### D HYDROGEN SULFIDE INFORMATION

The objective sands to be developed within the Heidelberg Complex GC 859/GC 903 are correlative with sands that have been penetrat ed within the Tahiti complex to the north (GC 596/GC640/GC 641). They have also been penetrated within the closer offsetting Caesar Tonga complex (GC 683/GC726/GC727/GC 770/GC771), as well as in the GC 859-1 discovery well and GC 903-3 delineation well in He idelberg. All in all the objective sand intervals have been penetrated in over 30 wells within this mini-b asin in Green Canyon. To our knowledge, none of
the wells listed above have encountered H2S in any of the intervals penetrated.

Since no (H 2 

### S) was encountered in any of these wells , Anadarko hereby requests the area be classified as a "zone where the ab sence of H2s has been confirmed.”

### E BIOLOGICAL, PHYSICAL, AND SOCIOECONOMIC INFORMATION

(a) Chemosynthetic Communities Report

The seafloor disturbing activities proposed in this plan ar e in approximately 5,268’ - 5,355’ of water. The
wells will be drilled with a DP Drillshi p or DP Semisubmersible drilling unit.



### Maps

A map prepared using 3-D seismic data to depi ct bathymetry, seafloor and shallow geological features, and surface location of the propos ed well is included in Section A.

Analysis

Features or areas that could support high-density chemosynthetic communities are not located within 2000 feet of each proposed muds and cuttings discharge location.

Features or areas that could support high-density chemosynthetic communities are not located within 250 feet of any se afloor disturbances.

(b) Topographic Features Map

The proposed activities are not with in 1,000 feet of a no-ac tivity zone or within the 3-mile radius zone of an identified topographic feature. Th erefore, no map is requ ired per NTL No. 2008-G04.

(c) Topographic Features Statement (Shunting)

Anadarko does not plan to drill more than two wells from the same surface location within the
Protective Zone of an identifie d topographic feature. Theref ore, the topographic features statement required by NTL No. 200 8-G04 is not applicable.

(d) Live Bottoms (Pinnacle Trend) Map

The activities proposed in this pl an are not within 200 feet of any pinnacle trend feature with vertical relief equal to or greater than 8 f eet. Therefore, no map is required per NTL No. 2008-
G04.

(e) Live Bottoms (Low Relief) Map

The activities proposed in this plan are not within 100 feet of any live bottom low relief features. Therefore, no map is required per NTL No. 2008-G04.

(f) Potentially Sensitive Biological Features



### The activities proposed in this plan are not within 200 feet of any potentia lly sensitive biological features. Therefore, no map is required per NTL No. 2008-G04.

### (g) Remotely Operated Vehicle (ROV) Monitoring Survey Plan

Green Canyon Blocks 859 & 903 are located within Deepwater Grid Area 10. This grid is considered to have “adequate ROV survey covera ge”, and therefore, un der the guidance set out in NTL No. 2008-G06, a Remotely Operated Vehicl e Monitoring Survey Pl an is not required.

(h) Threatened and Endangered Species Information

Under Section 7 of the Endangered Species Act (ESA) all federal ag encies must ensure that any actions they authorize, fund, or carry out are not li kely to jeopardize the continued existence of a listed species, or destroy or adversely modify its designated critical habitat. In accordance with the 30 CFR 250, Subpart B, effective May 14, 2007, and further outlined in Notice to Lessees (NTL) 2008-G04, lessees/operators are require d to address site-specific information on the presence of federally listed threatened or endangere d species and critical habitat designated under the ESA and marine ma mmals protected under the Marine Mammal Protection Act (MMPA) in the area of proposes activities under this plan.

Currently there are no designated critical habitats for the listed species in the Gulf of Mexico Outer Continental Shelf; however, it is possible th at one or more of thes e species could be seen in the area of our operations. The following table reflects the Federally-listed endangered and threatened species in the lease ar ea and along the northern Gulf coast:Species Scientific Name Status Potential Presence Critical Habitat Designated in Gulf of Mexico Lease Area Coastal

Marine Mammals

Sei whale Balaenoptera borealis E X a -- None

Blue whale Balaenoptera musculus E X a -- None

Fin whale Balaenoptera physalus E X a -- None
North Atlantic right whale Eubalaena glacialis E X a -- None

Humpback whale Megaptera novaeangliae E X a -- None

Sperm whale Physeter macrocephalus E X -- None

West Indian manatee Trichechus manatus latirostris E -- X Florid a (Peninsular)

Sea Turtles

Loggerhead turtle Caretta caretta T X X None

Green turtle Chelonia mydas T, E b X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys imbricata E X X None
Kemp’s ridley turtle Lepidochelys kempii E X X None

Birds

Piping Plover Charadrius melodus T -- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E -- X Coastal Texas (Aransas National Wildlife Refuge)

Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T -- X Coastal Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Smalltooth sawfish Pristis pectinata E -- X Southwest Florida and the Florida Keys

Invertebrates

Elkhorn coral Acropora palmata E -- X Flower Garden Banks

Terrestrial Mammals

Beach mice (Alabama, Choctawhatchee, Perdido Key, St. Andrew) Peromyscus polionotus E -- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = endangered; T = threatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be
present in the lease area.
b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

The Environmental Impact Analysis in Section N of this plan further discusses potential impacts and mitigation measures related to threatened and endangered species.

(i) Archaeological Report

Green Canyon Blocks 859 & 903 are not located in an area designated as having high archaeological potential and, as such, an Archaeological Report is not required per NTL No. 2011-JOINT-G01. However, an Archaeological Report prepared by Fugro Geoservices, Inc covering the proposed Green Canyon Blocks 859 & 903 well locations will be submitted along with this Supplemental Exploration Plan. The survey was conducted in accordance with the latest guidelines established by the BOEMRE in 2011.

(j) Air and Water Quality Information

This EP does not propose activities for which the State of Flor ida is an affected State. Therefore, the discussion required per NTL 2008-G04 is not applicable to this EP.(k) Socioeconomic Information

The activities proposed in this plan are not located offshore Florida. Therefore, socioeconomic information required per NTL 2008-G04 is not applicable to this EP.

### F WASTE AND DISCH ARGE INFORMATION

The following estimates were prepared utilizing Anad arko’s experience with si milar drilling operations. Estimated maximum discharge rates are reflected below. Projected amounts may vary during the course of drilling and/or completion operations.

(a) Projected Generated Wastes

Type of Waste Composition Projecte d Amount Treatment/Storage/Disposal Synthetic-based drilling fluids Synthetic-based drilling
muds 13,000 bbls/well Re-use and/or transport to shore in DOT approved containers to Fourchon, Louisiana and on to base/transfer station. If recycled, returned to vendor (Bariod or MI). Cuttings wetted with synthetic-based fluids Cuttings coated with synthetic drilling muds/fluids, including
drilled out cement 6,500 bbls/well Treated and discharge overboard *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on to the base/transfer station if oil still
remains

. Water-based drilling
fluids Water based drilling muds (NaCl saturated, seawater, freshwater, barite) 74,000 bbls/well** Discharge overboard or at seafloor

Cuttings wetted with
water-based fluids Cuttings coated with water-based drilling
muds/fluids 3,800 bbls/well Discharge overboard

Chemical product waste (well treatment fluids) Ethylene glycol
Methanol 7,487 bbls total ***

1,872 bbls total*** Transport to shore in DOT approved containers to Fourchon, Louisiana for pick up. Completion Fluids Brine, spent acid, prop sand, debris 3,000 bbls/well*** Transport to shore in DOT approved containers to Fourchon, Louisiana and on to Newpark Base. Non-pollutant completion fluids Low density uninhibited completion brines 5,000 bbls/well*** Discharge overboard

Workover fluids Brine, spent acid, prop sand, debris 3,000 bbls/well*** Transport to shore in DOT approved containers to Fourchon, Louisiana and on to Newpark Base.

