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	7,	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

comment	no.	19.		The	other	comme nts	were	addressed	in	a	separat e	submittal.

Modeling

Project Emissions

19. Provide	reason	the	impact	assessm ent	using	a	single	supply	boat is	appropriate	given simultaneous	operation	of	multiple	supply	boats	is	planned.

The	total	fuel	limit	provided	fo r	all	utilized	s upply	boats	is provided	as	justification.		The

emissions	from	the	mod eled	supply	boat	was	indicated	to	be	base d	on	the	proposed	fuel	limit	so the	impact	modeling	pr operly	represents	the impacts	from	one	or more	supply	boat	operations.

The	fuel	limit	for	the	all	supply	boats	is	based	on	24‐hour	and annual	periods.		Considering	the short	term	standards	(e.g.	1‐hour	NAAQS),		the	only	way	the	mod eled	single	supply	boat	would represent	the	worst‐case	supply	bo at	impact	would	be	if	the	fue l	limit	included	an	hourly	value

and	the	emissions	used in	the	modeling	were based	on	the	hourly fuel	limit	consumed	by	the single	boat.

The	application	indica tes	the	shortest	period	for	supply	boat	f uel	limit	was	24‐hours.		Multiple supply	boats	could	operate	under the	24‐hour	fuel limit,	althou gh	not	for	the	full	24‐hours period,	producing	larger	hourly	e missions	and	grea ter	impacts	t han	that	associated	with	a single	boat.Mr.	Krivo Page	2	of	2

Anadarko Response:

The	typical	supply	boat operating	scenario	consists	of	one	supp ly	boat	in	transit	and	one	or	two supply	boats	near	the	drillship	t ransferring	fuel	and	equipment at	any	given	inst ance	during	the proposed	project	activities.		Hen ce,	one	supply	boat	was	modele d	at	25	nautical	miles	from	the drillship	in	the	direction	of	th e	nearest	receptor	and	other	su pply	boats	were	assumed	to	be near	the	drillship	for	air	dis persion	modeling	analysis.

The	historical	supply	boat	fuel	usage	data	shows	that	one	suppl y	boat	consumes	maximum	of 100	barrels	of	fuel	in	a	day.		Hen ce,	Anadarko	conservatively	r equested	maximum	daily	fuel	limit of	200	barrels	per	day	to	cover	si multaneous	operations	of	two or	more	supply	boats.		The historical	supply	boat	fuel	usag e	data	also	shows	that	the	supp ly	boat	consumes	higher	amount of	fuel	(i.e.,	approximately	4.5 barrels	per	hour)	when	in	tran sit	carrying	load .		On	the	other hand,	the	same	supply	boat	consu mes	significantly	less	fuel	(i. e.,	approximatel y	1.75	barrels	per hour)	when	it	is	near	the	drills hip	for	transferring	equipment and	fuel.

Based	on	the	prior	experiences	wi th	the	similar	projects,	Anada rko	performed	a	short‐term	air dispersion	modeling	based	on	the emissions	resulti ng	from	the	e xpected	worst‐case	short–term supply	boat	fuel	usage	of	8.33 barrels/hour.		Note	that	8.33	ba rrels/hour	fuel	consumption represents	the	worst‐case	total	f uel	consumption	for	all	the	su pply	boats	within	25	nautical miles	of	the	drillship.		As	explai ned	above,	the	expected	worst ‐case	short–term	supply	boat	fuel usage	of	8.33	barrels/hour	adequat ely	covers	fuel	requirements for	one	supply	bo at	in	transit and	two	supply	boats	performing	t ransfer	operations	near	the	dr illship.

In	order	to	represent the	conservative	scenario,	the	proposed	a ir	dispersion	modeling methodology	assumes	th at	the	emissions	from	all	the	supply	boat s	(i.e.,	emission s	generated	by the	total	supply	boat	fuel	cons umption	of	8.33	barrels	per	hour )	would	be	released	at	25 nautical	miles	from	the	drillship	in	the	direction	of	the	neare st	receptor.		Hence,	a	point	source was	placed	at	25	nautical	miles	f rom	the	drillship	in	the	direc tion	of	the	nea rest	receptor	to represent	the	supply	boat	in	transit	and	assumed	that	short‐ter m	emissions	from	all	supply

boats	were	released	at	this	location.

Hence,	Anadarko	believes	that	th e	short	term	emi ssions	and	the proposed	air	dispersion methodology	represent	the	wor st‐case	impact	assessment.

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.