### September 2, 2015

Via Hand Delivery

Sean Alteri, Director Division for Air Quality 200 Fair Oaks Lane, First Floor Frankfort, Kentucky 40601

RE: John Sherman Cooper Power Station (AI 3808) Burnside, Pulaski County, Kentucky

2010 1

- Hour SO 2 

### NAAQS Designation Analysis

Dear Mr. Alteri:

East Kentucky Power Cooperative, Inc. (EKPC) submits the enclosed Air Dispersion Modeling Report

– Cooper Station

-- SO 2 

### NAAQS Designation Analysi s (the Report), prepared by Trinity Consultants, for the Division’s review and use. This analysis was prepared in support of the Division’s response to the U.S. Environmental Protection Agency’s (EPA) March 20,
2015 letter to Commissioner Bruce Scott of t he Kentucky Department of Environmental Protection (KDEP). The Report is the result of the dispersion modeling conducted pursuant to the Air Dispersion Modeling Protocol for Cooper Station SO 2 

### Designation Analysis submitted by EKPC to the Division on Augu st 3, 2015, as revised in response to subsequent discussion of comments from the Division and EPA, including the discussion on the August 27, 2015 conference call among EPA, the Division and EKPC.

A. Summary of Report Conclusions

The analysis demon strates that the maximum modeled impacts (expressed in the form of
the 1

- hour SO 2 

### National Ambient Air Quality Standard (NAAQS)) including emissions from Cooper Station, emissions from the selected regional sources, and the background concentration
are bel ow the 1

- hour SO 2 

### NAAQS. Specifically, the maximum combined impact is 173.1 μg/m 3 

### as compared to the 1

- hour SO 2 

### NAAQS of 196 μg/m 3 

### (75 ppb). Therefore, this modeling demonstrates that the area surrounding the Cooper Station should be designated attainmen t for
the 1

- hour SO 2 

### NAAQS.

B. Federally Enforceable Limits

As explained in the Report, EKPC modeled actual emissions from Cooper Unit 2 and allowable emissions from Cooper Unit 1. Cooper Unit 2 is subject to a federally enforceable

SO 2 

### emission limit of 95 percent removal efficiency 30

- day rolling average or 0.100 lb/MMBtu

SO 2 

### 30

- day rolling average, which has been in place since July 1, 2012. See Condition B.2.c. of
Title V Permit No. V

- 12

- 019R1, which was added to the permit pursuant to the Consent Decree

4775 Lexington Road 40391 Tel. (859) 744

- 4812 P.O. Box 707, Winchester Fax: (859) 744

- 6008 Kentucky 40392

- 0707 http://www.ekpc.coop

### September 3, 2015 Page | 2

between EPA and EKPC entered September 24, 2007 in Civil Action No. 04

- 34

- KSF. The Unit 2 modeled actual emissions reflect operation of the unit in compliance with this limit.

For Cooper Unit 1, EKPC modeled an allowable emission rate of 178 pounds/hour (0.165 lb/MMBtu) derived from the existing Title V permit limit of 3.3 lb/MMBtu SO 2 

### 24

- hour average assuming 95 percent reduction and operating at 1080 MMBtu/hr for 8,760 hours per year. The 95 percent reduction was applied to the existing permit limit because EKPC expects to meet a federally enforceable SO 2 

### emission limit of 95 percent removal efficiency 30

- day rolling average
or 0.100 lb/MMBtu SO 2 

### 30

- day rolling average on both Cooper units once the tie

- in of Unit 1
into the Unit 2 Dry Flue Gas Desulfurization (DFGD) System is complete later this year. EKPC
chose to model Unit 1 at 0.165 lb/MMBtu instead of 0.100 lb/MMBtu to account for the dual nature of the limit (either 95 percent removal or 0.100 lb/MMBtu) and the associated averaging period.

Although EKPC’s implementation of the Cooper 1 Reroute Project (with resulting emission reductions) was initiated to comply with the Consent Decree requirement for a Pollution Control Upgrade Analysis, upon further review, EKPC has de termined that the better course is to submit an application for revision of the Title V permit to impose the same limitation on Cooper Unit 1 as already spelled out in the permit for Unit 2. EKPC will work with the Division to assure that the permit revis ion is finalized before the July 2, 2016 deadline for EPA to make its designations of attainment status for the NAAQS. Once these limits are in place, EKPC’s position is that the Report reflects modeling of federally enforceable limits and that no
other l imits are necessary.

EKPC appreciates DAQ’s review of this submittal and use of this supplemental information in support of the classification of Pulaski County as attainment for the 1

- hour SO 2 

### NAAQS. As the Division and EPA are aware, EKPC has signific antly reduced SO 2 

### emissions from Cooper Station since 2012. Pursuant to the 2007 EPA Consent Decree, EKPC implemented additional SO 2 

### controls on Cooper Unit 2. EKPC is now in the process of adding

SO 2 

### controls to Cooper Unit 1 through the reroute project mentioned above which will be completed by the beginning of 2016. Cooper 1 and 2 will also meet the requirements of the Mercury and Air Toxics Standards (MATS) by April 16, 2016 in accordance with the one

- year extension of the initial deadline. EKPC’s s ignificant investment in Cooper Station demonstrates its importance to the EKPC generation and transmission system and the cooperatives it serves.

If you have any questions regarding this letter or the enclosed report, please let me know.
In addition to the two hard copies of the Report enclosed herewith, an electronic copy of the Report, including modeling files, is being transmitted today via email by Trinity Consultants to
Messrs. Ben Cordes and Kevin Davis.

Sincerely,

J erry Purvis
Director Environmental Affairs

2

### September 3, 2015 Page | 3

Enclosure

cc w/o enc.: Jackie Quarles

– DAQ
Rick Shewekah

– DAQ
Ben Cordes

– DAQ
Kevin Davis

– DAQ
John West

– OGC
Lance Huffman

– OGC George Schewe

– Trinity
John Colebrook

– Trinity Louis Petrey

- E KPC

3

## Environmental solutions de livered uncommonly well 

# AIR DISPERSION MODELING REPORT
COOPER STATION
SO 2 

# NAAQS DESIGNATION ANALYSIS

Prepared for: Jerry	Purvis Director,	Environmental	Affairs East	Kentucky	Power	Cooperative 4775	Lexington	Road,	P.O.	Box	707 Winchester,	KY	40392‐0707

Prepared By:

TRINITY	CONSULTANTS 1717	Dixie	Highway

Suite	900 Covington,	Kentucky	41011

September	1,	2015East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report i 

## TABLE OF CONTENTS

1. EXECUTIVE SUMMARY 1-1

2. INTRODUCTION 2-1

2.1. Facility Information

.............................................................................................................................................. 2

‐ 1

2.2. Basis for Analysis

................................................................................................................................................... 2

‐ 3



### 3. 1

‐ HOUR SO 2 

### DESIGNATION MODELING METHODOLOGY 3-1

3.1. Model Selection

...................................................................................................................................................... 3

‐ 1

3.2. Rural/Urban Option Selection in AERMOD

................................................................................................... 3

‐ 2

3.3. Meteorological Data

.............................................................................................................................................. 3

‐ 4

3.3.1. Surface Data

................................................................................................................................................................................ 3

‐ 7

3.3.2. Upper Air Data

........................................................................................................................................................................... 3

‐ 7

3.3.3. Land Use Analysis.......................................................................................................................

............................................... 3

‐ 8
3.4. Coordinate System

................................................................................................................................................ 3

‐ 9

3.5. Receptor Locations

............................................................................................................................................... 3

‐ 9

3.6. Terrain Elevations

.............................................................................................................................................. 3

‐ 11

3.7. Cooper Station Emission Sources

.................................................................................................................. 3

‐ 12

3.7.1. Cooper Unit 1 Modeled Emission Rate

.......................................................................................................................... 3

‐ 13

3.7.2. Cooper Unit 2 Modeled Emission Rate

.......................................................................................................................... 3

‐ 14

3.7.3. Combined Cooper Units 1 and 2 Modeled Emission Rate

..................................................................................... 3

‐ 16

3.7.4. Stack Parameter Selection

................................................................................................................................................. 3

‐ 16

3.7.5. Hourly Emissions File Creation

........................................................................................................................................ 3

‐ 17
3.8. Other Source Inventory

.................................................................................................................................... 3

‐ 17

3.9. Building Influences

............................................................................................................................................ 3

‐ 21

3.10. Background Concentrations

......................................................................................................................... 3

‐ 22

3.11. Modeling Files

................................................................................................................................................... 3

‐ 25



### 4. 1

‐ HOUR SO 2 

### DESIGNATION MODELING RESULTS 4-1

APPENDIX A: USE OF U* IN COOPER DISPERSION MODELING A-1

Criteria 3.2.2.e.i ‐ Scientific Peer Review

............................................................................................................... A

‐ 2

Criteria 3.2.2.e.ii ‐ Applicable on a Theoretical Basis

......................................................................................... A

‐ 3

Criteria 3.2.2.e.iii

– Availability of Databases

....................................................................................................... A

‐ 7

Criteria 3.2.2.e.iv

– Demonstration of No Biases Towards Underestimates

............................................... A

‐ 7

Criteria 3.2.2.e.v

– A Protocol Has Been Established

.......................................................................................... A

‐ 8



### APPENDIX B: NAAQS REGIONAL SOURCE INVENTORY

APPENDIX C: MODELING FILES ON CDEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report ii 

## LIST OF FIGURES

Figure	2‐1.		Aerial	Photograph	of	Cooper	Station 2‐2

Figure	2‐2.		Area	Map	of	Cooper	Station 2‐3

Figure	3‐1.		Distribution	of	Land	Use	within	3km	of	Cooper	Stat ion	 3‐3

Figure	3‐2.		Meteorological	Stations	and	SO 2 Monitors	in	the	Area	n ear	Cooper	Station	 3‐6

Figure	3‐3.		Modeling	TAD	Receptor Grid	Showing	Ex ample	Exclude d	Locations	over	Water	 3‐10

Figure	3‐4.		Innermost	Portion	of the	Proposed	Modeling	Recepto r	Grid	for	Cooper	 3‐11

Figure	3‐5.		Relief	Map	of	Area	w ithin	20	km	of	Cooper	Station 3‐12

Figure	3‐6.	Map	Showing	Region al	Source	Locations	and	SO 2 Emissions	Magnitude	ne ar	Cooper	Station	 3‐20

Figure	3‐7.		Results	of	Regional Source	Screening	Evaluation	ba sed	on	Q/d	Analysis	 3‐21

Figure	3‐8.		Wind	Rose	for	London‐Corbin	Airport	from	July	2012 –	June	2015	 3‐24

Figure	4‐1.		Spatial	Display	of	3‐year	Average	99 th Percentile	Annual	Distribution	of	Daily	Maximum	1‐hr	SO 2 Concentrations	Including	Background	 4‐2

Figure	A‐1.			Comparison	of	the	AERMOD	Model	with	and	without	t he	u*	Adjustment	 A‐2

Figure	A‐2.		Distribution	of	Hourl y	Observations	by	Wind	Speed Category	Bin	 A‐5

Figure	A‐3.		Distribution	of	Win d	Speeds	for	Cooper	Station	Impacts	above	100	μg/m 3 with	the	Default	AERMET

Dataset A‐6

Figure	A‐4.		Distribution	of	Win d	Speeds	for	Cooper	Station	Impacts	above	100	μg/m 3 with	the	U*_ADJ	AERMET

Dataset A‐6

Figure	A‐5.		Residual	Plots	Showin g	Improved	Performance	with	u *	and	No	Bias	toward	Underestimation	 A‐7East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report iii 

## LIST OF TABLES

Table	3‐1.		Modeling	TAD	Ur ban	/	Rural	Categories 3‐3

Table	3‐2.		Cooper	Station	Urba n/Rural	Determination	 3‐4

Table	3‐3.		Proximity	Analysis	of	Meteorological	Stations	to	Cooper	Station 3‐7

Table	3‐4.		Moisture	Calculation	for	Jackson	Airport	(inches	of precipitation)	 3‐9

Table	3‐5.		Example	of	Missing/OOC	SO 2 Emissions	Data	Filling	Technique 3‐15

Table	3‐6.		Example	of	Unit	2	SO 2 Emissions	during	Downtime 3‐16

Table	3‐7.		Cooper	Station	Source	Parameters 3‐17

Table	3‐8.		Summary	of	SO 2 Emissions	from	KyEIS	Facilitie s	near	Cooper	Station	and	Candid ate	SO 2 Monitoring

Stations 3‐23

Table	3‐9.		Selected	SO 2 Background	Concentration 3‐24

Table	4‐1.		Highest	4 th High	Modeled	1‐hour	SO 2 Results	for	Comparison	to	the	NAAQS 4‐1East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 1-1 

## 1. EXECUTIVE SUMMARY

Eastern	Kentucky	Power	Cooperati ve,	Inc.	(EKPC)	in	association with	our	air	quality	contractor,	Trinity Consultants	(Trinity),	submits	t his	dispersion	modeling	report for	the	air	quality	modeling	analysis	that	was performed	with	respect	to	EKPC ’s	John	Sherman	Cooper	Power	Stat ion	(Cooper)	and	the	surrounding	area. Cooper	consists	of	two	coal‐fired electricity	generating	units referred	to	as	Unit	1	and	Un it	2.		This	work	was undertaken	in	support	of	the	Kent ucky	Division	for	Air	Quality (KDAQ	or	Division)	response	to	the	March	20,

2015	letter	from	the	U.S.	Environm ental	Protection	Agency	(U.S. EPA)	to	Commissioner	Scott	of	the	Kentucky Department	for	Environmental	Pro tection	(KDEP)	regarding	designations	of	areas	currentl y	unclassified	with respect	to	the	2010	1‐hour	SO 2 National	Ambient	Air	Quality	Standard	(NAAQS).

In	that	letter,	U.S.	EPA	identifi ed	the	Cooper	Station	as	one	o f	the	Kentucky	sources	m eeting	the	criteria	for evaluation	of	unclassified	areas	in	the	first	round	of	designat ions	as	part	of	a	required response	by	U.S.	EPA	to

the	recent	Sierra	Clu b	vs.	Regina	McCar thy	Consent	Decree 1 .		Cooper	was	also	identified	on	the	U.S.	EPA	website listing	all	areas	wh ere	designations	would be	required	under	th e	Consent	Decree	by	July	2,	2016 2 ,	which	is accelerated	as	compared	to	the	fi nal	Data	Requirements	Rule	(DR R)	schedule. 3 The	criteria	to	determine	if	a source	was	subject	to	the	Consen t	Decree	are:		1)	a	nearby	moni tor	showing	a	violatio n,	or	2)	that	an	area contains	a	stationary	source	tha t	according	to	the	EPA’s	Air	Ma rkets	Database	either emitted	more	than	16,000

tons	of	SO 2 in	2012	or	emitted	more	than	2,600	tons	of	SO 2 and	had	an	emission	rate	of	at	least

0.45	lb	SO 2 /MMBtu	in	2012.		According	to	EPA’s	Air	Markets	Database,	the	C ooper	Station	emitted	7,428	tons

SO 2 in	2012	and	had	an	average	SO2 emission	rate	of	1.07	lb	SO 2 /MMBtu	in	2012.		U.S.	EPA stated	that	it	would base	the	designation	of	the	Pulaski	County	and	surrounding	area on	these	emission	cri teria	alone	as	no	SO 2 monitors	are	in	the	area	unless	KD AQ	submits	updated	recommenda tions	and	supporting	in formation	that	could be	considered	in	the	final	design ations.		To	that	end,	EKPC	is facilitating	a	modeling	analysis	to	aid	in	the designation	determination	fo r	the	Pulaski	County	area.

Dispersion	modeling	conducted	in	support	of	the	SO 2 NAAQS	attainment	demonstration	was	conducted following	the	modeling	Technical Assistance	Document	(TAD)	guid ance. 4 As	favored	by	the	guidance	and described	in	the	modeling	prot ocol	submitted	on	August	3,	2015, three	years	of	Con tinuous	Emissions Monitoring	System	(CEMS)	data	w ere	utilized	for	emissions	from	Unit	2.		As	recommended by	U.S.	EPA	in	their comments	provided	on	the	modeling	protocol 5 ,	SO 2 emissions	from	Unit	1	were	modeled	at	an	allowable	hourly emission	rate	assuming	8,760	hour s	of	operation,	determined	fro m	the	suite	of	permit	l imits	that	will	be applicable	to	this	unit	after	the	proposed	dry	flue	gas	desulfu rization	(DFGD)	SO 2 control	system	tie‐in	project	is completed	in	2015.		Because	this	air	pollution	co ntrol	project will	be	completed	well before	the	July	2016 attainment	designation	deadline,	the	Unit	1	modeled	emission	rate	reflects	the	allowable emission	rate	that	will be	in	place	at	the	time	of	the	SO 2 NAAQS	designations	under	the	Co nsent	Decree.		Modeling	the	pos t‐control

allowable	emission	rate	on	a	continuous	basis	for	an	affected	u nit	scheduled	to	be	co ntrolled	prior	to	the attainment	designation	deadline is	an	acceptable	approach	under both	the	modeling	TAD 6 and	the	final	DRR. 7 These	emissions	were	paired	with	static	( not	varying	by	hour)	e ngineering	estimates	of	exit	velocity	and

1 Order Granting Joint Motion to Approve and Enter Consent Decree and Denying Other Motions as Moot ,	Sierra	Club	et.	al.	v.	Regina McCarthy,	Administrator	of	the	United	States	Environmental	Prot ection	Agency,	United	States	Dis trict	Court,	Northern	District of California,	Docket	Nos.	120,	149,	March	2,	2015.