Trash and debris Refuse generated during operations 3,777 bbls total Transport to sh ore in disposal bags by vessel to shorebase for pickup by municipal operations. *Sanitary Wastes Treated human body

waste 11,330,000 gals total Chlorina te and discharge overboard

*Domestic Waste Gray water 11,330,000 gals total Chlorina te and discharge overboard Deck drainage Platform washings and
rainwater 7,931,000 bbls total Treat for oil and grease and discharge
overboard
Produced water N/A N/A N/A
Desalinization Unit S eawater 793,100 bbls total Discharge overboard Wash water Drill water (fresh) 113,300 bbls total Discharge overboard Blowout preventer
fluid Blend (3% Stack Magic & Filtered Fresh Water) 299,436 gals total Disc harge at seafloor

Ballast water Seawater 47,650 m3/year Discharge overboard Bilge water Seawater 718,322 bbls total Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor Nitrified cement slurry 1200 bbl s/well Discharge at seafloorFire water Seawater 137,142 bbls/ day/well Discharge overboard Cooling water Seawater 137,142 bbls/ day/well Discharge overboard
Produced Sand N/A N/A N/A
Used oil Excess oil from engine s 8,120 bbls total Transport in DOT approved containers to shore for recycling *The rig is designed for maximum personnel capacity of 200 pe ople. The discharge rates are based off of maximum personnel capacity but will generally not have this many pe rsonnel onboard during drilling and/or completion operations.

* *The actual volume ordered out will be an estimated 21,000 bbls/well of mud. Once on location this volume will be cut back and mixed with seawater to different desired mud weights which w ill increase the volume that is discharged at the seafloor. Th e estimated volume that will be discharged at the seafloor wi ll be approximately 74,000 bbls/well (NOTE: th ere will be twelve wells for a total of 888,000 bbls). ***This type of waste will not exist fo r the proposed GC 859 “J” and GC 903 “E” locations since only top-hole drilling for thes e wells will occur under this plan. This ty pe of waste will only occur for the additio nal 10 well locations proposed in GC 859 a nd
903 since these wells will be drilled to total depth and completed under this plan.

(b) Projected Ocean Discharges Type of Waste Total Amount to be Discharged Discharge Rate Discharge Method

*Sanitary Wastes 11,330,000 gals total 25 gals per person daily Chlorinate and discharge overboard
*Domestic waste 11,330,000 gals tota l 25 gals per person daily Chlori nate and discharge overboard Deck drainage 7,931,000 bbls total 3500 bbls/da y Treat for oil and grease and discharge Blowout preventer fluid 299,436 gals total 925 gals/week/well; Vents on a weekly basis Discharge at seafloor

Desalinization Unit 793,100 bbls total 350 bbls/day Discharge overboard
Wash water 113,300 bbls total 50 bbls/day Discharge overboard
Ballast water 47,650 m3/year Not continuous Discharge overboard Bilge water 718,322 bbls tota l 317 bbls/day Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor 14,400 bbls total 20 bbls/min Discharge at seafloor

Fire water 310,763,772 bbls total 137, 142 bbls/day Discharge overboard Cooling water 310,763,772 bbls total 137,142 bbls/day Discharge overboardCuttings wetted with Waterbased fluids 45,600 bbls total 1,000 bbls/hr max Discharge overboard

Water-based drilling fluids 888,000 bbls total** 1,000 bbl s/hr max Discharge at seafloor or overboard Cuttings wetted with Synthetic-based fluids 78,000 bbls total NA Treated and discharge overboard *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on to the base/transfer station if oil still
remains

. Non-pollutant completion
fluids 50,000 bbls total*** 100 bbl/hour Discharge overboard

*The rig is designed for maximum personnel capacity of 200 pe ople. The discharge rates are based off of maximum personnel capacity but will generally not have this many pe rsonnel onboard during drilling and/or completion operations.

* *The actual volume ordered out will be an estimated 21,000 bbls/well of mud. Once on location this volume will be cut back and mixed with seawater to different desired mud weights which w ill increase the volume that is discharged at the seafloor. Th e estimated volume that will be discharged at the seafloor wi ll be approximately 74,000 bbls/well (NOTE: th ere will be twelve wells for a total of 888,000 bbls). ***This type of waste will not exist fo r the proposed GC 859 “J” and GC 903 “E” locations since only top-hole drilling for thes e wells will occur under this plan. This ty pe of waste will only occur for the additio nal 10 well locations proposed in GC 859 a nd
903 since these wells will be drilled to total depth and completed under this plan.

(c) Modeling Report

The proposed activities under this plan do not meet the U.S. Environmental Protection Agency requirements for an individual NPDES permit. Th erefore, modeling report requirements per NTL No. 2008-G04 is not applicable to this EP.

### G AIR EMISSIONS INFORMATION

(a) Screening Questions

Screening Questions for EP’s Yes No Is any calculated Complex Total (CT) Emission amount (in tons) associated with your proposed exploration activities more than 90% of the amounts calculated using the following formulas: CT = 3400D 2/3 for CO, and CT = 33.3D for the other air pollutants (where D = distance to shore in miles)? No

Do your emission calculations include any emission reduction measures or modified
emission factors? Yes

Are your proposed exploration activities located east of 87.5 W longitude? No Do you expect to encounter H2S at concentrations greater than 20 parts per million (ppm)? No Do you propose to flare or vent natural gas for more than 48 continuous hours from any proposed well? No

Do you propose to burn produced hydrocarbon liquids? No

(b) Emissions Worksheets Air emissions worksheets have been prepared usi ng actual fuel usage from contracted drilling units. Actual fuel usage was calculated using data from th e Ensco 8500 and Trans Ocean Discoverer Spirit rigs. A different rig could possibly be utilized but the actua l fuel usage/air emissions will be equal to or less than the calculated plan emission amounts shown be low. Air emissions worksheets are enclosed as Attachment G-1.

(c) Summary Information

The following tables summarize information regarding the peak year emissions generated from the Plan Emissions and Complex Total Emissions:

If drilled with a DP Semisubmersible (Horsepo wer equal to or less than the Ensco 8500):
Air Pollutant Plan Emission Amounts 1 (tons) Calculated Exemption
Amounts 2 (tons) Calculated Complex Total Emission
Amounts 3 (tons) Particulate matter (PM) 73.40 4495.50 N/A Sulphur dioxide (SO 2 ) 336.70 4495.50 N/A Nitrogen oxides (NO

x ) 2525.00 4495.50 N/A Volatile organic compounds (VOC) 77.50 4495.50 N/A Carbon monoxide (CO) 562.12 89474.94 N/A

If drilled with a DP Drillship (Horsepower equal to or less than the T.O. Discoverer Spirit):
Air Pollutant Plan Emission
Amounts 1 (tons) Calculated Exemption
Amounts 2 (tons) Calculated Complex Total Emission
Amounts 3 (tons) Particulate matter (PM) 111.06 4495.50 N/A Sulphur dioxide (SO 2 ) 509.50 4495.50 N/A Nitrogen oxides (NO

x ) 3819.82 4495.50 N/A Volatile organic compounds (VOC) 116.34 4495.50 N/A Carbon monoxide (CO) 844.60 89474.94 N/AThe air emission calculations were calculated by:

