlonde· 4.00E-oS 1.29E-02 S.67E-02 Fluorine Formaldehyde" 2.40E..()4 7.77E"()2 3.40E-01 Hexancd 6.70E-oS 3.SSE+Q2 2.17E-02 96 9.S0E-02 Hydrogen Chloridc

..... 1.20E+OO 4.gSE+Ol \.SSE+OI 96 6.S0E+01 Hydrogen Fluoride"'J l.SOE-01 \.94E+OO S.50E+OO Isophorone· S.80E..()4 \.SSE-ol S.22E-01 Lead' 1.30E..()I S.69E-ol Manganese' 6.47E"()2 I.SIE+OO 3 7.94E+OO Mercury" 6.2SE-02 2.7SE-01 Methyl Bromide· 1.60E..()4 S.ISE"()2 2.27E-ol Methyl Chloride' S.30E..()4 I.72E-01 7.SIE"()1 MethyLEJhyl**Ke!Ql]e~** ___. 390Edl4
.._-- L26E-oI----

- --**j:S~E-oI** Methyl Hydrazinc· 1.70E..()4 S.SOE"()2 2.41 E-ol Methyl Methacrylate" 2.00E"()S 6.47E..()3 2.S3E-02 Methyl Tert Butyl Ether' 3.S0E-oS I. 13E-02 4.96E-02 Methylene Chloride' 2.9OE..()4 9.3SE-02 4.IIE"()1 Naphthalene' 1.30E-oS 9.71E+OO 4.21 E-03 90 I.S4E-02 Nickel" 9.71E-ol 4.2SE+OO Phenol" 1.60E"()S S.ISE"()3 2.27E-02 Polychlorinaterl**Dibenzofu~nS>** 2.01E-07 6.S0E-oS 2.SSE..()4 Polychlorinated Dibenzo-p-dioxins' 4.2SE-oS 1.39E-oS 6.07E-oS Propionaldehyde· 3.80E..()4 1.23E-01 S.39E-01 Selenium' 1.30E"()3 J.7SE-02 4.21E-ol 54 1.S4E+OO Styrene" 2.S0E"()S S.09E-03 3.S4E-02 Tetrachloroethylene' 4.30E-oS 1.39E-02 6.09E"()2 Toluene' 2.40E..()4 7.77E-02 3.40E..()I Vinyl Acetate' 7.60E-06 2.46E-03 1.0SE-02 Xylencs (0 and m)" 3.70E-oS 1.20E-02 S.24E-02

.. 

## - - 

## - - - - 

## - - - 

### - 

### - - 

## - - - - 

## - - 

# - - - - - 

### - -- - - - - - 

### - - 

### - Total 110 'Emissions based on acoal bum nte of323.6 tonslhr. "Emission lUte from AP-42 Table 1.1-12. Assumes emissioncontrol from spray**drye~** and fabric**filte~.** "Emission lUte from AP-42 Table 1.1-13. Assumes emission control from spny dryers and fabric filters. "Emission Rate from AP-42 Table 1.1-14. Assumes emission control from spray dryers and fabric liltm. 'Emission Rate from AP-42 Table 1.1-1S. Assumes emission control from spray dryers and fabric filtm. fEmission Rate from AP-42 Table I.I-IS. Assumes emission control from spray dryers and fabric**filte~.** •Assumed 96% control efficiency. '1991 Wyodak coal analysis. Assumed 90% control efficiency. Mercury assumed 3% control efficiency. 'Assumed 100% ofChlorine is converted to Hydrogen Chloride. 'Assumed 100% ofFluorine is corm:ned to Hydrogen Fluoride. 'Assumed 9S% control efficiency. Lead emission was based on an emission factor published by the USEPA in a document entitled, Toxic AirPollutalllEmission Faclors-A Compilation/orSelectedAir Toxic Compounds andSources. Design, Equipment Workpractice, orOperational Standards WAQSR Chapter 6, Section 6(h)(iii)(C) allows a specific design, equipment, workpractice, or operational standard ifit is not feasible to prescribe orenforce an emission limitation under the en'reria



### TB002555Black Hills Corporation (WYGEN 2) Pemlit Application Analysis, NSR-AP-C92 Page 19


### set forth in section 112(h)(2) ofthe Clean AirAct (CAA). Section 112(h)(2) ofthe CM defines "not feasible to prescribe or enforce an emission standard" as any situation in which the Administrator determines that: I) ahazardous airpollutant orpollutants**c~;::ot** 

### be emitted through a conveyance designed and constructed to emit or capture such polh':::':lt, or 2) the application ofmeasurement methodo:cD' 

### to aparticular class ofsources is not practicable due to technological and economic limitLi:.Jns. The first criteria is obviously not an issue because the HAPs are emitted through the PC boiler stack. The secondcriteria, however, is an issue for this :·-:ility. Although this section ofthe CM appears to be directed toward writing standards for aclass ofsources ratherthan an individual source, the fact remains that there is alackofex.isting data available.to**e~':** 

### .:tively establish emission limitations for each applicable HAP. Therefore, BlackHills**Corpora::~n** 

### proposed multi-pollutantcontrols (i.e. a low NOx burnerwith selective catalytic reduction, two spr:::' dryer absorbers, and two baghouses) rather than emission limitations for each HAP. Although**the~:** 

### technologies were originally intended to control criteriapollutants, recent data shows that they ar"

..:so effective in controlling**~s,-_Several ~x.amj.)les** 



### --- ---------are-given-below:"-**._~_.** 

### Beryllium Control

- 

### BlackHills Corporation proposed a fabric filter for control ofberyllium. The fate of beryllium compounds through aPC boiler andpost combustion air quality control devices is similar to that ofcoal ash. Some ofthe berylliumwill 

### be retained in the bottom ash while most will be collected in the particulate collection device. Berylliumemissions from different facilities vary with the amount of beryllium in 

### the coal burned. However, the use ofaparticulate control device, such as a fabric filter or electrostatic precipitator, is consistentlythe BACffor beryllium in the RACfIBACfILAER Clearinghouse (RBLC). BlackHills Corporation estimates that the fabric filter will remove approximately 90% ofberyllium emissions for apotential emissions rate of0.2 tpy. Hydrogen Chloride Control

-

### BlackHills Corporation proposed a semi-dry lime spray dryer/absorber and a fabric filter for control ofhydrogen chloride. Hydrogen chloride will react with lime (the reagent for the spray dryer/absorber) to form calciumchloride. Calcium chloride is a stable solid and can be removed with a fabric filter. BlackHills Corporation estimates that the lime spray dryer/absorber and fabric filter will remove approximately 96% ofhydrogen chloride emissions for apotential emissions rate of68 tpy. Hydrogen Fluoride Control

- 

### BlackHills Corporation proposed a semi-dry lime spray dryer/absorber and a fabric filter for control ofhydrogen fluoride. Fluoride emissions are formed from hydrogenation of fuel-bound fluorides. Hydrogen fluoride dissolves 

### in waterto form hydrofluoric acid. Hydrogen fluoride will reactwith lime (thereagent for the spray dryer/absorber) to form calcium fluoride. Calciumfluoride is a stable solid and can beremoved with afabric filter. BlackHills Corporation estimates thatthe lime spray dryer/absorber and fabric filter willremove approximately 96% ofhydrogen fluoride emissions for apotential emissions rate of8.5 tpy. Mercury Control

- 

### BlackHills Corporation proposed good combustion controls, SCR, a semi-dry lime spray dryer/absorber, and a fabric filter for control ofmercury. Mercury emissions result from trace levels ofthe element in the coal combusted. Mercury canbe emitted as different compounds, including



### TB002556Black Hills CorporanoD (WYGEN 2) PermitApphcauon AnalysIS, NSR·AP·C92 Page 20 elemental mercury, organic mercW)', Inorgamc mercury, and mercuric chloride to name a few. Because ofthe many patentlal forms, the amount ofmercury generated from PC boilers and the amount of reduction acruany achievedby air quality control deVlces is difficult to predict. The fate ofmercury compounds through a PC boiler and post combustlon air quality control deVlces is not well understood and vanes sigmficantly from boilerto boiler and coal to coal. Some ofthe mercury will be retamed m the bonom ash while most will pass through and 

### be reduced by various amounts in the air quahty control dev1ces. The use ofmulti-pollutant control technologies has been shown effective in conrroillng mercury. Although selective catalytiC reduction (SCR) does not directly capture mercury, it does partially oxidize some ofthe elemental mercury which aids in collection downsrream in the fabnc filter. Some ofthe mercury may be adsorbed by the lime (the reagent for the spray dryer/absorber) which also aids in collection downstream in the fabric filter. Good combustion controls to minimize the amount of fuel burned also decrease the amount ofmercury emitted. Black Hills Corporation estimates that good combustion controls, SCR, a semi-dry lime spray dryer/absorber, and a fabric filter will remove approximately 3% ofmercury emiSSions for apotential emissions rate of

### 0.3 tpy. 

### -;= 

## &00-A-

# /yeCA. ("
ParticulateMetal HAP Control- Black Hills Corporation proposed a spray dryer/absorber and a fabnc filter for control ofparticulate metal HAP emissions. These HAPs are trace metals which would are not**-expectedlo-volatili~trding**antimony, arseniC, be1jthum, chromIum, cobalt. manganese, nickel, and selenium. Black Hills Corporation estimates thatthe spray dryer/absorber and fabric filter will remove approximately 9QO/o ofparticulate metal HAP emissions. Proper Operation and Maintenance Section I12(h)(2) ofthe CAA indicates that requirements to assure proper operation and maintenance should be included ifa design orequipment standard is used. Proper operation and maintenance ofthe control equipmeotwill be necessary In orderto meet the emission limits for criteria pollutants and continuous monitoring is required forNOx, S02' and opacity. Fabric Filter Control Efficiency The multi-pollutant controls (i.e. a low NOx burnerwith selective catalytic reduction, two spray dryer absorbers, and two baghouses) proposedby BlackHills Corporation ultimately rely on the baghouse to collectHAP containing particles. Low NOx burners and selective catalytic reduction (SCR) increase the carbon content offly ash. HAPs are adsorbed onto the fly ash carbon and subsequently captured in the downstream baghouse. Spray dryer absorber (SDA) systems spray watercontaining an acid gas sorhent into areaction vessel where the acid gases and otherpollutants are reacted to form solidparticles that can be collected in the downstreambaghouse. Because the baghouse ultimately collects the HAP contaimng particles, the control efficiency ofthe baghouse is cntical. The Division focused the remainder ofthe case·by-case MACTTev1eW onbaghouse collection efficiencies. The RBLC data for PMlPM 10reviewed in the prev10us BACT section indicates that 0.0135IbIMMBtu is thebestcontrolled similar source. Although the RBLC shows two units with emission limits less than 0.0135 IblMMBru. these are much smaller units and are not considered "similar sources" under WAQSR., Chapter 6, Section 6(O(xiv). Note that the best controlled PC Electric Utility Boilerhas an emission limit orO.015 IbIMMBtu.



### TB002557Black Hills Corporation (WYGEN 2) Permit Application Analysis. NSR-AP-C92 Page 21 As previously discussed, WAQSR, Chapter 6, Section 6(h)(iii)(B) requires the MACT limit to achieve the maximum degree ofreduction which can be achieved utilizing the control technologies identified from "available information." Black Hills Corporation evaluated baghouses at emtssion levels of0.0 18, 0.015, and 0.0121bfMMBtu as discussed in the previous section on BACT. Based on the informatIOn provided, an emission level of0.012 IbfMMBtu can be achieved using membrane bags. Subsequent Promulgation ofa MACT Standard WAQSR, Chapter 6, Section 6(i)(iii) dIscusses promulgation ofa specific MACT standard after a caseby-case 

### MACT standard is issued. According to EPA. the target date for submittal ofthe proposed MACT standard is December 15,2003 with apromulgation date ofDecember 15, 2004. IfEPA meets these target dates, there will be aMACT standard in place when this facility is scheduled to begin operation in June 2005 and the facility will have to comply. Once the specific MACT standard is promulgated, the Division may in its discretion use any more stringent provisions ofthis case-by-case MACT determination when issuing or revising the Chapter 6, Section 3 operating permit. Conclusion 

### In summary, ithas been shown that multi-pollutant controls for criteria pollutants are effective in controlling HAPs. The emission limits and control efficiencyrequirements for criteria pollutants serve as surrogates for HAP limits. The Division concludes that a low NOx burner with selective catalytic reduction, two spray dryer absorbers with aminimum 90% S02 removal efficiency, and two baghouses with an emission limit of0.0 12 IbfMMBtu representMACT. 

### CHAPTER 5, SECfION 2 - NEW SOURCE PERFORMANCE STANDARDS (NSPS): New Source Performance Standards SubpartsDa and Yare applicable to the proposed source in accordance with WAQSR, Chapter

### 5, Section 

### 2. Subpart Da applies to electric utility steam generating units capable ofcombusting more than 250 MMBtulhourheat input for which construction or modification is commenced after September 18, 1978. The proposed PC boiler has a maximum heat input of

### 5, 145.7 

### MMBtuIhr (323.6 tons ofcoal perhour). Subpart 

### Y applies to coal preparation plants which process more than 200 tons per day with facilities that are constructed ormodified after October 24,1974. 

### Subpart Da

- PC Boiler: ParticulateMaller: SubpartDa limits particulate emissions from coal fired plants to 0.03 IblMMBtu, and 99% reduction of potential combustion concentration. Opacityis limited to 20% (6 minute average) except for one six minute period perhour ofnotmore than 27%. The proposedboiler emission limit ofO.0121blMMBtu will show compliance with the NSPS particulate matter emission limit. Furthermore, Subpart Da, Section 60.46a(a) states that compliance with the particulate matter emission limitation constitutes compliance with percentreduction requirements forparticulate matter. Section 60.47a(a) requires the operation ofacontinuous monitoring system for measuring the opacity ofemissions discharged to the atmosphere.



### TB002558Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 22 

### SulfurDioxide: Subpart Da limits S02 emissions from the proposed coal-fired boiler to either: I) 1.20 IblMMBtu and 90% reduction ofpotential emissions or 2) less than 0.60 IblMMBtu and 70c""

### reduction ofpotential emissions. Compliance with the SubpartDa emission limitation and percent :-eduction requirements are both determined on a 30 day rolling averagebasis. The proposed boiler emission limits ofO.15Ib/MMBtu (30 day average), 0.1: IblMMBtu (2 hour average), and 90% reduction ofpotential emissions will demonstrate**complia~.;e** 

### with the NSPS emission limitations. S02 inlet and outletcontinuous emission monitoring is required under Subpart Da to demonstrate compliance with the emission limit andpercentreduction require:-nents across the control device. Subpart Da also requires the operation ofa continuous monitoring syr-tem to measure oxygen or carbon dioxide content ofthe flue gases at eachlocation where sulfur dioxic..; vrnitrogen oxide emissions are monitored. Nitrogen Oxides: ------The""NSPSNO.-enm-ston1irmt for sources constrUcted afterJUly 9, 199T1sl.**~lbTmegawatt-hour** 

### gross-- -- energy output (30 day rolling avg.) and 0.15 IblMMBtu heat input (30 day rc. :ng avg.). The proposed NO. emission limit ofO.07lblMMBtu (30 day rolling average) is well below the NSPS limit of0.15 IbfMMBtu. 0.07lblMMBtu corresponds to O.72lb/megawatt-hour at full load, which is considerably less than the NSPS limitof 1.6 Ib/megawatt-hour, as shown in the following calculation:
0.07 /b 

### MMBru x 5,145.7 

### MMB/u hr 500MW = 0.72 Ib MW-hr 

### NO. continuous emission monitoring, acontinuous flow monitoring system, and a wattmeter to continuouslyrecord gross electrical outputin megawatt-hours are required under SubpartDa. Subpart Da also requires the operation ofa continuous monitoring system to measure oxygen orcarbon dioxide content ofthe flue gases at each location where sulfurdioxide ornitrogen oxide emissions are monitored. 