2 http://www.epa.gov/ai rquality/sulfurdioxide/designations/pdfs /sourceareas.pdf

3 Data Requirements Rule for the 1

‐ Hour Sulfur Dioxide (SO 2 ) Primary National Ambient Air Quality Standards (NAAQS): Final Rule, Federal	Register	Vol.	90	No.	16 2,	pages	51052‐51088,	August	21, 2015.

4 SO 2 NAAQS Designations Modeling Technical Assistance Document ,	Draft,	U.S.	EPA,	Research	Triangle	Park,	NC,	December	2013.

5 Email	from	Rick	Gillam	(U.S.	EP A,	Region	4)	to	Ben	Cordes	(KDAQ),	August	25,	2015

6 Ibid.

7 Ibid.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 1-2 temperature	for	the	two	relevant stack	configurations	following the	Unit	1	DFGD	tie‐in:		1)	Case	1	when	only Unit	1	is	operational,	and	2)	Cas e	2	when	both	Units	1	and	2	ar e	operational.		The	actual	stack	height	was	used

because	the	combined	U nit	1	and	2	stack	does	not	exceed	Good	En gineering	Practice	(GEP)	stack	height.

Nearby	sources	were	considered	wit hin	the	TAD‐suggested	20	km	r ange	of	Cooper,	but	also	out	to	50	km	to allow	comprehensive	consideration of	large	nearby	sources.		Of these,	the	Kingsford	Manufacturing	Company facility	(located	~	3	km	south	o f	Cooper)	was	determined	to	be the	only	regional	source	which	has	the	potential to	significantly	contribute	to	t he	location	of	Cooper	Station’s maximum	modeled	impacts .		All	other	sources	were distant	enough	to	fall	outside	o f	the	TAD	general	consideration guidance	and	were	likely captured	as	part	of	the regional,	rural	background	concen tration	selected	for	the	model ing	(26.9	μg/m 3 )	from	the	SO 2 monitor	located

at	Mammoth	Cave	National	Park.		This	monitor	was	determined	to be	representative	of	ba ckground	conditions in	Pulaski	County	and	not	influe nced	by	either	Cooper	or	Kingsf ord.

Given	this	strategy	and	characterization	of	sources	affecting	a ir	quality	in	the	Pulaski County	area,	the	analysis

demonstrated	that	the	maximum	mo deled	impacts	(expressed	in	the form	of	the	1‐hr	SO 2 NAAQS)	including emissions	from	Cooper	Station,	e missions	from	the	selected	regi onal	sources,	and	the	ba ckground	concentration

are	below	the	1‐hour	SO 2 NAAQS.		Specifically,	the	maximu m	combined	impact	is	173.1	μg/ m 3 as	compared	to

the	1‐hour	SO 2 NAAQS	of	196	μg/m 3 (75	ppb).		Therefore,	this	mode ling	demonstrates	that	the	area surrounding the	Cooper	Station	should	be	co nsidered	for	designation	as	atta inment.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 2-1 

## 2. INTRODUCTION

This	section	of	the	modeling	rep ort	provides	an	overview	of	the Cooper	Station	along	with	background

information	for	th e	basis	for	the	SO 2 designation	modeling.



### 2.1. FACILITY INFORMATION

EKPC	owns	and	operates	a	364	MW	c oal	fired	power	plant,	the	Joh n	S.	Cooper	Station	(Cooper),	located	in Pulaski	County,	approximately	three	quarters of	a	mile	northeast	of	the	town	of	Burnside,	Kentucky.		Cooper consists	of	two	generating	units (Title	V	ID	EU01	and	EU02).		T he	first	power	generati ng	unit	(EU01,	herein referred	to	as	Unit	1)	is	a	pulv erized	coal	fired	boiler	with	a maximum	continuous	rating	of	1,080	MMBtu/hr. The	second	unit	(EU02,	herein	ref erred	to	as	Unit	2)	is	a	pulve rized	coal	fired	boiler	with	a	maximum	continuous rating	of	2,089	MMBtu/hr.

Unit	1	is	currently	eq uipped	with	multiple control	devices	to	r educe	emissions	of	pol lutants	regulated	under

various	Federal	and	Co mmonwealth	programs. The	current	control s	include	an	electrostatic	precipitator	(ESP)

for	PM	control	and	low	NO X burners	for	NO X control.		Unit	1	is	undergoing a	duct	reroute	project	to	tie	i ts exhaust	into	the	existing	Unit	2	ductwork,	to	allow	for	further control	utilizing	both	an	DFGD	for	SO 2 control	and a	pulse	jet	fabric	filter	for	a dditional	PM	control.		Unit	2	is equipped	with	low	NO X burners,	selective	catalytic reduction	(SCR),	FuelSo lv	treatment,	DFGD,	and	pulse	jet	fabric	filter.		These	units	and	other	emissions generating	activities (emergency	generators,	etc.,	not	consider ed	under	the	Consent	De cree)	at	Cooper	Station are	subject	to	Title	V	operati ng	permit	V‐12‐019	R1,	issued	by KDAQ	on	August	14,	2013. Unit	1	and	Unit	2	are the	only	significa nt	sources	of	SO 2 emissions	at	Cooper	station,	and	a s	such,	these	a re	the	only	so urces represented	in	the	mo deling	analysis.

An	aerial	photograph	and	area	map	of	the	facility	and	surroundi ng	area	are	provided	i n	Figures	2‐1	and	2‐2, respectively.		Figure	2‐1	shows	th e	fence	line	and	buildings	at Cooper.		Figure	2‐2	shows	th e	facility	relative	to predominant	geographical	feature s	such	as	roads,	rivers,	and	to wns.		These	figures	and	the	locations	of	all
emission	sources,	structures,	an d	receptors	in	the	modeling	ana lysis	are	represented in	the	Universal Transverse	Mercator	(UTM)	coordi nate	system.		The	datum	is	base d	on	North	American	Datum	1983	(NAD	83). UTM	coordinates	for	this	analysi s	are	located	in	UTM	Zone	16. The	central	location	of	Cooper	Station	is approximately	714,250	meters	Eas t	and	4,097,343	meters	North	in Zone	16	of	the	UTM	system.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 2-2 Figure 2

‐ 1. Aerial Photograph of Cooper StationEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 2-3 Figure 2

‐ 2. Area Map of Cooper Station



### 2.2. BASIS FOR ANALYSIS

Following	the	May	2014	publicatio n	of	the	proposed	Data	Requirements	Rule,	the	U.S.	EPA was	sued	for	“failing

to	undertake	a	certain	nondiscret ionary	duty	under	the	Clean	Ai r	Act	(“CAA”),	42	U.S.C. §§	7401‐7671q,	and	that such	alleged	failure	is	actionable	under	section	304(a)(2)	of	t he	CAA,	42	U.S.C.	§	7604(a)(2).”		The	lawsuit

resulted	in	the	Consent	Decree that	was	entered	on	March	2,	201 5	in	the	U.S.	District	C ourt	for	the	Northern District	of	California	(same	as that	mentioned	above	and	refere nced	in	Footnote	1).		As	a	result	of	the	Consent Decree,	an	additional	designation phase	was	added to	the	two	de signation	phases	that	were	already	included	in the	U.S.	EPA’s	August	2015	final	D ata	Requirements Rule.		The	a dditional	phase	affects areas	with	stationary sources	that	meet	speci fic	emissions	criteria	laid	out	in	the	C onsent	Decree.		The	U.S.	EPA	released	a

memorandum	on	March 20,	2015	(referred	to	herein	as	the	2015	SO 2 Area	Designation	Guidance)	to	the Regional	Directors	clarifying	th e	path	forward	for	states	with sources	affected	by	the	decree. 8 EKPC	is	very

8 Updated Guidance for Area Designations for the 2010 Primary Sulfur Dioxide National Ambient Air Quality Standard ,	memorandum from	Stephen	Page	to	Regional	Ai r	division	Directors,	Regions	1 ‐10,	March	20,	2015.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 2-4 aware	of	these	requirements	and has	conferred	with	KDAQ	to	dete rmine	a	path	forward	t o	meet	the	deadlines for	modeling,	strategic	assessmen t,	and	eventual	designation	of the	area	around	Cooper	Station.

Under	the	DRR,	KDAQ	has	the	option	of	installing	a	new	monitor in	the	area	around	Cooper	Station	or performing	dispersion modeling.		A	schedule	for	completion	of	t he	designations	under DRR	is	established	as December	31,	2017	for	modeling	and December	31,	2020	for	monito ring.		The	deadline	req uired	by	the	Consent Decree,	however,	is	that	the	U.S. EPA	will	complete	a	round	of SO 2 designations	by	July	2,	2016.		To	meet	this deadline,	KDAQ	is	required	to	perform	dispersion	modeling	unles s	an	existing	ambient air	monitor	can	be shown	to	be	representative	of	th e	area	(insuffici ent	time	is	av ailable	to	begin	a	new	a mbient	source‐oriented monitoring	system).		Because	the exclusive	use	of	monitoring	da ta	for	the	designation	process	is	unlikely	due	to the	lack	of	a	monitoring	station in	sufficient	proximity	to	the Cooper	Station,	modeling	must	be	performed. Results	of	the	modeling	analysis will	be	used	to	allow	appropriate	designation	of	the	unclassified	area	around Cooper	as	in	attainment	of	the	1‐hour	SO 2 NAAQS.

EKPC	has	performed	this	modeling	analysis	and	is	providing	the results	to	KDAQ	to	assi st	in	the	designation process.		This	modeling	follows	t he	methodology	and	modeling	gu idance	from	the	U.S.	EPA	in	the	form	of	the	SO 2 NAAQS	designation	modeling	guida nce	TAD	and	assists	in	KDAQ’s	d etermination	of	the	a mbient	levels	of	SO 2 at the	1‐hour	averaging	period	in	the	area	around	Cooper	Station. This	report	only	covers	t he	dispersion	modeling requirement	and	does	n ot	cover	any	other	it ems	KDAQ	may	wish	to include	within	the	Pulaski	County	1‐hr	SO 2 NAAQS	attainment	recommendation due	to	be	submi tted	to	U.S.	EPA by	September	18,	2105.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-1 

## 3. 1-HOUR SO 2 

## DESIGNATION MODELING METHODOLOGY

As	prescribed	by	the	U.S.	EPA	in the	modeling	TAD,	dispersion	m odeling	can	be	used	in	place	of	ambient monitoring	to	evaluate	the	attainment	status	of	an	area	in	the vicinity	of	a	specific	sourc e,	in	this	case	the	EKPC Cooper	Station.		U.S.	EPA’s	ration ale	for	this	is the	distincti on	that	SO 2 sources	are	limite d	in	terms	of	the

distance	to	where	ambi ent	concentration	im pacts	occur.		In	prep aration	for	providing	modeling	guidance	for designation	analysis,	U.S.	EPA	reviewed	SO 2 ambient	monitoring	and	modeling of	concentrations	around	and

near	SO 2 sources	and	found	that	most	of	the	highest	impacts	fall	within a	few	10’s	of	kilometers	from	large

sources	and	a	few	kilometers	for smaller	sources.		Also	of	note was	that	the	gradient	of	th ese	concentrations	falls off	significantly	aft er	the	maximum	is	reach ed.		Thus,	the	mode ling	focuses	on	the	use	of	near‐field computational	methods	such	that U.S.	EPA’s	primary	preferred	in dustrial	source	model,	the	AERMOD	Model 9 ,	is the	primary	model	recommended	for	use.		In	addition	to	AERMOD	a nd	to	allow	the	best	representation	of

simulated	ambient	air concentrations,	the	mo deling	TAD	recommen ds:

Using	actual	emissions	as	an	inpu t	for	assessing	violations	to provide	results	that	reflect	current	actual	air quality	(i.e.,	modeling	that	simu lates	a	monitor)(allowable	emissions	may	also	be	used	w hich	will	result	in	a

more	conservative	estimate	of	actu al	ambient	air	impacts	of	the source);

Using	three	years	of	m odeling	results	to	ca lculate	a	simulated design	value	consistent	with	the	3‐year monitoring	period	required	to	deve lop	a	monitor	design	value	fo r	comparison	to	the	NAAQS;

Placing	receptors	for	the	model ing	only	in	loca tions	where	a	monitor	could	be	placed;	and

Using	actual	stack	heights	rather	than	following	the	Good	Engin eering	Practice	stack height	policy	when using	actual	emissions.

Following	this	modeling	philoso phy	and	guidance ,	the	remainder of	this	section	provid es	an	overview	of	the modeling	applied	to	the	Cooper	St ation	consistent	with	the	mode ling	protocol	submitted	to	KDAQ	on	August	3, 2015,	unless	stated	otherwise.



### 3.1. MODEL SELECTION

Modeling	was	performed	for	the	1‐hour	SO 2 analysis	following	the	modeling	TAD	guidance.		The	AERMOD	Mode l

Version	15181 10 ,	the	most	current	v ersion	released	by	U.S .	EPA	on	July	24,	201 5	on	the	Support	Center	for Regulatory	Air	Modeling	(SCRAM)	website 11 ,	was	used	to	perform	the	disp ersion	modeling.		The	proposed update	to	U.S.	EPA’s	modeling	guidance	in	the	form	of	the Guideline on Air Quality Models 12

, was	released	on	July 15,	2015	via	the	U.S.	EP A	technical	website 13 .		This	proposed	guidance	and	rev ised	AERMOD	model	have	options

that	could	affect	the	outcome	of dispersion	modeling	studies	an d	specifically	the	desig nation	modeling	herein. Some	of	these	options address	the	U.S.	EPA	and	modeling	community	concerns	that	AERMOD	does	not	perform well	during	low	wind	conditions because	turbulence	under	stable conditions	is	underestimated.

9 Addendum User’s Guide for the AMS/EPA Regulatory Model

– AERMOD ,	EPA‐454/B‐03‐001,	U.	S.	Environ mental	Protection	Agency, Research	Triangle	Park,	NC,	September	2004,	Revised	May	2014.

10 Stated	by	U.S.	EPA	to	be	part	o f	the	docket	at	Docket	ID	No. EPA‐HQ‐OAR‐2015‐0310	and	availabl e	as	of	date	of	submittal	of	t his
report.

11 http://www.epa.gov/ttn/scram/ dispersion_prefrec.htm#aermod

12 Guideline on Air Quality Models. Appendix	W	to	40	CFR	Parts	51	an d	52.		Federal	Register,	Nove mber	9,	2005.		pp.	68217‐68261.

13 http://www.epa.gov/ttn/scram/East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-2 When	AERMOD	is	run	with	a	meteor ological	dataset	derived	from	one‐minute	meteorological	data	as	is currently	recommended	by	U.S.	EPA,	low	wind	speeds	are	much	mor e	prevalent	than	in	pr ior	versions	of	the modeling	system	that	did	not	rel y	on	one‐minute	meteorological data.		These	low	wind	speeds	have	been	linked to	potential	overestimates	in	amb ient	concentrations	by	AERMOD. 14 These	overestimates	o ccur,	in	part,	due	to

an	underestimate	of	friction	veloc ity	(u*)	by	the AERMET	meteor ological	processor.		EPA	recognized	this underestimation	as	a	potential	i ssue	with	AERMET	(and	subsequen tly,	AERMOD)	and	rel eased	AERMET	Version 12345	which	included	a	beta	option ,	ADJ_U*,	which	allowed	the	f riction	velocity	(u*)	to	be	adjusted	using	the methods	of	Qian	and	Venkatram 15 to	better	account	for	turbulence	in	the	atmosphere	during	low wind	speed stable	conditions.		This	beta	option	was	first	released	in	AERM ET	version	12345,	was	upda ted	to	incorporate	a

modified	Bulk	Richardson	Numb er	in	version	13350,	was	further	m odified	to	adjust	u*	for	low	solar	elevation angles	with	version	14134,	and	wa s	most	recently	in	Version	151 81,	used	to	modify	the	calculation	of	the turbulence	measure,	M onin‐Obukhov	length. 16 Given	the	refined	nature	of	t his	beta	option	and	the	peer

reviewed	studies	which have	acknowledged	it s	accuracy,	EKPC	has incorporated	this	option	into	the	modeling analysis	to	allow	mo re	representative	and	more	accurate	modelin g	results.		Further	justification	for	inclusion	of the	beta	option	ADJ_U*	for	AERMET	is	presented	in	Appendix	A.

The	pollutant	identifi cation	was	set	to	“SO 2 ”	in	AERMOD,	which	allowed	for	additional	internal	model	option s	to be	available,	thus	enabling	the	output	options	to	be	configured properly.		Because	of	the probabilistic	form	of	the 1‐hour	NAAQS,	selecting	these	cor rect	input	options	allowed	AER MOD	to	properly	calculate	an	SO 2 design	value based	on	the	3‐year	average	of	the	99 th percentile	of	the	annual	distribution	of	the	daily	maximum	1‐h our concentrations	for	comparison	with	the	1‐hour	SO 2 NAAQS	of	196  g/m 3 (75	ppb).