Jill Fowler Regulatory Analyst (832) 636-1554 jill.fowler@anadarko.comEXPLORATION PLAN (EP)AIR QUALITY SCREENING CHECKLISTOMB Control No. 1010-0049OMB Approval Expires: September 30, 2003COMPANYAnadarko Petroleum CorporationAREAGreen CanyonBLOCK859 & 903LEASEOCS-G 24194 & 24197PLATFORMWELLGC903 "D & DD, E" and GC 859 "F, G, H, FF, GG, HH, I, II, J"COMPANY CONTACTJill FowlerTELEPHONE NO.832-636-1554REMARKSDrill and complete 10 wells, and conduct 2 topsetsForm MMS-138 (May 2001)Page 1 of 8EMISSIONS FACTORSFuel Usage Conversion FactorsNatural Gas Turbines Natural Gas Engines Diesel Recip. Engine REF. DATESCF/hp-hr 9.524 SCF/hp-hr 7.143 GAL/hp-hr 0.0483AP42 3.2-1 4/76 & 8/84Equipment/Emission Factorsunits PM SOx NOx VOC CO REF. DATENG Turbines gms/hp-hr 0.00247 1.3 0.01 0.83AP42 3.2-1& 3.1-1 10/96NG 2-cycle leangms/hp-hr0.00185 10.9 0.43 1.5AP42 3.2-1 10/96NG 4-cycle leangms/hp-hr0.00185 11.8 0.72 1.6AP42 3.2-1 10/96NG 4-cycle richgms/hp-hr0.00185 10 0.14 8.6AP42 3.2-1 10/96Diesel Recip. < 600 hp. gms/hp-hr 1 1.468 14 1.12 3.03AP42 3.3-1 10/96Diesel Recip. > 600 hp.gms/hp-hr 0.32 1.468 11 0.33 2.4AP42 3.4-1 10/96Diesel Boilerlbs/bbl 0.084 2.42 0.84 0.008 0.21AP42 1.3-12,14 9/98NG Heaters/Boilers/Burnerslbs/mmscf 7.6 0.593 100 5.5 84P42 1.4-1, 14-2, & 147/98NG Flareslbs/mmscf0.593 71.4 60.3 388.5AP42 11.5-1 9/91Liquid Flaringlbs/bbl 0.42 6.83 2 0.01 0.21AP42 1.3-1 & 1.3-3 9/98Tank Vaporslbs/bbl0.03E&P Forum 1/93Fugitiveslbs/hr/comp.0.0005API Study 12/93Glycol Dehydrator Ventlbs/mmscf6.6La. DEQ1991Gas Ventinglbs/scf0.0034Sulfur Content SourceValue UnitsFuel Gas3.33 ppmDiesel Fuel0.4 % weightProduced Gas( Flares)3.33 ppmProduced Oil (Liquid Flaring)1 % weightForm MMS-138 (May 2001)Page 2 of 8EMISSIONS CALCULATIONS 1ST YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorporaGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF, Jill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 21,532 1039.9956 24959.89 24 350 15.18 69.62 521.70 15.65 113.83 63.74 292.42 2191.14 65.73 478.07Ensco 8506 PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 150 10.44 47.87 358.71 10.76 78.26 4.70 21.54 161.42 4.84 35.222 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 100 6.53 29.96 224.51 6.74 48.98 1.96 8.99 67.35 2.02 14.69VESSELS>600hp diesel(tugs)00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-00 00.000.00Flowback After OIL BURN00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE625000 24 00.37 44.63 37.69 242.81 0.00 0.00 0.00 0.002014 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 70.40 322.95 2419.91 72.60 527.98EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 3 of 8EMISSIONS CALCULATIONS 2ND YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF,GJill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 21,532 1039.9956 24959.89 24.00 365.00 15.18 69.62 521.70 15.65 113.83 66.47 304.95 2285.05 68.55 498.56Ensco 8506 PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6.00 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6.00 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs) 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 24 40.37 44.63 37.69 242.81 0.02 2.14 1.81 11.662015 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 73.40 336.72 2525.11 77.50 562.12EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 4 of 8EMISSIONS CALCULATIONS 3RD YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF,GJill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 21,532 1039.9956 24959.89 24 365 15.18 69.62 521.70 15.65 113.83 66.47 304.95 2285.05 68.55 498.56Ensco 8506 PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 24 20.37 44.63 37.69 242.81 0.01 1.07 0.90 5.832016 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 73.40 336.71 2524.04 76.59 556.29EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 5 of 8EMISSIONS CALCULATIONS 4TH YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF, GG Jill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 21,532 1039.9956 24959.89 24 365 15.18 69.62 521.70 15.65 113.83 66.47 304.95 2285.05 68.55 498.56Ensco 8506 PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs)00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 2440.37 44.63 37.69 242.81 0.02 2.14 1.81 11.662017 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 73.40 336.72 2525.11 77.50 562.12EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 6 of 8EMISSIONS CALCULATIONS 5TH YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF, GG Jill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 21,532 1039.9956 24959.89 24 365 15.18 69.62 521.70 15.65 113.83 66.47 304.95 2285.05 68.55 498.56Ensco 8506 PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs)00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 2420.37 44.63 37.69 242.81 0.01 1.07 0.90 5.832018 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 73.40 336.71 2524.04 76.59 556.29EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 7 of 8COMPANYAREABLOCKLEASE PLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Cor Green Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H,FJill Fowler832-636-15540OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel21,532 1039.9956 24959.89 24 365 15.18 69.62 521.70 15.65 113.83 66.47 304.95 2285.05 68.55 498.56Ensco 8506 PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew)14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply)9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs)000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply)000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-00 00.000.00Flowback After OIL BURN00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE62500024 4 0.37 44.63 37.69 242.81 0.02 2.14 1.81 11.662019 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 73.40 336.72 2525.11 77.50 562.12EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES4495.50 4495.50 4495.50 4495.50 89474.94135.0COMPANYAREABLOCKLEASE PLATFORM WELLCONTACT PHONE REMARKSAnadarko Petroleum Cor Green Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H,FJill Fowler832-636-15540OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel21,532 1039.9956 24959.89 24 89 15.18 69.62 521.70 15.65 113.83 16.21 74.36 557.18 16.72 121.57Ensco 8506 PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel00.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew)14805 715.0815 17161.96 6 38 10.44 47.87 358.71 10.76 78.26 1.19 5.46 40.89 1.23 8.922 trips/week VESSELS>600hp diesel(supply)9266 447.5478 10741.15 6 25 6.53 29.96 224.51 6.74 48.98 0.49 2.25 16.84 0.51 3.67VESSELS>600hp diesel(tugs)000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew)000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply)000.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-00 00.000.00Flowback After OIL BURN00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE62500024 1 0.37 44.63 37.69 242.81 0.00 0.54 0.45 2.912020 YEAR TOTAL32.14 147.83 1149.54 70.84 483.89 17.89 82.07 615.44 18.90 137.08EXEMPTIONCALCULATIONDISTANCE FROM LAND IN MILES4495.50 4495.50 4495.50 4495.50 89474.94135.0SUMMARYCOMPANY AREABLOCKLEASEPLATFORM WELLAnadarko Petrol Green Canyon #REF!#REF!GC903 "D & DD, E" anEmittedSubstanceYearPMSOxNOxVOCCO2014 70.40322.95 2419.91 72.60527.982015 73.40336.72 2525.11 77.50562.122016 73.40336.71 2524.04 76.59556.292017 73.40336.72 2525.11 77.50562.122018 73.40336.71 2524.04 76.59556.292019 73.40336.72 2525.11 77.50562.122020 17.8982.07615.4418.90137.082021 0.000.000.000.000.002022 0.000.000.000.000.002023 0.000.000.000.000.00Allowable4495.50 4495.50 4495.50 4495.50 89474.94Form MMS-138 (May 2001)Page 8 of 8EXPLORATION PLAN (EP)AIR QUALITY SCREENING CHECKLISTOMB Control No. 1010-0049OMB Approval Expires: September 30, 2003COMPANYAnadarko Petroleum CorporationAREAGreen CanyonBLOCK859 & 903LEASEOCS-G 24194 & 24197PLATFORMWELLGC903 "D & DD, E" and GC 859 "F, G, H, FF, GG, HH, I, II, J"COMPANY CONTACTJill FowlerTELEPHONE NO.832-636-1554REMARKSDrill and complete 10 wells, and conduct 2 topsetsForm MMS-138 (May 2001)Page 1 of 8EMISSIONS FACTORSFuel Usage Conversion FactorsNatural Gas Turbines Natural Gas Engines Diesel Recip. Engine REF. DATESCF/hp-hr 9.524 SCF/hp-hr 7.143 GAL/hp-hr 0.0483AP42 3.2-1 4/76 & 8/84Equipment/Emission Factorsunits PM SOx NOx VOC CO REF. DATENG Turbines gms/hp-hr 0.00247 1.3 0.01 0.83AP42 3.2-1& 3.1-1 10/96NG 2-cycle leangms/hp-hr0.00185 10.9 0.43 1.5AP42 3.2-1 10/96NG 4-cycle leangms/hp-hr0.00185 11.8 0.72 1.6AP42 3.2-1 10/96NG 4-cycle richgms/hp-hr0.00185 10 0.14 8.6AP42 3.2-1 10/96Diesel Recip. < 600 hp. gms/hp-hr 1 1.468 14 1.12 3.03AP42 3.3-1 10/96Diesel Recip. > 600 hp.gms/hp-hr 0.32 1.468 11 0.33 2.4AP42 3.4-1 10/96Diesel Boilerlbs/bbl 0.084 2.42 0.84 0.008 0.21AP42 1.3-12,14 9/98NG Heaters/Boilers/Burnerslbs/mmscf 7.6 0.593 100 5.5 84P42 1.4-1, 14-2, & 147/98NG Flareslbs/mmscf0.593 71.4 60.3 388.5AP42 11.5-1 9/91Liquid Flaringlbs/bbl 0.42 6.83 2 0.01 0.21AP42 1.3-1 & 1.3-3 9/98Tank Vaporslbs/bbl0.03E&P Forum 1/93Fugitiveslbs/hr/comp.0.0005API Study 12/93Glycol Dehydrator Ventlbs/mmscf6.6La. DEQ1991Gas Ventinglbs/scf0.0034Sulfur Content SourceValue UnitsFuel Gas3.33 ppmDiesel Fuel0.4 % weightProduced Gas( Flares)3.33 ppmProduced Oil (Liquid Flaring)1 % weightForm MMS-138 (May 2001)Page 2 of 8EMISSIONS CALCULATIONS 1ST YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorporaGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF, Jill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24 350 23.78 109.07 817.30 24.52 178.32 99.86 458.10 3432.64 102.98 748.94Discoverer Spirit PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 150 10.44 47.87 358.71 10.76 78.26 4.70 21.54 161.42 4.84 35.222 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 100 6.53 29.96 224.51 6.74 48.98 1.96 8.99 67.35 2.02 14.69VESSELS>600hp diesel(tugs)00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITYDERRICK BARGE diesel00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-00 00.000.00Flowback After OIL BURN00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00CompletionGAS FLARE625000 24 00.37 44.63 37.69 242.81 0.00 0.00 0.00 0.002014 YEAR TOTAL40.74 187.28 1445.14 79.70 548.38 106.51 488.63 3661.41 109.84 798.85EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 3 of 8EMISSIONS CALCULATIONS 2ND YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF,GJill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24.00 365.00 23.78 109.07 817.30 24.52 178.32 104.14 477.73 3579.75 107.39 781.04Discoverer Spirit PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6.00 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6.00 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs) 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 24 40.37 44.63 37.69 242.81 0.02 2.14 1.81 11.662015 YEAR TOTAL40.74 187.28 1445.14 79.70 548.38 111.06 509.50 3819.82 116.34 844.60EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 4 of 8EMISSIONS CALCULATIONS 3RD YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF,GJill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24 365 23.78 109.07 817.30 24.52 178.32 104.14 477.73 3579.75 107.39 781.04Discoverer Spirit PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 24 20.37 44.63 37.69 242.81 0.01 1.07 0.90 5.832016 YEAR TOTAL40.74 187.28 1445.14 79.70 548.38 111.06 509.50 3818.75 115.43 838.77EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 5 of 8EMISSIONS CALCULATIONS 4TH YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF, GG Jill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24 365 23.78 109.07 817.30 24.52 178.32 104.14 477.73 3579.75 107.39 781.04Discoverer Spirit PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs)00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 2440.37 44.63 37.69 242.81 0.02 2.14 1.81 11.662017 YEAR TOTAL40.74 187.28 1445.14 79.70 548.38 111.06 509.50 3819.82 116.34 844.60EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 6 of 8EMISSIONS CALCULATIONS 5TH YEARCOMPANYAREABLOCK LEASE PLATFORM WELLCONTACTPHONE REMARKSAnadarko Petroleum CorpGreen Canyon#REF! #REF!GC903 "D & DD, E" and GC 859 "F, G, H, FF, GG Jill Fowler832-636-1554 0OPERATIONSEQUIPMENTRATING MAX. FUEL ACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HR GAL/DNat. Gas EnginesHP SCF/HR SCF/DBurnersMMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLING PRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24 365 23.78 109.07 817.30 24.52 178.32 104.14 477.73 3579.75 107.39 781.04Discoverer Spirit PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00PRIME MOVER>600hp diesel0 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00BURNER diesel000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00AUXILIARY EQUIP<600hp diesel 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.632 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28VESSELS>600hp diesel(tugs)00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00FACILITY DERRICK BARGE diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00INSTALLATION MATERIAL TUG diesel00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(crew) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00VESSELS>600hp diesel(supply) 00 0.00 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00MISC.BPD SCF/HR COUNTTANK-0000.000.00Flowback After OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Completion GAS FLARE625000 2420.37 44.63 37.69 242.81 0.01 1.07 0.90 5.832018 YEAR TOTAL40.74 187.28 1445.14 79.70 548.38 111.06 509.50 3818.75 115.43 838.77EXEMPTIONCALCULATIONDISTANCE FROM LAND INMILES4495.50 4495.50 4495.50 4495.50 89474.94135.0Form MMS-138 (May 2001)Page 7 of 8COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS
Anadarko Petroleum Cor Green Canyon #REF! #REF! GC903 "D & DD, E" and GC 859 "F, G, H, F Jill Fowler 832-636-155 4 0 OPERATIONS EQUIPMENT RATING MAX. FUEL ACT. FUEL RUN TIME MAXIMUM POUNDS PER HOUR ESTIMATED TONS Diesel Engines HP GAL/H R GAL/D Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CO DRILLING PRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24 365 23.78 109.07 817.30 24.52 178.32 104.14 477.73 3579.75 107.39 781.04 Discoverer Spirit PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
BURNER diesel 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AUXILIARY EQUIP<600hp diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 156 10.44 47.87 358.71 10.76 78.26 4.88 22.40 167.88 5.04 36.63 2 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 104 6.53 29.96 224.51 6.74 48.98 2.04 9.35 70.05 2.10 15.28 VESSELS>600hp diesel(tugs) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