### Subpart Y - Coal Handling Facilities: SubpartY ofthe New Source Performance Standards limits opacity to less than 20% from all coal processing and conveying equipment (includingbreakers and crushers), coal storage systems. and coal transfer and loading systems at WYGEN 2.


### ALLOWABLE EMISSIONS: The allowable emissions for eachpoint source, based on the BACT and MACTreviews and the 'lblMW-hrNOx limit ofNSPS SubpartDa, are shown in the following tables:



### TB002559BlackHills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 23 

### PC**Boi1n~** 

### Emissions (PC-OOl)

Pollutant 

### IblMMBtu Iblhr' IbfMW-hr 

### tpf
NO. 0.07 (30-day rolling) 360.2 (30-day rolling) 1.6 (30-day rolling) 1,578

3,381 771.9 (30-day rolling)

874.8 (2-hrblock) 0.15 (30-day rolling)

0.17 (2-hrblock) 90% Minimum Removal Efficie:1cy (30-day rolling)

................................................................................................u

_ _ •••••••••••••••••••



### PMJPM\o 0.012 61.7 270 CO 0.15 771.9 3,381



### .............................................................................................................................................................
_ - 

### _-_.-

_ ".



### VOCs 0.01 51.5 225 IEmissions based on 5,145.7 MMBtuIhrheat input. 2Based on 8,760 operating hours peryear.**-~----** ----- 

### -- ---- -- ---- --- - -----



### Material Handling PMJPM,o Emissions Source No. Source gr/dscf dscfm 

### lblhr tpyl 

### CDC-OOI Coal Storage Silo Top Dust Collector 0.009 23,604 1.8 8.0
CDC-002 Coal Storage Silo BottomDust Collector 0.009 7,343 0.6 2.5
CDC-003 Coal TransferBuilding Dust Collector 0.009 7,343 0.6 2.5
CDC-004 UnitTransfer and Silos Dust Collector 0.009 32,521 2.5 11.0 LDC-001A Lime Unloading Silo DustCollector 0.01 1,259 0.1 0.5 LDC-001B Lime Unloading Silo DustCollector 0.01 1,259 0.1 0.5 RDC-OOI FGD Waste Recycle Storage Bin Dust Collector 0.01 2,623 0.2 1.0 RDC-002A/B2 

### FGD Waste Loadout Silo Dust Collectors 0.01 5,245 0.4 2.0

I 

### Basedon 8,760 operating hours peryear. 2

### Only one ofthese units (RDC-002A or RDC-002B) will be in service at anyone time.



### TB002560BlackHills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 24 

### ANALYSIS OF AIR QUALITY MODELING: PSD Applicabilitv: As statedpreviously, the proposed WYGEN 2electrical generating facility is classified as a "major emitting facility" as defined in Chapter 6, Section 4(a)(i) ofthe Wyoming Air Quality Standards and Regulations

## 0NAQSR). Therefore, PSD regulations are applicable for the proposed construction ofthis facility. Potential annual emissions in tons peryear (TPY) from the proposed construction ofthe WYGEN 2 facility are provided in the Prevention ofSignificantDeterioration (PSD) Applicability section. As an applicz.::: for aPSD permit, BlackHills Corporation (BHe) must conduct ambient airquality analyses for**t~:~** proposed WYGEN 2 facility to verify compliance with Wyoming Ambient Air Quality Standards

## 0Nn.A.QS) and Prevention ofSignificantDeterioration (PSD) increments. Specifically, an analysis**ofth~** Jredicted impacts on the ambient airquality from the proposed facility is required for all pollutants fo:- which standards have been establishedunder PSD regulations, WAQSR, or the Federal Clean AirAc:. 2I1d are emitted in significantamounts. Regulated pollutants include (1) pollutants for which aNatiC'::,1 Ambient Air Quality Standard (NAAQS) exists**(crit~lutants)** and (2)pth.er pollutantS, 

### whi:li are regulated by

## tne Environmental Protection Agency (EPA), for which no NAAQS exist**(non-cri~:~a** pollutants). Based on the comparison ofthe emission rates from the proposed facility to the PSD significant emission rates provided in the PSD Applicability section, the pollutants emitted in significant quantities are NO., CO, S02' PM,o, VOCs, sulfuric acid mist, fluorides, as hydrogen fluoride 

### (HF), mercury, andberyllium, and a full impact analysis is required under PSD regulations for these nine (9) pollutants. As shown in the emissions table in the PSD Applicability section ofthis analysis, the proposed emissions ofTotal Reduced Sulfurcompounds (TRS) and lead are estimatedtobe below the PSD significant emission rates as aresult ofthe proposed operation ofthe WYGEN 2 facility, and these two (2) pollutants are not subject to any further airquality impact analyses underPSD regulations. There are no PSD increments for VOCs orozone. Additionally, there are no regulatory models applicable to modeling VOC emissions from stationary sources inrural areas to assess potential ozone formation, therefore, an ambient impact analysis was notperformed for VOC emissions associated with the proposed modification. Additionally, Wyoming's regulations do not contain ambient standards for sulfuric acid mistmercury, orberyllium. However, Wyoming's regulations do require that sulfuric acid mist, mercury, andberyllium emissions be addressed through analysis ofBest Available Control Technology (BACT). The Division's review ofBACT for sulfuric acid mist, mercury, and beryllium emissions from the proposed WYGEN 2 facility has addressed the emissions ofthese pollutants in sufficientdetail, and the application ofBACTwill minimize the ambientimpacts from the emissions of these three (3) pollutants. As aresult, no modeling analyses are requiredby the Division for assessing the impacts ofthese pollutants on the ambient airquality. 

### Significant Impact Analysis: The proposed emissions ofNO., CO, S02' and PM\O from the WYGEN 2 facility were modeled for these four (4) criteriapollutants to determine the significant impact area for each criteria pollutant. HF emissions were not included in this analysis, as HF is not aregulated pollutant underPSD. The significant impact area is a circular area defined by the radius ofinfluence (R01) for which the required



### TB002561Black Hills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 25 

### air quality modeling analyses for the W

### AAQS and PSD increments are carried out. The ROJ is the distance from the proposed source or modification to the most distant pointwhere the dispersion modeling analyses predicts a significant ambient impact will occur. Table 1 shows the maximum modeled NO

.. CO, S02' and PM

## ,o impacts from the proposed WYGEN 2 facility, and compares the maximum concentrations to the PSD Class II significant impact levels (SILs) and pre-construction monitoring levels. The designated Class II SILs as specified by the EPA, and in WAQSR, Chapter 6, Section 2(c)(ii)(A) are also provided In 

### Table 

### I. 

### Table 1 Comparison ofMaximum Modeled AmbientImpacts to PSD Class II 

### SILs and Pre-Construction Monitoring Levels
WYGEN2 PC lITM Location of PSD PSD Pre Constr.

Ambient Boiler Maximum Impact Qass II Further DeMinimis Monitoring Ave. Impact Load (meters) Significance Analysis Levels Required Pollutant Period (Jlglm l ) 

### (%) Levels**RegtJ~ ~~r1]J).**  (Yesl1'-lo)

.

..

### - 

### _.-.- ----- --East l'lonn (Jlg/mJ ) (YesINo) NO, Annual 0.1 50 473124 4901600 I No 14 No CO I-bour 69.2 100 469024 4902900 2,000 No


### -- 

### - 8-hour 15.5 75 468324 4904400 500 No 575 No S02 3-hour 44.1 100 469024 4902900 25 Yes


### -- - 24-hour 7.3 100 469024 4902900 5 Yes 13 No Annual 0.2 50 473124 4901600 I No


### -- 

# - 24-bour 4.6 100 468824 4903600 5 No 10 No PM 10 Annual 0.6 469324 100 4904200 1 No 

# -- -- EPA guidance contained in the New Source Review Workshop Manual, October 1990, states that in the event thatthe maximum modeled ambient impact ofaproposed emissions increase is below the appropriate ambient airquality significance level for all locations and averaging periods, the EPA does not require any furtherNAAQS orPSD Class II increment analyses forthatpollutant. As shown inTable 1, the maximum predicted ambient airconcentrations ofNOx' 

### CO, and PM 10 

### are all less than the significance levels for Class II areas for all applicable averaging periods. Additionally, the model predicted impacts are also below the significantmonitoring concentrations for all four (4) criteria pollutants. Therefore, no furtherNAAQS, orequivalently, no further WAAQS modeling analyses for NOx, 

### CO, orPMJO are required. While pre-construction monitoring is not required, the applicanthas established an ambient**S~** 

### monitoring site located approximately 1.6 kilometers south-southeast ofthe proposed WYGEN 2 facility, next to the WyodakResources Site4 monitor. The ambient monitoring site began collecting hourly



### TB002562Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 26 ambient S02 data on September 27, 2001. The UTM coordinates ofthe mo::itor location are Zone 13 (470083,4902531). Based on the applicant's significant Impact analysis using the 1999 on-site :-:-eteorological data from Pacificorp's Wyodakmonitoring site, the only criteria pollutantwhich has !:-:1pacts above the PSD Class 

### II SILs is**S~,** and based on this analysis, it was determined that the 3-hou!" Jnd 24-hour SOJ ROI were approximately 2.1 Ian and 10.2 

### lan, respectively. PSD guidance recommends that 

### adistance of50 km be added onto the ROls to define the maximum distance out to which the interacting source inventory would be compiled and used in the WAAQS and PSD increment analyses. Based on the significant impact analysis, the Division compiled an interactive**S~** source inventory for the applicant to be used in the WAAQS and PSD increment consumption modeling analyses. This inventory primarily consisted of existing S02 sourceslocated at the Wyodakcomplex, where the WYGEN 2 facility is being proposed. The Two ElkUnit One PC Boiler was also included in the inventory, and is located approximately 71 kilometers southeastofthe proposed WYGEN 2 facility. Analvsis Overview: The applicanthas submitted ambient air quality analyses to evaluate model predicted impacts on near-**------ffIetdand--rar-fle1~ceptors.** Thenear-he1oanalyses consIst of

### WAAQS, PSD Class 

### II increment consumption analyses, and ambient air impacts ofHazardous AirPollutants (HAPs) associated with the proposed WYGEN 2 facility, which were completedusing the Industrial Source Complex model (ISC3). The far-field analyses consist ofPSD Class I increment consumption and analyses ofimpacts to Air Quality Related Values (AQRVs), and were completed using the CALPUFF modeling system. 

## Near-Field Modeling Analysis
Model Justification: The applicant used the Environmental Protection Agency (EPA) Industrial Source Complex 3rd generation model (lSC3), version 00101 to assess the air quality impacts from the WYGEN 2 facility on near-source receptors 

## « 50 kilometers). The short-term version (lSCSD) ofthe model was used to determine annual and short-term near-field concentration estimates ofND., CO, S02' PM\o, HF, and HAPs. The dispersion model simulations were nul with recommended regulatory defaults, and in accordance with the current Guideline on Air Quality Models. Options used in the analyses were rural dispersion coefficients with no exponential decay, final plume rise, stack tip downwash, default wind profile exponents, default vertical potential temperature gradients, and calms processing routines. Buoyancy-induced dispersion is used except where the Schulman-Scire downwash algorithms are employed by the model. In addition, the applicant used Trinity Consultant's version ofEPA's Building Profile Input Program to determine downwash parameters to include m the ISCSD model runs. Terram at ornearthe WYGEN 2 facility is rolling with terram heights exceeding some stacktop elevations, and can be characterized as complex terram. EPA has specified that the model ofchoice for multiple sources in an mdustrial setting located in complex terrain, with source-receptor distances less than 50 kilometers is ISC3. 

### Meteorological Data: Initially, the applicant used one year ofsurface meteorological data collectedby Hampshire Energy

### in 1981 for aproposed facility nearWyodak, WY. The meteorological towerused to collect the data was


### TB002563Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 27 

### located approximately 16 kilometers SSE ofthe proposed WYGEN 2 facility. The surface meteorological data were obtained from October 15, 1980

- October 14, 1981 at aheight of60 meters. It was laterdetennined that Pacificorp already had an on-site meteorological data monitoring program established for the Wyodak complex.**Thel"~fore,** 

### the Division required the modeling analyses submitted for the WYGEN 

### 2 facility to be simulated t:sing the Wyodakmeteorological data collected by Pacificorp. These data were collected from March I, 

### IS:)9

- February 28, 2000; the winds were measured using an anemometerheight of 10 meters. Twice-daily upper air soundings collected**~:** 

### Rapid City, South Dakota (Station #24090) were processed for the same time period and merged with t..;:; 

### Pacificorp Wyodak hourly data. A wind rose which represents the annual average surface wind :::attems from theWyodak meteorological data for 1999-2000 is shown in Figure I. The average ofthe w:-:d flow data statistics for this meteorological data indicates the predominant winds originate'from the '

..' ..it-southwestthrough the southeast directions approximately 46% ofthe time, The annual average calcul::.ted wind speed for this data is approximately 7.5 meters/sec (16.7 miles perhour). The percentage ofc:':n winds for this data set equates to 0.79% (68 hours). A comparison between the two**meteorologic~"** 

### data sets indicated that the modeled impacts were similar for both sets ofdata and adequately demonstr:.

...:3 

### compliance with all applicable ambient air quality ------standards:·--- Backeround Concentrations: The S02 background values used in the Wyoming Ambient Air Quality Standards (WAAQS) modeling analysis for S02 were obtained from the ambient monitoring data conducted by Pacific Power and Light at three sites overthe course ofone year. The S02 background values listed inTable 2 were obtained from two ofthose sites located near the Wyodak area, eitherthe North orTowermonitoring sites, depending upon which site produced the maximum background value for each averaging period. Table 2 Background Concentrations Used in WYGEN 2 Near-Field Modeling Analyses

Pollutant Averaging Period Background Concentration S02 3-Hour 

### 99 Ilglm3 

### S02 24-Hour 

### 36 Ilglm3 

### SO, Annual 3 ug/m3



### Emissions and Stack Parameters: The emissionrates and stackparameters for all proposed sources at the WYGEN 2 facility are provided inTable 3. There are two (2) sources identified as FGD Waste Loadout Silo DustCollectors being proposed for the WYGEN 2 facility. The applicant has indicatedthat only one ofthe two FGD Waste Loadout Silo DustCollectors will be operated at any time. Both ofthese sources have the sameproposed PM

## ,o emission rates and stackparameters, therefore, only one ofthese sources (RDC002A) was included in the modeling analyses.