### 3.2. RURAL/URBAN OPTION SELECTION IN AERMOD

As	stated	in	Section	6.3,	Urban/Rural	Determination,	of	the	mod eling	TAD,	for	any	dispersion	modeling	exercise

for	SO 2 ,	the	“urban”	or	“rural”	determin ation	of	the	location	surround ing	the	subject	sour ce	is	important	in determining	the	applicable	boundary	layer	characteristics	that affect	a	model’s	calculation	of	ambient concentrations	as	well	as	the	po ssible	invocation	of	AERMOD’s	4‐hour	half‐life	applicable	to	SO 2 in	urban	areas. Thus,	a	determination	was	made	o f	whether	the	a rea	around	the	C ooper	Station	was	urban	or	rural.

The	first	method	discussed	in	t he	modeling	TAD	(also	referring therein	to	Section	7.2.3c	of the	Guideline	on	Air Quality	Models,	Appendix	W)	was used	to	determine	the	urban	or rural	status	of	the	area around	Cooper.		This	is the	“land	use”	technique	because it	examines	the	various	land	u se	within	3	km	of	Coop er	and	quantifies	the percentage	of	area	in	various	la nd	use	categories.		Following	t his	guidance,	2011	land use	data	(most	recent available)	were	obtained	from the	U.S.	Geological	Survey 17 through	ArcGIS	and	a	3	km	radius	circle	inscribed electronically	around	the	Coop er	stack	coordinates.		All	data	w ere	georeferenced	and tabulated	using	the categories	shown	in	Table	3‐1	fo r	urban	and	rural	designation.

14 Wenjun Qian and Akula Venkatram, “Performance of Steady State Dispersion Models Under Low Wind

‐ Speed Conditions,” Boundary

‐ Layer Meteorology, no. 138 (2011): 475

‐ 491.

15 Ibid

. 16 http://www.epa.gov/ttn/scram/7thconf/aermod/aermet_mcb3.txt ; http://www.epa.gov/ttn/scram/7thconf/aermod/aermet_mcb4.txt ; http://www.epa.gov/ttn/scram/7 thconf/aermod/AERMET_mcb5.pdf ; http://www.epa.gov/ttn/scram/7 thconf/aermod/AERMET_mcb6.pdf

17 http://www.mrlc.gov/viewerjs/East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-3 Figure	3‐1	shows	the	layout	of the	land	use	where	greens,	yello ws	and	browns	are	farmland,	forests,	and grasses,	pinks	are	non‐urban	deve loped	lands,	and	red	and	dark red	are	urban	areas.		Table	3‐2	shows	the results	of	this	land	categoriza tion	process.		As	can	be	seen	th e	area	is	predominantly rural	by	an	overwhelming margin	at	93	percent,	and	theref ore,	was	treated	as	rural	in	th e	AERMOD	Model.

Table 3

‐ 1. Modeling TAD Urban / Rural Categories

Figure 3

‐ 1. Distribution of Land Use within 3km of Cooper Station Modeling TAD

Rural or Urban

11 Open Water A5 Water Surfaces rural

12 Perennial Ice/Snow A5 Water Surfaces rural
21 Developed, Open Space A1 Metropolitan Natural rural
22 Developed, Low Intensity R1 Common Residential rural

23 Developed, Medium Intensity I1, I2, C1, R2, R3 Industrial/Commercial/Compact

Residential urban

24 Developed, High Intensity I1, I2, C1, R2, R3 Industrial/Commercial/Compact

Residential urban

31 Barren Land A3 Undeveloped (Grasses/Shrub) rural
41 Deciduous Forest A4 Undeveloped (Wooded) rural
42 Evergreen Forest A4 Undeveloped (Wooded) rural
43 Mixed Forest A4 Undeveloped (Wooded) rural
52 Shrub/Scrub A3 Undeveloped (Grasses/Shrub) rural
71 Grassland/Herbaceous A3 Undeveloped (Grasses/Shrub) rural
81 Pasture/Hay A2 Agricultural rural
82 Cultivated Crops A2 Agricultural rural
90 Woody Wetlands A4 Undeveloped (Wooded) rural
95 Emergent Herbaceous Wetlands A3 Undeveloped (Grasses/Shrub) rural Auer Land-Use Classification 2011 NLCD Land Cover ClassificationEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-4 Table 3

‐ 2. Cooper Station Urban/Rural Determination



### 3.3. METEOROLOGICAL DATA

Meteorological	data	was	required	as	input	to	the	AERMOD	model	t o	allow	the	characteriza tion	of	the	transport and	dispersion	of	the	Cooper	Stat ion	emissions	in	the	atmospher e.		As	per	the	modeling TAD,	three	years	of

recent	data	coincidental	with	t he	latest	three	years	of	Cooper CEMS	data	reflecting	SO 2 controls	on	Unit	2 (beginning	July	1,	2012)	was	obtai ned	from	the	most	representat ive	and	nearby	National	Weather	Service (NWS)	sites.		Data	obtained	from the	NWS	included	surface	(gene rally,	10	m	tower‐based)	and	upper	air (radiosonde)	meteorological	da ta	for	the	most	recent	three	full year	data	set	(July 1,	2012	through	June	30, 2015)	and	was	processed	from	arch ived	data	from	the	most	repres entative	NWS	meteorological	station	in	the vicinity	of	the	Cooper	Station. Representativeness	was	determi ned	on	the	basis	of	proximity,	similarity	in	terms of	land	use	(and	its	effect	on	surface	roughness,	albedo,	and	B owen	ratio),	and	meteorological	judgement. AERMOD‐ready	meteorological	data was	prepared	using	the	latest version	of	the	AERMET	meteorological processing	utility	(Version	15181) .		Standard	U.S.	EPA	meteorol ogical	data	processing guidance	was	used	as
outlined	in	a	recent U.S.	EPA	memorandum 18 as	well	as	other	AERMET	and	associated	processor	documentation

. Additionally,	the	beta	option	AD J_U*	was	selected	during	proces sing,	as	mentioned	in	Section	3.1.

A	preliminary	evaluation	of	the	NWS	meteorological	data	sites	w ithin	approximately	150	km	indicated	that several	airports	were	located	in	t he	region	including	Somerset‐ Pulaski	Airport	(KSME,	6.6	km	to	Cooper Station),	Wayne	County	Airport	(KEKQ,	28.3	km	to	Cooper	Station ),	and	London‐Corbin	McGee	Field	(KLOZ,	46.9 km	to	Cooper	Station).		Figure	3‐ 2	shows	the	locations	of	the	a irports	having	meteorolo gical	data	sets	that	were considered	for	this	modeling.		Of these	candidate	sites,	the	mo st	representative	site,	the	London‐Corbin	Airport, was	the	only	site	having	the	su fficient	hour‐by‐hour	and	one‐mi nute	meteorological	data	s ets	that	can	be	used	in the	dispersion	modeling.		Table	3 ‐3	presents	the	results	of	a	N WS	identification	exercis e	based	on	proximity	to

18 Fox,	Tyler,	U.S.	Environmenta l	Protection	Agency.	2013.		“Use of	ASOS	Meteorological	Data	in	AERMOD	Dispersion	Modeling.”
Available	Online: http://www.epa.gov/ttn/scram/g uidance/clarification/20130308_Me t_Data_Clarification.pdf Category ID Category Description Percent

11 Open Water 12.9%

21 Developed, Open Space 9.2%

22 Developed, Low Intensity 14.4%

23 Developed, Medium Intensity 5.3%

24 Developed, High Intensity 1.7%

31 Barren Land 3.9%

41 Deciduous Forest 31.1%

42 Evergreen Forest 0.9%

43 Mixed Forest 2.7%

52 Shrub/Scrub 0.2%

71 Grassland/Herbaceous 5.4%

81 Pasture/Hay 11.9%

82 Cultivated Crops 0.4%

95 Emergent Herbaceous Wetlands 0.3%

Total 100.0%

Urban 7.0%

Rural 93.0% Pecent Land Categorization ArcGIS Analysis Results for Cooper StationEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-5 Cooper	Station	where	meteorologic al	stations	without	adequate	d ata	are	designated	with	red	highlighting	and

candidate	stations	for	the	model ing	analysis	are	designated	wit hout	highlighting.		As	can	be	seen,	other candidate	sites	have	the	appropri ate	one	minute	data	sets,	but are	located	farther	aw ay	and	in	a	different geographical	setting	than	the	Cooper	Station.		Oak	Ridge	Airpor t	(KOQT)	is	in	a	much	more	rugged	terrain	and Blue	Grass	Airport	in	Lexington	i s	located	in	much	more	open	an d	rolling	terrain.

Thus,	based	on	the	site	proximit y,	similarity	of	land	use	and	g eographical	setting,	and	ge neral	climatic	features, the	most	representative	July 1,	2012	through	June	30,	2015	surf ace	meteorology	data	for the	modeling	of	the Cooper	Station	was	determined	to be	that	of	the	London‐Corbin	A irport	(KLOZ,	WBAN	No.	03849).		With	regard to	the	required	upper	air	data, which	is	more	regional	in	natur e	and	reflects	the	ov erall	higher	altitude meteorological	conditions,	the	c losest	and	most	representative site	is	from	the	Nashville	International	Airport (KBNA,	WBAN	No.	13897).East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-6

Figure 3

‐ 2. Meteorological Stations and SO 2 Monitors in the Area near Cooper StationEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-7 Table 3

‐ 3. Proximity Analysis of Meteorological Stations to Cooper Station



### 3.3.1. Surface Data

Unprocessed	hourly	surface	meteo rological	field	data	was	obtain ed	from	the	U.S.	National	Climatic	Data	Center (NCDC)	for	the	London‐Corbin	Air port	Regional	Airport	(KLOZ)	fo r	July	1,	2012	through	June	30,	2015	in	the standard	ISHD	(integrated	su rface	hourly	data)	format 19 .		This	data	was	suppl emented	with	TD‐6405	(“1‐ minute”)	wind	data	for	each	station 20 and	processed	using	the	latest version	of	the	AERMINUTE	pre‐pr ocessing tool	(version	14337).		A	threshold	wind	speed	of	0.5	m/s	was	us ed	in	AERMET	as	per	U.S.	EPA	guidance.		The “Ice‐Free	Winds	Group”	AERMINUTE	o ption	was	selected	due	to	the fact	that	a	sonic	anemometer	was	installed at	KLOZ	on	November	11,	2005 21

.



### 3.3.2. Upper Air Data

In	addition	to	surface	meteorological	data,	AERMET	requires	the use	of	data	from	an	upper	air	sounding	to estimate	mixing	heights.		Upper	ai r	data	from	the	nearest	U.S. National	Weather	Servic e	(NWS)	radiosonde equipped	station	was	utilized	in the	modeling	analysis.	In	this case,	upper	air	data from	the	Nashville International	Airport	(KBNA,	W BAN	No.	13897)	was	obtained	from the	National	Oceanic	and	Atmospheric Administration	(NOAA)	in	FSL	(Fo recast	Systems	Laboratory)	form at 22 for	July	1,	2012	through	June	30,	2015.

19 ftp://ftp.ncdc.noaa.gov/pub/data/noaa/

20 ftp://ftp.ncdc.noaa.gov/pub/data/asos‐onemin

21 http://www.nws.noaa.gov/ops2/Sur face/documents /IFW_stat.pdf

22 http://www.esrl.noaa.gov/raobs/ Station Name WBAN

Station

ID Station

Call Si gn Lat. Lon g

. UTM East ( m ) UTM North ( m ) ASOS One

Minute Data

A vailable? Distance

to Cooper

( km )
Somerset‐Pulaski	Co‐J.T.	Wils 63815 KSME 37.054 ‐84.615 712,075 4,103 ,523 No 6.6

Wa y ne	Count y Air p or t 63882 KEKQ 36.855 ‐84.856 691,139 4,080,933 No 28.3

Ldon‐Crbn	A p t‐M g ee	Fld	A pt 03849 KLOZ 37.087 ‐84.077 759,811 4,108,522 Yes 46.9
Stuart	Powell	Fld 99999 KDVK 37.578 ‐84.77 696,918 4,161,333 No 66.3

Middlesboro‐Bell	Count y Air p o 63875 K1A6 36.611 ‐83.738 791,758 4,056,677 No 87.5

Oak	Rid g e 53868 KOQT 36.024 ‐84.238 748,887 3,990,140 Yes 112.7

Blue	Grass	Air p or t 93820 KLEX 38.041 ‐84.606 710,085 4,213,070 Yes 115.8
Crossville	7	Nw 63855 ‐‐ 36.014 ‐85.135 668,068 3,987,110 No 119.5

Glas g ow	Munici p al	Air p or t 00361 KGLW 37.033 ‐85.95 593,386 4,099,049 No 120.9
Versailles	3	Nnw 63838 ‐‐ 38.095 ‐84.747 697,564 4,218,753 No 122.6
Crossville	Memorial	‐Whitson 03847 KCSV 35.951 ‐85.081 673,072 3,980, 216 Yes 124.2

Lee	Count y Air p or t 00274 K0VG 36.654 ‐83.218 838,097 4,063,158 No 128.5

Mount	Sterlin g Mont g omer y Cou 00146 KIOB 38.067 ‐83.983 764,673 4,217,548 No 130.4 Julian	Carroll	Air p or t 03889 KJKL 37.591 ‐83.314 825,468 4,166,829 Yes 131.1

U pp er	Cumberland	R g nl 99999 KSRB 36.056 ‐85.531 632,308 3,991,158 No 134.1

Ca p ital	Cit y Air p or t 53841 KFFT 38.185 ‐84.903 683,657 4,228,420 Yes 134.6

Mc	Ghee	T y son	Air p or t 13891 KTYS 35.818 ‐83.986 772,307 3,967,956 Yes 141.8

Bowlin g Green	21	Nne 63849 NBWG 37.25 ‐86.233 568,021 4,122,882 No 148.4

Godman	Aaf	Air p or t 13807 KFTK 37.9 ‐85.967 590,819 4,195,223 No 157.5
Louisville		Intl‐Standiford	F 93821 KSDF 38.181 ‐85.739 610,442 4,226 ,649 Yes 165.8

Bowman	Field	Air p or t 13810 KLOU 38.228 ‐85.664 616,936 4,231,956 Yes 166.1

Central Coordinates of Cooper: 714,250 4,097,343East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-8 

### 3.3.3. Land Use Analysis

Parameters	derived	from	analysis of	land	use	data	(surface	roug hness,	Bowen	ratio,	and	albedo)	are	also required	by	AERMET.		In	accordance	with	U.S.	EPA	guidance,	thes e	values	were	determin ed	using	the	latest version	of	the	AERSURFACE	tool	(version	13016). 23 AERSURFACE	reads	gridded	l and	use,	land	cover	data	as provided	by	the	United	State s	Geological	Survey	(USGS) 24 and	associates	such	data	wit h	representative	values	of the	three	parameters	listed	abov e.		Typically,	the	land	use	ana lysis	would	be	based	on	mo isture	conditions	at	the location	of	the	meteorological	d ata,	that	is,	the	London‐Corbin Airport	which	would	be	th e	best	representation	of the	data	in	terms	of	wet,	dry,	o r	average	conditions	in	compari son	to	the	30‐yr	average s	for	the	most	recent complete	calendar	years	(in	th is	case,	1985	through	2014).		The London‐Corbin	Airport ,	however,	is	missing several	years	in	this	time	peri od	and	thus,	another	more	comple te,	nearby	set	of	precipitation	data	was	used, namely	that	of	the	Jackson	Julia n	Carroll	Airport	located	in	Br eathitt	County,	Kentuc ky	about	80	km	to	the

northeast	in	similar	terrain	to	th at	of	London‐Corbin	Airport. To	make	the	moisture	conditions	determination, climatological	records	of	the	a nnual	precipitation	in	each	mode led	year	(July	1,	2012	through	June	30,	2015) were	compared	to	the	1985‐ 2014	climatological	record 25

.

Table	3‐4	shows	the	30 year	precipitation	by month	for	Jackson along	with	the	seasonal	totals,	averages,	and

30 th percentile	high	and	low	values .		These	were	compared	to	the	ac tual	rainfall	in	each	season	for	each	year	of July	1,	2012	through	June	30,	2015 which	determined	the	average ,	wet,	or	dry	option	in	AERSURFACE.		Other specific	AERSURFACE	settings	w ere	used	that	represent	the	locat ion	of	the	London‐Corbin	Airport meteorological	station.		These	s ettings	include	location	coordi nates,	monthly	versus	seasonal	differentiation, aridity,	and,	of	course,	the	sur face	moisture	determination	whi ch	was	just	discussed.		Thi s	determination	is	used in	AERSURFACE	to	adjust	the	Bowe n	ratio	estimated	by	AERSURFACE ,	which	in	turn	affect s	the	calculation	of the	daytime	mixing	hei ghts	used	in	AERMOD.

23 U.S.	Environmental	Protection Agency.		2013.	“AERSURFACE	User ’s	Guide.”		EPA‐454/B‐08‐001,	Revised	01/16/2013.		Available
Online: http://www.epa.gov/scram001/7thconf/aermod/aersurface_userguide .pdf

24 http://www.mrlc.gov/viewerjs/

25 National	Climactic	Data	Center .	2014	Local	Climatological	Dat a	(LCD).East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-9 Table 3

‐ 4. Moisture Calculation for Jackson Airport (inches of precipitation)



### 3.4. COORDINATE SYSTEM

In	all	modeling	input	and	output files,	the	locations	of	emissi on	sources,	structu res,	and	receptors	are represented	in	the	appropriate	Zone	of	the	Universal	Transverse Mercator	(UTM)	coordinate	system	using	the North	American	Datum	1983	(NAD83) .		The	Cooper	Station	and	the	surrounding	area	lies within	Zone	16.