FACILITY DERRICK BARGE diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 INSTALLATION MATERIAL TUG diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 VESSELS>600hp diesel(crew) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 VESSELS>600hp diesel(supply) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

MISC. BPD SCF/HR COUNT
TANK- 0 0 0 0.00 0.00

Flowback After OIL BURN 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Completion GAS FLARE 625000 24 4 0.37 44.63 37.69 242.81 0.02 2.14 1.81 11.66

2019 Y EAR TOTAL 40.74 187.28 1445.14 79.70 548.38 111.06 509.50 3819.82 116.34 844.60

EXEMPTION
CALCULATION DISTANCE FROM LAND IN MILES 4495.50 4495.50 4495.50 4495.50 89474.94
135.0COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS
Anadarko Petroleum Cor Green Canyon #REF! #REF! GC903 "D & DD, E" and GC 859 "F, G, H, F Jill Fowler 832-636-155 4 0 OPERATIONS EQUIPMENT RATING MAX. FUEL ACT. FUEL RUN TIME MAXIMUM POUNDS PER HOUR ESTIMATED TONS Diesel Engines HP GAL/H R GAL/D Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CO DRILLING PRIME MOVER>600hp diesel 33,732 1629.2556 39102.13 24 89 23.78 109.07 817.30 24.52 178.32 25.39 116.49 872.87 26.19 190.44 Discoverer Spirit PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 PRIME MOVER>600hp diesel 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
BURNER diesel 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AUXILIARY EQUIP<600hp diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3 trips/week VESSELS>600hp diesel(crew) 14805 715.0815 17161.96 6 38 10.44 47.87 358.71 10.76 78.26 1.19 5.46 40.89 1.23 8.92 2 trips/week VESSELS>600hp diesel(supply) 9266 447.5478 10741.15 6 25 6.53 29.96 224.51 6.74 48.98 0.49 2.25 16.84 0.51 3.67 VESSELS>600hp diesel(tugs) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

FACILITY DERRICK BARGE diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 INSTALLATION MATERIAL TUG diesel 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 VESSELS>600hp diesel(crew) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 VESSELS>600hp diesel(supply) 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

MISC. BPD SCF/HR COUNT
TANK- 0 0 0 0.00 0.00

Flowback After OIL BURN 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Completion GAS FLARE 625000 24 1 0.37 44.63 37.69 242.81 0.00 0.54 0.45 2.91

2020 Y EAR TOTAL 40.74 187.28 1445.14 79.70 548.38 27.07 124.20 931.14 28.37 205.95

EXEMPTION
CALCULATION DISTANCE FROM LAND IN MILES 4495.50 4495.50 4495.50 4495.50 89474.94
135.0SUMMARYCOMPANY AREABLOCKLEASEPLATFORM WELLAnadarko Petrol Green Canyon #REF!#REF!GC903 "D & DD, E" anEmittedSubstanceYearPMSOxNOxVOCCO2014 106.51 488.63 3661.41 109.84 798.852015 111.06 509.50 3819.82 116.34 844.602016 111.06 509.50 3818.75 115.43 838.772017 111.06 509.50 3819.82 116.34 844.602018 111.06 509.50 3818.75 115.43 838.772019 111.06 509.50 3819.82 116.34 844.602020 27.07124.20 931.1428.37205.952021 0.000.000.000.000.002022 0.000.000.000.000.002023 0.000.000.000.000.00Allowable4495.50 4495.50 4495.50 4495.50 89474.94Form MMS-138 (May 2001)Page 8 of 8

### H OIL SPILL INFORMATION

(a) Oil Spill Response Planning

(i) OSRP Information

All the proposed activities and facilities in this EP are covered by the Regional Oil Spill Response Plan (OSRP) approved on Septembe r 25, 2013 for Anadarko Pe troleum Corporation and its subsidiaries, Anadarko US Offshore Corporation and Anadarko E&P Company L.P. (Company Numbers 00981, 02219 and 00148, respectivel y) in accordance with 30 CFR Part
254.