### TB002564

# N



# w E

CALM WINDS .79%



### WIND SPEED CLASS BOUNDARIES (METERS/SECOND)


### NOTES: DIAGRAM OF THE FREQUENCY OF OCCURRENCE OF EACH WIND DIRECTION. WIND DIRECTION IS THE DIRECTION FROM WInCH THE WIND IS BLOWING. EXAMPLE

- WIND IS BLOWING FRO;! THE NORTH 4.6 PERCENT OF THE TI::E. 

# FIGURE 1 WINDROSE STATION NO: 99999 PERIOD: 1999 FILE: WYODAK99.ASC PACIFICORP WYODAK SUBMITTED BY B V

$ort .... [ 

# BEE-LINE TB002565 

# S ,11.0 

### 8.5 

### I



# ] 3.3 5.4 1.8

## Table 3 Stack Parameters and Emission Rates or WYGEN 2 Sources

Flow**I~** 

### ;1} 1.978.496 1,483.872 989,2411 1,978, 1,483.812 989,248 Os Vs 

### Emission Sources and Stack Parameters Represented in BHC W GEN 2 WAAQS and PSD Modeling Analyses Modeled UTM Zone 13 Modeled Paramclers (SI11011.11 Source UTM (N) Elev. 115 1'5 Vs Os

### ~Hgk' 500 MW PC Boiler (100% Load) ASTKl00 469.435 4,903.973 500 MW PC Boiler 05% Load) ASTK75 469,435 4,903,973 500MW PC Boller (50% Load) ASTK50 469,435 4,903,973 500 MW PC Boiler (100% Load) STSTKl00 469,435 4.903.973 344 20.00 500 MW PC Boiler (75% Load) STSTK75 469.435 4,903,973 344 1500 500 MW PC Boller (50% Load) STSTK50 469,435 4,903,973 344 10.00 

## n Coal Silo Dust Collector (Top) CDCOOI 469,197 4,903.574 1.344 67.67 293 10.35 1.143 3.1 222.00 68 33.95 3.75 22.500 Coal Silo Dust Collector (Bottom) CDC002 469,209 4,903.576 1,344 2.44 293 10.43 0.635 1.1 8.00 68 34.22 2.08 7.000 Coal Transfer Bldg Dust Collector CDCl103 469.384 4,903.636 1,344 2.44 293 10.43 0.635 1.1 800 68 34.22 2.08 7.000 Unil Transfer & Silo Dust Collector CDC004 469,508 4,903,868 1,341 78.64 293 10.28 1.346 5.1 258.00 68 3372 4.42 31.000 FGD Wasle Storage Bin Dust Collector RDCOOI 469.491 4.903.920 1,341 20.12 293 10.35 0.381 0.9 66.00 68 33.95 125 2.500 Lime Unloading Silo Dust Collector A LDCOOIA 469.467 4,903,869 1.341 42.67 293 11.18 0.254 0.4 140.00 68 36.67 083 1.200 Lime Unloading Silo Dust Collector B LDC001B 469.467 4.903.869 1,341 42.67 293 11.18 0.254 0.4 140.00 68 36.67 0.83 1,200

. ;1' 'VaSle Loadoul Silo Dust Collector AI RDC002A 469.518 4,903.977 1.341 44.20 293 10.56 0.533 1.8 145.00 68 34.65 1.15 5,000

I ( ;i Llle FGD Waste Loadout SUo Dust Collector will be operated at any time. ,rt-term emission rates used In modeling analyses. Bolb Silo Dust Collectors have the same slACk parameters and proposed PMIO emission rates. I I 

## I

I

### I I

,Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP·C92 Page 28 Both the WAAQS and incrementmodeling analyses included several interactive (nearby) sources of**S~,** which are provided in Table 3a. Emission rates for all sources were represented in the modeling analyses based on an operational schedule of8,760 hours per year. Good Engineering Practice lGEP) Stack Height Determination: The building downwash effect on aplume is governed by the projected buildir::-; width, the building height, the exhaust stackheight, and the relative location ofthe exhaust stack :.;) :ny nearby buildings or structures. The applicant used Trinity Consultant's version ofthe EPA Buildin<:: .Jrofile Input Program (BPIP) to determine downwash parameters to include in the model runs for eaC.l :lew source at the WYGEN 2 facility. The BPIP software program performs adetailed**downwas~** analysis using the most currentEPA approved BPIP to determine Good Engineering Practice (GEP) 

### su.:.: height for each source. A comparison ofthe BPIP calculated GEP Equation #1 stack heights versus the: ;:roposed stackheights for all point sources at the WYGEN 2 facility indicates that the proposed stack ::eightofthe PC Boiler is equal to GEP, and the particulate handling sources are all less than the GEP Ec;c:"'tion #I stack height, or below GEP. Therefore, direction specific building dimensions for all structures •.1athave the potential to induce building downwash on the particulate handling sources at WYGEN 2 \\ ''; used in the modelit.:!g.

_ --------1;s:nir m utrlations;-Adcumparisonofth'e'catculated GEP EquatIOn 1fTSfilCKheighiS**ve.-s~s** the proposed stack heights for the new sources at the WYGEN 2 facility is provided in Table 4.
Table 4 WYGEN 2 Proposed (Modeled) StackHeight vs. Calculated Maximum GEP Equation 1 StackHeieht
Source ill Source Description Proposed Stack GEP Eq. 1 Heieht (m) Stack Heif;?;ht (m) PCSTK100 PC Boiler 190.5 190.5

CDC001 Coal Silo Dust Collector (Top) 67.7 174.5 CDC002 Coal Silo Dust Collector(Bottom) 2.4 174.5 CDC003 Coal Transfer Bldg DustCollector 2.4 187.5 CDC004 UnitTransfer & Silo Dust Collector 78.6 190.5 RDCOOI FGD Waste Storage Bin Dust Collector 20.1 190.5 LDC001A Lime Unloading Silo DustCollectorA 42.7 190.5 LDCOOIB Lime Unloading Silo DustCollector B 42.7 190.5 RDC002A FGD Waste Loadout Silo Dust Collector A 44.2 190.5

K JI [II 'HI 

## Fnn Wpdp

## T .nlllrinl1t**~iln** nm:t 

### r, R 44 ? lQO Ii

1Only one ofthe two (2) FGD Waste Loadout Silo Dust Collectors will be operated at any time.



### TB002567

## Table 3a Stack Parameters and Emission Rates for Interactive Sources ofS02
Interactive S02 Emission Sources and StackParameters**Repres~nted** 

### in WAAQS and PSD Modeling Analyses Modeled Consumes lITM Zone JJ lSI HnILs) Modeled Parameter:! (English llulU) Source SOJ UTM (E) UTM (Nil Eley. Vs Ds 115 Ts Vs Ds Flow (ID) (ft) (odm)

TB002S6H Page 1 of 1BlackHiEs Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-C92 Page 29 

### Receptor Grid: The near-field (WAAQS and PSD Class II) modeling simulations were conducted using the receptor configuration shown in Figure 2, with the exception that the additional (11 x 11 matrix) 100 meter fine grid was only added into the receptor grid for the NO. and S02 analyses. Receptor locations used In 

### the far-field modeling analyses are described in the associated text. The modeling analyses were completed using 1,188 discrete Cartesian receptors in a nested rectangular grid network that extended 15 kilometers from the location ofthe proposed WYGEN 2 facility. The receptor grid network consisted ofreceptors laid out using: 100 meter spacing from the property line out to**appro;~imately** 

### 3 kilometers (eastboundary) to 8kilometers (west boundary), 500 meter spacing out to 5 kilomc::=rs, and 1,000 meter spacing out to 15 kilometers, along with discrete receptors placed along the faci;;:y fence line. Specifically, eighty-one (81) discrete Cartesian receptors were placed at 50 meter intervals**~long** 

### the Wyodak complex fence line. Recepto:- :ocations used in the near-field modeling analyses were interpolated from electronically formatte

.. terrain maps in the vicinity ofthe WYGEN 2 facility. The terrain data have been created from United**~-~~es** 

### Geological Survey (USGS) 7.5 minute Digital Elevation Model (DEM) files, and include**---------7(X--mld1·~** 

### .JcarionnrrUTM-cOOl'dirunes, anae1evabons 10 

### eIther feet or meters. The density ofthe terrain datapoi- ; is approximately 30 meters inboththe east-west and north-south directions, and does not vary with latitude. 

### Atwo-dimensional representation of the local topography, based on the elevations ofthe selected receptors is shown in Figure 2a.


### WYOMING AMBIENT AIR QUALITY STANDARDS (W

### AAQS) ANALYSIS As 

### stated earlier, the applicant used the on-siteWyodakmeteorological data in arevised modeling analysis for the proposed WYGEN 2 facility, and demonstrated that the ambient impacts from the proposed WYGEN 2 facility were greater

### than the PSD Class II SILs for So.z for the 3-hour and 24-hour averaging periods. Therefore, according to EPA guidance, the applicant is required to conduct a full impact analysis for this criteriapollutant, which includes considering emissions from interactive or nearby emission sources (proposed and existing), and separate analyses for the WAAQS and PSD increments.

• SulfurDioxide (S02) • The applicant modeled the proposed S02 sources at the WYGEN 2 facility, along with the emissions of S02 from nine (9) nearby (interactive) sources to determine compliance with the 3-hour, 24-hour and annual WAAQS of 1300 Jlg/m 3

, 

### 260 Jlg/m3

, 

### and 60 Jlg/m), respectively. The highest second highest (HSH) modeled 3-hour and 24-hour ambient**S~** 

### concentrations were 327.1 Jlg/m3 

### and 124.2 Jlg/m3
, 

### respectively, and the maximum model predicted annual So.z concentration was 9 Jlg/m3• 

### Results ofthe WAAQS analysis for S02 indicate thatthe modeled concentrations from all S02 sources are below the 3- hour, 24-hour and annual WAAQS for S02after adding in S02 background concentrations to the model predicted impacts. Based on the results ofthis analysis, the Division is satisfied that the WAAQS for S02 will be protected. Results oftheWAAQS modeling analysis for S02 are provided inTables 5-7. Isopleth plots ofthe 3-hour, 24-hour and annual modeled So.z impacts are shown in Figures 3-5, respectively.



### TB002569

## FIGURE 2 

# BHC WYGEN 2 RECEPTOR GRID USED IN MODELING ANALYSIS FOR S02 455000 460000 465000 470000 475000 480000

4915000 4915000

4910000

_ C1 

## a



# ... a E 

# - 4905000 

### C! 

# :zttl:

### EIX


### , 4900000 

# .I! 

# .,I 

## ..... i 

## ..... , 

## -, 4895000 r : 

## 1
..J! 4890000



### i
480000 475000 470000 ......**:--:_.,~.** 8MCwrOEH 2**f~U~'1**

### ·--~·d;:

465000**--------------~------** --- -

460000 455000 4900000

4895000

-

'--;-'**--~_** .. T -'---'------'----- -'----"---'-----'-----'----------,-- 4905000

--

4890000 _ 4910000 CI) 

### J.4 Q) +J

### -----aJ

# a 

# -

UTM EASTING 

## (meters)
Total Receptors in grid = 1819 receptors Fence line Receptors = 81 receptors



### TB002570

## FIGURE 2a ELEVATION CONTOURS REPRESENTING**LOCJ~** 

## TOPOGRAPHY IN WYGEN 

# 2 MODELING**ANAL~~ES** 460000 462000 464000 466000 468000 470000 472000 47"::0 476000 478000

4900000

4894000 4896000 4898000 4902000 4904000 

### t! 

# :z :I

### EC£



### E

### O 4908000 

# - Ci $. Q 4906000 

### + Q 

# e

.... 4910000 4912000 1380 l.> O.



# , \ , \ , f, 

## " '< \ , 

# ,".

, 

## .,.. ,N

, 0 , .,- 

# -- , ',i /
-- '.



# -" 

## / / 

# / /

4898000

4896000

4894000 4900000 4902000 4904000 4910000 4912000

4908000 

# - (I) Q) +J 

### <rnOsooo Q) 

# a 

# -

460000 462000 464000 466000 468000 470000 472000 474000 476000 478000 

## UTM 

## EASTING (meters)

CONTOUR INTERVAL 

### = 20 Meters



### TB002571

# FIGURE 3 WAAQS ANALYSIS - HSH 3-HOUR S02 CONC IMPACTS FROM WYGEN 2 + 

## NEARBY SOURCES 455000 460000 465000 470000 475000 480000

.-. - _. _. - 

### - ----._-- ... 

# .. '

0- I/') 4915000 4915000



### t! 

## 2 I- 

# ::r J): 4900000 C 

## 2

to- 

# ... 4895000 4910000

_ 

### u ). Q 

## + -Q



# e

....

.. 4905000 So· 

### / 

# " I**~-_.** - .• .,."..**.~**
., \/**~,**



# (J-so-j**So~,\** 

# ,r-"", ,;>t)[ 4890000

# L...-,---l----J.,--!..-~~-~,**--'~ ~,_,**  _'

__ 

# _LJ - til Cl



# - 4890000

## .~**~l ~.~**  • IQ 

# - 4910000 (J) 

### <U -IJ 

### <U 

# a 

# - 4905000 C!) 

### Z H 

# :z: E-i 

### 0 4900000 

### Z 

# rJ p

455000 460000 465000 470000 475000 480000 

# UTM EASTING (meters)

HSH Modeled 3-HR Impact

- 1999 Pacificorp Wyodak Met Data
(BACKGROUND NOT INCLUDED)



### TB002572

## FIGURE 4 WAAQS ANALYSIS - HSH 24-HOUR S02 CONe IMPACTS FROM WYGEN 2 + 

## NEARBY SOURCES 460000 465000 470000 475000 480000

4915000 4915000

4910000

_

J i

4895000 .J i 

# ., I 

### i, 

# i 4890000 . 

### ---.\

" / , ' -./ I r--

### J

--_....:....**-'-~-' --~**  

### <0.-\

I /

/ I 

### a $. Q

. / \ \ 0+-

. - ....•

# ~: " ,./ 0

# .,.~~.~:>--,-=,--- -

# ~905000 

# -.' '

__."-6>**~.-** 

# .'/ H5H

### 2~HR 502 Pedicted Impact.

## i

. .. '::." .,_.'

. 124.2 ug/m3 at (470,024; 4,902,800):

,.**~~." .~.-**  '.**~()** ,/:\**~.>** ,"

.. _. ....l.-....:..-

__•

__ ._ ... .. WYGEN 2 FENCE UNE
.

.

### _----- , 4890000 -,i
, 4900000

4895000

- 4905000 _ 4910000 (I) OJ +l OJ 

## ----S-


# -

455000 460000 465000 470000 475000 480000 

## UTM EASTING 

## (meters)

HSH Modeled 24-HR Impact

- 1999 Pacificorp Wyodak Met Data
(BACKGROUND NOT INCLUDED)



### TB002573

## FIGURE 5 WAAQS ANALYSIS - ANNUAL S02 CONC IMPACTS FROM WYGEN 2 + 

## NEARBY SOURCES 455000

4915000

4900000



## .- 4895000

.. 