### 3.5. RECEPTOR LOCATIONS

The	dispersion	modeling followed	the	guidance	of	the	modeling	T AD	in	terms	of	only	putting	receptors	in	areas where	it	is	feasible	to	place	an	actual	monitor.		Consistent	wi th	the	example	in	Figure	3‐3	from	the	modeling TAD,	no	receptors	were	placed	in lakes,	rivers	or	similar	areas .		As	the	modeling	TAD	states:

“In areas where it is not feasible to place a monitor (water bodies, etc.), receptors can be ignored or not placed in those locations. In any case, receptor placement should be of sufficient density to provide

resolution needed to detect significant gradients in the concentrations, with receptors placed clo ser together near the source to detect local gradients and placed farther apart away from the source. In addition, the user should place receptors at key locations such as around facility fence lines (which define

the ambient air boundary for a particular source) or monitor locations (for comparison to monitored

concentrations for mo del evaluation purposes).” YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL Winter Spring Summer Fall

1985 3.50 2.02 3.27 0.78 5.50 4.19 9.74 5.24 1.40 4.97 6.89 1.74 49.24 7.26 9.55 19.17 13.26

1986 1.84 5.44 1.56 0.95 2.42 2.15 2.73 2.49 3.27 2.38 9.32 3.06 37.61 10.34 4.93 7.37 14.97

1987 2.70 3.46 1.90 3.70 2.25 3.22 6.37 2.64 2.92 0.51 3.15 5.98 38.80 12.14 7.85 12.23 6.58

1988 2.59 2.00 3.09 2.97 4.50 1.37 4.56 4.15 7.82 1.85 6.12 4.03 45.05 8.62 10.56 10.08 15.79

1989 3.48 7.61 6.74 3.23 6.43 6.96 2.21 5.22 7.37 7.36 4.28 2.40 63.29 13.49 16.4 14.39 19.01

1990 2.56 6.27 3.16 2.95 5.08 4.02 4.18 4.21 1.86 4.73 2.91 12.97 54.90 21.8 11.19 12.41 9.5

1991 3.16 4.46 6.08 2.67 4.99 7.01 4.46 2.96 2.62 2.13 5.22 9.35 55.11 16.97 13.74 14.43 9.97

1992 1.87 3.12 5.80 1.66 4.61 4.08 6.67 3.20 3.66 1.60 3.23 4.92 44.42 9.91 12.07 13.95 8.49

1993 2.05 3.54 5.28 3.26 3.74 4.82 4.70 7.70 6.58 4.63 5.08 4.28 55.66 9.87 12.28 17.22 16.29

1994 7.28 7.42 11.78 5.52 3.37 4.85 3.74 6.11 2.45 2.53 2.73 2.98 60.76 17.68 20.67 14.7 7.71

1995 7.16 3.71 3.51 4.90 9.91 4.22 1.77 2.07 4.01 5.03 4.18 2.36 52.83 13.23 18.32 8.06 13.22

1996 5.63 3.11 5.46 5.95 5.86 4.35 4.96 3.01 6.47 4.00 7.28 2.72 58.80 11.46 17.27 12.32 17.75

1997 3.53 2.97 9.76 1.51 5.01 9.15 2.40 4.38 2.03 2.29 4.04 2.21 49.28 8.71 16.28 15.93 8.36

1998 3.76 4.45 2.86 10.00 6.28 8.29 2.46 2.47 2.09 2.59 2.98 5.16 53.39 13.37 19.14 13.22 7.66

1999 6.55 3.04 3.17 3.44 2.47 2.66 2.75 6.58 1.13 3.08 2.65 2.56 40.08 12.15 9.08 11.99 6.86

2000 2.63 3.53 1.94 4.97 4.33 6.80 5.69 4.38 4.92 1.07 1.47 4.35 46.08 10.51 11.24 16.87 7.46

2001 2.50 3.72 2.17 1.69 4.39 4.19 6.43 2.41 1.09 1.41 1.82 2.55 34.37 8.77 8.25 13.03 4.32

2002 4.09 1.24 7.96 4.11 5.23 4.98 5.50 1.72 3.48 6.39 3.61 4.28 52.59 9.61 17.3 12.2 13.48

2003 2.10 7.89 1.47 5.14 5.98 7.54 3.95 5.12 4.33 2.20 5.49 3.78 54.99 13.77 12.59 16.61 12.02

2004 4.23 3.77 3.87 4.01 10.78 6.18 7.02 2.39 7.55 4.96 4.37 3.27 62.40 11.27 18.66 15.59 16.88

2005 5.12 3.03 3.52 7.47 2.50 2.78 4.08 3.92 0.51 1.57 2.66 3.18 40.34 11.33 13.49 10.78 4.74

2006 5.57 1.85 2.89 4.57 3.61 3.24 3.87 3.69 6.39 5.49 2.43 2.03 45.63 9.45 11.07 10.8 14.31

2007 2.83 1.20 2.71 3.22 1.82 2.15 4.05 2.64 2.49 3.80 3.37 5.18 35.46 9.21 7.75 8.84 9.66

2008 2.46 3.41 4.14 4.00 3.24 3.94 6.13 1.16 0.67 1.46 3.03 6.86 40.50 12.73 11.38 11.23 5.16

2009 5.80 1.73 3.52 3.64 9.22 7.03 6.40 3.55 4.88 3.54 0.80 5.96 56.07 13.49 16.38 16.98 9.22

2010 4.27 3.11 2.43 2.61 7.92 5.60 3.34 3.51 2.05 1.68 5.77 2.97 45.26 10.35 12.96 12.45 9.5

2011 2.72 3.97 4.74 10.20 6.69 5.49 6.02 3.07 3.20 4.25 5.48 4.18 60.01 10.87 21.63 14.58 12.93

2012 4.86 3.90 4.07 2.67 4.20 1.91 7.39 4.75 6.77 4.24 0.84 6.39 51.99 15.15 10.94 14.05 11.85

2013 5.73 1.91 4.63 3.70 4.23 6.36 6.62 10.04 1.27 2.13 3.01 7.09 56.72 14.73 12.56 23.02 6.41

2014 3.15 4.47 5.51 5.43 2.30 3.12 5.77 8.55 2.35 7.77 2.97 2.49 53.88 10.11 13.24 17.44 13.09

2015 2.12 4.06 6.26 10.29 1.74 7.42 6.18 18.29 7.42 0

Precipitation location from http://www.ncdc.noaa.gov/cdo-web/datatools/findstation Upper 30th 13.27 16.31 14.97 13.23 KJLK precipitation data - obtained 2014 cumulative report from http://www1.ncdc.noaa.gov/pub/orders Lower 30th 10.05 11.15 12.22 8.1 7

2010 A A A A A = average precip 2011 A W A A W = wet precip 2012 W D A A D = dry precip 2013 W A W D

2014 A A W A

2015 D W W Note: 30year Local climatological Data for Jackson, KY was used due to missing data for London-Corbin airportEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-10 Figure 3

‐ 3. Modeling TAD Receptor Grid Showing Example Excluded Locations over Water

The	proposed	receptor	grid	for	t he	modeling	of	the	Cooper	Stati on	combined	a	multi‐nested,	circular	Cartesian grid	at	various	spacing	interval s	centered	on	the	main	Cooper	S tation	stack	along	with	receptor	points	on	the facility’s	fence	line.		For	the	a ir	dispersion	modeling	analyse s,	ground‐level	concentrations	were	calculated	from

the	fence	line	out	to	the	locati on	and	magnitude	of	the	signifi cant	concentration	gradi ent	as	specified	by	the modeling	TAD.		To	accommodate	th e	possible	farthest	extent	of	t his	modeling	domain	an d	receptor	grid,	the receptors	are	a	series	of	nested	grids	as	follows:

Fence Line Grid: “Fence	line”	grid	consisting	o f	evenly‐spaced	receptors	50	meters	apart	placed	along	the main	fence	line	of	the	Cooper	Station,

Fine Cartesian Grid: A	“fine”	grid	contai ning	100‐meter	spaced	receptors	extending to	3	km	from	the center	of	the	property	and	beyond	the	fence	line,

Medium

‐ Fine Cartesian Grid: A	“medium‐fine”	grid	containing 250‐meter	spaced	receptors	exte nding

from	3	km	to	5	km	from	the	cent er	of	the	facility,	exclusive	of receptors	on	the	fine	grid,

Medium

‐ Coarse Cartesian Grid: A	“medium‐coarse”	grid	contain ing	500‐meter	spaced	receptors extending	from	5	km	to	10	km	from	the	center	of	the	facility,	e xclusive	of	receptors	on	the	fine	and	medium‐ fine	grids,East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-11 Coarse Cartesian Grid: A	“coarse	grid”	containing	1,000‐ meter	spaced	receptors	extendi ng	from	10	km	to

20	km	from	the	center	of	the	fac ility,	exclusive	of	receptors	o n	the	fine,	medium‐fine,	and	medium‐coarse grids.

Figure	3‐4	shows	the	i nnermost	grids	of	the	proposed	receptors used	in	the	modeling.		As	can	be	seen,	receptors

in	the	Cumberland	River	have	been eliminated.		Also	shown	is	th e	current	fence	line	of	th e	facility	(innermost line	of	yellow	receptors)	and	th e	property	line	as	a	red	annota tion	to	show	the	extent	of EKPC	property	holdings

in	the	area.

Figure 3

‐ 4. Innermost Portion of the Proposed Modeling Receptor Grid for Cooper



### 3.6. TERRAIN ELEVATIONS

The	terrain	elevation	for	each receptor,	building,	and	emission source	was	determined	u sing	USGS	1	arc‐second National	Elevation	Data	(NED).		The	NED,	obtained	from	the	USGS 26 ,	has	terrain	elevations at	30‐meter	intervals. Using	the	AERMOD	terrain	processo r,	AERMAP	(version	11103),	the terrain	height	for	each	receptor,	and outlying	buildings	included	in	the	model	was	determined	by	assi gning	the	interpolated	h eight	from	the	digital terrain	elevations	surrounding	e ach	source.		These	were	used	di rectly	in	the	AERMOD	model.

In	addition,	AERMAP	was	used	to	c ompute	the	hill	height	scales associated	with	each	ele vated	receptor	located above	the	Cooper	Station	source	b ase	elevation.		This	computati on	enables	the	model	to determine	the	effect that	terrain	will	have	on	plumes from	the	sources.		AERMAP	sear ches	all	nearby	elevation points	for	the	terrain height	and	location	that	has	the	greatest	influence	on	each	rec eptor	to	determine	the	hill height	scale	for	that receptor.		AERMOD	then	uses	the hill	height	scal e	in	order	to	s elect	the	point where	a	plume	may divide	between

26 http://www.mrlc.gov/viewerjs/East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-12 going	around	a	terrain	feature	an d	lofting	over	the	feature. Review	of	the	area	indicat es	that	a	few	hills	exist near	the	Cooper	Station	and	thus ,	the	inclusion	of	terrain	elev ations	in	the	modeling	is	paramount.		Figure	3‐5 shows	a	relief	map	of	the	area.

Figure 3

‐ 5. Relief Map of Area within 20 km of Cooper Station



### 3.7. COOPER STATION EMISSION SOURCES

The	Cooper	Station	has	only	one major	source	of	continuous	SO 2 emissions,	which	is	the	main	stack	associated

with	coal‐fired	Units	1	and	2.		Other	intermittent	sources	of	S O 2 emissions	include	an Emergency	Diesel Generator	(Unit	08), a	Communication	Tower Emergency	Generator (Unit	12),	Fire	Pump	Engine	(Unit	13),	and

the	Burnside	Service	Center	Em ergency	Generator	(Unit	14).		All are	permitted	to	opera te	no	more	than	100East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-13 hours	per	year	in	non‐emergency	s ituations	and	thus,	do	not	contribute	to	the	annual	distribution	of	daily

maximum	1‐hour	SO 2 concentrations. 27

In	addition,	actual	hourly	and	annual	SO 2 emissions	from	these	diesel	fuel and	propane‐fired	emergency	e ngines are	negligible	given	the	relativ ely	small	horsepower	rating	of the	engines	and	the	very	l ow	sulfur	content	of	the

fuels	used.		Consistent with	U.S.	EPA’s	guidance 28 for	treatment	of	intermittently operated	source	like	emergency engines	in	1‐hr	SO 2 and	NO 2 NAAQS	demonstrations,	EKPC	exclu ded	these	engines	from	the	mod eled	source inventory	and	only	considered	SO 2 emissions	from	Units	1	and	2	in	the	modeling	analysis.

The	preferred	modeling	approach	for	establishing	modeled	emissi on	rates	recommended	i n	the	modeling	TAD	is the	use	of	CEMS	data,	where	available,	as	a	CEMS‐derived,	hour‐by‐hour	modeled	emission rate	dataset	provides the	most	accurate	representation of	the	actual	emissions	histor y	of	the	source	for	th e	relevant	time	period considered	in	the	modeling.		Cu rrently	and	in	the future,	the	c ombined	flows	of	each	unit at	Cooper	Station	exit through	a	common	stack.		The	foll owing	discussion	recognizes	th is	fact	and	is	geared towards	defining	the

individual	and	combined	st ack	emissions and	flows.

Further	details	regarding	the	deri vation	of	the	modeled	hour‐by ‐hour	SO 2 emission	rates	representing	the	sum

of	the	actual	emissions	from	Uni t	2	and	the	allo wable	emissions from	Unit	1	and	the	combined	Unit	1	and	2	stack parameters	for	each	relevant	C ooper	Station	operating	mode	(i.e .,	both	units	running	and	only	Unit	1	running) are	presented	in	the	f ollowing	subsections	with	explicit	refere nces	to	the	associated	model	input	parameter derivation	spreadsheet	included in	Appendix	C	to	this	modeling report.



### 3.7.1. Cooper Unit 1 Modeled Emission Rate

Because	Unit	1	is	undergoing	modification	to	tie‐in	the	exhaust gases	into	the	existing	dry	flue	gas desulfurization	(DFGD)	currently serving	Unit	2,	use	of	Unit	1 CEMS	data	from	the	relevant	time	period	is	not representative	of	future	emissions	or	impacts.		This	SO 2 emissions	control	project	fo r	Unit	1	is	expected	to	be completed	by	January	1,	2016	whic h	is	well	before	the	consent	d ecree‐driven	July	2016	SO 2 NAAQS	attainment designation	deadline.

Under	these	circumstan ces,	an	allowable	SO 2 emission	rate	for	Unit	1	is	appl ied	for	every	hour	of	the	mode led meteorological	period.		T he	Unit	1	allowable	SO 2 emission	rate	in	its	current	co nfiguration	is	3.3	lb/MMBtu	on a 24‐hour	average	basis	(refer	to	C ondition	B.2.c	for	Unit	1	on	p age	3	of	80).		In	addition, after	Unit	1	is	tied	into the	DFGD,	it	will	become	subject	to	an	additional	limit	of	95% control	or	0.100	lb/MMBtu on	a	30‐day	rolling average.		Based	on	this	suite	of	SO 2 emission	limits	which	will	be federally	enforceable,	EKPC	perf ormed dispersion	modeling	of	an	emissi on	rate	equivalent	to	0.165	lb SO 2 /MMBtu	(i.e.,	178	lb/hr	based	on	the maximum	heat	input	cap acity	of	Unit	1	of	1,080	MMBtu/hr).		This	emission	rate	is	derived	by	taking	95%	of	the current	Title	V	permit limit	of	3.3	lb	SO 2 /MMBtu.		As	a	further	measure	of added	conservatism,	this	rate was modeled	assuming	8,760	hours	of	o peration,	rather than	only	mod eling	this	rate	at	times	when	Unit	1	was actually	running	during	the	mo deled	three‐year	period.		EKPC	be lieves	that	the	emission limits	discussed	above (i.e.,	3.3	lb	SO 2 /MMBtu	and	95%	reduction	or	0.100	lb	SO 2 /MMBtu)	are	sufficient	to	support	the	modeled emission	rate,	and	no	additional limits	are	necessary.		This	mo deling	approach	is	differen t	than	proposed	in	the

27 Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1

‐ Hour NO 2 National Ambient Air Quality
Standard ,	Memorandum	from	Tyler	fox,	Lead er	Air	Quality	Modeling	Group to	U.S.	EPA	Regional	Air	Div ision	Directors,	March	1,

2011.

28 Ibid.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-14 modeling	protocol,	but	reflects	consideration	of	EPA	Region	4’s comments	on	the	m odeling	protocol 29 and discussions	with	KDAQ.