(ii) Spill Response Sites

Primary Response Equipment Location(s) Preplanned Staging Location(s) 

### Houma, Louisiana Harvey, Louisiana Venice, Louisiana Lake Charles, Louisiana Galveston, Texas Fourchon, Louisiana Harvey, Louisiana Venice, Louisiana Cameron, Louisiana Galveston, Texas

(iii) OSRO Information

Anadarko maintains a contract w ith Clean Gulf Associates (CGA) for spill response equipment. Various equipment locations are staged throughout the Gulf of Mexico. CGA equipment can be referenced on their website: http://www.cleangul fassoc.com/. Personnel would be obtained from the Marine Spill Response Corporation’s (MSRC) STARS network, including a supervisor to operate the equipment.

In addition Anadarko has a contract with the Marine Spill Response Co rporation (MSRC) for spill response equipment. MSRC stages equipm ent throughout the Gulf of Mexico and has recently completed a large expansion of its resources, with particular focus on deepwater. The expansion is known as “Deep Blue”. 

### MSRC capabilities and a complete equipment listing are available online at: http:// www.msrc.org/.

Anadarko is a member of the Helix Well Cont ainment Group (HWCG), a combination of the Helix Fast Response System (HFRS) and the co mmon equipment and services. This agreement
allows access to subsea well contai nment and well shut-in equipment.

Anadarko is also a member of the Marine Well Containment Co mpany (MWCC), which provides access to containment response capabilities and includes subsea dispersant injection equipment.

### (iv) Worst-Case Scenario Determination

Category Regional OSRP EP EP Type of Activity Exploratory Exploratory Exploratory
Facility Location (area/block) GC 683 GC 859 GC 903

Facility Designation GC 683 “G” GC 859 “J” GC 903 “E”

Distance to Nearest
Shoreline 120 miles 135 miles 135 miles

Storage Tanks (total) N/A N/A N/A
Flowlines (on facility) N/A N/A N/A
Pipelines N/A N/A N/A
Uncontrolled Blowout 410,000 bopd* 263,660 bopd 244,402 bopd
Type of Oil(s) Oil Oil Oil
API Gravity 28.9 o 31.4 o 31.4 o

*The volume denoted in the Regional OSRP is higher t han the NTL No. 2010-N06 (403,608 bopd) calculations approved under EP Plan Control No. S-7623. Anadarko elected to denot e a higher volume in the Regional OSRP for planning purposes to demonstrate equipment re sponse capabilities per previous discussions with Mr. Mike Tolbert.



### Anadarko has determined that the worst-case scenario from the activities proposed in this Supplemental EP does not supersede the wors t-case scenario for Green Canyon Block 683 as previously filed in the Regional OSRP.

Since Anadarko has the cap ability to respond to the worst-case spill s cenario included in our Regional OSRP, and since the worst-case scenario s determined for our EP does not replace the
worst-case scenario in our Regional OSRP last approved on September 25, 2013, I hereby certify that Anadarko has the capability to respond, to th e maximum extent practicable, to a worst-case discharge, or a substantial threat of such a discha rge, resulting from the ac tivities proposed in our
EP.

(b) Worst-Case Discharge Volume Assumptions

Worst-case discharge (WCD) calculations and assump tions within this section utilized guidelines and requirements pursuant with NTL No. 2010-N 06. The following information summarizes the WCD scenario and assumptions used for Gr een Canyon (GC) Blocks 859 & 903. Please note
that EP location J is referred to as the GC 859 #3 well and locati on E is referred to as GC 903 #5 in the following WCD summary:

Discussions regarding geologic information are considered proprietary and have been omitted from this public copy of the EP. Note, some attachments have been not included due to proprietary information.

(c) Oil Spill Response Discussion

For the purpose of NEPA analys is, the largest spill volume or iginating from the proposed activity would be an uncontrolle d blowout of the well during drilling operations at 263,660

### BOPD with an API gravity of 31.4 o 

### . A discussion of the blowout scenario from this proposed activity is included within this Supplemen tal EP in accordance with NTL No. 2010-N06.

Land Segment and Resource Identification Modeling

Trajectory of a spill and the probability of its impacting a land segment have been projected utilizing information in the Oil Spill Risk An alysis Model (OSRAM) for the Central Gulf of Mexico. Additional information may be referenced in the “Oil-Spill Risk Analysis: Contingency Planning Statistics for Gulf of Mexico OC S Activities” (OCS Report MMS 2004-026), using the average conditional probability for 3, 10, and 30 day impacts.

Green Canyon Blocks 859 & 903 ar e located within Launch Ar ea 46. According to the BOEM OSRAM, the trajectory indicates a 3% probabili ty of potential impact to the shoreline in Cameron and/or Plaquemines Parish, Louisian a. The results are shown in Table H-2.

Cameron and/or Plaquemines Parish are identified as the most probable potential impacted parish or county within the Gulf of Mexico for this op eration. Cameron Parish is located in Louisiana and includes Cameron Prairie National Wildlife Refuge (NWR), East Cove Unit (a part of the Cameron Prairie NWR), Lacassine NWR, and Sabine NWR. Plaquemines Parish is also located in Louisiana and includes Delta NWR, Pass-a-L outre Wildlife Management Area (WMA), and
Bohemia State WMA.

Response

Anadarko will make every effort to respond to the worst-case discharge as effectively as possible. Response equipment available to respond to the worst-case discharge and the estimated time of a spill response from oil spill detecti on to equipment deployment on-site is included in Table H-3. The table estimates individual times needed for procurement, load out, travel time to the site and deployment. In the event of an actual incident equipment and times can vary.

For the purpose of response scenario discussion, an uncontrolled blowout of the well would be considered the largest potential spill vol ume at 263,660 BOPD. An AD IOS weathering model was run based on a similar type of oil expected to be produced from this well. Based on this information, approximately 15% (39,549 bbl s) of the initial volume would be evaporated/dispersed within 24 hours.

If approved and appropriate, 4 sorties (8,000 ga llons) from the Basler ai rcraft and 8 sorties (9,600 gallons) from two DC-3 aircrafts could disperse approximately 7,540 barrels of oil.

If the conditions are appropriate, and the necessary approvals and permits have been obtained, in-situ burning may be utilized. Based on in -situ burn operations du ring Deepwater Horizon, approximately 5% (13,183 bbls) of the total initial wo rst case discharge could be burned after natural evaporat ion/dispersion.

Although unlikely in a spill lasting thirty (30) da ys, potential shoreline impact in Cameron and/or Plaquemines Parish, Louisiana could occur de pending on environmental conditions (wind,

### currents and temperature) at the time of an in cident. Nearshore response may include the use of shoreline boom on beach areas, or protection/sorbent boom on vege tated areas. Surveillance and real time trajectories would aide in determining the most appropriate strategies to respond to a spill.

Table H.3 provides an example of offshore a nd nearshore equipment, response times, and personnel to respond to a spill of 224,111 bbls, which is the estima ted amount that would remain considering natural evaporation/ dispersion at 24 hours. This amount could be further reduced through the application of aeria l and subsea dispersants, and in-situ burning provided such applications/actions were approved.

Anadarko’s contingency plan for de aling with this worst-case disc harge would be to activate its Spill Management Team and equipment resources as described in its Gulf of Mexico Regional Oil Spill Response Plan (OSRP) and provide con tinuous support for the duration of the event. Response resources are activated and supplemen ted according to need. These resources would remain engaged in the response until the incident is deemed complete or until released by
Unified Command.

Anadarko is a member of the Helix Well Cont ainment Group (HWCG), a combination of the Helix Fast Response System (HFRS) and the co mmon equipment and services. This agreement
allows access to subsea well contai nment and well shut-in equipment.

Anadarko is also a member of the Marine Well Containment Co mpany (MWCC), which provides access to containment response capabilities and includes subsea dispersant injection equipment.