# '" 460000 465000 470000 475000



### /
\ 

# -'- 480000

\ 4915000

4910000 

# ... l I ( 4 ( 

# , 4905000

4895000

4890000

455000 460000 465000 470000 475000 480000 

## UTM EASTING (meters)
Annual Modeled Impact

- 1999 Pacificorp Wyodak Met Data
(BACKGROUND NOT INCLUDED)



### TB0025i4Black Hills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 30 The S02 contribution from the sources at the proposed WYGEN 2 facility at the maximum impact receptor location was 14.7 j.1g!m3 (HSH 3-hour), 2.4 j.1g/m3 (HSH 24-hou:) and 0.1 llg!m3 (annual), which indicates that less than 5% ofthe maximum modeled**S~** impact from a:: sources can be attributed to the emissions ofsulfurdioxide from the proposedWYGEN 2 facility. Table 5 

### Highest Second Highest 3-HourSOl Modeling Results for WAAQS Analysis Receptor Percent Modeled Location HSH Background To::' 3-Hour of

Year 3-Hour 3-Hour 3-Hour S02 3-hour (Zone 13) SOl Cone. S02 Cone. S02 CC71C. WAAQS WAAQS X(m) Y(m) (uwmJ) (llwm3) (uJ;. :-:-j) (llg/m3) for**SO~** 1999 468724 

# I 4903400 327.1 99 42C._ 1300 33% Table 6



### --- ----HighestlIecond**Highest-2~HourSOiMolieling-Results** 

### ic"W

### AAQS·AnalysIs Receptor Percent Modeled Location HSH Background Total 24-Hour of

Year 24-Hour 24-Hour 24-Hour S02 24-hour (Zone 13) S02 Cone. S02 Cone. S02 Cone. WAAQS WAAQS X(m) Y(m) (llg!m3) (llg!m3) (Ilg!nr) (llg/m3) for**SO~** 1999 470024 

# I 4902800 124.2 36 160.2 260 62% Table 7 

### Annual S02 Modeling Results for WAAQS Analysis Receptor Percent Modeled Location Maximum Background Total Annual of

Year Annual Annual Annual S02 Annual (Zone 13) S02 Cone. S02 Cone. S02 Cone. WAAQS WAAQS X(m) Y(m) (llg!m3) (j.1g/m3) (llg!m3) (llg!m3) for SO, 1999 470024 

# I 4902700 9 3 12 60 20%



### • Hydrogen Fluoride (HF). Total hydrogen fluoride (HF) emissions from theproposedWYGEN 2 facility will be 8.5 TPY. HF emission factors were detenninedbased on a 1991 WyodakMine coal analysis which indicated 63.0 ppm by weight fluorine content. Itwas assumed that all fluorine in the coal is converted to HF when the coal is combusted. HF emissions will be controlledthrough the use ofspray dryer absorbers in conjunction with abaghouse system. The HF acid gases will react with the calcium oxide (CaO) 

### in the SOz scrubbing process. The resulting particulate, calcium fluoride (CaFJ, is then removed by the fabric filter baghouse.



### TB002575Black Hills Corporation (WYGEN 2) Pennit Application Analysis, NSR-AP-C92 Page 31 

### The applicant modeled the proposed HF e:r:ssions to determine the maximum I2-hour, 24-hour, 7-day, and 30-day concentrations ofHF on the am"::>ient air quality. The HF impacts were based on the maximum model predicted concentration ;::.Jffi 

### the applicant's ISC3 model simulation for the PC boiler stackusing an emission rate input of0.2<15 :..,Tams per second. The ISCSD model does not have an optic:-. for calculating impacts for a7-day averaging period. Therefore, the 24-hour impacts were**assu:-:.~d** 

### to conservativelyrepresent the 7-day impacts. The maximum predicted HF impacts are sumrr.:.rized in Table 8. Based on the results ofthis analysis, it is apparentthat the modeled impacts ofHF are well below Wyoming's standards, and no violations ofthe Wyoming standards for HF were predicted. Table 8 

### HF Modeling Results for WAAQS Analysis Averaging Maximum Predicted HF Standard

Period Concentration**(~glm3) (~g/m3)** 

-- 

### If.015-- 12nours 3.0 24 hours 0.001 1.8

7 days 0.001 0.5 30 days 0.002 0.4 Hazardous Air Pollutants <HAPs) Analysis: Emissions associated with

## thePC Boilercontain certain pollutant species which are listed underTitle III ofthe U.S. Clean AirAct Amendments of 1990, as Hazardous Air Pollutants (HAPs). The HAPs emitted in the greatestquantities are benzene, chromium, cyanide, hydrogen chloride, hydrogen fluoride, manganese, nickel, and selenium. Specifically, it was estimated by the applicant that emissions of hydrogen chloride would be 68 TPY, and t.;e total potential HAPs emitted by the PC Boiler are estimated to be 110 tons per year (TPY). The applicantmodeled ambient air concentrations from fifty-five (55) different HAPs at orbeyond the facility property line using the ISCSD model. A constant emission rate of 10 lblhrwas used in the modeling simulations, and the modeled concentrations were ratioed up or down using the estimated HAP emission rate to derive the individual impacts from eachHAP. The HAP concentrations were predicted by the model for I-hour, 8-hour, 24-hour, and annual averaging periods. The HAP concentrations were compared to pollutantimpacts listed 

### in the National AirToxics Information Clearinghouse's (NATICR) Data Base ReportofFederal, State, andLocal AirToxics Activities (September 1992). The NATICH database lists Acceptable AmbientLevels (AALs) 

### for I-hour, 8-hour, 24-hour, and annual averaging periods for various states in the United States. Wyoming has not established standards for the HAPs listed in the NATICH Data Base, therefore the modeled HAP concentrations were compared to the least stringent and most stringentAALs found in the NATICH database for each emitted HAP and applicable averaging periods.



### TB0025i6Black Hills '::vrporalion (WYGEN 2) Permit Appi.:ationAnalysis, NSR-AP-C92 Page 32 A total of220 modeled concentrations (55 HAPs x 4 averaging periods) were compared to the available concentrations listed in the NATICH data base, and nineteen (19) ofthe 220 comparisons were found to exceed the most stringent AALs, with some ofthe 19 values representing the same HAP for a different averaging period, and none ofthe modeled HAP concentrations exceeded the least stringent AALs. A listing ofthe HAP impacts compared to most stringent and least stringentNATICH AALs are provided In Table 9. It shouldbe noted that a large majority ofthe modeled HAP concentrations were one to four orders ofmagnitude lower than the corresponding AALs referenced in the NATICH data base. Gfthe fifty-five HAP pollutants emitted by the proposed WYGEN 2 PC Boiler, seven (7) HAPs are listed as known or suspected carcinogenic compounds as referenced in EPA's Integrated Risk Information System**(~S)** Data Base. A unitrisk factor was obtained for each ofthese seven (7) compounds to calculate t::e incremental risk associated with inhalation due to long-term exposure. The unit risk factors have been cenved to quantify the number ofpeople that could potentially contract cancer per million people in**2~** average population. The risk factors are extremely conservativebased on the assumption that the saro.,Jledpopulation will be exposed to the maximum model predicted concentration ofthe carcinogen ofinterest for 24 hours per day over aperiod of70 years.**--The-increr::~:1tahisk-asscrciJnedwtthmh-alanon**due tolong-term exposure was calculated by multiplying each maxi:--.:m model predicted annual HAP concentration by the unit risk factor for each ofthe seven HAPs, and multiplying this estimated value by one million to determine the risk on the basis of 1 in a million. Results ofthe risk assessment are shown below:



### Pollutants Acetaldehyde Arsenic Beryllium Bromoform Cadmium Chloroform Formaldehyde 

### Modeled Concentrations

5.9 

### x 10's 

### Ilg/m3 6.2 

### x 10's Jlg/nt 1.2 

### x 10's Jlg/m 3 4.0 

### x 1**O~** 

### Ilg/m3 5.3 

### x**10~** 

### Ilg/m3 6.1 x 1**O~** Jlg/m 3 2.5 

### x 10's Jlg/m3 

### Unit RiskFactors 2.2 

### x 

### 1**O~** 

### m 3

### /Jlg 4.3 

### x 10.3 

### ml/Jlg 2.4 x 1003 m3

### /Jlg 1.1 

### x**10~** 

### m3

### /Jlg 1.8 x 10.3m)/Jlg 2.3 

### x lO-s

### m3/llg 

### 1.3 x 

### lO' sm)/llg 

### Calculated Risk Less than IlMillion 

### Less than IlMillion Less than IlMillion Less than IlMillion Less than IlMillion Less than I

### 1Million Less than IlMillion The risk assessment indicates that the calculated risk ofcontracting cancerdue to long-term exposure from any ofthe seven (7) carcinogenic HAPs is less than one in a million. This analysis has addressed the estimated carcinogenic HAPs from this modification, and the results indicate that the operation ofthe proposed WYGEN 2 facility shouldnotpose any extreme risks from long-term exposure.


### PREVENTION OF SIGNIFICANT DETERIORAnON (PSD) ANALYSIS Based on the results ofthe significant impact analysis, the BHC must conduct ambient air quality analyses to evaluate the impact**ofS~** emissions from the proposed WYGEN 2 facility, including all interacting increment consuming sources ofSO:z located within the significant impact area 

### + 50 Ian ofthe proposed modification to demonstrate compliance with applicable PSD Class 1and Class II increments. Additionally, as required by Wyoming Air Quality Standards and Regulations (WAQSR) Chapter 6, Section 4(b)(i)(B), the applicant must submit additional impact analyses related to impacts on visibility,



### TB002577

### Table 9 I 

### Comparison ofModeled HAP Concentrations

## fro~ WYGEN 2 to NATICH Values

\

I

=' 

### Hazardous Air Pollutant Impacts Compared to the Most Stringent and Least Stringent 

### NATICH Limits NATICII NATICH NATICH NATfH NATICH NATICH NATICI·1 NATIOI

Most leasl Most le sl Most leost Most I.cnsl Stringent Slrlngcl1l Stringenl Slrln&enl Slrlngenl Stringent Sfringcnl Siringcni Annual Annual Annual I-llour I-Hour I-II0ur 8-lIour 8-Hour g-Hollr 24-lIour 24-lIour 24-IIOllr Impact Impacl Impacl Impacl Impaci Imp,cl Implel Impact Impacl Impact Impacl ImpOtl l'ollUlanl (ltg/ml ) (ug/m') (Ilg/m') "IKlm') (Ilg/m') (1lg/111 1) (ltg/m') (ltg/m') (ltglm') (Ilg/m') (ltg/m') (Ilg/m') 2.4-Dinilrololuene 2.90E-oS 1.I0E-02 1.50E-02 41S7E-06 4.20£+01**4.20E~01** 1.22E-06 1.50e-02 3.57E+01 460E·07 3.60e+00 1.50E+01 2·Chloroacetophenone 7.25E-07 3.20E-01 3.20E-01 1.22E-04 

### - 3.06E-05 3.00E-03 6.00E+00 1.15E·05 7.20E-oI 7.50E+00 Acetaldehyde 5.90E-05 4.ooE-01 5.00E-OI 9.9IE-03 2.70E+00 

# ,JOt] 2.49E·03 I.SOE+OO 4.29E+03 9.36E-04 4.S9E+00 1.80£+04 Acelophenone I.SSE-06 1.00E+02 1.00E+02 2J61 E·04 1.50E+02 1.50E 02 6.55E-05 

# - 2.46£-05 4.00£+00 4.9IE+03 Acrolein 3.00£·05 4.00E-04 8.30£-0I 5;04E·03 690E-03 6.70£ 00 1.27£-03 2.30£-03 5.40£+00 4.76£-04 6.00£-01 380E+05 Antimony 828£-06 3.00E-01 4.00£+01 1.39E·03 1.50£+01 1.50E+01 3.49£·04 5.00£-03 1.19E+01 1.3IE-04 1.20£+00 1.00E+01 Arsenic 6.2IE-05 2.30E-07 670E-01 1.04£-02 3.20E-01 3.20Elol 2.62E-03 2.00E-03 2.00E+00 9.86E-04 2.00E-02 3.30E+00 Benzene 1.35E-04 I.OOE·OI 1.00E+02 2.26E·02 6.30E+02 

# .,DEr 5.68E-03 3.00E-01 1.60E+02 2.14E-03 1.14E+00 320E+02 Benzyl Chloride 7.2SE-05 1.00E-02 1.67E+01 1.22E·02 2.00E+01 2.00E 01 3.06E-03 5.00E-02 1.00E+02 1.15E-03 7.34E+00 1.03E+02 Beryllium 1.24E-05 4.IOE·06 1.00E-02 2.09E-03 6.00E-02 6.00E 02**5.2'F.-O~** 2.00E-05 2.00E-02 1.97E-04 1.00E-03 2.00E-02 Biphenyl iliF.-07 1.00E-02 S.OOE+OO 296E-05 742E-06 1.30E-02 3,IOE+01 2.79E-06 3.40E-01 1.26E+02 Bls(2-elhylhexyl)phlhalote 7.56E-06 2.30E-01 1.20E+02 1.27E·03 1.00E-01 

# 'JOT 319E-04 S.00E-02 SOOE+OI 1.20E-04 3.00E-02 200E+02 OrOlllororm 4.04E-06 1.00E-02 S,OOE+OO 6,78E-04 150E+02 ISOE 02 1.70E-04 520E-02 1.00E+02 641 E-OS 1.20E+01 5 I7E+02 Cadmillm 5.28£·06 5.50E-06 I67E-01 887E-04 170E+00 I 70£ 00 2.23E-04 1.00E.()4 5.00E-01 838E-05 3.00E-03 8.30E-01 Carbon Disulfile 1.35E-05 1.00E·02 1.00E+02 2.26E·03 910£+01 9.IOE 01 

### 5.6sE-04 3.00E-01 8.60E+01 2.14E-04 1.86£-01 7.14£+02 Chlorine 

# - I.5E+OO 1.00E+01 2.90E·02 6.90E 01 1.50E-02 6.00E+01 

### - 3.75E-02 750E+01 Chlorobenzcne 2.28E-06 

### - 3.83E-04 

# - 6.00E±' 961E-05 

### - 36IE-05 Chlororornl 611E-06 4.30E-03 1.67E+02 103E-03 600£+01 2.58E-04 5,00E-01 1.20E+03 969E-OS 1.60E+01 490E+02 Chromium 2.49E·04 8.30E-08 680E-OI 4.17E-02 I.IOE+OI 1.1 OE 1 1.05E-02 5.00E-04 2.S0E+00 3.94E·03 1.20E-01 8.30E+00 Coball 4.14E-05 5.00E-02 3.30E-01 6.96E-03 