### 3.7.2. Cooper Unit 2 Modeled Emission Rate

As	referenced	in	Section	2.6	of	t he	modeling	protocol	submitted on	August	3,	2015,	EKPC	has	relied	on	CEMS data	from	Unit	2	directly	with	n o	alterations	or	refinements	be cause	this	boiler	has	b een	tied	into	the	DFGD system	during	the	entire	modeling period.		This	data	is	also	ex pected	to	represent	future operation	of	this	unit

after	the	Unit	1	duct rerouting	project	is	c ompleted	and	in	any	year	after	the	July	2016	SO 2 NAAQS	designation deadline.		Using	coal	heat	input capacity	as	a	measure	of	the	s ize	of	each	electric	gener ating	unit	at	the	Cooper Station,	Unit	2	is	nearly	two	ti mes	larger	than	Unit	1	(i.e.,	2 ,089	MMBtu/hr	for	Unit	2	versus	1,080	MMBtu/hr	for Unit	1).		Design	evaluations	and engineering	judgement	suggest the	Unit	2	SO 2 emissions	profile	will	not	change as	a	result	of	adding	a	relativel y	small	amount	of	additional	e xhaust	flow	and	SO 2 emissions	loading	contributed by	the	smaller	Unit	1	after	the	ti e‐in.		In	light	of	these	fact s,	EKPC	possesses	a	complete	t hree‐year	record	of	valid

SO 2 emissions	data	reflective	of	current	and	future operation	of	U nit	2	while	operating	under	a	federally

enforceable	SO 2 emission	limit	that	mandates	e fficient	operation	of	the	DFGD	( refer	to	the	95%	SO 2 removal efficiency	or	0.100	lb	SO 2 /MMBtu	emission	limit	applicable	o n	a	30‐day	rolling	average	ba sis	in	Condition	B.2.c of	Title	V	Permit	V‐12‐019	R1	on	page	11	of	80).		With	basicall y	two‐thirds	of	the	future	SO 2 emissions	from Cooper	Station	characterized	by	C EMS	data	collected	in	the	repr esentative	three‐year	timeframe	selected	for	the modeling,	EKPC	does	not	believe it	would	be	appropriate	or	just ified	to	consider	other modeled	emission	rate derivation	techniques	for	Unit	2 (e.g.,	modeling	an	allowable	e mission	rate).

The	CEMS	data	handling	and	acquisition	system	(DHAS)	for	Unit	2 produces	hourly	average	SO 2 emission	rates (refer	to	column	C	of	the	1

. Unit 1 & 2 Emissions tab	in	model	input	parameter	sp readsheet	in	Appendix	C)	based

on	the	measured	SO 2 concentration	and	flow	rate	in	the	Unit	2	exhaust	after	it	exi ts	the	DGFD	but	before	it merges	with	the	currentl y	uncontrolled	(for	SO 2 )	Unit	1	exhaust	stream	at	the	b ase	of	the	combined	Unit	1	and 2 stack.		A	comprehensive	review	of	the	hourly	SO 2 emissions	dataset	for	Unit	2	generated	by	the	DAHS	indicates two	issues	requiring	data substitution	techniques.

First,	missing	and	out‐of‐control	data	flagged	by	the	DAHS	was	indicated	(refer	to	TRUE	values	in	column	D	of

the 1. Unit 1 & 2 Emissions tab	in	the	model	input	paramet er	spreadsheet	in	Appendix	C). Missing	values	and out‐of‐control	(OOC)	data	period s	are	required	to	be	filled	with	estimated	SO 2 emission	rates	because	actual

emissions	were	occurri ng	during	these	events.		The	emissions	we re	just	not	being	mea sured	and	recorded properly	for	these	hours.		Of the	26,280	data	points	in	the	3‐y ear	hourly	SO 2 emission	rate	data	set	for	Unit	2, only	48	hours	spread	over	19	even ts	were	flagged	by	the	DAHS	as	missing	or	OOC	when	Uni t	2	was	in	operation (99.92%	data	completeness	in	3‐yea r	period).		No	single	missing or	OOC	data	period	exc eeds	more	than	6	hours

in	duration.

Given	the	very	limited number	and	duration	of	missing/OOC	data periods,	EKPC	chose	a linear	interpolation filling	technique	usin g	the	two	good	data	points	surrounding	th e	missing/OOC	data	peri od	rather	than	a	more complex	technique	involving	emi ssion	factors	or	use	of	peak	val ues	from	a	representative	range	of	boiler operating	conditions.		This	interp olation	technique	was	perform ed	using	the	FORECAST	function	in	Microsoft ® Excel.		The	first	required	field	t o	execute	this	function	is	a missing/OOC	data	period	cou nt	(refer	to	column	F	of

the 1. Unit 1 & 2 Emissions in	the	model	input	pa rameter	spreadsheet	in	Appendix	C)	that	s tarts	at	1	for	the	first missing/OOC	hour	from	an	event	and	continues	counting	until	a	v alid	data	point	is	encou ntered.		The	sequential integer	list	of	missing/OOC	hours	for	each	event	defines	the	nu mber	of	data	points	for	which	an	interpolation

29 Email	from	Mr.	Rick	Gillam,	EPA Region	4	Environmental	Engine er/Air	Modeler	to	Mr.	Ben	Co rdes,	KDAQ	Air	Dispersion Modeling	Section	Supervisor, RE: EKPC Cooper Station ‐ 1

‐ Hour SO2 Air Dispersion Modeling Protocol ,	August	17,	2015	and	email
from	Mr.	Gillam	to	Mr.	Cordes on	August	25,	2015;	conference	ca ll	between	EKPC,	KDAQ	and	EPA	Region	4	on	August	27,	2015.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-15 calculation	is	required.		For	exa mple,	if	three	sequential	data points	were	missing,	the counter	sets	the	first missing	hour	to	1,	the	second	mi ssing	hour	to	2, and	the	third missing	hour	to	3.		The	next	field	required	for	this function	is	the	last	good	hour	be fore	the	missing/OOC	data	period	starts	and	the	firs t	good	hour	after	the missing/OOC	data	period	ceases.		These	SO 2 emission	rates	define	the	starti ng	point	and	end point	for	the linear interpolation	(refer	to columns	G	and	H	of	the 1. Unit 1 & 2 Emissions in	the	model	input	pa rameter	spreadsheet in	Appendix	C).		The	final	field	required	for	the	function	is	t he	range	of	missing/OOC	hou rs	where	a	0	is	assigned to	the	position	of	the	last	good hour,	and	a	value	one	greater than	the	duration	of	the missing/OOC	event	is assigned	for	the	first	good	value after	the	missing/OOC	period. Table	3‐5	provides	an	example	of	how	the FORECAST	function	is	applied	to	p erform	linear	interpolation	where	blue	text	indicates data	directly	from	the CEMS	DAHS,	black	text	indicates	a	calculated	value,	green	highlights	indicate	a	good	d ata	hour,	and	orange highlights	indicate	a	missing/ OOC	hour	requiring	filling.

Table 3

‐ 5. Example of Missing/OOC SO 2 Emissions Data Filling Technique

The	missing/OOC	data	flag	built	i nto	the	DAHS	indicates	a	6‐hou r	block	of	missing	data occurred	from	11/14/12 11	AM	until	11/14/12	at	5	PM.		The last	good	reading	before	the missing/OOC	data	period	starts	(1.10	lb/hr) and	the	first	good	reading	after the	missing/OOC	ends	(13.60	lb/hr)	defines	the	bounds	for	the	SO 2 emission	rate interpolation	(i.e.,	range	of	“Y” values).		The	starting	“X”	va lue	for	the	interpolation	is	always	set	to	hour	0	and the	ending	“X”	value	is	set	to	o ne	hour	higher	than	the	duratio n	of	the	event	(7	in	this	ca se).		With	these	inputs,

the	results	of	the	FORECAST	func tion	creates	a	smooth	line	of	6 data	points	connecting	th e	last	good	hour	before the	event	to	the	first	good	hour after	the	event.		An	identical approach	was	applied	to	all 19	events	in	the	Unit	2

SO 2 emissions	data	set.

The	second	issue	requiring	addi tional	data	processing	occurred when	the	operating	param eter	data	tag	for	Unit 2	operating	time	(refer	to	column	E	in	the 1. Unit 1 & 2 Emissions tab	of	the	model	input parameter	spreadsheet in	Appendix	C)	is	set	to	zero	for several	hours	while	the	Unit 2	CEMS	is	indicating	emi ssions	greater	than	zero (refer	to	column	C	in	the	1.	Uni t	1	&	2	Emissions	tab	of	the	mo del	input	parameter	spre adsheet	in	Appendix	C). During	the	vast	majority	of	thes e	hours,	Unit	1	is	running.		Th e	Unit	2	operating	hour	tag is	a	definitive	indication of	operating	status,	so	EKPC	zer oed	out	the	anomalous	Unit	2	SO 2 emissions	data	during	Unit	2	downtime.		This

data	substitution	for	Unit	2	dow ntime	was	accomplished	by	simply	adding	logic	to	the	filled	Unit	2	SO 2 emission rate	calculation	(refer	to	column	K	of	the 1. Unit 1 & 2 Emissions in	the	model	input	parameter	spreadsheet	in Appendix	C)	that	uses	the	CEMS‐monitored	SO 2 emission	rate	only	if	the	operating	time	flag	is	greater	than 0

minutes.		The	first	instance	in the	3‐year	data	period	where	th is	type	of	data	substitution	was	completed	for	an

invalid	hour	is	shown	in	Table	3‐6.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-16 Table 3

‐ 6. Example of Unit 2 SO 2 Emissions during Downtime

The	modeled	emission	rate	discu ssion	in	Section	2.6	of	the	mode ling	protocol	indicated startup	and	shutdown

emissions	would	be	handled	in	a manner	consistent	with	U.S.	EPA ’s	intermittent	source	guidance	regarding

whether	or	not	such	events	could be	excluded	from	the	modeling	analysis.		In	accordance	with	relevant guidance,	the	CEMS	data	was	not	further	processed	to	remove	SO 2 emissions	during	startup	or	shutdown	of	Unit

2.



### 3.7.3. Combined Cooper Units 1 and 2 Modeled Emission Rate

The	combined	stack	for	Cooper	Uni ts	1	and	2	is	represented	as	a single	point	source	in	the	SO 2 modeling analysis.		As	such,	the	modeled emission	rate	must	represent	th e	combined	SO 2 emissions	from	b oth	Units	1	and

2.		The	filled	Unit	2	actual	emi ssions	dataset	obtained	from	th e	CEMS	defines	the	SO 2 emissions	contribution from	Unit	2	on	an	hour‐by‐hour	b asis	(refer	to	Column	D	of	the 3. Model Input Parameters tab	of	the	model	input parameter	spreadsheet	in	Appendix C).		The	fixed	allowable	emis sion	rate	for	Unit	1	applied	on	a	continuous basis	(refer	to	Column	C	of	the 3. Model Input Parameters tab	of	the	model	input	pa rameter	spreadsheet	in Appendix	C)	is	added	to	the	Unit 2	actual	emission	rate	that	va ries	on	an	hour‐by‐hou r	basis	to	define	the

modeled	emission	rate	for	the	co mbined	Unit	1	and	2	stack	(refe r	to	Columns	E	and	F	of	the 3. Model Input

Parameters tab	of	the	model	input	paramete r	spreadsheet	in	Appendix	C).



### 3.7.4. Stack Parameter Selection

In	Table	2‐3	of	the	modeling	pro tocol,	EKPC	indicated	a	single set	of	stack	parameters	would	be	used	for	all hours	of	the	modeling	analysis	b ased	on	the	design	stack	gas	co nditions	when	both	Units 1	and	2	are	running determined	from	the	design	study supporting	the	Unit	1	DFGD	tie ‐in	project.		Upon	further	consideration,	EKPC determined	that	such	an	approach could	overestimate	the	stack	exit	velocity	at	times when	only	Unit	1	was operating.		To	address	this	issue,	the	final	selection	process involved	picking	from	two	se ts	of	design	flow	rates: 1)	both	Units	1	and	2	running	wit h	both	units	exhaust	routed	through	the	DFGD	(i.e.,	th e	original	design	case presented	in	Table	2‐3	of	the	modeling	protocol),	and	2)	only	U nit	1	running	with	its	exhaust	routed	through	the DFGD.		The	flow	rates	and	corresp onding	exit	velocities	assigne d	in	these	two	cases	are	documented	in	the modeling	input	parameter	spreadsheet	in	Appendix	C	(refer	to	Co lumns	H	and	I	of	the 2. Stack Parameters tab	in the	model	input	parameter	spread sheet	in	Appendix	C)	and	are	pr esented	in	Table	3‐7.

Finally,	the	stack	temperature	for	all	Cooper	Station	operating cases	is	set	to	160	deg. F	which	represents	the design	basis	for	the	DFGD	and	pr ovides	the	best	estimate	of	the exhaust	conditions	from the	combined	Unit	1

and	2	stack	after	the	Unit	1	DFG D	tie‐in	project	is	completed. Review	of	actual	in‐duct exhaust	temperatures	for

Unit	2	downstream	of	the	DFGD	in dicates	this	design	value	may	u nderestimate	actual	stack	temperatures	that

will	occur	after	the	Unit	1	tie‐i n,	and	thus,	this	input	parame ter	is	expected	to	result in	conservatively	high modeled	impacts	(i.e.,	lower	stac k	temperatures	p roduce	lower	t hermal	buoyancy,	less	pl ume	rise,	and	higher modeled	impacts	when	all	other	p arameters	are	held	constant).East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-17 Table 3

‐ 7. Cooper Station Source Parameters



### 3.7.5. Hourly Emissions File Creation

The	final	step	in	the process	of	assigning	model	input	paramete rs	for	the	Cooper	Station	1‐hr	SO 2 NAAQS

attainment	demonstration	modelin g	analysis	is	developing	the	ho urly	emission	rate	and	stack	parameter	file	fed to	AERMOD.		The	previously	discu ssed	hour‐by‐hour	varying	model ed	emission	rate	for Units	1	and	2	on	a combined	basis	is	assigned	to	the	hourly	emissions	file.		The	C ooper	Station	operating	sta tus‐based	exit	velocity is	then	assigned	depending	on	wh ether	both	units	are	operating or	only	Unit	1	is	operating	(refer	to	column	G	of

the 3. Model Input Parameters tab	in	the	model	input	paramet er	spreadsheet	carried	forward	f rom	column	I	of

the 2. Stack Parameters tab	in	the	model	input	paramet er	spreadsheet	in	Appendix	C). The	constant	exit temperature	discussed	previously is	assigned	to	every	hour	in	the	modeling	period.		F inally,	the	modeled emission	rate,	stack	temperature, and	exit	velocity	are	merged	into	an	hour‐by‐hour	text	string	which	matches the	syntax	of	the	AERM OD	hourly	emissions	fi le	invoked	with	the SO	HOUREMIS	keyword	( refer	column	J	of	the

3. Model Input Parameters tab	in	the	model	input	paramet er	spreadsheet	in	Appendix	C).



### 3.8. OTHER SOURCE INVENTORY

Other	sources	of	SO 2 emissions	in	the	area	surroun ding	the	Cooper	Station	were	eval uated	for	inclusion	in	the modeling.		This	evaluation	is	do cumented	in	the	regional	inventory	processing	spreadsheet	provided	on	the	CD in	Appendix	C.

Consistent	with	the	modeling	TAD ,	the	determination	of	which	so urces	to	model	followed	a	multi‐step	process. With	the	goal	of	the	modeling	be ing	to	determine	those	sources that	could	cause	or	contribute	to	a	NAAQS violation,	the	factors	considered in	developing	the	modeling	in ventory	included	the	magnitude	of	the	SO 2 emissions,	the	source	parameters ,	the	proximity	to	Cooper,	and the	level	and	extent	of the	impact	of	the	nearby source.		As	recommended	(and	ref erred	to	by	the	modeling	TAD)	b y	the	additional	clari fications	memorandum

of	2011 30 which	is	applicable	to	both	SO 2 and	NO 2 ,	several	options	for	screening	out	regiona l	inventory	sources were	considered	(the	AERSCREEN	model	approach	in	the	2011	memor andum	was	not	used)	and	include:

1. Analyzed	contour	plots	of	each	fully	modeled	source	(AERMOD)	wh ich	clearly	depict	the	impact	area	of the	source,	preferably	overlaid on	a	map	that	identifies	key	ge ographic	features	that	may	influence	the dispersion	patterns.		The	concentration	contour	plot	also	serve d	to	visually	depict the	concentration gradients	associated	with	the	source’s	impact	and	the	overlay	o f	adjacent	concentration	gradients	from nearby	sources.

30 Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1

‐ hour NO 2 National Ambient Air Quality
Standard ,	memorandum	form	Tyler	Fox	to Regional	Air	Division	Directors, March	1,	2011. Model ID Description UTM

Easting 3

(m) UTM
Northing 3

(m) Elevation (m) Emission

Rate (lb/hr) Stack Height

(ft) Temp. (F) Flow

Rate 1

(acfm) Exit
Velocity 1

(ft/s) Diameter (ft) Note
COOPER Units	1	&	2	Operating 714,250 4,097,343 243.84 CEMS 260 160.0 1,100,000 72.05 18.0 2 COOPER Only	Unit	1	Operating 714,250 4,097,343 243.84 178.20 260 160.0 260,000 17.03 18.0 2

1 Stack	flow	rates	and	exit	velocities	for	Units	1	&	2	in	opera tion	and	Unit	1	operating	alone	are	based	on	design	study	perfo rmed	by	engineering firm	contracted	to	perform	Unit	1	tie‐in	to	DFGD.

