DRAFT

EPA Completeness Comments on Anadarko Petroleum Corporation, OCS Air Permit 

Application for Drilling and Exploration Activities in the Eastern Gulf of Mexico dated 

December 2012

Regulatory Applicability

1. Section 4 of the application contains the Regulatory Applicability Analysis for all 

emission units onboard the Discoverer Spirit, and emission units onboard the support 

vessels that will contribute to the stationary sources aspects of the vessel while attached 

to the OCS source. The applicability of the New Source Performance Standards (NSPS) 

and the National Emission Standards for Hazardous Air Pollutants (NESHAPS) is 

dependent on the model year of the emission sources. The application does not provide 

the model year of all emission sources subject to the regulatory applicability analysis. 

The application should provide the model year of all regulated emission sources in order 

to support the analysis. For the third party emission sources, the model years and 

compliance certificates will be required to confirm compliance once the specific engines 

have been determined. 

Best Available Control Technology Analysis (BACT) 

2. The BACT analyses for diesel engines in section 5 of the application identified 

Replacement of Older Engines with Newer Engines and EPA Tier 2 Standards as 

available control technologies. The Replacement of Older Engines with Newer Engines 

should identify the cleanest engines that are currently available; this may be EPA Tier 2, 

EPA Tier 3 compliant engines, or another cleaner engine. The BACT analyses for the 

diesel engines, (specifically DR-GE-07, DR-GE-08, DR-AC-01, DR-AC-02, third party 

engines, and SV-PE-01 through SV-PE-08), should identify what the cleanest engines are 

for each applicable unit, and use the cleanest available engine for any applicable cost 

analyses.

a. The NOx, CO, PM/PM10/PM2.5, and VOC BACT analyses for the Emergency 

Diesel Engine are provided in Sections 5.1.2, 5.2.2, 5.3.2, 5.5.2 of the application, 

respectively. Step 2 eliminated Replacement of Older Engines with Newer 

Engines as a feasible control technology because this would be cost prohibitive. 

However, the application does not contain a cost analysis for replacing the 

existing Emergency Diesel Generator with a newer engine. For this control 

technology to be considered technically infeasible, the application should provide 

a cost analysis in Step 4 of the BACT analyses to determine if replacing the air 

compressor engines with new cleaner engines is cost prohibitive.
b. The NOx, CO, PM/PM10/PM2.5, and VOC BACT analyses for the Air Compressor 

Engines are provided in sections 5.1.3, 5.2.3, 5.3.3 and 5.5.3 of the application, 

respectively. Step 1 of the BACT analyses identified Replacement of Older 

Engines with Newer Engines as a technically feasible control technology. In step 

2 of the BACT analyses, this option eliminates the control technology as 

technically infeasible because it would be extremely cost prohibitive. For this 

technology to be considered technically infeasible the application should provide 

a cost analysis in Step 4 of the BACT analyses to determine if replacing the air 

compressor engines with Tier 2 compliant engines is cost prohibitive.

3. The application has identified Painting Operations as a source of PM/PM10/PM2.5 and 

VOC emissions and included BACT analyses for both of these pollutants in sections 

5.3.13 and 5.5.14, respectively. These analyses propose best management practices as 

BACT for both pollutants, which includes down spraying of paint and use of a shroud or 

barrier around the area being painted. However, the description of the emission source, 

on page 31 of the application, explains that the airless spray transfer efficiency also 

affects emissions. The application states that the potential-to-emit (PTE) calculations 

were done assuming a 50% transfer efficiency, but Anadarko is proposing to use a 30% 

transfer efficiency, which would result in higher emissions from the painting operation. 

The vendor information provided in the application does not contain the transfer 

efficiency expected for the proposed airless sprayer. Please provide documentation for 

the transfer efficiency of the proposed model sprayer and provide revised PM/PM10/PM2.5

and VOC BACT analyses consistent with the top-down approach to evaluate the various 

transfer efficiencies.

Emission Calculations

1. The emission calculation description in section three, and throughout the application, 

states that the associated support vessels (i.e., supply and anchor handling boats) and 

equipment (e.g., engines) are unknown so a representative supply boat (HOS Coral), 

handling boat (Kirt Chouest), and third party equipment were used to develop 

representative emissions. This language is also used to describe the third party engines on 

the drillship. The EPA recommends using worst-case rather than representative emissions 

for all emission units to allow the use of any available support vessel or equipment 

without the possible need for an additional impact assessment or further emission 

limitations.

2. It is unclear how the total worst-case well completion emissions were calculated.

a. Each well completion scenario uses both the emission units listed in Table 1 on

page 4 of Appendix B and emission units on the drillship and support vessels. For 

example, each of the four well completion scenarios will use the Main Engines, 

listed as DR-ME-01 through DR-ME-06, (it is assumed that these engines are the 

same as the drillship engines listed in the first part of the emission calculations, 

DR-GE-01 through DR-GE-06). Yet, this results in a discontinuity. The total 

emissions from each well completion scenario, listed at the bottom of Table 1 on 

page 4, do not result from a summation of the emission units listed on this page. 
The application indicates that the additional units will be used during a given well 

completion scenario, but the information provided does not clearly show how 

many hours these emission units will operate. Please provide additional 

information that details how the totals for the worst-case well completion 

scenarios were calculated. 

b. The PTE for the project was calculated by summing the emissions from the worstcase support vessel and the emissions from the drillship. However, the emissions 

from the worst-case well completion scenario, provided in Table 1 of Appendix 

B, lists these emissions as higher for all pollutants except for CO when compared 

to the emissions from the worst-case support vessel. As mentioned above, the well 

completion scenarios will use engines onboard the drillship and support vessel,

and it is unclear if these totals have already been accounted for in the worst-case 

well completion totals. It is not clear if the emissions generated from units used 

solely for the well completion activities are mutually exclusive from the supply 

boats, and should therefore be added to the PTE and not omitted. Additional 

information is needed to demonstrate why the worst-case emission units used 

solely for the well completion scenario have not been incorporated in the PTE. 