## - - I 1.75E-03 5.00E-04 2.00E+00 6.51E-04 120E-01 S.30E-01 Cumelle 5.49E-07 9.00E-OJ S.83E+02 9.22E-05 

# - I 2.31 E-05 2.46E+OO 5,86E+03 8.71 E-06 588E+02 246E+04 Cyanide 2.S9E-04 5.00E+01 167E+01 435E-02 

### - 1.09E-02 5.00E-02 HOE-OI 4.11 E·03 830E+01 I 25E+02 Dimelhyl SlIlfnle 4.97E-06 1.00E-02 2.40E+00 8.35E-04 

### - \ 2.IOE-04 5.00E-03 250E+00 7.88£-OS 3.00E-03 S.20E+OO Elhyl Chloride 4.35E-06 

### - 7.30E-04 

### . I 1.83E-04 

### - - 6.90E-05 

### - Elhylbenzene 9.73E-06 1.18E+02 1.45E+03 1.63E-03 4.50E+03 4.50E+/lJ 4.IOE-04 4.34E+00 4.35E+04 I.S4E·04 1.ISE+02 4.34E+04 Elhylene Dlbromide 1.24E-07 6.70E-OS 2.47E+00 2.09E-05 910E-02

### 9.IOE-~2 5.24E-06 720E+02 ISSE+03 1.97E-06 240E-02 770E+02 Elhylene Dichloride 4.14E-06 3.80E-OJ 1.48E+02 6.9SE-04 530E+01 530E+ 3 1.75E-04 400E-01 1.00E+03 6.57E·05 960E+00 670E+02 Fluorine 

### - 2.00E-01 S.OO£+OI 3 IOE-02 600E+00 160E-02 2.00E+02 4,80E-0I 270£+01 Formaldehyde 2.49E-05 7.69E-02 7.69E+00 417E-03 2.00E+01 200E+QI 1,05E-03 ISOE-02 1.80E+01 3.94E-04 3.30E-01 1.20E+01 lIexane 6.94E-06 1.76E+02 1.76E+02 1.1**~E-03** SJOE+03**5.30E+d~** 293E-04 I76E+00 3,60E+04 1.IOE-04 I.IOE+OO 290E+04 Note: Facility exceedances ofthe NATICH limits are presented in bold and underlined. I

'£8002578

### Table 

### 9 (CODtiDuel Comparison ofModeled HAP Concentrations from WYGEN 2 to NATICH Values I

1 

### Hazardous Air Pollutant Impacts Compared to the Most**Stri~gent** 

### and Least Stringent NATICH Limits NATICH NATICH NATICH NATIC;:H NATICH NATICH NATICH NATICH

Most Least Most Leasl Most Least Most Lell5t Stringent Stringent Stringent**Slring~nt** Stringent Stringent Stringent Stringenl Annual Annual Annual I-Hour I-Hour I-Hour 8-lIour 8-Hour 8-Hour 24-Hour 24-Hour 24-Hour Impact Impact Impacl Impacl Impact Impa¢t Impact Impact Impact Impaci Impact Impact Pollutant (Ilg/m') (Ilg/m') (J.lg/m') (ilg/m') (Ilg/m') (J.lg/m 'l) (J.lg/m') (Jlg/m') (J.lg/m') (JIg/m') (J.lg/m') (Jlg/m') Hydrogen Chloride 4.97E-03 1.00E-01 1.40E+02 8_35[-01 7.50E-02**2.00~j~3** 2.10£-01 1.40E-01 1.80E+02 7.88E-02 2.03E+00 2.00E+03 Hydrogen Fluoride 6.21 E-04 340E-01 1.00E+02 j"]4[:'Oi 260E-02**5.63E.~2** 2.62[-02 2.50E-02 6.19E+01 986E-03 3.00E-02 1 88E+02 Isophorone 6.0IE-05 2JOE+01 8.33E+01 1.01 E-02 2 80E-0I 280E- I**2~3E·03** 250E-01 4.60E+02 9.53E-04 600E"01 226£+03 Lead 416E·05 700E·02 1S0E"00 698[·03 1.7SE-OJ I 50[·03 3.00E·'00 6.60[-04 1.40E·01 251lF+01l Mangnnesc 580E-04 I 2.40E·0I 1 19E"02 9.7-4[-02**3ll0E-II~** 250l:+PI USE-02 1.00[·02 500E+01 9.20E·03 3 IOr·02**100E~m** Mercury 2.01 E-05 1.00E·02 2.40E-01 

### :J17E-iD 1.50E+00 1S0E+PO 8.47£-04 HOE·04 200E+00 3.19E-04 6.00£-04 1.70£+04 Methyl Bromide 1.66E-OS 6.00£-03 4.80E+02 278E·03 5.00E+02**5.00E~2** 699E·04 190E-01 4.00E+02 263E-04 528E+00 320E+02 Methyl Chloride 549E-05 1.00E-02 2.52E+03 9.22E·03 2.07E+00 HOE I 2.3 I[-03 1.03E+00 2.IOE+·03 8.71£-04 9.50£+00 1.70£+03 Methyl Elhyl Kelune 4.04E-05 321E+01 197E+03 6.78E·03 885E+00 740E+P3 1.70[-03 590E+00 1.40E+04 6.41 E-04 370E+00 5.90E+04 Melhyl Hydrnzine 1 76E-OS 2.20E·02 1 17E+00 2.96E-03 300£+0(J 300E+00 742[-04 ROOE-03 1.90E-01 279£-04 4561'.-02 1.901'.+00 Melhyl Maerylllic 2.01E-06 2.23[+(J 1 I 37[+03 3481:·0-1 

# 760;1'**R7JE-O~** 4.10[+00 4.10[+04 329E-05 820EI(J0 103E+O,( Mcthyl Ter! Ulltyl Ether 3.62E-06 

### - 6.09E-04 

## - 1.53[-04 5.7SE-05 Methylene Chloride 3.00E-05 240E-02 84E+03 5.04E-03 1.74E+01 1.21E-03 180E+00 1.00E+03 4.76E-04 9.45E+00 875E+03 Naphthalene 1 35E-06 1.43E+01 1.67E+02 226E-04 7.90E-01 6.30E+ 2 5.68E-OS 5.00E-01 1,00E+03 2.14E-05 1.43E+01 500E+04 Nickel 3.11 [-04 3.30E-OS 3.30E+00 S.22E-02 570E+00 5.70E+bo 1.31 [-02 2.00E·03 S.OOE+OO 493E-03 6.00E-03 1.70E+01 Phenol 1.66E-06 1.90E+01 4.56E+02 2.78E-04 9.50E-01

## 3.20~+r2 699E·OS 190E·01 1.90E+03 2.63E-05 4.56E+01 320E+02 Polychlorinated Dibel1l0hlfftl1s 2.08E-08 349E-06 

### - 878E-01 3.30E-07 

### - Polychlorinated Dibenzo-p·dloxlns 4.43E-09 7.44E-07 

### - 1.87E-07 

## - 7.o3E-08 Propionoldcyde 3.93E-OS 

### - - 6.6IE-03 

### - - 1.66E-03 4.29E+03 4.29E+(l1 r ., --: 01
- Selenium 1.3SE·04 200E-01 4.80£+00 2.26E-02 6.00E+00**6.00E~0** 5,68[·03 200E-03 4.76EIOiJ 2**:~** CJ 4::: ')I 2(E JI Styrene 2.59E-06 1.15E+00 7.16E+02 4.35E-04 1.06E+01 3.50E 3 1.09E-04 213E+00 S.07E+03 4.11 E-05 J34E+00 213E+04 Tetrachloroethylene 4.45E-06 1.00E-02 804E+03 7.48E-04 137E+01**1.IOE+~4** 1.88E-04 339E+00 3.75E+03 1.06E-05 7.10E+02 5.70E+03 Toluene 2.49E-05 1.02E+0I 7.50E+03 4.I7E-03 I.OOE+OO 4.70E+ J I.OSE-03 377E+OO 8.90E+03 3.94E-04 4.70E+00 317E+04 Vinyl Acetate 7.78E-07 9.57E+00 I.SOE+OI 132E-04 7.00E·01**7.00E-~1** 332E·.05 3.50E·0I 830E+02 1.25E-05 4.00E-01 580E+02 Xylcnes (0 And 111) 3.83E-06 1.18E+01 1.45E+03 6.43E-04 65 IE+OO S.50E+ 3 I 62£-04 4.34£+00 103E+04 6.08E-OS 2.10E+00 4.34E+04 Note: Facility exceedances ofthe NATIel! limits are presented in bold and underlined.

'1'8002579Black Hills Corporation (WYGEN 2) PermitApplication Analysis. NSR-AP-C92 Page 33 soils and vegetation, acid deposition and secondary growth effects associated with the proposed modification. PSD Class II Increment Consumption:

• Sulfur Dioxide (SOl) • The proposed**SO~** emissions from the \-IYGEN 2 facility are 3,381 TPY, which is above the PSD significant emission rate of40 TPY. 7;erefore, aPSD analysis is required under Wyoming Air Quality Standards and Regulations, Chapter 6, ection 4 (b)(i)(A)(I), to determine impacts from all**S~** sources within the significant impact area for ',.YGEN 2 which consume increment in Class II areas. The emission rates and stackparamete,::; for all proposed**SO~** sources at the WYGEN 2 facility are provided in Table 3, and the interactiv;;**~nearby)** sources ofS02' are provided in Table 3a. The applicant submitted a modeling analysis to com;::re the predicted impacts to the PSD Class II 3-hour, 24-hour and annual increment levels of512 Jlg/nt, 91 Jlg/m3 and 20 Jlg/m3

, respectively. Several ofthe interacting S02 sources are located at the Wyodal: (:omplex. which is also the proposed location ofthe WYGEN 2 facility. The highest second highest 3-hour ane' '"'4-hour ambient**S~** concentrations predicted in this analysis were 247.6 Jlg/m3 and 80.5 Jlg/m3

, respectively; the maximum model predicted annual**S~** concentration was 6 Jlg/m3• The SO:! contribution from all sources at the WYGEN 2 facility at the maximum impact receptor locations was 14.3 Jlg/m3 (3-hour) and 3.2 Jlg/m3 (24-hour), and 0.05 Jlg/nt (annual), which indicates that less than 5% ofthe modeled PSD Class II increment for**S~** is consumedby the sources at the proposed WYGEN 2 facility. Results ofthe PSD Class II increment analysis for SOz indicate that themodel predicted impacts from all S02 sources at the proposed WYGEN 2 facility are below the 3-hour, 24-hour and annual PSD Class II increments for S02' Therefore, the Division is satisfied that the proposed facility will not exceed the PSD Class II increments for**S~.** Isoplethplots showing the 3-hour, 24-hour and annual modeled So, increment consumption are shown in Figures 6-8, respectively. A summary ofthe ISCSTI model predicted concentrations from the increment consumption analysis are provided in Table 10 below: Table 10 Comparison of Modeled 

### S02 Impacts to PSD Class II Increments
PSD PSD Contribution Location Class II Class II from Averaging Modeled Increment 

### WYGEN2 Impact (l!g/m3) 

### UThl-E UTM-N Pollutant Period (lIo/mJ) (l!g/m3) (m) (m) Annual 6 20 0.05 469,424 4,903,100 S02 24-hour 80.5 91 3.2 469,324 4,903,100 3-hour 247.6 512 14.3 469,424 4,903.100



### TB002580

## FIGURE 6 PSD IC ANALYSIS - HSH 3-HOUR S02 CONC IMPACTS FROM WYGEN 2 

# + NEARBY IC SOURCES 460000 465000 470000 475000 480000

4915000 -. .__ ;_-L..,-_
..- - ..... _.

,-- '""-, 

# !

., 4915000

4910000 J 

# - (I)
I (lJ +J

# ~~ 

# - 4905000 ...J t!) 

### Z H 

## :x= 

## o**-~Z2i'** 4900000

4895000

4890000 WYGEN 2 FENCE UNE --\

. -, \

### ooסס491 , 

# ""**-~~** ....( 

# \**~~~ ~.>**  

# \ ','--' '1 :**,,/~** ...; (

# --os~~)':~; -=ur490SOOO c, I 

# 25,\ ",'\ .,**~.t; ,!~)**  

# 1 E 

## v· ""- / I !:iSH 3-HR502 Pedicted Increment

- 4900000 ( -SO>

.

### ~47.6 uglm3 at (469,424; 4,903,100)

_



## '"' 

# \"-

t I 

# ,,';J I, 0: 4895000 11)1 

### V 

# t

4890000

455000 460000 465000 470000 475000 480000 

## UTM EASTING 

## (meters)

HSH Modeled 3-HR Impact

- 1999 Pacificorp Wyodak Met Data



### TB002581

## FIGURE 7 PSD IC ANALYSIS - HSH 24-HOUR S02 CONC IMPACTS FROM WYGEN 2 + 

## NEARBY IC SOURCES 455000 460000 465000 470000 475000 480000

4915000 4915000

4890000 / 

## ._----"'_-" :........ II) 

# " r \

, I I 4890000 

# L

i i jO 4895000'

# l 

# f 4900000 

### o.I

### lii\~~ 4905000 ' _ 4910000 

## en QJ 

### +oJ



# -

455000 460000 465000 470000 475000 480000 

## UTM EASTING (meters)

aSH Modeled 24-HR Impact

- 1999 Pacificorp Wyodak Met Data



### TB002582

# FIGURE 8 PSD Ie ANALYSIS

- MAX ANNUAL S02 CONC IMPACTS FROM WYGEN 2 

# + NEARBY IC SOURCES 455000 460000 465000 470000 475000 480000

...**~,--._** .......,._---,**·I-·---·-~--** -.**-~_** .."---.-

_..