2 As	indicated,	only	one	Modeling	ID	exists	in	the	AERMOD	input file,	however	stack	exit	velocity	is	varied	within	an	hourly	e mission	input	file with	respect	to	the	specific	Units	operating	for	a	given	hour.

3 UTM	coordinates	are	represented	in	NAD83	datum	Zone	16.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-18 2. Identified	meteorological	condit ions	that	control	the	source’s impacts.		Use	the	MAXDAILY	or MXDYBYYR	AERMOD	output	options	t o	help	identify	the	appropriate time	periods	to	be	used	to calculate	controlling	design	valu es.		Meteorological	data	sets were	cross‐checked	with	model‐generated dates	of	highest	concentrations	to	assist	in	iden tifying	these controlling	meteorological	conditions.

3. Using	a	wind	rose	of	the	meteoro logical	data	in	the	modeling	ca n	help	to	analyze	flow	patterns	and determine	the	potentia l	for	the	cross‐coincidence	of	impacts	fr om	various	sources.

EKPC	implemented	eleme nts	of	all	three	regional	screening	metho ds.		Because	this	implementation	was	more robust	than	applying	the	AERSCREEN	Model,	that	method	was	not	d eemed	necessary	and	was,	thus,	not	used.

An	additional	technique	for	diff erentiating	contributing	source s	is	the	use	the	“20D	method” 31 .		The	20D	method says	that	if	the	ratio	of	the	em issions	to	the	distance	between sources	is	less	than	20	(Q/d	<	20),	a	source	does not	need	to	be	included	in	the	modeling.		The	specification	of	the	variables	in	the 20D	analysis	include:

 Q	=		Annual	actual/potenti al	emissions	in	tons/year

 d	=		Distance	from	the	target	so urce	in	kilometers	to	the	Coope r	Station

Because	both	allowable	(or	potential)	and	a ctual	emissions	are	referenced	in	the	model ing	TAD	for	use	in modeling	regional	sources,	a	Q/d	ratio	based	on	both	site‐wide actual	and	site‐wide	potential	emissions	has been	developed	(refer	to	the	Q‐D	A nalysis	tab	in	t he	regional	i nventory	processing	sprea dsheet	provided	on	the CD	in	Appendix	C).

Figure	3‐6	shows	all	SO 2 source	locations	within	50	km	o f	the	Cooper	Stat ion	that	repor ted	actual	SO 2 emissions
in	2013.		An	actual	annual	SO 2 emissions	magnitude	indicator	categorized by	size	and	color	of the	source	marker on	the	map	is	used	to	differentiat e	larger	sources	from	smaller sources	(see	legend	on	figure).		Of	the	16	facilities emitting	SO 2 within	20	km	of	the	Cooper	Station,	only	one	source	[Kingsford	Manufacturing	Company	(KMC)] has	actual	annual	emissions	grea ter	than	2.5	tpy.		With	the	exc eption	of	KMC,	the	cumulative	annual	SO 2 emissions	from	all	sources	wit hin	20	km	of	Cooper	are	only	8.5 tpy	on	actual	emissions basis	and	40	tpy	on	a potential	emissions	basis	(refer	to	columns	G	and	I	in	the NAAQS 20D List tab	of	the	regional	inventory processing	spreadsheet	in	Appendix	C).		In	comparison	to	the	mo deled	SO 2 emission	rates	from	Cooper	Unit	1 and	2,	these	small	sour ces	generate	negligi ble	quantities	of	SO 2 emissions.		Furthermore,	the	vast	majority	of

these	sources	are	located	to	the north	of	Cooper	Station	which is	in	a	low	frequency wind	sector	for	wind directions	causing	transport	from the	regional	source	locations to	the	area	of	highest	impacts	for	Cooper	(refer to	frequencies	for	“blowing	from” wind	sectors	in	Figure	3‐8	fo r	north,	northeast,	and	northwest	quadrants	of the	London‐Corbin	airport	meteor ological	station’s	wind	rose). Finally,	the	cumulative	Q/d	ratio	for	all	sources within	20	km	of	the	Cooper	Stati on	other	than	KMC	is	1.5	tpy/km on	an	actual	emission s	basis	and	6.2	tpy/km on	a	potential	emissions	basis,	w hich	are	both	wel l	below	the	2 0	tpy/km	threshold	that	applies	on	an	individual source	basis.		Based	on	this	Q/d profile	for	sources	within	20 km	of	Cooper	Station,	eve n	if	all	sources	were considered	to	form	a	“cluster”,	th eir	cumulative	Q/d	ratio	woul d	still	support	screening the	sources	out	of	the regional	inventory.

When	the	additional	38	facilities located	between	20	and	50	km from	the	Cooper	Station	are	added	to	the regional	inventory	evaluation,	al l	but	one	source	[EKPC	Laurel Ridge	Landfill	Gas	to	Energ y	(LGTE)	Facility]	has

actual	annual	SO 2 emissions	below	3.5	tpy.		The	EKP C	Laurel	Ridge	LGTE	Facility (with	actual	SO 2 emissions	of 36.1	tpy	and	potential	SO 2 emissions	of	41.3	tpy)	is	locate d	approximately	45	km	east	of the	Cooper	Station.		The London‐Corbin	airport	meteorolog ical	station	wind	rose	in	Figur e	3‐8	indicates	a	very	l ow	frequency	of	winds

31 A Screening Method for PSD ,	letter	from	Eldewins	Haynes,	N orth	Carolina	Air	Permit	Unit	to	Lewis	Nagler,	EPA,	Region	4, Meteorologist,	July	22,	1985.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-19 blowing	from	the	East	to	the	West	that	would	favor	transport	of SO 2 emissions	from	the	Laurel	Ridge	LGTE Facility	to	the	area	surrounding	the	Cooper	Station.		In	additi on,	the	single	stack	locat ed	at	the	Laurel	Ridge LGTE	Facility	is	only	33	feet	ta ll	which	does	not	favor	the	typ e	of	long	range	transport needed	to	significantly overlap	with	the	Cooper	Station impacts,	especially	considering the	moderately	complex	terrain	associated	with

the	area	between	the	landfill	an d	Cooper	Station.		As	a	final	s creening	technique,	EKPC	evaluated	the	combined Q/d	for	all	sources	be tween	20	km	and	50	km from	the	Cooper	Sta tion	and	again	determin ed	these	ratios	(1.1 tpy/km	on	an	actual	emissions	ba sis	and	5.7	on	a	potential	emis sions	basis)	do	not	suppo rt	the	addition	of	any regional	inventory	sources	beyond 20	km	of	the	Cooper	Station.

To	ensure	any	SO 2 impacts	from	the	small	sources screened	out	of	the	inventory	a re	accounted	for	within	the NAAQS	analysis,	EKPC	is	proposin g	to	use	a	conservative	backgro und	concentration	based on	the	design	value	in

the	form	of	the	1‐hr	SO 2 NAAQS	from	the	selected	Mammoth	Cave	SO 2 monitoring	station	( refer	to	Section	3.10). Selecting	the	design	value	from a	background	monitor	versus	tem poral	pairing	of	monitored	background

concentrations	with	modeled	co ncentrations	generally	offers	the ability	to	implement	mo re	extensive	screening of	small	regional	sources	due	to the	higher	magnitude	of	the	ba ckground	concentration	included	in	the	NAAQS demonstration.		Therefore,	EKPC	be lieves	the	regional	inventory screening	process	and	background

concentration	selection applied	for	the	Cooper	SO 2 NAAQS	analysis	achieve	an	a ppropriate	balance	between more	extensive	regional	source	s creening	and	selection	of	a	con servatively	high	backg round	concentration.

As	shown	in	Figure	3‐7	and	Tables	B‐1.1	and	B‐1.2	of	Appendix	B ,	the	KMC	facili ty	in	Burnside,	Kentucky	is	the only	nearby	SO 2 emissions	source	that	is	of	suff icient	magnitude	and	proximity to	warrant	consideration	in	the refined	modeling.		The	modeled	so urce	parameters	for	KMC	are	pr ovided	in	Table	B‐1.1	of	Appendix	B.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-20 Figure 3

‐ 6. Map Showing Regional Source Locations and SO 2 Emissions Magnitude near Cooper StationEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-21 Figure 3

‐ 7. Results of Regional Source Screening Evaluation based on Q/d Analysis



### 3.9. BUILDING INFLUENCES

The	U.S.	EPA’s	Building	Profile Input	Program	(B PIP)	with	Plume Rise	Model	Enhancements	(PRIME)	(version 04274),	was	used	to	account	for	bu ilding	downwash	influences	on the	Unit	1	&	2	main	stack.		The	purpose	of	a building	downwash	analysis	is	to determine	if	the	plume	dischar ged	from	a	stack	will	be	influenced	by	the turbulent	wake	of	any	onsite	bui ldings	or	other	structures,	res ulting	in	downwash	of	the	plume.		The	downwash of	the	plume	can	result	in	eleva ted	ground‐level	concentrations in	the	near	wake	of	a	building	and	is	required	for consideration	in	the	modeling.		F or	“other”	sources	that	are	mo deled	in	the	area,	downwa sh	was	not	considered, as	considering	this	ph enomenon	would	reduce the	impacts	from	th ese	sources	at	the	location	of	the	Cooper Station’s	maximum	impacts.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-22 

### 3.10. BACKGROUND CONCENTRATIONS

As	described	in	Section	8	of	the modeling	TAD,	the	inclusion	of background	ambient	mo nitored	concentrations as	part	of	the	NAAQS	demonstratio n	is	important	in	determining	and	deciphering	the	cumulative	ambient	air impacts.		As	recommended	by	the modeling	TAD,	a	first	tier	appr oach	(i.e.,	the	most	con servative	option	from among	the	available	background	c oncentration	selection	techniqu es)	based	on	monitored	design	values	for	the latest	three	year	period	was	impl emented	for	the Cooper	Station	NAAQS	analysis.

As	with	many	locations	i n	Kentucky,	a	nearby	SO 2 monitor	within	the	immediate vicinity	of	the	Cooper	Station does	not	exist	and,	therefore, regional	sites	were	evaluated	fo r	use	to	characterize	the	background

concentration.		This	selected	mo nitoring	site	should	not	be	inf luenced	by	the	subject	facility,	which	is	not expected	to	be	the	case	for	SO 2 emissions	from	Cooper	Station	an d	any	of	the	candidate	monitor ing	locations. Nearby	sources	with	a	significan t	concentration	gradient	were	e xplicitly	modeled,	and	t he	closest	monitors	were assessed	to	determine	similarity of	natural	and	insignificant	l ocal	source	contribution s	to	those	around	the Cooper	Station.

Due	to	the	lack	of	a	proximal	SO 2 monitoring	site,	a	regional	site	was	determined	to	be	the	best	choice	for characterizing	background	concen trations.		As	shown	in	Figure	3 ‐2,	three	SO 2 monitors	are	located	within	150 km	of	the	Cooper	St ation,	namely:

1. Nicholasville	(21‐113‐0001)

2. Lexington	(21‐067‐0012)

3. Mammoth	Cave	National	Park	(21‐061‐0501)

Consideration	of	each	monitor	as an	appropriate	background	moni tor	includes	the	following	site‐specific selection	criteria	(adapted	from the	guidance	provided	in	Section	8.2	of	Appendix	W):

1. The	distance	from	Cooper	St ation	to	the	monitor,

2. The	land	use	in	the	surrounding area	as	compared	between	Cooper Station	and	the	monitor,

3. The	likelihood	of	influence	from nearby	local	population‐related	sources	(vehicles,	res idential	heating,	etc.)

and	industrial sources,	and

4. Ability	of	the	monitor	to	captu re	the	impacts	of	sources	that	a re	small	and/or	dista nt	from	the	Cooper Station	not	explicitly	modeled	d ue	to	being	screened	out	of	the regional	inventory.

The	Nicholasville	monitor	(21‐113‐0001)	site	is	located	approxi mately	99	km	north	of	C ooper	Station	and	18	km southwest	of	the	city	center	of	L exington.		The	Nicholasville	s ite	has	a	monitoring	obj ective	of	population exposure	and	an	u rban	measurement scale	with	a	scale	definition of	4	km	to	50	km.		The surrounding	land	use and	location	are	light	density residential/commercial	surrounde d	by	rural	agricultura l	areas.		To	assess	the influence	of	nearby	industrial	s ources	on	monitored	concentrati ons,	EKPC	evaluated	the sum	of	annual	actual and	potential	emissions	from	all facilities	located	within	the same	two	screening	dist ances	applied	in	the regional	inventory	selection	pr ocess	(i.e.,	20	km	and	50	km). As	shown	in	Table	3‐ 8,	the	combined	SO 2 emissions	from	industrial	source s	within	both	20	km	and	50	km	from	the	Nicholasville	monitor	is	not	at	all comparable	to	the	combined	SO 2 emissions	in	the	Cooper	Station	airshed.		The	higher	SO 2 emissions	totals	in	the area	surrounding	the	Nicholasvi lle	monitor	would	likely	explain the	significantly	higher	1‐hr	SO 2 NAAQS	design value	from	this	monitor	(40.0	μg/m 3 )	in	the	most	recent	three‐year period	(2012	through	2014)	as	c ompared	to the	same	three‐year	average	desig n	values	from	the	other	candid ate	monitoring	stations	(34.8	μg/m 3 for	the Lexington	monitor	and	26.9	μg/m 3 for	the	Mammoth	Cave	monitor).		Considering	these	relevant	features	of	theEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-23 Nicholasville	monitor,	EKP C	does	not	consider	the	SO 2 ambient	concentrations	measur ed	at	this	monitoring	site to	be	representative	of the	expected	backgro und	concentrations in	the	area	surroundin g	the	Cooper	Station.

Table 3

‐ 8. Summary of SO 2 Emissions from KyEIS Facilities near Cooper Station and Candidate SO 2 Monitoring Stations

The	Lexington	monitor	(21‐067‐0012) site	is	the	next	closest	SO 2 monitoring	station	located	at	approximately 119	km	north	of	Cooper	Station	within	the	city	of	Lexington,	KY .		The	surrounding	lan d	use	and	location	are medium	density	residential/comm ercial	because	the	site	is	locat ed	just	north	of	the	urban center	of	Lexington. Due	to	the	urban	setting	of	this monitor,	the	site	captures	num erous	urban	SO 2 sources	including	a	high	density of	stationary	industrial	sources ,	mobile	sources,	and	residenti al	and	commercial	sources.		The	influence	from these	urban	sources	is	not	repre sentative	of	the	area	surroundi ng	Cooper	Station. The	industrial	SO 2 emissions profile	affecting	the	Lexington monitor	characterized	by	the	Ky EIS	summary	data	presente d	in	Table	3‐8	is	also not	comparable	to	the	industrial	SO 2 emissions	profile	of	the	Cooper	Station’s	airshed.

The	Mammoth	Cave	National	Park monitor	(21‐061‐0501)	monitor	is located	approximatel y	139	km	to	the	west of	Cooper	Station.		It	has	a	mon itoring	objective	of	general/ba ckground	without	a	speci fied	measurement	scale. Due	to	its	background	status,	th is	monitor	is	thought	to	be	rep resentative	of	rural	areas with	similar	influences to	the	air	quality	around	Cooper Station.		The	Mammoth	Cave	mon itoring	site	has	the	lowest	SO 2 design	value	of the	candidate	monitoring	station s	most	likely	due	to	the	signif icantly	lower	SO 2 emissions	totals	from	industrial sources	surrounding	the	monitorin g	station.		As	shown	in	Table	3‐8,	the	SO 2 emissions	totals	in	the	area surrounding	the	Mammoth	Cave	moni tor	are	most	comparable	to	the Cooper	Station’s	airshed	from	among	the candidate	monitoring	stations.		Also,	given	the	wind	patterns	i n	the	area	(as	shown	by	the	London‐Corbin Airport	wind	rose	in	Figure	3‐8),	this	monitor	is	expected	to	r eflect	the	minor	contribut ions	from	sources	in	the area	surrounding	the	Bowling	Green ‐Glasgow	combined	statistical area	(CSA)	which	has	a	similar	population (218,870)	to	the	combined	populatio ns	of	the	two	nearby	micropo litan	statistical	area s	surrounding	the	Cooper Station,	namely	Somerset,	Kentuc ky	and	London,	Kentucky	(191,14 1).		In	addition,	the	Lexington‐Fayette metropolitan	statistic al	area	(MSA)	in	which	the	Nicholasville and	Lexington	monitors	a re	located	has	a	much higher	population	(494,189)	than	an y	of	the	urban	centers	locat ed	near	the	Mammoth	Cav e	monitoring	site	or Cooper	Station.		As	population	is the	most	direct	indication	of regulated	air	pollutant	emissions	from	non‐ industrial	sources	(i.e.,	mobile sources,	residential/commercia l	sources,	etc.),	these	ob served	population	trends

can	be	used	with	the	industrial	source	SO 2 emissions	data	summary	in	Table	3‐8	to	obtain	an	overall

characterization	of	the	SO 2 emissions	profile	affecting	the Cooper	Station	and	each	of	the candidate	monitoring

sites. Location Sum of Annual Actual SO 2
Emissions for Facilities

within 20 km 1

( t

py) Sum of Annual Potential

SO 2 Emissions for

Facilities within 20 km 1

( t py) Sum of Annual Actual SO 2
Emissions for Facilities

within 50 km 1

( t py) Sum of Annual Potential

SO 2 Emissions for

Facilities within 50 km 1

( t

py)

Cooper	Station 2 53.58 238.50 205.45 1,123.85

Nicholasville	Monitor 2,098.07 8,211.61 3,387.71 40,809.09 Lexington	Monitor 138.50 7,644.32 3,378.49 40,887.00

Mammoth	Cave	Monitor 0.56 44.29 9.15 572.03

1 Sum	of	annual	actual	or	potential	emissions	from	2013	KyEIS	e xport	within	specified	distances	from	Cooper	Station	or	candida te monitoring	locations.