3. From Table 1 and Table 3 of Appendix B it is unclear how the emissions for the Main 

Propulsion Generator Engines (DR-GE-01 through DR-GE-06) were calculated. The 

detailed emission calculations for DR-GE-01 through DR-GE-06 are provided in this 

section. However, in Table 1 underneath the rows for the Main Propulsion Generator 

Engines there is a row titled, “Main Engines Worst-Case Operating Emissions 

(Maximum 325 bbls/day of fuel used for all main engines).” The application does not 

provide information how the numbers in this row were calculated. The emissions in this 

additional row are more than the emissions from a single engine, but less than the 

emissions from two engines. This row of emissions was used to provide the total drillship 

emissions used for the PTE, and not a summation of the six engines. Therefore, it appears 

that Anadarko will only operate one Main Propulsion Generator Engine at a time. Please 

provide additional calculations for the row titled “Main Engines Worst-Case Operating 

Emissions (Maximum 325 bbls/day of fuel used for all main engines),” and please 

explain why these emissions are representative of worst-case operation. 

4. The emission calculation tables for the Main Propulsion Electrical Generator Engines 

notes that the data used for the CO emissions factor is based on data from Wärtsilä LNE 

engine specifications for operating at 50% load, and “The more conservative factor is 

chosen between the stack test (December 2010) and Vendor Provided Data,” footnote 1 

found in Appendix B. However, based on a review of the Stack Test Report, found in 

Appendix H, the highest emission rates occur not at 50% load, but at an approximate load 

of 20%. Emission limits will be established with emissions presented in the permit 

application. The application should verify that the main engines will be able to meet the 

emissions at 50% load.
Modeled Operational Scenarios 

Temporary Source Exemption – The content of the application assumes the project will qualify 

as a temporary emission source (i.e., project duration less than 2 years), and therefore will be 

exempted from the ambient impacts assessment as provided in 40 CFR 52.21(i)(3). The 

following comments are associated with this exemption.

5. The provided PSD Class I area modeling is not, as indicated in the application, to 

demonstrate compliance with the PSD Class I increments, NAAQS, and AQRV but to 

demonstrate compliance with the exemption requirement of no project impacts to any 

PSD Class I area.

6. For a source to qualify as a temporary emission source it must meet several requirements, 

including that the source must demonstrate that its emissions will not impact any Class I 

area, and that no area where an applicable increment is known to be violated 40 CFR 

52.21(i)(3)(i). The application does not address the requirement that the project will have 

no impacts in any area with known violations of the PSD increments.

Project Drilling and Support Vessels – The following comments are associated with the project 

emission sources used in the impact assessment. 

7. Section 2.1 of the Class I Area Air Quality Dispersion Modeling Analysis Report 

(Appendix D) indicates worst-case support vessels emissions were modeled. This section 

states the hourly, daily, and annual emissions were estimated for the worst-case boats to 

conservatively account for the worst-case emissions from the support vessels potentially 

available to support operations of the drillship. However, the description provided earlier 

in the application describes these sources as representative. This apparent discrepancy 

should be clarified. 

In addition, the equivalence determination provided in section 3.1 of the application 

addresses the emission calculations procedures, but not the reason the selected engine 

and/or support vessel provide the worst-case emissions from those available. Please 

provide additional supporting information. 

The following comments are associated with the input parameters used in the ambient impact 

modeling.

8. The Appendix D modeling report indicates the support vessels were modeled while 

docked at the drillship, as well as when within 25 miles en route to and from the drillship, 

and that all emissions were modeled as emitted from the single drillship stack. It is 

unclear which method was used; the modeling procedure used for the support vessel 

emissions should be clarified. 

9. The Q/D analysis indicates emission sources operating intermittently or seasonally were 

adjusted to account for year round operation. This adjustment does not appear 

appropriate given the Federal Land Manager’s guidance states that the Q value used in 

this assessment should be the sum of maximum 24-hour emissions of all visibility 
impairing pollutants annualized in tons per year. The adjustment procedure and its 

appropriateness should be explained. 

Requests for Clarification

1. Table 1-2 on page 3 of the application lists the project’s PTE. The PTE for PM10 is listed 

at 33.60 tons per year. However, “Table 1-Annual Emissions Summary (tons/year)” 

found on page 4 of Appendix A, lists the total emissions for PM10 from the drilling 

operating scenario as 23.03 tons per year. Please clarify this discrepancy and provide the 

correct PTE for PM10. 

2. The NOx, CO, PM/PM10/PM2.5 and VOC BACT analyses for the drillship third party 

engines selected LNE design as BACT, sections 5.1.8, 5.2.8, 5.3.8, 5.5.8, respectively. 

These BACT analyses have ranked LNE design in Step 3; however, Step 1 of the BACT 

analyses did not identify LNE design as an applicable control technology. Please correct 

this inconsistency in the application and verify that LNE design is part of BACT control 

for NOx, CO, PM/PM10/PM2.5, and VOC from the third party engines. 

3. Table 2-2 of in the Representation of Modeled Sources section, on page 2-4, gives the 

stack parameters used in the modeling analysis. These parameters were based on the 

stack test report found in Appendix H which lists temperatures in Kelvin. However, the 

temperature provide in Table 2-2 appears to be in degrees Fahrenheit (Rankin) rather than 

Kelvin.