4915000

- .. 4915000 i 

### L I

_ 4910000 

# I fIl Q) +l : 4910000 • WYGEN 2 FENCE UNE

- 

### ,- I 

# (''-,
; 

### \ I 

# /\_" ,-./

# ----~- - - -

# "'~- - -'

# ----\_~----~.**--/;;~ "~**  ) 0 

### J---- 4905000

-- '\ 

### <..../ 

# .J 

# l 

# <tc \**~,~** "'1 

# 1
Annual 502 Pedleted Inc

..me,' Con,umptio,

# (,~ 6 ug/m3 at (469,424; 4,903,100) 

# r 

# 1 t!> 

## Z H 

### tI: 

### 0 4900000 

## Z
D
4895000 

# -

4890000

455000 460000 465000 470000 475000 

# UTM EASTING (meters)

Maximum Annual Impact

- 1999 Pacificorp Wyodak Met Data



### TB002583

# - BlackHills Corporation (WYGEN 2) PermitApplication Analysis,**NSR-AP-C~:** Page 34 

## Far-Field Modeling Analysis**~odeIJustification:** To evaluate potential impacts atreceo'')rs farther away than 50 

### km from the proposed WYGEN 2 facility, the applicant used CALPUF -;:hich is aLong Range Transport (LRT) model. Specifically, the CALPUFF modeling software packal'::**~onsists** ofameteorological data pre-processor (CALMET), an air dispersion model (CALPUFF), wL:h uses meteorological dataprocessedby the CALMET model, and apost-processorprogram (CALPCST) that uses the hourly concentration (ordeposition) values estimatedby CALPUFF to provide various outputs, including visibility impacts and acid deposition estimates. Although the CALPUFF model 

### has notbeen formally accepted as an Appendix A model listed in the Guideline on AirQuality Models, itwas designed and developed 

### as a generalizednonsteady-state airquality modeling system for regulatory use. A short description ofeach ofthe three models thatcomprise the CALPUFF modeling software package is providedbelow. CALMET

### Model: CALMET is a diagnostic model that develops hourly wind and temperature fields on athree-dimensional gridded modeling domain. Associated two-dimensional fields such as mixing height, surface characteristics**and~isper~ioni>roperrie£-{)f--the-terrain-are-inclnded**in the fi1e-produced bythe-cALMET model. CALMET includes a diagnostic wind field generatorcontaining objective analysis procedures, parameterized treatments ofdiurnal slope flows, kinematic terrain effects, terrain blocking effects, a divergence minimization procedure, and a micro-meteorological model for overland and overwater boundary layers, Additionally, the CALMET model can utilize gridded prognostic meteorological data from various mesoscale models such as 

### MM5 tobetterrepresentregional wind flows and slope/valley circulations. The CALMET model allows the user to "weight" various terrain influence parameters by defining the radius ofinfluence for surface and upper airmeteorological observations in the domain to characterize the**10caJi~eq** meteorological conditions. Version 

### 5_2, Level 000602a ofthe CALMET model was used for this analysis. CALPUFF

### Model: CALPUFF is amulti-layer, multi-species non-steady state Lagrangian pufftransport model which can simulate the effects oftime- and space--:arying meteorological conditions on pollutant transport, transformation, and removal. CALPUFF can use the three-dimensional wind fields developed by the CALMET model, or simple single**stat:~n** winds in a format consistent with the meteorological files used to drive the ISCST3 steady-state Gauss:an dispersion model (screen mode). The Class I Area modeling analyses were completed using CALPUFF in a refined mode, which uses three-dimensional wind fields. CALPUFF uses terrain-following coordinates and has several options available to consider terrain effects on ground-level concentrations. CALPUFF also has the ability to treat subgrid scale complex terrain. CALPUFF contains apuffsplitting algorithm based on the dividing streamline calculated internally by the model. CALPUFF also has the ability to incorporate several optional methods for estimating dispersion coefficients based on similarity theory, turbulence measurements, Pasquill-Gifford (PG) or McElroy-Pooler coefficients. CALPUFF contains algorithms for near-source effects such as building downwash, transitional plume rise, partial plume penetration, subgrid scale terrain interactions. as well as longer range effects such as vertical wind shear, wet scavenging, dry deposition, chemical transformation using aqueous-phase or dry-phase chemistry. CALPUFF can accommodate arbitrarily-varying poin! source and grldded area emissions. Most ofthe algorithms contain options to treat the physical processes



### TB002584BlackE:lls Corporation (WYGEN 2) PennitA;:plication Analysis, NSR-AP-C92 Page 35
at different levels ofdetail depending on the options used in the model application. Version 5.4, Level 000602_01 ofthe CALPUFF model was used for this analysis. CALPOST Model: CALPOST is a post-processing program designed to produce ranked tabulations ofaverages ofselected pollutant concentrations, with various options for computing time-averaged concentrations and deposition fluxes predicted by the CALPUFF model. CALPOST can process hourly sulfate and nitrate concentrations using concurrent hourly relative humidity values to produce extinction coefficients for the time-averaging periods ofinterest. CALPOST computes visibility impacts in accordance with the Interagency Workgroup on 

### Air Quality Models (IWAQM) guidance, and the Federal LandManagers' 

### Air Quality Related Values Workgroup (FLAG) Phase I Report. Version 5.4, Level 000602_1 ofthe CALPOST model was used for this analysis. 

## CALPUFF Screening Analysis Initially,**~he** applicant used the CALPUFF modeling system to run CALPUFF in the screening mode, commc-y referred to as "CALPUFF Lite". In this mode, CALPUFF can be driven by data from a single

___**~eJ~Q[C .'gicaLstationlhatis~ompatible--with**  -the--lSC-8B--air-tiispersion-model;-which-bypassesthe

## neea to run C .LMET, a complex model that generates a 3-dimensional wind field based on the selected meteorc.Jgy, along with terrain and land use data files. In the single-station mode, CALPUFF assigns the single value ofeach variable read from the meteorological data file to all grid points in the domain. resulting in a spatially uniform gridded field. However, the CALPUFF model does not assume that the meteorological conditions are steady-state, which allows the important effects ofcausality to be simulated even with the single-station meteorological data. This approach is not as onerous as a refined CALPUFF simulation using fully developed three dimensional wind fields. However, using CALPUFF in the screening mode h;lS the potential ofproducing higher maximum**impa~SC-3--mooel** using

-**--~thesame** meteorology, because the CALPUFF model can handle phenomena such as calm winds, wind reversals, and fumigation events, and causality, which the ISC3 model neglects. The meteorological data used in the CALPUFF screening modeling analysis consisted offive years of surface observations (1986-1990) for Casper, Wyoming. These data were taken from the National Climatic Data Center's (NCDC) Solar and Meteorological Surface Observational Network (SAMSON) CD-ROM set. These five (5) years were then combined with Rapid City, South Dakota upper air twice-<1aily mixing height data downloaded from EPA's SCRAM web site for the same five-year period. This data set was processed for wet deposition to provide CALPUFF with sufficient data to execute the MESOPUFF II chemistry transformation algorithms that are built into the CALPUFF modeling system. The meteorological data set also included the extended meteorological variables, which are the surface friction velocity, Monin-Obukhov length, a time-varying surface roughness length, precipitation rate and precipitation type code. which are required ifdry or wet deposition are being modeled. The IWAQM Phase II guidance recommends that the domain should extend at least 50 Ian beyond the outer most receptorring. The grid cells used to define the domain for each Class IorClass II area are different sizes due to the relative distance from the proposed WYGEN 2 facility to each area ofinterest. The size ofthe grid cells ranged between 193 km and 263 km on a side, after including the 50 km distance.



### TB002585BlackHills Corporation (WYGEN 2) PermitApplicationAnalysis, NSR-AP-C92 Page 36 

### Significant Impacts at Oass I Areas: The applicant 

### used CALPUFF in the screening mode to compare the model predicted impacts on the mandatory Class 

### I Areas with the proposed PSD Class 

### I Significant Impact Levels (SILs) for NO., S02, and PM\o' The CALPUFF screening analysis for the Class 

### I Sll..s was based on operation ofthe PC Boilerat 100 percent ofbase load. The stack parameters and emissionrates for the PC Boiler that were used in the CALPUFF screening analysis for assessing Class 

### I impacts at the mandatory Federal Class 

### I Areas: Wind Cave National Park (WCNP) and Badlands National Park (BNP), and atthe Tribal Class I Area: Northern Cheyenne Indian Reservation (NCIR) are presented below:
SOl Rate NO. Rate 

### PM

## ,o Rate

Note: Sulfuric acid mist (HIS0,) emissions were represented in the CALPUFF model as SO. The receptors used in the CALPUFF screening analysis for comparison againstthqrroposed Class I 

### SILs-**--~ ~--c"On-slsre(rorapaffial** **nrig~Of** receptors, also known as receptor arcs. The receptor arcs used in the CALPUFF screening analyses subtending an angle ofapproximately 90 degrees, extending out from either edge ofthe Class I area with the receptors spaced circumferentially every one degree within the receptor are, as perthe EPA guidance documententitled, Long-Range-Transport Screening Technique Using CALPUFF. A single receptor arc was used for each Class I area: WCNP, BNP, and NCIR. The results ofthe CALPUFF screening analysis indicated that the NO, and PM 10 impacts were below the proposed Class I SILs. However, the SO} impacts at the two (2) mandatory Federal Class I Areas (W€NP;BNPT,-andlhe-Ttib"aIClas-n-l\Tea{NCIR") were-aoo-ve theproposedClass IsrLs**f~~** the 3-hour and 24-hour averaging periods, but were below the annual Class I SIL for SOz. Therefore, additional Class I increment analyses for SOl were conducted using CALPUFF in a refined mode. Visibility Analvsis: The applicant submitted a visibility impact analysis using the CALPUFF screening methodology, and followed the methodologies provided in the FLAG Phase I Report, (December 2000). The applicant originally submitted the visibility analysis using the proposed emission rates. However, based on the Division's BACTreview, and the subsequent establishment ofBACT emission rates for NO, and PM IO• the applicant reran the CALPUFF screening analysis using thc revised emiSSIOn rates. The stack parameters and emission rates for the PC Boiler that were used in the CALPUFF screemng analysis for assessing visibility impacts at the Class and Class II areas are presented below:
S02 

### S04 NO, PM 10 Stack Stack Stack Stack Rate Rate Rate Rate Height Temp Velocity Diameter Source (g/s) (g/s) (gls) (g/s) (m) (OK) (m/s) (m) PI Rnilf'r 11077 70d 4'i \0 77R lQO .;; 144 \ ')() 0 771 Note: Sulfunc acid mist (H}SOJ) emissions were represented in the CALPUFF model as SO.



### TB002586Black Hills Corporation(WYGEN 2) PermitApplicationAnalysis, NSR-AP-C92 Page 37 The receptors used in the CALPUFF screening analysis for determining visibility impacts consisted of the same receptor arcs as used to determine significantimpacts at Class I 

### areas. However, an additional receptor arc was added for the Cloud PeakWilderness 

### Area (CPW

### A), which is a Class 

### II area. The backgrOlmd extinction computation 

### was carried outby the CALPOST model using Visibility Method Option 

### #6, which computes extinction from speciated PM measurements, and uses the FLAG relative humidity (RH) hourly adjustment factor applied to the observed and modeled sulfate andnitrate. The applicant used seasonal values for hygroscopic lightextinction efficiency, dry extinction efficiency, j(R.H), baseline light extinction at BNP andWCNP thatwere provided as natural background estimates**i~** the FLAG Phase 

### I Report, as suggestedby the National ParkService (NPS). However, there were no values for NCIR or

### CPWA. Therefore, the data to calculate light extinction atWCNP were used to represent the NCIR and CPWA, as suggestedby the National Park Service (NPS). The light extinction for the hygroscopic species were computed using seasonalj(RH) adjustment factors forboththe model predicted concentrations and for thebackground concentrations. The 

### RH factors are unitless, and the values thatwere used in the visibility impact analysis for Badlands were taken from the FLAG Phase 

### I Report: 

### 3.1 (Winter), 2.6 (Spring), 2.2 (Summer), and 2.8 (Fall). The corresponding 

### j(RH) values for Wind Cave were obtained in the same manner. - --- -- - In the applicant's analysis, the background sulfateconcentration was setto 0.2 ug!nr for all 12 months, and the background soil concentration was set to 

### 4.5 uglnt for all 12 months, the remaining four (4) background extinction coefficients for nitrates (N0l)' coarse particulate matter (pMC), organic carbon (OC), and elemental carbon (BC) were setto zero for all 12 months, as recommended in the FLAG Phase I Report. Abackground ozone value of40 ppb and abackground ammonia value of 10 ppb were used in the CALPUFF and CALPOST simulations for the visibility impact analyses. After the CALPOST model calculates the seasonal background light extinction from all species, light extinction due. to Rilyleigb

_ scattering-isTdOeOt01liecalculated seasonal background extinc-tion. The value for Rayleigh scattering used in this analysis was 10 inverse megameters (Mm-I ). The regional haze impacts were based on the maximum modeled 24-hour average sulfate

## (sq0) and nitrate (NO)'), and PM10 concentrations**(~g/m)** predicted by the CALPUFF model. The nitrate and sulfate transformation rates were computed internally by the CALPUFF model using the MESOPUFF 

### II dry chemistry scheme, which assumes that all nitrate and sulfate flux fully convert to ammonium sulfate «(NH4)2S04) and ammonium nitrate «(NlL)NO). A 24-hour source extinction (b1Oun:C)' expressed in IDverse megameters (Mm· I ) is determined by the CALPOST model using the following equation:

where: 1.375 1.29 JtRH) 3 0.6 the ratio ofammonium sulfate to sulfate molecular weights the ratio ofammonium nitrate to nitrate molecular weights 

## = the hourly relative humidity factor for a given hour the light scattering efficiency for nitrates and sulfates (m 2 /gram) the light scattering efficiency for coarse particles PM1o·PMu (m2 /gram) The 24-hour average source and seasonal background extinction, expressed in Mm", are used to estimate the corresponding 24-hour average change in extinction by the following equation:



### TB002587BlackHills Corporation (WYGEN 2) PermitApplicationAnalysis, NSR-AP-C92 Page 38

where:**~bal%=(b~·100 ~bex,%**  is the incremental change in regional**h<:.Z~,** expressed in percent Using this method, the maximum CALPUFF predicted 24-hour co::.:entrations ofS02' SO., NO., lINO), NO), and PM\o were used to calculate the change in lightextinctic- =rom the proposed 

### WYGEN 2 PC Boiler. This change in extinction was comparedto a five percent (:i%) and 10 percent (10%) change in light extinction over the seasonal backgroWld extinctions for

### WCl\.), BNP, and NCIR.. which are Class 

### I areas, and also for the CPWA, which is a Class 

### II area. The results ofthe visibility impact analysis atthe WCNP, BNP, NCIR., and CPWA using the CALPUFF screening methodology were greaterthan the 5% change in light extinction at each Class 

### I area, and were above a 10% change in light extinction for one (1) day at CPWA. The maximum change 

### in extinction from the proposed PC Boiler, the number ofdays greaterthan 5% change, and number ofdays greater than 10% change in light extinction using the CALPUFF screening methodology are shownbelow: Results from CALPUFF Screening Visibility Analysis Using BACfEmission Rates

. _ --Max-Change.in ---#-J)ays->-5o/crA--# Days

### ->-t0% ti

. Class 

### I Areas: Badlands National Park North Cheyenne Reservation Wind Cave National Park Class II Area: Cloud PeakWilderness Area LightExtinction 7.3% 8.5% 8.0%

15.3% Light Extinction 1 11 6

19 Light Extinction 

# o o o

The applicant conducted a variation ofthe screening analysis by using a small subset ofthe receptor arcs that were located at the Class 

### Iand Class 

### II areas ofinterest. As a result, 

### 8receptors were used in the arc for WCNP, 16 receptors were used in the arc for BNP, 25 receptors were used in the arc for NCIR, and 4 receptors were used in the arc for CPWA. The results ofthis additional analysis indicated smaller changes in light extinction at each Class 

### Iand Class 

### IT area, and the total number ofdays with a change in light extinction greater than 5% decreased, as well as producing zero days having greater than a 10% change in light extinction.
Results ofAdditional CALPUFF Screening Analysis Using BACT Emission Rates With a Subset ofthe Receptors in the Arcs

Class I Areas: Badlands National Park North Cheyenne Reservation Wind Cave National Park Class II Area: Cloud Peak Wilderness Area Max Change in Lil!ht ExtinctIOn 4.4% 1.8% 5.2%

8.1% # Days> 5% Light Extinction 

# o o 1 # Days > 10%ti LilZht Extinction 

# o o o

o

TB002588Blac!: -·lills Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-C92 Page 3S! Basec on the results ofthe additional CALPUFF screening analysis using the smaller arcs ofreceptors, no fi..;r- ••ler visibility impact analyses were submitted for the proposed

### WYGEN2 facility. 

## CALPUFFRefined Analysis
The :-.**~licant** conducted a Class I incrementconsumption analysis for S02 using a refmed CALPUFF**anal:'~** .J, based on a three-dimensional CALMETwind field createdby the Division. This CALMET wine _.eld was developed by the Division to enable applicants to use CALPUFF in a refined mode in order**~J** estimate air quality impacts from new sources as part ofthe New Source Review (NSR) process. 