2 Combined	SO 2 emissions	from	facilities	in	area	surrounding	Cooper	Station	e xcludes	emissions	from	Cooper	Station,	as	these	emissions
are	the	subject	of	the	1‐hr	SO 2 NAAQS	demonstration	modeling.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-24 Figure 3

‐ 8. Wind Rose for London

‐ Corbin Airport from July 2012

– June 2015

Based	on	an	application	of	the	a forementioned	background	monitor	selection	criteria	to the	candidate	sites within	150	km	of	the	Cooper	Station,	the	Mammoth	Cave	National Park	site	was	chosen	to	represent	the background	concentration	for	the Cooper	Station	modeling	analys is.		Since	the	Mammoth	Cave	monitor	is already	located	such	that	it	will	capture	a	true	background	con centration	for	the	Cooper	Station,	no	further processing	of	the	monitor	data	w as	necessary	to	generate	tempor ally	varying	background	concentrations	or	to

exclude	influences	from	modeled	sources.		As	shown	in	Table	3‐9 ,	the	fourth	highest	d aily	maximum	1‐hr	SO 2 concentrations	per	year	average over	the	most recent	three‐year period	(2012‐2014)	from	the	Mammoth	Cave monitor	was	used	to	calculate	the	background	concentration	applied	using	the	BACKGROUND	keyword	in AERMOD	input	file.

Table 3

‐ 9. Selected SO 2 Background Concentration

Site ID City County State Downwind

Direction to

Monito r Distance

to Cooper ( km ) SO 2 Background

Concentration 1

(μg/ m 3 )

21‐061‐0501 ‐‐ Edmonson KY W 139.1 26.9

1 Three‐year	average	for	2012‐2014	of	the	99 th percentile	(4 th highest)	1‐hour	daily

maximum	concentrations.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 3-25 

### 3.11. MODELING FILES

All	modeling	files	are	provided	t o	KDAQ	in	electronic	format	on a	compact	disk	included	in	Appendix	C.		Model and	processor	input,	output,	and data	files	are	included.		Spre adsheets	tabulating	Coop er	Station	and	regional source	model	input	parameters	referenced	in	previous	sections	o f	this	modeling	report	a re	also	provided	on	the modeling	file	CD	in	Appendix	C.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 4-1 

## 4. 1-HOUR SO 2 

## DESIGNATION MODELING RESULTS

Dispersion	modeling	of	the	Cooper Station	was	conducted	using	the	AERMOD	Model	(Version	15181).		Included in	this	modeling	were	the	Cooper Station	CEMS	emissions	data	fo r	Unit	2,	Cooper	Statio n	allowable	emissions data	for	Unit	1,	Kingsf ord	Manufacturing	Company	potential	emis sion	rates,	and	an	appropriate	background concentration.		Table	4‐1	presen ts	the	overall	results	of	the	C ooper	Station	1‐hr	SO 2 NAAQS	designation modeling	including	contributions from	all	modeled	sources	and	t he	background	concentrat ion	expressed	in	the

form	of	the	1‐hour	SO 2 NAAQS	(a	3‐year	average	of	the	99 th percentile	of	the	annual	distribution	of	daily maximum	1‐hr	concentrations).		A s	can	be	seen	from	Table	4‐1,	t he	combined	maximum	concentration	is	less than	the	NAAQS	and	thus,	the	a rea	surrounding	the	Cooper	Statio n	is	expected	to	be	achieving	the	1‐hr	SO 2 NAAQS	and	should	be	designated	as	attainment	in	the	upcoming	ro und	of	Consent	Decree‐driven	attainment designations.

Table 4

‐ 1. Highest 4 th High Modeled 1

‐ hour SO 2 Results for Comparison to the NAAQS

Figure	4‐1	shows the	distribution	of	1‐hour	SO 2 concentrations	across	a	portion of	the	modeling	domain	closest to	Cooper	Station	and	the	area	o f	maximum	impacts	as	a	further graphical	presentation of	the	concentration

estimates	and	their	di stribution.		The	maximum	impacts	as	descr ibed	with	coordinates	in	Table	4‐1	and	as shown	with	the	orange	isopleth	in	Figure	4‐1	occur	to	the	north east	of	the	Cooper	Statio n	on	and	near	a	hill	in the	prevailing	wind	directi on.		Concentrations	of	SO 2 in	other	areas	are	much	less	as	can be	seen	by	the

distribution	around the	Cooper	Station.

Averaging

Period Year for Met. Data NAAQS
( μ g/ m 3 ) Maximum
Impact
( μ g/ m 3 ) Background

Concentration 2

( μ g/ m 3 ) Combined

Maximum

Impact
( μ g/ m 3 ) UTM

East 3

( m ) UTM

North 3

( m ) Date Exceeds
NAAQS?

1‐hr 1 Max.	3‐ y r	Av g . 196 146.2 26.9 173.1 714,550 4,098,043 ‐‐ No

1 Evaluated	the	three‐ y ear	avera g e	4th	hi g hest	dail y maximum	1‐hour	out p ut	for	com p arison	a g ainst	the	NAAQS.

3 UTM	coordinates	are	re p resented	in	NAD83	datum	Zone	16. 2 Based	on	SO 2 ambient	monitoring	data	from	the	Edmonson	County	monitor	in	Bo wling	Green,	Kentucky	(Site	ID	21‐061‐0501)	located	within Mammoth	Cave	National	Park.	Background	concentration	for	1‐hr	m odeling	is	the	three‐year	average	from	2012	to	2014	of	the	99th percentile	daily

maximum	1‐hr	concentrations.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report 4-2 Figure 4

‐ 1. Spatial Display of 3

‐ year Average 99 th Percentile Annual Distribution

of Daily Maximum 1

‐ hr SO 2 Concentrations Including BackgroundEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-1 

## APPENDIX A: USE OF U* IN COOPER DISPERSION MODELING

When	AERMOD	is	run	with	a	meteor ological	dataset	derived	from	one‐minute	meteorological	data	as	is currently	recommended	by	U.S.	EPA,	low	wind	speeds	are	much	mor e	prevalent	than	in	pr ior	versions	of	the modeling	system	that	did	not	rel y	on	one‐minute	meteorological data.		These	low	wind	speeds	have	been	linked to	potential	overestimates	in	amb ient	concentrations	by	AERMOD. 32 These	overestimates	o ccur,	in	part,	due	to

an	underestimate	of	friction	veloc ity	(u*)	by	the AERMET	meteor ological	processor.		EPA	recognized	this underestimation	as	a	potential	i ssue	with	AERMET and	released	A ERMET	Version	12345	whi ch	included	a	beta option,	ADJ_U*.		The	ADJ_U*	beta option	allows	the	friction	vel ocity	(u*)	to	be	adjusted using	the	methods	of	Qian

and	Venkatram 33 to	better	account	for	turbulence in	the	atmosph ere	during	low wind	speed	stable	conditions. This	beta	option	was	updated	to incorporate	a	modified	Bulk	Ric hardson	Number	in	version	13350,	was	further modified	to	adjust	u*	for	low	so lar	elevation	angles	with	versi on	14134,	and	was	most	recently	used	to	modify

the	calculation	of	the	turbulenc e	measure,	Monin‐Obukhov	length in	Version	15181. 34 Given	the	refined	nature of	this	beta	option	and	the	peer reviewed	studies	which	have	ac knowledged	its	accuracy,	EKPC	has	incorporated this	option	into	the	modeling	an alysis	to	allow	more	representa tive	and	more	accura te	modeling	results.

Because	the	u*	option	is	not	a	default	option	in	AERMOD,	the	co mbined	use	of	AERMOD	plus	the	u*	adjustment in	the	meteorology	file	(generate d	by	AERMET)	would	no	longer	h ave	“preferred”	status	in the	sense	that	it	is	a model	to	be	used	for	regulatory purposes	without	additional	reg ulatory	authority	approval .		To	substantiate	that the	adjusted	friction	velocity	option	in	AERMOD	is	a	valid	mode l	to	use	in	this	situation,	Section	3.2	of	Appendix W	describes	steps	to	be	considered to	allow	the	use	of	the	u*	adjusted	AERMOD	as	an	a cceptable	alternative

model.		The	section	also	describ es	criteria	for	determining	the acceptability	of	an	alternative	model.			Section 3.2.2.b	states	that	satisfying	any one	of	the	three	alternative conditions	may	make	use	of	an	alternative	model acceptable.		Condition	1	states that	the	alternative	model	will demonstrate	equivalency .		But	in	this	case	the AERMOD	Model	is	the	p referred	model	of	choice	with	just	an	opti on	change	(making	it	alt ernative).		Because	the

model	cannot	have	a	demonstration of	equivalency	to	itself	and the	option	change will	result	in	di fferent	results, this	condition	is	not	applicable.		This	leaves	the	satisfaction of	Conditions	2	and	3	as	criteria	to	accept	the	u* option	in	AERMOD.		Condition	2	requires	the	formal	submittal	of a	protocol	to	allow	demonstration	of	superior performance	whic h	is	acceptable	to	the	control	agency	and	to	EK PC.		This	type	of	study	would	require appropriate	ambient	ai r	quality	monitoring	a nd	side‐by‐side	mod eling	and	comparisons which	were	beyond	the scope	of	this	project.

Thus,	Condition	3	was	reviewed	an d	followed	along	with	the	individual	criteria	to	meet its	requirements. Section	3.2.2.e	states	that	a	pref erred	model	may	be	used	provi ded	that	five	criteria	are	met.		These	are:

i. The	model	has	received	a	scientific	peer	review;

ii. The	model	can	be	demonstrated	to be	applicable	to	the	problem	o n	a	theoretical	basis;

iii. The	data	bases	which	are	necessary	to	perform	the	analysis	are available	and	adequate;

iv. Appropriate	performance	evaluati ons	of	the	model	have	shown	tha t	the	model	is	not	biased	towards underestimates;	and

v. A	protocol	on	methods	and	proced ures	to	be	follo wed	has	been	es tablished.

32 Wenjun Qian and Akula Venkatram, “Performance of Steady State Dispersion Models Under Low Wind

‐ Speed Conditions,” Boundary

‐ Layer Meteorology, no. 138 (2011): 475

‐ 491.

33 Ibid.

34 http://www.epa.gov/ttn/scram/7thconf/aermod/aermet_mcb3.txt ; http://www.epa.gov/ttn/scram/7thconf/aermod/aermet_mcb4.txt ; http://www.epa.gov/ttn/scram/7 thconf/aermod/AERMET_mcb5.pdf ; http://www.epa.gov/ttn/scram/7 thconf/aermod/AERMET_mcb6.pdfEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-2 Review	of	these	criteri a	as	well	as	the	responses	to	each	within	the	context	of	modeling the	Cooper	Station	have shown	the	use	of	the	u*	option,	as	generated	by	AERMET	in	the	m eteorological	file	and	u sed	in	AERMOD,	to	be valid	and	representative	for	the	m odeling	domain	in	the	vicinit y	of	the	Cooper	Station.		The	response	to	each criteria	is	given	in	the	follo wing	Appendix	A	subsections.



### CRITERIA 3.2.2.e.i - SC IENTIFIC PEER REVIEW

The	use	of	an	adjusted	friction velocity	in	AERMOD	has	received scientific	peer	review	an d	been	evaluated	both by	U.S.	EPA	modelers	as	well	as others	in	the	scientific	and	mo deling	community.		Two	examples	are:

The	paper	entitled	“Performance of	Steady‐State	Dispersion	Mode ls	Under	Low	Wind‐Speed	Conditions”	by Wenjun	Qian	and	Akula	Venkatram, Boundary	Layer	Meteorology,	Volume	138,	pp	475‐491,	2011.		This paper	examined	the	AERMOD	Model to	estimate	dispersion	under	lo w	wind	speed	events.		Two	tracer studies,	the	Prairie	Grass	Experi ment	and	the	Idaho	Falls	exper iment,	were	compared	to	the	use	of	AERMOD with	and	without	u*	adjustments. The	analysis	reports	that	the tendency	of	AERMOD	to	overestimate ambient	air	impacts	du ring	low	wind	speed	events	was	reduced	by incorporating	an	empi rical	modification. This	modification	is	incorporate d	into	the	AERMET	program	throu gh	the	U*_ADJ	keyword.		This	option generates	the	enhanced	friction	velocity	sets	on	a	low	wind	spe ed,	stable	atmosphere,	h our‐by‐hour	basis.

Also	in	his	email	memorandum	d ated	June	26,	2013,	George	Bridge rs	of	the	U.S.	EPA’s	O ffice	of	Air	Quality Planning	and	Standards,	notes	th at	“The	AERMET	BETA	option	is	b ased	on	a	peer	reviewed	study	(Qian	and Venkatram,	2011)	which	also	includ es	independent	evaluations	of the	new	u‐star	estimates...”.

In	his	April	23,	2013	presentation at	the	Regional/State/Local Modeling	Meeting	in	Dallas,	Texas,	Roger Brode	showed	“improved	AERMOD	p erformance”	when	including	the	u *	adjustment.		The	figures	below from	Mr.	Brode’s	presentation	dem onstrate	the	enhanced	performa nce	of	AERMOD	for	tw o	field	data	bases, namely	the	Oak	Ridge	Study	and	t he	Idaho	Falls	Study.		The	clos er	the	points	are	to	the	center	line	of	each graph,	the	better	the	model	performance.

Figure A

‐ 2. Comparison of the AERMOD Model with and without the u* AdjustmentEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-3 

### CRITERIA 3.2.2.e.ii- APPLICABLE ON A THEORETICAL BASIS

Over	the	past	several	years	many	s cientific	studies	have	noted that	Gaussian	dispersion	models	tend	to	over predict	concentrations	at	low	wi nd	speeds.		In	the	early	days	o f	dispersion	modeling when	the	threshold

velocities	of	the	Na tional	Weather	Servic e	anemometers	were	a	f ew	miles	per	hour,	the common	use	of	1.0	m/s as	the	lowest	wind	speed	that	would	be	considered	in	the	model was	prevalent.		The	m odeling	community recognized	that	winds	lower	than	that	would	result	in	ambient	c oncentration	estimates	that	were	not

coincidental	with	ambient	monito red	values	at	these	same	low	wi nd	speed	conditions.		Because	concentration	is inversely	proportional	to	wind	s peed	as	wind	speeds	dip	below	1 m/s,	concentrations	are greater.		In	addition, other	studies	and	field	research	showed	that	winds	tend	to	meander	during	low	wind	sp eeds,	meaning	that	the wind	was	not	in	only	one	directi on	during	the	time	step	of	the Gaussian	models,	namely one	hour,	but	tended	to change	over	the	time	step.		The	relationship	between	this	pheno menon	and	the	friction	velocity	calculations	in AERMET	determined	that	adjusting the	u*	could	have	the	same	eff ect	as	adjusting	plume	meander	and	was better	estimated	empirically	(as demonstrated	in	the	peer	revie w	paper	by	Qian	and	Venkatram).

In	reviewing	the	frequency	distri bution	of	winds	from	the	Londo n‐Corbin	(MaGee	Field)	Airport	for	the	period of	record	of	this	modeling	analysis,	the	number	of	hours	in	the range	of	0.28	m/s	(t he	lower	limit	where AERMOD	will	make	a	calculation)	and	less	than	2.1	m/s	wind	spee d	is	11,224	hours	over the	three	year	period
of	record	or	42.7%.		This	distribu tion	is	shown	in	Table	A‐1	an d	Figure	A‐2.		Thus,	the	consideration	of	better science	in	terms	of	the	u*	adjust ment	is	applicable	and	reasona ble	given	this	relativel y	high	frequency	of	low

wind	occurrences.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-4 Table A

‐ 1. Distribution of Hourly Observations by Wind Speed and Wind DirectionEast Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-5 Figure A

‐ 3. Distribution of Hourly Observations by Wind Speed Category Bin

As	a	further	measure	of	assessing the	importance	of	low	wind	sp eeds	in	the	meteorological	dataset	for	the Cooper	Station	SO 2 NAAQS	demonstration,	EKPC	evalua ted	the	wind	speeds	associated with	maximum

concentrations	when	the	default AERMET	processing	was	employed and	when	the	U*_ADJ	option	was implemented.		For	any	hourly	impa ct	from	the	Cooper	Station	abo ve	100	μg/m 3 (approximately	50%	of	the	1‐hr

SO 2 NAAQS)	identified	in the	results	from	the default	and	U*_ADJ	modeling	runs,	EKPC	determined	a	wind	speed

associated	with	the	ev ent.		The	resulting	w ind	speed	dataset	wa s	then	plotted	in	a	histogram	format	to determine	the	cumulative	frequenc y	of	impacts	within	selected	b ins	of	wind	speed.		The se	plots,	shown	in Figures	A‐3	and	A‐4	for	the	default	and	U*_ADJ	cases,	respectiv ely,	show	a	significant	bias	towards	low	wind

conditions	in	the	default	mode relative	to	the	overall	distribu tion	of	wind	speeds	with in	the	meteorological dataset.		The	percenta ge	of	wind	speeds	be low	2.1	m/s	contribut ing	to	Cooper	Station impacts	above	100	μg/m 3
in	the	default	case	is	78.3%	v ersus	only	42.7%	in	the	overall	w ind	speed	distribution.		When	such	a	large percentage	of	high	impacts	are	co ntrolled	by	a	single	type	of	m eteorological	condition	(i .e.,	low	wind	speeds	in stable	conditions),	a	potential	overestimate	inherent	to	the	mo del	is	most	likely	the	cause	rather	than	an underlying	meteorological	phenomenon	influencing plume	dispersi on.		When	the	U*_ADJ	option	is	used,	the percentage	of	winds	below	2.1	m/s	contributing	to	Cooper	Statio n	impacts	above	100	μg/m 3 drops	significantly to	only	49.3%.		This	value	is	in line	with	the	overall	percenta ge	of	wind	speeds	below 2.1	m/s	in	the	selected meteorological	dataset	(42.7%),	a nd	thus,	indicates	the	U*_ADJ option	yields	a	prof ile	of	controlling meteorological	conditions	for	ma ximum	impacts	that	is	not	unrea listically	biased	to wards	low	winds. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000CumulativePercentageofValidHoursNumberofValidHours

Wind Speed Category Bins (m/s) Freq.