In the event of a blowout, Anadarko may:

1. Evacuate personnel, if necessary. Deploy emer gency responders in an effort to preserve human life, if necessary.

2. Assess the damage and attempt to stop the flow at the source, if safe to do so, to reduce the amount of oil discharged. 3. Notify agencies.

4. Assess the amount of oil that has been sp illed and calculate add itional potential of oil flow. A continuous aerial surveillance program would be used to assess the growth of the
slick and the volume of oil on the water. Ob servations of the si ze of the slick on the water, combined with observations at the s ource, would be used to provide a constant update. Additional potential to release fuel from the remaining tanks onboard the dynamically positioned (DP) semi-submersible drilling rig would be determined by marine surveyors. Operations and Unifie d Command would continue to assess the adequacy of response equipment capacities based on this continually updated mass
balance.

### 5. Convene the Spill Management Team (SMT). Organize Unified Command and establish objectives and priorities.

6. Monitor the oil spill with aerial surveillance and obtain tr ajectories. If oil is seaward bound, going away from land, discuss additiona l strategies with Unified Command.

7. If oil is moving in the direction of a shoreline and weather co nditions are favorable, request approval to u tilize dispersants.

a. Prior to commencing application operati ons, conduct an on-site survey in consultation with natural resource specialists to determ ine if any threatened or endangered species are present in the projected application ar ea or otherwise at risk from dispersant application.

b. Upon approval, mobilize one Basler aircraft and two DC-3 aircrafts from Houma, with surveillance aircraft and spotter. Mobili ze MSRC contracted aircraft(s) if needed. Rotate aircraft, spraying the leading edge of the spill and working back to the source. Monitor/sample for effectiveness (U SCG SMART Team). Truck additional dispersants from CGA/MSRC stockpile to Houma, if necessary.

c. Dispersants are most effective when app lied as soon after discha rge as possible, since weathering of the oil decreas es dispersant effectiveness. The estimated window of opportunity for most effectiv e use of dispersants is w ithin 48-72 hours post-release. The oil may still be dispersible after 72 hours on the water surface, but the effectiveness of dispersant use would likely be diminished after th e oil has been on the water for more than three days. Ultimat ely, the USCG SMART monitoring protocol will be used to determine whether or not dispersant operations are effective.

d. Once the CGA HOSS barge is on locati on and in the skimming mode, dispersants would only be used if required and approved.

8. Deploy offshore mechanical oil containment and recovery equipment. Attempt to recover
as much oil at sea as possible, utilizing:

a. The CGA HOSS barge, will be positioned in a stationary mode, will be situated downwind and down-current from location fo r long-duration, high-volume skimming. Based on average travel times, the HO SS barge could be on location within approximately 28 hours of the release. The de-rated skimming capacity of the HOSS barge is 43,000 bbls per day. However, only the oil encountered by a skimmer can be
recovered. In order to maximize oil encount er rate, boom will be deployed in a V-configuration in front of the HOSS barge to funnel oil to the skimmers. If necessary, temporary barges can be ac tivated to support continuous skimming operations. (These barges arrive on-site at approximately the same time as the HOSS barge.) For an on-going release, multiple barges are deployed to provide for continuous off-loading of skimmer storage vess els and shuttling of recovered oil to an

### onshore waste handling facility. Sufficient barges are available to provide enough temporary storage for continuous recovery operations.

b. CGA’s Fast Response Units (FRU) woul d arrive on-scene between approximately
14.8-23 hours of the initial rele ase. These skimmers operate downstream of the HOSS barge and are used to recover pockets and streamers of oil that may move past the large stationary skimmer. Each FRU has 200 barrels of on-board storage. Approval will be requested to decant water after gravity separation, through a hose forward of the skimmer, to optimize temporary storage capacity. A 42" Boom will be utilized to
concentrate oil so that it is thick enough to be skimmed.

9. Dispersants, Fast Response Units (FRU), Oil Spill Response Vessels (OSRV or R/V) would typically work daylight hours onl y. The HOSS barge can operate continuously, including night operations. Available technology will be considered such as remote sensing devices that will enable 24 hour surveillance, trajecto ries, and planning. All response vessels are designed to be able to remain offshore continuously throughout the response. Even if sea conditions prohibit effective skimming, these resources would remain offshore until skimming operations could be commenced again. Safety would remain the first priority.

10. Prepare Site-Specific Waste Management Pla n, Site Safety Plan, Decontamination Plans,
Communications and Medical Plans.

11. If oil becomes a threat to any shoreline, da ta from the aerial survei llance, weather reports, and trajectories would be used to direct onshore teams to deploy protection/containment boom with reference to Area Contingency Pl ans and in coordination with State and
Federal On-Scene Coordinators.

a. Implement pre-designated strategies.

b. Identify resources at risk in spill vicinity.

c. Develop/implement appropriate protection tactics.

12. Establish Site-Specific Wildlif e Rescue and Rehabilitation Plan.

The following types of additional support may be required for a blowout lasting 120 days.

 Additional Oil Spill Remova l Organization (OSRO) personnel to relieve equipment operators

 Vessels for supporting offshore operations

 Field safety personnel

 Continued surveillance and m onitoring of oil movement

 Helicopter, video cameras

 Infra red (night time spill track ing) capabilities, X-band radar

###  Barge to transport recovered oil from offshore skimming system, and temporary storage barges to onshore disposal sites th at are identified in Area Contingency Plans (ACP)

 Logistics needed to support equipment:

- Staging areas

- Parts, trailers, and mechanics to maintain skimmers and boom

- Fueling facilities

- Decontamination stations

- Dispersant stockpile tran sported from Houston to Houma or other potential command post locations

- Communications equipm ent and technicians

 Logistics needed to s upport responder personnel

- Medical aid stations

- 

### Safety personnel

- Food

- Berthing

- Additional clothing/safety supplies

- Decontamination stations

Louisiana CZM Containment Response Information
Anadarko has the capability to respond and cont ain, to the maximum extent practicable as defined in 30 CFR 254.6 and 30 CFR 250.26(d)(1), to the estimated wors t case discharge (WCD) associated with the proposed activity within 30 days. Deployment time for surface containment equipment is subject to availability and loca tion, weather conditions, potential security zones around the spill site, and site/well specific assessment data. Personnel safety is always first and
foremost. Refer to further detail s on equipment and timing provided in Section H–Oil Spill Information and Table H-3 of the EP.

The potential WCD will be further evaluated du ring the Application for Permit to Drill (APD) process, including the Well Containment Screen ing Tool (WCST) and associated subsea containment plan for enhanced planning purposes.

There will be no new or unusual technology deployed that has not been previously deployed for Gulf of Mexico oil spill prev ention, control, and/or cleanup.Table H-1

Worst Case Discharge Calculation (Based on Blowout during Drilling Operations)

Calculations for Uncontrolled Blowout> 10 miles from shore: Blocks 859 & 903

i. Type of Oil (crude, condensate, diesel) Crude

ii. API Gravity 31.4 o

iii. EP Location Used for NTL No. 2010-N06 WCD for GC 859 & 903 SEP GC 859 well “J”

iv. Largest Anticipated WCD Rate during blowout 263,660 BOPD

v. WCD Total for Drilling Operations for GC 859 & 903 (> 10 miles from shore): 263,660 BOPDTable H-2

Trajectory by Land Segment

Following are the average conditional probabilities (expresse d as percent chance) that an oil spill starting at a particular launch area will contact a land segment as included in the BOEMRE Oil Spill Risk Analysis Model (OSRAM) for the Central Gulf of Mexico. This information can be found on the BOEMRE website using 3/10/30 day potential impact, as applicable. The results are listed below.