### Computational & Sampling Grids: The computational grid used to define the modeling domain for the 

### WYGEN 2 analysis was developed for the Division's**~orth** £ast Y{yoming METeorological (NEWMET) project, and included the development ofa new expanded MM5/CALMETdatabase for the PowderRiver Basin that includes several downwind Class I areas. This computational, or meteorological grid, consists of134 east-west and 

### 94 north-south 5 

### krn x 5 

### krn grid cells, including cell elevation and land use. Total areal coverage of the NEWMET computational domain was 670 

### krn x 470 

### Ian. Recepmrs.ateach..areaofinterest

### were··· . spaced every two (2) kilometers.-**Meteorolo~ical** 

### Inputs: The NEWMET database included two hundred forty (240) surface meteorological sites based on several different monitoring networks. The monitoring networks and number ofsites are provided below: 

### Surface Data Monitoring Network National Climatic Data Center (NCDC) National Weather Service Sites(NWSL Automated-WeatherData Ne1W6rk{A-wDN)'

- . -- Remote Automated Weather Stations (RAWS) North Dakota S02 Monitoring Sites CASTNET Sites Powder River Basin (PRE) Surface Coal Mines # 

### Sites 

### 64 40 118



### 3 3 12 

### MM5 Data The CALMET wind field data were initialized using 36 kilometer resolution data from the National Center for Atmospheric Research (NCAR) Mesoscale Meteorological model, Srh Generation (M!vlS) prognostic data from the calender year of 1996. 

### Upper Air Data: Upper-air meteorological measurements are very sparse in the domain (typically 

### 300-krn apart or more) and are only collected twice daily; the resultant three-dimensional meteorological fields generated by CALMET using upper air observations are typically highly uncertain and not dynamically balanced. However, much improved and more realistic meteorological fields are obtained when output from a coarse grid prognostic meteorological model, such as MMS, is used as input to CALMET. For the NEWMET project, the 1996 36-km resolution MMS meteorological model database generated by the 

### U.S. EPA Office ofAir Quality and Planning Standards (OAQPS) was used. Since the 1996 MMS database essentially provides an hourly upper-air meteorological sounding every 36-km across the



### TB002589BlackHills Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-C92 Page 40 modeling domain with dynamicallybalancedmeteorological variables, upper air observational data were not used in the CALMET simulations. Sensitivitytests were done both with, and withoutthe upper air observations, and it was concluded thatthe omission ofthe observed upper air data would not significantly affect the resulting CALMET wind field. 

### Vertical Layers Eight (8) vertical layers were used 

### in developing the CALMET wind field, with vertical cell face heights located at 0,20,50, 100,250,500, 750, 1000, and 3000 m above ground level (AGL). Additional vertical layers could 

### be added to enhance the vertical resolution in CALMET. 

### Composite Wind Field: The geophysical, prognostic, surface air, upper air, and precipitation data were processed**an~** merged into single monthly files to generate large CALMET.DAT files (-1.4-GB/month), which are used to run the CALPUFF and CALPOST simulations. The CALMET.DAT file contains gridded fields ofu and v wind components, mixing heights, PGT stability categories, micro meteorological parameters, RH, and precipitation data based on the meteorological data input to the CALMET diagnostic wind model. All meteorological and geophysical data are then used in CALMET to produce a three-dimensional wind fieJeton.a**griqd~~LmQdeUng** domain. .-.-- -- - . -_. --- Due to the large extent ofthis computational grid, the curvature ofthe earth mustbe taken into account when calculating distances. To account for the earth's curvature in the modeling domain, the grid cells are identified using a Lambert-<:onfonnal projection. and the locations ofall sources and receptors used in the CALPUFF analyses were converted to this projection system to maintain the correct reference. Elevations for these discrete receptors were derived from electronic I :250,000 scale DEMs. The applicant initially found severeD**problel!l~. i!l.Jh~**  

### .wiIl9 fiell;!**.inpuls.JQr~** months, and could not 

# run the refinedCAL"fiUFF analyses with the chemistry (CHEM) and dry deposition (DRY) switches

-turned on, without the CALPUFF model simulation aborting. As aresult, the applicant only used the

CALPUFF refmed analysis to evaluate the impacton Class I increments. The Division and the consultant that developed the MM5/CALMET database were able to determine the cause ofthe problems with the wind field were related to surface pressure values at some ofthe Powder River Basin (PRE) monitoring sites which were extremely small, ranging from

# ° millibar to 200 millibar, which affected the chemistry and dry deposition algorithms, and caused the CALPUFF model to stop running. These data values were reset to represent missing surface pressure values, and there were no longer any problems \vith the CALPUFF orCALPOST simulations. However, these problems were corrected too late in the DIVlsion's review ofthe applicant's modeling analyses, and the applicant determined that it was not feasible to utilize the revised wind field inputs in the AQRV analyses. As aresult ofthe problems discovered in the wind field mput data, the inputs to the composite wind field underwent a thorough quality assurance/quality control review by the Division and the consultant that developed the wind field, and additional review ofthe data are now being evaluated by the Di,:,ision. As a result, it appears that additional refinements in the wind field may be necessary, and additional quality assurance/quality control reviews will be required.



### TB002590**-~---------** - -

### BlackHills Corp<>ration (WYGEN 2) 

### PermitApplication Analysis, NSR-AP-C92 

### Page41 

### PostProcessing ofCALPUFF Concentrations: The CALPOST model generates concentration values and wet and dry 

### deposition values for various averaging periods, as well as producing deciview change and change in lightextinction for evaluating visibility impacts. The applicant used CALPOSTto post-process CALPUFF concentrations to obtain estimated 24-hour averaged S02, sulfate (SO.), NO., nitric acid (HN0J)' nitrate (NO), and PM 10 

### concentrations at eachreceptor, and to estimate the Top-50 24-houraverage sulfate and nitrate concentrations. CALPOST will only allow the processing ofa single species ata time, therefore, four (4) sets ofCALPOST simulations were run, one simulation for each area ofinterest. CALPOST was also used to calculate 3-hour and 24-hourand annual averaged S02 concentrations for determining Class I increment consumption atthe three (3) Class 

### JAreas: Wind Cave National Park (WCNP), Badlands National Park (BNP), and the Northern CheyenneIndian Reservation (NCIR). 

### PSD Class I Increment Consumption:

• SulfurDioxide (SOJ • The proposed S02 emissions from the WYGEN 2 facility are 3,381 TPY, which is above the PSD significant emission rate of40IPY.**Therefo~ILana~sisJSJequiredlJ!lder** 

### Wyoming Air Quality ---:::CStandards and Regulations, Chapter 6, Section 4 (b)(i)(A)(D, to determine impacts from all S02 sources within 

### the significantimpact area for WYGEN 2which consume increment at Class I areas. Based on the results ofthe Class I SIL analysis using the CALPUFF screening methodology, the applicant conducted aClass Iincrement consumption analysis for S02 using CALPUFF in arefined mode. The S02 emissionrates proposed by the applicant for the PC Boiler at 100 percent ofbase load were used in the PSD Class I increment analyses, and the model predicted impacts were compared to the PSD Class I3-hour, 24-hour, and annual increment levels of25**~glmJ,** 

### 5**~m3** 

### and 2j.lg!m!, respectively. AsurTirilaiYofthe S02 emissions andstickparameters for all sources, including interacting sources that were represented in the PSD Class Iincrement consumption analysis are presented inTable 11 below:



### TB002591BlackHills Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-C92 Page 42 Table 11 StackParameters and S02 Emission Rates Used in PSD Class I Increment Consumption Analysis

S02 S02 Stack Stack Stack Rate Rate Height Stack**Te~")** Velocity Diameter Source (g/s) (TPY) (m) 

# rK) (m/s) (m) PC Boiler 110.22 3,831 190.5 344 20.00 7.71



# - KFx Heat 1 0.05 2 18.3 466 

# I 11.91 0.91 KFx Heat

### 2 0.05 2 18.3 466 11.91 0.91 KFx Incinerator 1.38 48 30.5 477 19.75 0.91



# - Two Elk Unit 1 57.27 1,991 103.6 344 27.40 4.94



# - - WYGEN 1 25.58 889 89.9 342 

# I 27.44 2.82



### . ..**_~.**

# __.-

- 

### -

.- 

### Neil Simpson 2 

### 25SR- ----889 

### --89

... 

### 9--

- -342-+--R:44-

### c----z:8l--

'0 

### ----- - .- ENCOAL Buckskin 2.41 84 68.6 353 13.72 1.22 Total S02 Emissions: 7,736 TPY Several ofthe interacting S02 sources are located at the Wyodakcomplex, which is also the location of the proposed WYGEN 2 facility:

- Results ofthe PSDClassfincrement analysis for SO! indicate that the model predicted impacts from all

S02 sources at the proposed WYGEN 2 facility and the interacting sources are below the 3-hour, 24-hour and annual PSD Class I increments for SO!, Therefore, the Division is satisfied that the proposed facility will not exceed the PSD Class I increments for S02' A summary ofthe CALPUFF predicted S02 increment consumption from the proposed WYGEN 2 facility are provided in Table 12, and the total increment consumed by all S02 sources represented in this analysis are provided in Table 13.



### TB002592P';.ckHills Corporation (WYGEN 2) f'e8lit ApplicationAnalysis, NSR-AP-C92 fa;e43 

### Table 12 Comparison of Modeled SOl 

### Impacts From WYGEN 

### 2 

### PC Boiler to 

### PSD Class I Increments

Badlands 3-Hour 121 185.833 -25.780 0.9 4% 24-Hour 3 164.662 -49.005 0.3 7% Annual 3 164.662 -49.005 0.03 3% Wind Cave 3-Hour 735 117.374 -40.747 1.3 5% 24-Hour 735 117J74 -40.747 0.6 12% Annual 748 117.371 -36.879 0.05 5%

-- 

### Jrth£he)'enne

.**~our-** -289 

### -112MO**--t-5~~1a-** 

### L8**-70~** 

### 24-Hour 301 -129.383 153.22438 OJ 6% Annual 520 -96.640 168.684 0.01 1%

Table 

### 13 Comparison of Modeled S02 

### Impacts From All 

### Increment 

### Consuming SOzSources to 

### PSD.class! Increments

4% 

### 0.04 197.3783 -12.236 164.662 -49.005 117.371 -36.879 119.300 -38.812 117.371 -36.879 -113.976 149.359 -152.493 147.429 -96.639 180.278 520 Annual Annual 748 0.13 13% North Cheyenne 

### 3-Hour 273 2.7 11%



### TB002593BlackHills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 44 

### Commercial. Residential. and Industrial Growth Analysis: There will 

### be an increase in the local labor force during the constructionphase associated with this modification, but this increase will be temporary, and will not result inpermanent significantcommercial orresidential growth. 

### It is anticipated that mostofthe labor force during the construction phase will commute from nearby communities. The electrical generating capacity createdby the proposed modification should nothave a significant effectupon the industrial growth in the immediate area as the total electrical generating capacity will be soldto the powergrid and used by several other states. Population increase is a secondary growth indicatorofpotential increases in air quality levels. Changes in air quality due to population increases are related to the amount ofvehicle traffic, commercial and industrial facilities, and domestic fuel usage. No new long termjobs will be created as aresult ofthe proposed modification, therefore, it can be concluded that there will be minimal effects to air quality associate with secondary growth. 

### Soils and Vegetation Analysis: The soils in this area have textural and drainagecharacteristics that limitthe amount ofwaterthe soils can retain and make available for plant growth. Vegetation in this region ofnortheastern Wyoming is sparse.**predomi~~ly** sagebrush. The applicantreI'Qrts that_there arc no ]istedthreatened-or**~dangered-­** species known to exist in this region. The National Ambient Air Quality Standards (NAAQS), or equivalently, the WAAQS have been established to protect public health and 'welfare from any adverse effects ofcriteria pollutants. The WAAQS analyses for N02. S02' HF, and PM\o indicated that the modeled impacts for these pollutants were below the WAAQS for all applicable averaging periods. Therefore, it is expected that there would not be any adverse impact to soils and vegetation in the vicinity ofthe proposed WYGEN 

### 2 facility or at other sites distant from the plant. 

### Acid Deposition Analysis: As stated earlier, the applicant is proposing to increase emission rates ofS02 above the significant emission rate that triggers PSD review for this pollutant. Therefore, an acid depositlOn analysis is required to examine the impacts from sulfate deposition as part ofthe analysis for AQRVs. Emissions ofnitrogen oxides. sulfur dioxide, and other sulfur compounds have the potential to convert to nitrate and sulfate compounds in the atmosphere, and can be deposited as nitric and sulfuric acids into sensitive lakes and other waterbodies. and increase the acidity ofthese water bodies; nitrogen and sulfur that is deposited in a dry deposition mode may also contribute to acid deposition impacts. All ofthe effects ofacid deposition are not well known, however, large amounts ofacidic deposition can slgmficantly affect soils, vegetation, lake chemistry and aquatic habitats ofsensitive species. The applicant submitted the results sources represented in the acid deposition analyses consist ofthe proposed PC Boiler at WYGEN 2. The USFS has identified a sensitive lake: Florence Lake, in which potential acid deposition impacts are to be evaluated. Florence Lake is in the Cloud Peak Wilderness Area (Class II area). The estimation ofthe percent change in acid neutralizing capacity**(~ANC),** or alkalinity, was evaluated by the applicant for Florence Lake using a screening level assessment to determine acid deposition impacts. The screening level assessment to calculate changes in ANC was perfonned using the guidance document, Screening Methodology for Calculating ANC Change to High



### TB002594Black Hills Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-C92 Page 45 Elevation Lakes. authoredby the USFS, and released in January, 2000. This technique quantitative>; estimates the change in alkalinity ofa sensitive waterbody (i.e., mountain lake) associated with**pre~icted** ambient modeled concentrations ofsulfates and nitrates. The total potential loss ofANC, in**~eqJL,** was comparedto the baseline ANC for Florence Lake. F.::::d on the baseline ANC value for Florence Lake, the calculatedpercent change in ANC was comparee; tt:" the significance criteria establishedby the USFS, which are 10% for waterbodies withbaseline Al\':'3 greater

### than 25**~eqlL,** and a 1.0**~eqlL** change for waterbodies with abaseline ANC less than 25**~e:'** :.. The baseline ANC for Florence lake is 38.3 ueqlL, and the maximum calculated MNC for Florence**.~:J.ke** was 0.86%, which is below the 10% significancecriteria. Therefore, it canbe shown that the**chang,:~** in ANC from potential acid deposition impacts due to the proposed WYGEN 

### 2 facility are below the applicable USFS significance criteria, and are expected to be minimal. SummarY: The modeled ambient impact ofthe proposed facility by itselfwas below the PSD Class 

### II significart impact levels for all pollutants but sulfurdioxide (SOl)' The applicant's modeling analyses demons:.. .:.te compliance with Wyoming Ambient AirQuality Standards for all criteria pollutants and hydrogen fluoride"and also**indicat~themodelpredictedimpacts onP~D·Glass+andtlassiI-areas**  

### are l:: ;ow all applicable PSD increments. The Division has reviewed and verified the source parameters, default settings, and related modeling inputs used in the near-field and far-field modeling analyses that were submitted in the WYGEN 

### 2pennit application and subsequent revisions. Selected options used in the far-field modeling input files were chosen based on sensible meteorological and geophysical data assessments to accurately represent the modeling domain, associated wind field, and pufftransport and dispersion in a systematic approach. As a result, the Division is**_~tisfi~d** that**th~icant** has demonstrated compliance

### with all applicable -ambIent air quality standards through the required modeling analyses using EPA approved models and methodologies. CONCLUSION: The Division is satisfied that the proposed WYGEN 2 facility will comply with all applicable Wyoming Air Quality Standards and Regulations. The Division is proposing to issue a pennit for the facility with the following pennitconditions: PERJ"tIT CONDITIONS: L Authorized representatives ofthe DiVIsion ofAIr Quality shall be given permission to enter and inspect any property, premise orplace on or at which an airpollution source is located or is being constructed or installed for the purpose ofinvestigating actual orpotential sources ofair pollution. and for determining compliance ornon-compliance with any rules, regulations. standards, permits or orders. 2. All commitments and descriptions set forth in the application for this permit, unless superseded by a specific condition ofthis permit, are incorporated herein by this reference and are enforceable as conditIOns ofthis permit.



