UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 4 

Foster Wade 

Statoil Gulf Services, LLC 

2103 City West Boulevard, Suite 800 

Houston, Texas 77042 

ATLANTA FEDERAL CENTER 

61 FORSYTH STREET 

ATLANTA, GEORGIA 30303-8960 

May 7, 2014 

Subject: Title V Permit Significant Modification and PSD Permit Major Modification Application OCS 

Permit OCS-EPA-R4012 for Drilling and Exploration Activities in the DeSoto Canyon Lease Blocks 

Dear Mr. Evans: 

This letter is in response to your application dated March 27, 2014, and received by this office on 

April 1, 2014, for changes to your existing Outer Continental Shelf (OCS) permit OCS-EP A-R40 12. 

The existing permit was issued on October 28, 2013, pursuant to Section 328 of the Clean Air Act 

(CAA) under the OCS Air Regulations at 40 CFR 55 from the United States Environmental Protection 

Agency (EPA) Region 4. The permit regulates air emission activities from the mobilization and 

operation of deep water drilling vessels and associated support fleets at multiple lease blocks on the 

OCS in the Eastern Gulf of Mexico. The proposed PSD revision and Title V significant modification 

would revise engine load and fuel consumption requirements, as well as various operating parameters 

for the Maersk Developer drilling vessel based on recent emissions testing data. Changes in the cement 

and barite handling/transfer activities were also proposed. 

After our initial review of the above application and supporting information, we have determined that 

the application is incomplete and additional information is necessary in order for EPA to make a 

preliminary determination. Enclosed is a list of the information required. Please provide a response to 

the comments enclosed within 60 days of this letter. 

Your application is considered incomplete until this information is received and evaluated and the EPA 

has determined that the application contains all information needed to propose a permit decision. Please 

notify the EPA if a complete response is not possible within 60 days of this letter. Multiple submittals, 

as information becomes available, are acceptable and will allow us to continue to process the application 

while receipt of additional information is pending. As the EPA continues processing your application, 

we may identify additional information that will be essential to develop a preliminary determination and 

make a permit decision, including information that may be needed in response to public comments. 

Based on information received in the March 2014 application, business confidentially under 40 CFR 2 

subpart B is not claimed for any information provided to us. 

Internet Address (URL) • http://www.epa.gov 

Recycled/Recyclable • Printed wnh Vegetable Oil Based Inks on Recycled Paper (Minimum 30% Postconsumer) 
If you have any questions concerning the review of your application, please contact Lori Shepherd of 

my staff at ( 404) 562-8435. 

Enclosure 

Cc: Don Evans, Statoil 

Kjersti Seim, Statoil 

Michael Carbon, ENVIRON 

Sincerely, 

~ 111. ilii-OK_ 

Heather M. Ceron 

Chief 

Air Permits Section 
ENCLOSURE 

EPA Completeness Comments on Statoil Gulf Services, LLC, 

OCS Air Permit Modification Application for Drilling and Exploration Activities 

in the DeSoto Canyon Lease Blocks dated March 2014 

1. Offshore Support Vessels (OSVs) and crew boats are not dedicated to any particular drilling 

vessel or campaign. Therefore, to allow for flexibility to use any available vessel in the support 

fleet and to more efficiently meet project needs, Statoil determined the total hours of operations 

for up to 3 OSVs and 1 crew boat operating simultaneously based on historical drilling 

campaigns using representative vessels, the OSV Peyton Candies and the crew boat Sybil 

Graham. Statoil then used AP-42 emissions factors in conjunction with this determination to 

estimate annual and maximum hourly emissions from the support vessels. Annual emissions 

were based on two main engines per support vessel running at 100 percent load for 2,570 hours 

for the OSV s and 618 hours for the crew boat per campaign of approximately 180 days per year. 

Maximum hourly emissions for the support vessels were based on two main engines on each 

support vessel running at 75 percent load, and the short-term NAAQS and PSD increment 

analysis assumes crew and supply boats operate at 50% load for 18 hours a day. 

Because the support vessels are not owned or operated by Statoil directly, the EPA is concerned 

that compliance demonstration monitoring and recordkeeping will be too onerous and difficult to 

maintain on an ongoing basis throughout each drilling campaign to demonstrate continual 

compliance. Permit requirements that would be necessary using this approach may include 

monitoring and recordkeeping associated with hours of operation, engine load, and gallons of 

diesel fuel used by each support vessel when within 25 miles of the drilling vessel. 

Please provide a specific methodology for demonstrating continual compliance with the 

operating limitations assumed for the third party vessels. 

2. Although Statoil is not proposing to add any additional lease blocks with this permit 

modification, they have requested authorization to conduct drilling activities at locations in the 

eastern Gulf of Mexico further from the Class I areas addressed in the application's air quality 

analysis. 

Please provide specific information on what is being proposed with respect to any lease block 

"further from shore and Class I areas," and a corresponding discussion or demonstration 

regarding how the modeling conducted for this application incorporates the proposed expansion. 

3. Please provide more specific information regarding how the gross annual fuel limitations will be 

used to ensure compliance with annual and short term standards given the 12 varying operating 

scenarios presented in the application and the absence oflimiting conditions on the hours of 

operation for the Developer's main engines. Please include corresponding details of a 

compliance methodology, including specific information regarding how load data will be logged 

and continual compliance demonstrated in the discussion. 

4. Please provide a discussion regarding the variability of emissions rates at a given load, from the 

eight identical main engines on board the Developer, including any insight that the engines' 

manufacturer may be able to provide. 
The following does not affect completeness of this application. 

Region 4 received the following comment from Jill Webster at the U.S. Fish and Wildlife Service on 

May 1, 2014. 

The Fish and Wildlife has completed its review ofStatoil's PSD permit modification forwarded to 

our office on April 3, 2014. While we do not agree with the results of the visibility modeling (ie. 

modeling results indicate that the change in extinction exceeds 5%for the model year 2001, Table 

5.4.11-4), we do not object to the permit modification and the Class I analyses. We are basing our 

decision on the temporary nature of the project and the conservatism of the emission estimates 

modeled. 

Therefore, please be aware that if any changes are made to the project emissions or to fundamental 

project operating parameters, additional review by the U.S. Fish and Wildlife Service will be necessary.