ANADARKO PETROLEUM CORPORATION 1201 LAKE ROBBINS DRIVE, THE WOODLANDS, TEXAS 77380

P.O. BOX 1330 HOUSTON, TEXAS 77251

‐ 1330 U.S.A. PH. (832)636

‐ 1000



### February	5,	2014

Mr.	Stanley	Krivo U.S.	EPA	Region	4 61	Forsyth	Street,	S.W. Atlanta,	GA	30303‐8960

RE: Anadarko BlackHawk and BlackHornet OCS Air Permit Application for Drilling, Exploration, and Maintenance Activities in the Eastern Gulf of Mexico
EPA’s Follow up Comments in Email Dated January 16, 2014

Dear	Mr.	Krivo:

EPA	Region	4	provided	follow‐up comments	via	email	on	January	1 6,	2014	to	the	responses	submitted by	Anadarko	Petroleum	Corporat ion	(Anadarko)	in	November	2013. This	letter	addres ses	the	follow	up comments	except	for	the	comment related	to	air	dispersion	model ing	(i.e.,	a	comment	related	to	validity of	the	air	impact	assessment	usin g	a	single	supply	boat)	Refer to	EPA’s	incompleteness	letter	for	a specific	comment	number	provided	in	this	letter.

21. Ozone	data	used	in	CAL PUFF	modeling	analyses

The	use	of	ozone	data	representat ive	of	the	modeling	domain	and /or	the	PSD	Cl ass	I	area	is appropriate.		Data	acquired	at	Sumatra,	FL	would	be	appropriate for	St.	Marks	and	Bradwell	Bay Class	I	impact	analyse s.		The	appropriateness	for	application	a t	the	Breton	PSD	C lass	I	area	has

not	been	addressed.

Anadarko Response:

Per	discussions	with	Stanley	Kri vo	of	EPA	Region	4,	Mr.	Rahul	P endse	of	Trinity	Consultants contacted	Ms.	Jill	Webster	of	US Fish	and	Wildlife	Service	[Fed eral	Land	Manager	for	Breton NWR]	on	December	10,	2013	and	obta ined	a	confirmation	that	use of	ambient	ozone	data	from	a monitor	in	Sumatra,	FL	(code‐SU M	156)	for	AQRV	analysis	for	Bre ton	NWR	Class	I	area	is acceptable	to	US	Fish	and	Wildlife	Service.

22. Screening	ambient	concen tration	levels	for	s oils	and	vegetation

The	EPA	referenced	scre ening	ambient	concen tration	levels	were not	addressed	in	the response.		Rather	the	response	rei terated	the	fact	that	the	pro vided	qualitative	conclusion	was

### Mr.	Krivo Page	2	of	4

based	on	the	Secondary	NAAQS.		C omparison	of	the	screening	leve ls	in	“A	Screening	Procedure for	Impacts	of	Air	Pollution	Sou rces	on	Plants,	Soils,	and	Anim als”	were	not	provided.

Anadarko Response:

Comparison	of	screening	levels	for pollutants	for	which	air	dis persion	modeling	was	performed (i.e.,	CO	and	NO 2 

### )	is	presented	in	Table	1	below. Per	procedures	described	in	S ection	5.1	of	“ A Screening Procedure for Impacts of Air Pollution Sources on Plants, Soils, and Animals ”	(EPA Guidance	Document),	the	background	concentration	was	added	to	t he	modeled	concentrations. The	background	concentration	dat a	was	obtained	from	the	monitor ing	station	located	at Houma,	Louisiana.		The	monitorin g	station	located	at	Houma,	Lou isiana	was	considered	as	a representative	monitoring	station based	on	its	proximity	to	the project	location	as	well	as	the

Gulf	of	Mexico	shoreline.		The	mo st	recent	meteorological	data for	three	calendar	years	(2010	to 2012)	were	considered	for	obtaining a	background	concentration.

As	shown	in	Table	1,	total	(modeled	concentration	+	background) 1‐hour	concentration	for	CO	is less	than	the	EPA	screening	concen tration	for	1‐week.		Since	th e	total	concentration	of	CO	for	1‐ hour	averaging	period	would	be	eq ual	or	higher	than	the	concent ration	of	CO	for	1‐week averaging	period,	the screening	concentratio n	of	CO	for	1‐week averaging	period	was	compared against	the	total	concentration of	CO	for	1‐hour	averaging	peri od	as	a	conservative	approach. The	same	logic	was	applied	for	comparison	of	total	1‐hour	conce ntration	of	NO
x 

### against	4‐hour and	8‐hour	screening	concentrations	of	NO
x 

### .

Table 1 ‐ Comparison of Screening Levels for Modeled Criteria Pollutants

Pollutant Averaging
Period Air Dispersion

Analysis

Results ‐ Class II Receptors Background

Concentration

[1] Total EPA Screening

Concentrations

[2] Total > EPA Screening?