Cum.	%East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-6

Figure A

‐ 4. Distribution of Wind Speeds for Cooper Station Impacts above 100 μg/m 3

with the Default AERMET Dataset

Figure A

‐ 5. Distribution of Wind Speeds for Cooper Station Impacts above 100 μg/m 3

with the U*_ADJ AERMET Dataset 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000CumulativePercentageofHoursw/1‐hrSO2Impacts>100μg/m3NumberofHoursof1‐hrSO2Impacts>100μg/m3

Wind Speed Category Bins (m/s) Freq.

Cum.%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 200 400 600 800 1,000 1,200 1,400 1,600

<3 0.3‐1.0 1.0‐2.1 2.1‐3.6 3‐6‐5.7 5.7‐8.8 8.8‐11CumulativePercentageofHoursw/1‐hrSO2Impacts>100μg/m3NumberofHoursof1‐hrSO2Impacts>100μg/m3

Wind Speed Category Bins (m/s) Freq.

Cum.%East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-7 

### CRITERIA 3.2.2.e.iii – AV AILABILITY OF DATABASES

The	test	data	bases	and	reportin g	for	low	wind	speed	observatio ns	and	evaluation	are	available	to	assess	model performance.		The	data	bases	appl icable	to	this	discussion	and use	of	the	u*	option	in	AERMET	and	AERMOD

are:

Idaho	Falls	Study‐	Sagendorf	JF,	Dickson	CR	(1974)	Diffusion	un der	low	wind	speed,	inversion	conditions. NOAA	Technical	Memorandum	ERL	ARL‐52,	89	pp.

Prairie	Grass	Study	‐ Barad	ML	(ed)	(1958)	P roject	Prairie	Gras s.		A	field	program	in	diffusion.	Geophysical research	paper	no.	59,	vols	I	(300 pp)	and	II	(221	pp).	AFCRF‐T R‐58‐235.	Air	Force	Cambridge	Research Center,	Bedford,	Massachusetts;	un der	Model	Evaluation	Database s	on	U.S	EPA’s	website	‐ http://www.epa.gov/ttn/scram/dispersion_prefrec.htm

Oak	Ridge	Study	‐	NOAA	Technica l	Memorandum	ERL	ARL‐61,	1976.	D iffusion	under	Low	Wind	Speed Conditions	near	Oak	Ridge,	Tenne ssee.	Wilson,	R.	B.,	G.	Start, C.	Dickson,	N.	Ricks.	Ai r	Resources	Laboratory, Idaho	Falls,	Idaho.

In	addition,	the	AERMET	source	code	and	all	input	data	required for	implementing	the	U*_ADJ	are	publicly

available	on	U.S.	EPA’s	SCRAM	website.



### CRITERIA 3.2.2.e.iv – DEM ONSTRATION OF NO BIASES TOWARDS UNDERESTIMATES

As	demonstrated	in	a	number	of	s tudies	over	the	past	3‐5	years, including	the	2010	study	by	AECOM 35 ,	the	use of	the	u*	adjustment	in	dispersio n	modeling	has	not	shown	any	b ias	towards	underestimating	the	ambient

concentrations	due	to	sources	an d	emissions.		A	repeat	use	of	t he	same	Oak	Ridge	data set	in	2013	by	the	U.S. EPA	in	their	model	performance	ev aluation	demonst rates	both	the	improved	performance	of	AERMOD	with	u* option	and	no	bias	towards	underes timation	as	shown	in	Figure	A ‐5.

Figure A

‐ 6. Residual Plots Showing Improved Performance with u* and No Bias toward Underestimation

35 AERMOD	Low	Wind	Speed	Evaluation	Study	Results,	AECOM	prepare d	for	the	American	Petroleum Institute,	Washington,	DC, March	22,	2010.East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Report A-8 

### CRITERIA 3.2.2.e.v – A PROT OCOL HAS BEEN ESTABLISHED

A	modeling	protocol	was	provided	to	KDAQ	by	EKPC	on	August	3,	2015 36 which	provided	a	de tailed	overview	of the	model	selection	process,	pot ential	options	to	be	considered,	source	and	building	considerations,	receptor grids,	meteorological	data,	oth er	source	invento ries,	and	antic ipated	tabular	and	graphic al	outputs.		Section	2.1 of	the	protocol	describes	the potential	frequent	occurrence	of low	winds	due	to	the	EPA‐recommended	use	of the	one‐minute	meteorological	data	available	from	the	National Oceanic	and	Atmosph eric	Administration website.		The	consideration	of	the	use	of	the	LOWWIND	options	w as	briefly	mentioned	in	the	modeling	protocol. The	additional	and	separate	cons ideration	of	the	u*	option	was certainly	of	interest	al though	not	called	out specifically	in	the	protocol.		C omments	received	via	email	from Rick	Gillam	(U.S.	EPA,	R egion	4)	on	August	17,

2015	included	one	reference	to	the selection	of	the	use	of	the low	wind	options,	that	being:

Section 2.1, Page 11: The protocol discusses the possibility of using the LOWWIND “beta

‐ options”

contained in the latest version of AERMOD (Version 15181). Use of these options could be allowed, but it is important to understand that these are non

‐ regulatory “beta

‐ options,” and thus are “alternative model options” requiring appro val from EPA Region 4 pursuant to Section 3.2.2 of 40 CFR Part 51, Appendix W.

EKPC	selected	the	U*_ADJ	option instead	of	the	LOWWIND	option	m entioned	in	the	protoc ol	because	it	is	a better	representation	of	impact s	due	to	the	Cooper	Station	in	l ow	wind,	stable	atmosph eric	conditions	that	are common	in	the	area.		The	u*	option	has	also	been	subject	to	ext ensive	peer	review	and	thu s	the	likelihood	of	the approval	of	its	use	for	this	m odeling	exercise	is	greater.

No	specific	protocol	for	impleme nting	the	U*_ADJ	option	in	AERM ET	is	needed	since	invoking	this	option	only includes	the	selection	of	a	single	keyword.

36 August	3,	2015	Letter	from	Jerry Purvis	(Director,	Environment al	Affairs,	EKPC)	to	Sean	Alteri (Director,	Division	for	Air	Qu ality, Commonwealth	of	Kentucky), Air Dispersion Modeling Protocol Cooper Station SO 2 Designation Analysis (dated	July	31,	2015).East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Approach B-1 

## APPENDIX B: NAAQS REGIONAL SOURCE INVENTORYModel ID DescriptionUTMEasting1(m)UTMNorthing1(m)Elevation2(m)PTEEmissionRate(tpy)EmissionRate(g/s)StackHeight(ft)StackHeight(m)Temp.(F)Temp.(K)Exit Velocity(ft/s)Exit Velocity(m/s)Diameter(ft)Diameter(m)NoteKINGFRD1ACC Stack714,965 4,094,231 263.73 5.78 0.16638974.0022.561,800.001,255.446.314.1210.703.26 4KINGFRD2 Briquet Dryer A Stack 714,948 4,094,126 268.32 41.00 1.17936075.0022.86232.00384.367.120.463.421.04 4KINGFRD3 Briquet Dryer B Stack 714,964 4,094,141 267.36 29.74 0.85554075.0022.86235.00385.953.716.373.421.04 4KINGFRD4 Briquet Dryer C Stack 714,973 4,094,148 266.52 31.19 0.89712075.0022.86259.00399.351.215.593.421.04 4KINGFRD5 Waste Heat Boiler Stack 714,992 4,094,424 264.03 27.90 0.80269420.006.10400.00477.642.4412.942.000.61 5B-1. AERMOD Model Inputs: SO2 NAAQS Inventory Sources2Source coordinates obtained from to-scale site plan in Figure 2-2 of the May 2013 Title V renewal application.5No stack parameters are included for the Waste Heater Boiler (KyEIS Eqpt. ID COMB001) in the 2014 KyEIS. Stack parameters were obtained from Section II of the DEP7007 N form submitted with the May 2013Title V renewal application.3Imported sources into AERMOD and ran AERMAP with 1-arc second (approximately 30 meter resolution) NED data to get source elevations.1Unless otherwise noted, source parameters are obtained from the 2014 KyEIS report for the Kingsford Manufacturing Company facility in Burnside, KY.4Stack parameters for ACC Stack and Briquet Dryer A, B, & C Stacks obtained from the 2014 KyEIS Faciltiy General Report differed from those parameters obtained through Section II of the DEP7007 N formsubmitted with the May 2013 Title V renewal application. Due to the discrepancy, the Title V renewal application stack parameters were taken as the most up to date parameters for the modeling analysis.Table B-1.1. Kentucky Regional Inventory Sources Modeled as Point Sources for SO2 NAAQS Analysis1East Kentucky Power CooperativeCooper StationBurnside, KentuckyPage B-1B-1. AERMOD Model Inputs: SO2 NAAQS Inventory SourcesAI ID Facility NameUTM East(m)UTM North(m)Distance toCooper, (d)(km)Plant-wideActualEmissions (Q)(tpy)Actual Q/d(tpy/km)Plant-widePotentialEmissions (Q)(tpy)PTE Q/d(tpy/km)Screened OutBased on"20D" Rule?3837 Somerset Wood Products Inc 714,167 4,096,069 1.3 0.90.73.32.6 Y108315 Bluegrass Wireless LLC - Bend of the Lake (COW2) 715,141 4,099,610 2.4 0.00.00.00.0 Y39770 Hinkle Contracting Co LLC - Tatesville Asphalt Plant 716,645 4,093,017 4.9 0.00.01.40.3 Y6340 Glen Oak Lumber & Milling Inc 715,368 4,103,286 6.0 0.00.00.00.0 Y99096 Forever Pets Cremation Services LLC 711,127 4,102,727 6.2 0.40.10.40.1 Y3813Armstrong Hardwood Flooring Co715,287 4,103,5926.30.20.03.80.6 Y3804American Standard Brands713,166 4,103,9586.70.00.00.00.0 Y76491 River Metals Recycling LLC Somerset 713,205 4,104,431 7.2 2.30.32.30.3 Y116249 KY Utilities Co - Alcalde Substation 718,966 4,102,792 7.2 0.00.00.00.0 Y108314 Bluegrass Wireless LLC - Slate Branch (COW14) 706,577 4,098,872 7.8 0.00.00.00.0 Y108316 Bluegrass Wireless LLC - Somerset Bypass East 716,184 4,105,219 8.1 0.00.00.00.0 Y3842 Continental Refining Company LLC 712,519 4,105,527 8.4 0.10.00.30.0 Y3809 General Electric Lighting LLC - Somerset Glass Plant 711,611 4,109,205 12.2 2.00.26.00.5 Y71569 Hinkle Contracting Co LLC - Somerset Asphalt Plant 715,110 4,109,540 12.2 0.30.018.11.5 Y3806 Eagle Hardwoods Inc 710,601 4,112,048 15.2 2.20.14.40.3 Y4171 Monticello Flooring & Lumber 692,401 4,081,670 26.9 0.60.03.10.1 Y81844 Cowboy Charcoal USA 692,897 4,079,461 27.9 0.70.00.60.0 Y4170 Mago Construction Co LLC - Monticello Plant 693,230 4,077,896 28.6 1.80.133.81.2 Y37652 Hinkle Contracting Co LLC - Casey Asphalt Plant 697,890 4,124,384 31.6 0.30.018.10.6 Y38966 East Anderson Hardwoods LLC 708,180 4,132,991 36.2 0.30.00.30.0 Y3893 Superior Battery Manufacturing Co 678,696 4,104,394 36.2 0.00.00.10.0 Y108206 Bluegrass Wireless LLC - Cold Hill 751,979 4,105,255 38.5 0.00.00.00.0 Y40420 Federal Bureau Of Prisons 733,125 4,063,318 38.9 0.00.044.61.1 Y8882 Wayne Dry Kilns Inc 682,971 4,072,423 40.0 0.20.00.20.0 Y4162American Woodmark Corp682,571 4,072,07340.50.00.00.90.0 Y108068 Cumberland Cellular GP - Casey South 680,966 4,121,535 41.1 0.00.00.00.0 YTable B-1.2. List of Regional Inventory Sources Eliminated from the 1-hr SO2 NAAQSInventory Due to "20D"' Rule1East Kentucky Power CooperativeCooper StationBurnside, KentuckyPage B-2AI ID Facility NameUTM East(m)UTM North(m)Distance toCooper, (d)(km)Plant-wideActualEmissions (Q)(tpy)Actual Q/d(tpy/km)Plant-widePotentialEmissions (Q)(tpy)PTE Q/d(tpy/km)Screened OutBased on"20D" Rule?108705 Cumberland Cellular GP - Dunnville677,268 4,116,18441.50.00.00.00.0 Y38846 BPM Lumber LLC 752,839 4,114,950 42.4 0.80.02.10.0 Y750 Tarter Gate Co Inc 676,855 4,118,729 43.1 0.00.00.00.0 Y38878 Doric Products Co 757,990 4,097,719 43.7 0.00.00.00.0 Y37648 Columbia Gulf - Clementsville Transmission Station 674,505 4,117,083 44.4 0.20.00.90.0 Y40452 East KY Power Coop - Laurel Ridge Landfill 758,536 4,102,707 44.6 36.10.841.30.9 Y2581 Laurel Ridge Landfill 758,665 4,102,526 44.7 0.00.04.60.1 Y40268 Elmo Greer & Sons Inc - Portable Hanson Quarry Plant 734,592 4,137,300 44.8 1.10.018.10.4 Y108069 Cumberland Cellular GP - Pricetown 681,435 4,128,360 45.2 0.00.00.00.0 Y51036 Metal Products Inc 759,420 4,095,721 45.2 0.00.00.00.0 Y84396 Hinkle Contracting Co LLC - London Portable Asphalt Plant 758,248 4,108,900 45.5 0.50.022.20.5 Y108060 Cumberland Cellular GP - Liberty 683,637 4,131,307 45.7 0.00.00.00.0 Y50732Accent Marble Inc755,137 4,118,55546.10.00.00.00.0 Y108181 Bluegrass Wireless LLC - Corbin Station 760,399 4,094,402 46.2 0.00.00.00.0 Y2571 Bimbo Bakeries USA Inc 757,897 4,113,888 46.7 0.00.00.10.0 Y2556Aisin Automotive Casting Inc761,029 4,102,74747.10.00.00.10.0 Y108125 Bluegrass Wireless LLC - Lily (COW13) Portable 761,464 4,104,803 47.8 0.00.00.00.0 Y40709 Elmo Greer & Sons LLC - Morentown Rd - Portable 758,384 4,115,723 47.8 0.30.024.00.5 Y38869 London Rotary Forms Inc 760,096 4,112,289 48.2 0.00.00.00.0 Y2573 Elmo Greer & Sons LLC - Farriston Asphalt Plant 908 761,662 4,106,413 48.3 0.10.01.80.0 Y38861 Jasper Iron & Metal Co 761,805 4,105,770 48.3 3.40.13.40.1 Y2568 Cumberland Forest Product - Fariston Facility 761,693 4,106,693 48.4 0.00.00.00.0 Y2591 Robinson Stave Co 754,550 4,124,091 48.4 0.20.00.30.0 Y2559 Chaney Lumber Co 762,199 4,104,313 48.5 0.50.00.50.0 Y108182 Bluegrass Wireless LLC - Siler 762,520 4,092,277 48.5 0.00.00.00.0 Y45671 CTA Acoustics Inc - Corbin Facility763,071 4,088,90049.50.10.00.20.0 Y108072 Cumberland Cellular GP - Cartwright 673,173 4,069,541 49.6 0.00.00.00.0 Y1Source list excludes facilities with plant-wide actual emissions of 0 tpy SO2.East Kentucky Power CooperativeCooper StationBurnside, KentuckyPage B-3East Kentucky Power Cooper ative – Cooper Station
1-Hour SO 2 NAAQS Designation Modeling Approach C-1 

## APPENDIX C: MODELING FILES ON CD