### TB002595BlackHills Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-C92 Page 46


### 3. A major source, as definedby Chapter 6, Section 3 (b)(xvii}

# 0: the WAQSR, shall file a complete application to obtain an operating permit within 12 months 

### a::.:r commencing operations. 

### 4. All notifications, reports and correspondence required by th:-;**~ennit** shall be submitted to the Stationary Source Compliance ProgramManager, 

### Air Quali**~.** Division, 122 West 25th Street. Cheyenne, 

### WY 82002 and a copy shall 

### be submitted to the [.:trict Engineer, Air Quality Division, 1043 Coffeen Ave, Suite D, Sheridan, WY 82801. 

### 5. Owner or operator shall furnish the Administrator written notification of: (i) the anticipated date ofinitial startup not more 

### than 60 days orless 

### than 30 days priorto such date, and; (ii) the actual date ofinitial start-up within 15 days after such date in accordance with Chapter 6, Section 2(i) ofthe WAQSR. 6.**----~---** The date ofcommencement ofconstruction shall be reported to the Administrator within 30 days ofsuch date. The pennit shall become invalid ifconstruction ormodification is not commenced within 24 months ofthe date ofpermit issuance or ifconstruction is discontinued for a period of 24 months or more iILaccordancewithChapter**6TSection-2(h}.of.the.WA~** The Administrator may extend such time period(s) upon a satisfactory showing that an extension is justified. 

### 7. Performance tests shall be conducted and a written report ofthe results submitted within 30 days ofachieving maximum design rate but not laterthan 90 days following initial start-up in accordance with Chapter 6, Section 2(j) ofthe WAQSR. The operator shall provide 15 days prior notice ofthe test date. Ifmaximum design production rate is not achieved within 90 days ofstart-up, the Administrator

### may**~effilire** testinA-at rate**~cttievedandagain** when 

### maximum rate

## IS-achIeved.

-- - 8. Emission rates shall not exceed levels in the following tables: PC Boiler Emissions (PC-OO1) Pollutant IbtM:MBtu Iblhr IblMW-hr tpy

3,381 771.9 (30-day rolling)

874.8 (2-hrblock) NO, 0.07 (30-day rolling) 360.2 (30-day rolling) 1.6 (30-day rolling) 1,578



### .........................................................................................................................--

_ _--_ 

### - 0.15 (30-day rolling)

0.17 (2-hr block) 90% Minimum Removal Efficiency (30-day rolling) 0.012 61.7 270 CO 0.15 771.9 3,381

••••••••••••••••• u ••

_ _ ••

_ .

VOCs 0.01 51.5 225



### TB002596Black Hills Corporation (WYGEN 2) PermitApplicationAnalysis, NSR-AP-C92 Page 47 Material Handling

### PMlPM,o Emissions SourceNo.
COC-oOl Source gr/dscf
Coal Storage Silo Top DustCollector 0.009 Ib/hr
1.8 tpy
8.0 CDC-002 CDC-003 CDC..{)04 LDC-oOIA LOC-001B RDC-oOl Coal Storage Silo Bottom

### DustCollector Coal TransferBuilding DustCollector UnitTransfer ane Silos DustCollector Lime Unloading:;]o DustCollector Lime Unloading S:lo DustCollector FGD Waste Recyc.e Storage BinDustCollector 0.009 0.009 0.009 0.01 0.01 0.01 0.6 0.6 

### 2.5 0.1 0.1 0.2 

### 2.5 2.5 11.0 0.5 0.5 1.0 RDC-oO2AlB I FGD Waste Loacout Silo DustCollectors 0.01 0.4 2.0
I Only one ofthese units (RDC-002A 

### c..- RDC-002B) will be in service at anyone time.



### ----**--~----** ------------------- 9. Initial performance tests, reqt:.•.edby Condition 7 ofthis permit, shall consist ofthe following unless an alternative is approved 

### in writing by the Division: A) NO. 30 day rolling average - Initial testing and compliance determination shall follow 40 CFR 60.46a, 40 CFR 60.47a, and 40 CFR 60.48a. B) S02

- EPA Method 6C orequivalent shall beemIJIoyedto detennine initjal compliance

- withthe

### SO~ 2llOUT enussion limit. Tests shall consist of3 runs of2 hours each. C) S02 30 day rolling averagelPercent Reduction Requirements

- Initial testing and compliance determination shall follow 40 CFR 60.46a, 40 CFR 60.47a, and 40 CFR 60.48a. D) PMlPM 10 - Material Handling: EPA Methods 1-5, front halfonly, shall be employed to determine initial compliance with the particulate emission limits established by this permit. PC Boiler: Testing shall follow 40 CFR 60.48a E) Opacity

- PC Boiler and Coal Handling: EPA Method 9 and the procedures In WAQSR, Chapter 5, Section 2(i) shall be employed to determine initial compliance with opacity limits established by this permit. FGD Waste and Lime Handling: EPA Method 9 shall be employed to determine initial compliance with opacity limits established by this permit.



### TB002597

### BlackHills Corporation(WYGEN 2) PermitApplicationAnalysis. NSR-AP-C92 Page 48
F) CO

- EPAMethod 10 orequivalent shall be employed to determine initial compliance with the CO emission limit establishedby this permit. G) VOCs

- EPA Method 18 and Method 25 or equivalent shall be employed to determine initial compliance with the VOC emission limit establishedby this permit. 10. The following testing shall be performed and awrittenreport ofthe results submitted within 90 days afterinitial start-up: A) PC Boiler Stack shall be testedto determine NIl) emissions following EPA Conditional TestMethod 27 (CfM-027) orequivalentmethods. Results ofthe tests shall be reported in units oflblhr andppm., on a dry 

### basis corrected to 3 percent O2, 

### B) PC Boiler exhaust shall be testedpriorto control devices and at the PC Boiler Stackto determine total fluoride emissions and control efficiency following EPA Method 13A, 13B, orequivalentmethods. Results ofthe tests shall bereported in units oflblhr and -.E0ntrol**efficiency~** 

### .**.~_ -~---** 



### --- C) PC Boiler exhaust shall be tested priorto control devices and at the PC Boiler Stack to determine hydrogen chloride emissions and control efficiency following EPA Method 26 or equivalent methods. Results ofthe tests shall be reported in units oflblhr and control efficiency. 11. Prior to any performance testing or monitor certification testing required by this permit, a test protocol shall be submitted to the**Div~ion for~pproval,**  

### at least 30**d~ys** 

### priJ2!" to testing. Results

.onne testS-snalroe"submitted

# tothis office within 45 days ofcompleting. 12. Opacity shall be limited as follows: A) Visible emissions from the PC boiler (PC-001) shall be limited to 20% opacity (6-minute average) except for one 6-minute period per hour ofnot more than 27 percent opacity in accordance with NSPS. SubpartDa, 40 CFR 60.42a(b). B) Opacity shall be limited to less than 20% from all coal processing and conveying equipment (including breakers and crushers), coal storage systems, and coal transfer and loading systems in accordance with NSPS, Subpart Y, 40 CFR 60.252(c) as determined by 40 CFR Part 60, Appendix A, 

### Method 9. C) Opacity from any other source ofemissions at this facility shall be limited to 20% opacity in accordance with WAQSR, Chapter 3, Section 2(a) as determined by 40 CFR Part 60. Appendix A, Method 9. 13. Black Hills Corporation (BHC) shall use the following in-stack continuous emission monitoring (CEM) equipment on the PC Boiler stackto demonstrate continuous compliance with the emIssion limits set forth in this permit:



### TB002598BlackHills Corporation (WYGEN 2) Permit Application Analysis, NSR-AP-C92 Page 49
A) BHC shall install, calibrate, operate, and maintain amonitoring system, and recorc.. the output ofthe system, for measuring NO. emissions discharged to the atmosphere :..., units IblMW-hr, IblMMBtu and lb/hr. The NO. monitoring system shall consist oftt.-; fonowing: i) A continuous emission NO. monitorlocated 

### in the PC boiler stack ii) A continuous flow monitoring system for measuring the flow ofexhaust gases discharged into the atmosphere. iii) A watt meter to measure gross electrical output in megawatt-hours on a continuous basis. iv) An in-stackoxygen orcarbon dioxide monitor for measuring oxygen or carbon dioxide contentofthe flue gas at the location NO. emissions are monitored. B) BlackHills Corporation shall install, calibrate. operate, and maintain a S02 monitoring system, and record the output ofthe system, for measuring emissions discharged to the atmosphere in units ofIbIMMBtu, lb/hr and measuring the control efficiency ofthe S02 control device. The S02 monitoring system shall consist ofthe f?l1owing: i) Continuous emission S02 monitors located at the inlet and outlet to the S02 control device. ii) A continuous flow monitoring system for measuring the flow ofexhaust gases discharged into the atmosphere. iii) An in-stack oxygen or carbon dioxide monitor for measuring oxygen or carbon dioxide content ofthe flue gas atthe location ofeach**SO~** monitor. C) Black Hills Corporation shall install, calibrate, operate, and maintain a monitoring system, and record the outputofthe system, for measuring the opacity ofthe emissions discharged to the atmosphere. D) Each continuous monitor systemlisted in this condition shall comply with the following: i) NSPS Subpart Da, Standards ofPerformance for Electric Utility Steam Generating Units (40 CFR 60.47a). ii) Monitoring requirements ofWAQSR, Chapter 5, Section

# 2m including the following: a) 40 CFR 60, Appendix B, Performance Specification I for opacity, Performance Specification 

### 2 for NO, and SO!' and Performance



### TB002599BlackHills Corp<lration(WYGEN 2) PermitApplicationAnalysis, NSR-AP-C92 Page 50 Specification 3 for O2orCO2 , The monitoring systems must demonstrate linearity in accordance with Division requirements and be certified in both concentration (ppm) and units ofthe standard (lblMMBtu, IblMW-hr and lblhr). b) Quality Assurance requirements**c~** 40 CFR 60, Appendix F. c) BlackHills Corporation shall**de'!~20p** and submit for the Division's approval a Quality Assurance**pl~_** for the monitoring systems listed in this condition. 14. Following the initial performance tests, compliance with**t--~** limits set forth in this permit shall be determined with data from the continuous monitoring 

### bjstems requiredby Condition 13 of this permitas follows: A) Exceedances ofthe limits shall be defined as foIlco's: i) Any 30-dax

__**~"01ling** average ofNO, eL_ "3ions which**exceedsJIJ~JblMW-hr** output-based standard or IblMMBtu 

### 1:' ":tcalculated in accordance 40 CFR Part 60. Subpart Da, 60.46a, 6O.47a, 60.48a. Any 30-dayrolling average which exceeds the lblhrNO. limit as calculated following the methodology in Subpart Da for the IblMMBtu emission limit. ii) Any calculated 2-hourblockaverage ofS02 emissions as measuredby the PC Boiler stack S02 outlet CEM which exceeds the IblMMBtu or lblhrlimit established in this permit. The 2-hour average emission rate shall be determIned at the endOfeacn"i-houroperating block,and calculated"as the arithmetic average ofthe previous two operating hours S02 stack emission rates. iii) Any 30-day rolling average which exceeds the Ib/MMBtu S02 limit and the percentreduction requirements calculated in accordance 40 CFR Part 60, Subpart Da, 60.46a, 60.47a, and 60.48a. Any 30-day rolling average which exceeds the lblhr S02 limit as calculated following the methodology in Subpart Da for the IblMMBtu emission limit. iv) Any 6-minute average opacity, except for one 6-minute period per hour ofnot more than 27 percent opacity, in excess of20 percent in accordance with NSPS, Subpart Da, 40 CFR 60,42a(b). B) Black Hills Corporation will comply with all reporting and record keeping requirements as specified in WAQSR, Chapter5, Section 2(g) and 40 CFR Part 60, Subpart Da. Reporting and record keeping requirements for the 30-day rolling lblhr NO. and S02 and 2-hour fixed S02 emission rates shall follow the same requirements as the NSPS IblMMBtu standards.



### TB002600BlackHills Corporation (WYGEN 2) PermitApplication Analysis, NSR-AP-Cn Page 51 

### 15. BlackHills Corporation**sr.~::** 

### comply with all applicable requirements of40 CFR 60 SubpartDa and SubpartY. 16. BlackHills Corporation**sl:~.:l** 

### install, operate, and maintain aloading spout designed to minimize fugitive dust from loading .7:D waste. The loading spout shall have an outer sleeve for dust withdrawal orequivalent 

### ac... shall be connected to the FGD Waste Loadout Silobaghouses (RDC-002A, RDC-002B) ·c.) 

### :ninimize fugitive dust

17. 

### To minimize transport emissions, lime and FGD waste shall 

### be entirely enclosed in the haul trucks. Unpaved haul roads will 

### be treated with suitable chemical dust suppressants in addition to waterto control fugitive dust emissions. All treatedroads will be maintained on a continuous basis to the extentthat the surface treatmentremains viable as a control measure. 18. BlackHills Corporation shall comply with acidrain programregulations in WAQSR, Chapter 11, Section 2. 19. That BlackHills Corporation shall continue to operate in accordance with the requirements of40

_



### ----- -----eFRi>ans--50-and 58 an approved'amolent

### S02 monitoring program. The monitor shall be operated through Septemberof2002 and shall resume upon startup ofWYGEN 2. Data generated shall be submitted in an approved format on a quarterly basis, within 60 days following the end ofthe quarter. A quality assurance plan for the monitoring network.. as required by 40 CFR Part 58, shall be submitted for approval within 30 days ofstartup of WYGEN2. 20. Records required by any applicable regulation orpermit condition shall be maintained for a minimum-perioo1:'ffivei-5)

### years.mdshallberea-auyaccessi01eto Division representatives,



### TB002601