( μ

g/m 3 ) ( μ g/m 3 ) ( μ g/m 3 ) ( μ g/m 3 )

CO 1	hour 13.66	 3561	 3575

‐‐	 ‐‐

1	week ‐‐		 	‐‐	 ‐‐ 1,800,000	 No

NO 2 1	hour 5.04	 119	 124

‐‐	 ‐‐

4	hours ‐‐		 	‐‐	 ‐‐ 3,760	 No

8	hours ‐‐		 ‐‐		 ‐‐ 3,760	 No

1	year 0.09	 49	 50 94‐188	 No

[1]	To	represent	the	most	conserva tive	scenario,	the	background hourly	concentrations	were	obtained	by choosing	the	maximum	of	the	dailymaximum	concentrations	for	th ree	calendar	years.		The	background	annual concentrations	were	obtained	by choosing	the	average	of	daily	m ax	concentrations	for	three	calendar	years	at Houma,	LA	monitoring	station. [2]	Screening	concentrations	set in	Table	3.1 of	the	EPA	Guidanc e	Document.



### As	described	in	Section	5.2.2	of	t he	EPA	guidance	document,	the source’s	potential	to	emit	in tons	per	year	could	directly	be	c ompared	with	the	significant	e mission	rates	listed	in	Table	5.6

and	Table	5.7	of	the	EP A	Guidance	Document for	pollutants	that were	not	modeled	using	an	air dispersion	modeling	program.		Tab le	2	and	Table	3	provide	a	lis t	of	pollutants	fo r	which	the	air

### Mr.	Krivo Page	3	of	4

dispersion	modeling	was	not	requi red	for	the	proposed	project. Table	2	and	Table	3	also provide	a	comparison	of	potentia l	emissions	of	these	pollutants and	corresponding	Screening Thresholds	specified	in	the EPA	guidance	document.

Table 2 ‐ Comparison of Significant Emission Rates for Direct Acting Pollutants.

Pollutant Averaging
Period Significant

Emission Rate (SER) Proposed

Emission Rate Proposed

Emission Rate

> SER?

(T/year) (T/year)

SO 2 1	hour	 160

1.02 No

3	hours	 170 No

Annual	 171 No

Pb 3	months	 11	 0.02 No

Beryllium 1	month	 0.057	 <0.001 No



### As	shown	in	Table	2,	proposed	e mission	rates	for	all	pollutants are	less	than	their	respective

SERs.		As	described	in	Section 5.2.2	of	the	EPA	Guidance	Docume nt,	the	proposed	emission	rates of	the	trace	elements	were	adjust ed	to	reflect	expected	life	of the	project	(i.e.,	five	years.)		Since

Anadarko’s	lease	for	the	BlackHa wk	and	BlackHornet	drillships	w ill	be	expiring	in	five	years,	the life	of	the	project	is	con sidered	as	five	years.

Table 3 ‐ Comparison of Significant Emission Rates for Trace Elements

Pollutant [1] EPA Screening

Concentrations

(for 10 years

source life) [2] EPA Screening

Concentrations

(for 5 years

source life) [3] Project

Emission

Rate Emission

Rate > SER?

(T/year) (T/year) (T/year)

Arsenic 0.4	 0.8	 <0.001	 No

Cadmium 0.037	 0.074	 <0.001	 No

Chromium 1.1	 2.2	 <0.001	 No

Cobalt 1.2	 2.4	 <0.001	 No

Lead 24	 48	 0.017	 No

Manganese 0.33	 0.66	 <0.001	 No

Mercury 61	 122	 <0.001	 No

Nickel 67	 134	 <0.001	 No

Selenium 0.67	 1.34	 <0.001	 No

[1]	Includes	only	those	pollutant s	which	are	expected	to	be	emi tted	during	the	project.

[2]	The	smallest	value	among	the significant	emission	rates	cri teria	for	soils,	plant	tissues,
and	animals	from	Table	5.7	o f	the	EPA	Guidance	Document.
[3]	The	significant	emission	rates	are	converted	based	on	a	sou rce	lifetime	of	five	years.

### Mr.	Krivo Page	4	of	4

As	shown	in	Table	3,	proposed	e mission	rates	for	all	pollutants are	less	than	their	respective SERs.		Hence,	no	furth er	analysis	is	required.

24. Confirm	the	Breeze	software	used	t he	unmodified	v ersions	of	the regulatory	CALPUFF	modeling

system.

The	response	indicates	the	approv ed	versions	of	the	CALPUFF	mod eling	system	were

used.		Confirmation	is	needed	tha t	the	BREEZE	modeling	system	u ses	for	this	analysis incorporates	the	unmodified	regul atory	versions	of	CALMET,	CALP UFF,	and	CALPOST.

Anadarko Response:

Trinity	confirms	that	the	BREEZ E	software	used	the	following unmodified regulatory	versions of	the	CALPUFF	Modeling	System	fo r	the	submitted air	dispersion modeling	analysis:

 CALPUFF	version	5.8,	level	070623
 CALMET	version	5.8,	level	070623
 CALPOST	version	6.221,	level	080724

Please	do	not	hesitate	to	contac t	Mr.	Rahul	Pendse,	Trinity	Con sultants	at	(225)	346‐4003	or	Ms.	Sara Carlson,	Anadarko	at	(832)	636‐1273 if	you	have	any	questions	o r	require	additional information.