Area/Block OCS-G Launch
Area Land Segment and/or Resource Conditional Probability (%)

3 days 10 days 30 days

Green Canyon Blocks 859 & 903

Drilling (135 miles from shore) G24194
& 24197 LA 46

Central Planning

Area Matagorda County, TX Brazoria County, TX Galveston County, TX Jefferson County, TX Cameron Parish, LA Vermilion Parish, LA Lafourche Parish, LA Terrebonne Parish, LA Plaquemines Parish, LA --

--

--

--

--

--

--

--

-- --

--

--

--

--

--

--

--

-- 1
1
2
1
3
1
1
1
3Table H-3WCD Scenario Drilling Activities – Based on a singlewell uncontrolled blowout (135 miles from shore)Green Canyon Blocks 859 & 903263,660 BOPD (initial volume)224,111 BOPD (after evaporation/dispersion)API Gravity 31.4oOffshore Equipment from Spill Detection to Equipment Deployment Response Time: GreenCanyon Blocks 859 & 903Spill Team Area Responders (STARS) called out by Marine Spill Response Corporation (MSRC)Vessel of Opportunity=VOOEMS=Enterprise Marine ServicesK-Sea=K-Sea Operating PartnershipNearshore Equipment from Spill Detectionto Equipment Deployment Response Time: Green Canyon Blocks 859 & 903*Some equipment may be used offshoreup to approximately 25 miles from shoreH-3 (continued)

Operational Limitations of Response Equipment

 HOSS Barge–8 foot seas

 Fast Response Unit (FRU)–8 foot seas

 Oil Spill Response Vessel (OSRV and R/V)–4 foot seas

 Boom–3 foot seas, 20 knot winds

 Dispersants–winds more than 25 knots, visibility less than 3 nautical miles or ceiling less than 1,000 feet

### I Environmental Monitoring and Envi ronmental Mitigation Measures

(a) Monitoring

If required, Anadarko will monitor loop currents per NTL 2005-G05.

Anadarko subscribes to Wilkins Weather Service which provides real-time weather conditions such as tropical depressions, st orms and/or hurricanes entering the Gulf.

(b) Incidental Takes

Although marine mammals may be seen in the area, Anadarko does not believe that its operations proposed under this EP will result in the harassment, capture, collection or killing of any mammals covered by th e Marine Mammal Protection Act.

Anadarko will operate in accordance with applicable regulations, including:

NTL No. 2012-G02 – “Implementation of Se ismic Survey Mitigation Measures and Protected Species Observer Program”
BSEE NTL No. 2012-G01 “Marine Trash and De bris Awareness and Elimination”, and
JOINT NTL No. 2012-G01 “Vessel Strike A voidance and Injured/Dead Protected Species Reporting”

### J LEASE STIPULATIONS INFORMATION

Lease Sale # 182:

Military Area: Green Canyon Blocks 859 & 903 is located within Military Warning Area W-92. Anadarko will contact the Naval Air Station, Air Operations Department, New Orleans, Louisiana in order to coordinate and control the electromagnetic emissions during these proposed operations.

Marine Protected Species: Th is stipulation is meant to reduce the potential taking of marine protected species. Anadarko will ope rate in accordance with JOINT NTL 2012- G01 to minimize the risk of vessel strikes to protected species and will report observations of injured or dead protected species. Anadarko will operate in accordance with BSEE NTL 2012-G01 to preven t intentional and/or acciden tal introduction of debris
into the marine environment.

### K Support Vessels and Aircraft Information

(a) General

Type Max. Total Fuel Tank Storage Capacity Max. No. in Area at any Time Trip Frequency or Duration Supply Vessel 336,227 gallons 1 2 trips/week Helicopter 735.3 gallons 1 10 trips/week

Crew Vessel 50,000 gallons 1 3 trips/week Tug Boats N/A N/A N/A

(b) Diesel Oil Supply Vessels

Fuel for the rig will be transported via a supply vessel as follows:

a. Size of fuel supply vessel: 230 feet

b. Carrying capacity of fuel supply vessel: 336,227 gallons

c. Frequency that fuel supply vessel will visit the facilities: twice per week

d. Routes the fuel supply vessel will use to travel between the onshore support base and proposed facility: 6 miles from Port Fourchon to the mouth of Bayou Lafourche, then approximately 128 miles to GC 859 & 903.

(c) Vicinity Map

A vicinity map is included in this section as Attachment K-1.

(d) Produced Liquid Hydrocarbons Transportation Vessels

Produced liquid hydrocarbons from future flow tests on wells in Green Canyon Blocks 859 & 903 will be transported by barge. Anadarko will also flare a ma x volume of 30MMSCF/well total during the 48 hour flow test period. Flow test s will not exceed 48 hours/well without further approval.

Transport Method Vessel Capacity Average Volume to be Loaded (per transfer) No. of Transfers (Yearly Average) Barge 1/well

(e) Summary of Method to Transfer Liquid Hydrocarbons to the Transporting Vessel

Production from the wells will be rout ed through portable surface well test equipment and safety controls aboard the rig. Gas will be flared and liquids (oil & water) will be collected in US Coast Guard approved tanks and a barge. The wells will be produced / cleaned up and measured using various meters through portable surface well test equipment including a separator. A three phase separator will be used to analyze water cut if present. All liquids (hydrocarbons and water) will then be transferred to a coast guard approved barge via tested & approved petroleum transf er hose. We will have a Safe Breakaway Coupling (KLAW) installed between the hoses connecting the barge-end and the rig-end. If this device parts the KLAW is designed to contain all fluids from both hoses.(e) Solid and Liquid Wastes Transportation Type of
Waste Composition Total Projected Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or
mud Syntheticbased drilling
muds 156,000 bbls 13,000 bbls/well Re-use
and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility) or USLL (landfarm).

Cuttings
wetted withsyntheticbased muds Cuttings coated with synthetic drilling muds, including
drilled out

cement 3,900-7,800
bbls 325-650
bbls/well*

*An estimated 5-10% of cuttings may be transported to
shore Re-use and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility) or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 7,487 bbls
**

1,872 bbls** 100 bbls/month

25 bbls/month Transport to shore in
DOT approved
containers for pick up Chemwaste in Sulphur,
LA and Veolia Port Arthur, TX or to Newpark,
Port Arthur as nonhazardous waste. Can be returned to
vendor and/or used at another facility;
MEG is solidified and disposed of in
a landfill.
Methanol is
incinerated or used for fuels blending.

Completion
fluids Brine, spent acid, prop sand, debris 30,000
bbls** 3,000 bbls/well Transport to
shore in
DOT approved
containers
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand, debris 30,000
bbls** 3,000 bbls/well Transport to
shore in
DOT approved
containers
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.Trash and
debris Refuse generated during operations 3,777 bbls 50
bbls/month/well Transport to
shore in disposal bags by vessel to
shorebase for pickup by municipal operations Recycled Material in ARC, New Iberia, LA. Trash disposed of at
SWDI landfill. Recycled and/or disposed in
landfill.

Used oil Excess oil from engines 8,120 bbls 430 bbls/120 days/well Transport in
DOT approved
containers to
shore for pick up American Recovery Fourchon, LA Recycled

*Total amount assumes 12 wells with 2,266 Total No. of Days **This type of waste will not exist for the proposed GC 859 “J” and GC 903 “E” locations since only top-hole drilling for these wells will occur under this plan. This type of waste will only occur for the additional 10 well locations proposed in GC 859 and 903 sinc e these wells will be drilled to total depth and completed under this plan.Green Canyon Blocks 859 and 903October 2013Environmental Impact Analysis for Supplemental Exploration PlanPage 2Figure 1. Location of Green Canyon Blocks 859 and 903.

### L ONSHORE SUPPORT FACILITIES INFORMATION

(a) General

Per NTL No. 2008-G04, the following tables reflect the onshore facilities Anadarko may utilize to provide supplies and service support for the activities proposed in this EP.

Name Primary Location(s ) Existing/New/Modified
Anadarko Service Base Fourchon, Louisiana Existing Anadarko Service Base (Helicopter base) Houma, LA Existing

Name *Alternate Locations Existing/New/Modified
Anadarko Service Base Galveston, TX Existing
Anadarko Service Base Cameron, LA Existing
Anadarko Service Base Lake Charles, LA Existing
Anadarko Service Base Houma, LA Existing
Anadarko Service Base Pascagoula, MS** Existing *In the unlikely event Anadarko’s primary service base cannot be utilized Anadarko will exercise the use of an alternate service base during drilling and/or completion operations.

**Helicopter base only

(b) Support Base

No support base construction or expans ion is planned for these activities.

(c) Waste Disposal

Disposed wastes describe those wastes generated by the proposed activity that are disposed of by means other than by release into the water of the GOM at the site where they are generated. These wastes can be disposed of by offsite release, injection, encapsulation, or placement at either onshore or offshore permitted locations for th e purposes of returning them back to the
environment.

Type of
Waste Composition Total Projected Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or
mud Syntheticbased drilling
muds 156,000 bbls 13,000 bbls/well Re-use
and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility) or USLL (landfarm).Cuttings
wetted withsyntheticbased muds Cuttings coated with synthetic drilling muds, including
drilled out

cement 3,900-7,800
bbls 325-650
bbls/well*

*An estimated 5-10% of cuttings may be transported to
shore Re-use and/or transport to shore in
DOT approved
containers. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility) or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 7,487 bbls
**

1,872 bbls** 100 bbls/month

25 bbls/month Transport to shore in
DOT approved
containers for pick up Chemwaste in Sulphur,
LA and Veolia Port Arthur, TX or to Newpark,
Port Arthur as nonhazardous waste. Can be returned to
vendor and/or used at another facility;
MEG is solidified and disposed of in
a landfill.
Methanol is
incinerated or used for fuels blending.

Completion
fluids Brine, spent acid, prop sand, debris 30,000
bbls** 3,000 bbls/well Transport to
shore in
DOT approved
containers
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand, debris 30,000
bbls** 3,000 bbls/well Transport to
shore in
DOT approved
containers
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur. USLL
Galveston and Fourchon
Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Trash and
debris Refuse generated during operations 3,777 bbls 50
bbls/month/well Transport to shore in disposal bags by vessel to
shorebase for pickup by municipal operations Recycled Material in ARC, New Iberia, LA. Trash disposed of at
SWDI landfill. Recycled and/or disposed in
landfill.

Used oil Excess oil from engines 8,120 bbls 430 bbls/120 days/well Transport in
DOT approved
containers to
shore for pick up American Recovery Fourchon, LA Recycled

*Total amount assumes 12 wells with 2,266 Total No. of Days **This type of waste will not exist for the proposed GC 859 “J” and GC 903 “E” locations since only top-hole drilling for these wells will occur under this plan. This type of waste will only occur for the additional 10 well locations proposed in GC 859 and 903 sinc e these wells will be drilled to total depth and completed under this plan.

### M COASTAL ZONE MANAGEM ENT ACT INFORMATION

### TEXAS COASTAL MANAGEMENT PROGRAM

The following is an evaluation that includes findi ngs relating the coastal effects of the proposed
activities and associated facilities to the relevant enforceable policies of the Texas’ Coastal Management Program (TCMP), Title 31, Part 16, Chapter 501, Subchapter B :

(Category 2) Construction, Operation & Maintenance of Oil & Gas Exploration & Production
Facilities

No operations are proposed in or near any critical areas. The proposed activities are explorative in nature, so no facility construction is proposed. Th e proposed activities are located approximately 245 miles from the Texas shoreline; therefore we expect no adverse impacts to CNRAs or beach access and use rights of the public. All activities sh all be conducted in a manner that minimizes significant impacts to coastal resources. No adverse effects to Texas’ coastal area are expected in association with the proposed activities.

(Category 3) Discharges of Wastewater and Disposal of Waste from Oil and Gas Exploration and
Production Activities

No discharge of wastewater or disposal of waste from the proposed activities will occur in the Texas’ coastal zone; therefore no impact to Texas’ coastal waters is expected.

(Category 4) Construction and Operation of Solid Waste Treatment, Storage, and Disposal Facilities

No construction of solid waste facilities or expans ion of existing facilities in the coastal zone are proposed in the attached plan, therefore, no adver se effects on any features of Texas’ coastal cone are expected.

(Category 5) Prevention, Response, and Remediation of Oil Spills

The proposed activities will be covered under an approved Regional Oil Spill Response Plan. The plan is in place, practiced, and updated as n ecessary. The best practical techniques shall be utilized to prevent the release of pollutants or t oxic substances into the environment. All involved vessels and facilities are designed to be capable of prompt response and adequate removal of accidental discharges of oil. In addition, th e proposed activities are 245 miles from shore; therefore no damages to natural resources are exp ected as the result of an unauthorized discharge
of oil into coastal waters.

(Category 6) Discharge of Municipal and Industria l Waste Water to Coastal Waters

No discharges from the proposed activities will o ccur in coastal waters. The proposed activities are 245 miles from shore; therefore there will be no effect on coastal waters.(Category 8) Development in Critical Areas

None of the proposed activities will occur in a criti cal area; therefore no effects to Texas’ coastal zone are expected. The activity will not jeopardi ze the continued existence of species listed as endangered or threatened, and will not result in likelihood of the destruction or adverse
modification of a habitat determined to be a critical habitat under the Endangered Species Act. The activity will not cause or contribute to vi olation of any applicable surface water quality standards. The activity will not violate any requirement imposed to protect a marine sanctuary.

(Category 9) Construction of Waterfront Facilities and Other Structures on Submerged lands

No waterfront facilities or other structures are pr oposed on submerged lands in the Texas coastal zone, therefore the proposed activities are not expected to have any adverse impacts on submerged lands.

(Category 10) Dredging and Dredged Material Disposal and Placement

No dredging or disposal/placement of dredged ma terial is proposed; therefore no adverse effects to coastal waters, submerged lands, critical area s, coastal shore areas, or Gulf beaches are expected.

(Category 11) Construction in the Beach / Dune System

The proposed activities do not include any construction projects in critical dune areas or areas adjacent to or on Gulf beaches, therefore, no im pact to Texas’ beach or dune systems are expected.

(Category 15) Alteration of Coastal Historic Areas

The proposed activities do not include any alteration or disturbance of a coastal historic area; therefore, no impacts are expected to adversely affect any historical, architectural, or archaeological site in Texas’ coastal zone.

(Category 16) Transportation

The proposed activities do not include any transpor tation construction projects within the coastal zone; therefore, no impacts to Texas’ coastal zone are expected.

(Category 17)
Emission of Air Pollutants

The proposed activities shall be carried out in conformance with applicable air quality laws, standards, and regulations. Emissions from th e proposed activities are not expected to have significant impacts on onshore air quality becau se of the prevailing atmospheric conditions, emission heights, emission rates, and the dist ance of these emissions from the coastline. Theproposed activities will occur approximately 2 45 miles from shore and will be within the exemption limits set by BOEM, therefore, no im pacts to Texas’ coastal zone is expected.

(Category 18) Appropriations of Water

The proposed activities do not include the impoundment or diversion of state water, therefore, no impacts to Texas’ coastal zone is expected.

(Category 20) Marine Fishery Management

The proposed activities are located approximately 245 miles from shore and are not expected to have any effect on marine fishery management or fishery migratory patterns within waters in the
coastal zone of Texas.

(Category 22)
Administrative Policies

The necessary information for applicable agencies to make an informed decision on the proposed activities has been provided In conclusion, all activ ities shall be consistent with Texas’ coastal management program and shall comply with all relevant rules and regulations. No activities are planned within any critical areas. Activities will be carried out avoiding unnecessary conflicts with other uses of the vicinity.

### MISSISSIPPI COASTAL ZONE M ANAGEMENT ACT INFORMATION

As authorized by the Federal Coastal Zone Management Act (CZMA), The State of Mississippi developed a Coastal Management Pr ogram (CMP) to allow for the review of proposed Federal license and perm it activities affecting any coasta l use or resources, in or
outside of the Missi ssippi Coastal Zone.

The OCS related oil and gas exploratory a nd development activities having potential impact on the Mississippi Coastal Zone are based on the location of the proposed facilities, access to those sites, best practic al techniques for drilling locations, drilling equipment guidelines for the prevention of adverse environmental effects, effective environmental protection, emergenc y plans and contingency plans.

Below are goals identified by the State of Mississippi and our comments and/or corresponding cross references:

Goal 1: To provide for reaso nable industrial expansion in the coastal area and to ensure the efficient utilization of waterfront industrial sites so that suitable sites are conserved for water dependent industry.

The activities proposed in this plan are base d out of Fourchon, Louisi ana. The activities will not provide any industrial expansion on the coastal area of Mississippi. Therefore Mississippi coastal areas will be cons erved for water dependent industry.

Goal 2: To favor the preservation of the coastal wetlands and ecosystems, except where a specific alteration of specific coastal wetlands would serve a higher public interest in compliance with the public pur poses of the public trust in which the
coastal wetlands are held.

Goal 2 is addressed in Section N, Environm ental Impact Analysis. The nearest proposed
activities will be 210 miles from the Mississippi coast.

Goal 3: To protect, propagate and conserve the state’s seafood and aquatic life in connection with the revitalization of the se afood industry of the State of Mississippi.

Goal 3 is addressed in Section N, Environm ental Impact Analysis. Little impact to the seafood industry can be expected due to the activities occurring 210 miles from the Mississippi coast.

Goal 4: To conserve the air and waters of the state, and to protect, maintain and improve the quality thereof for public use, fo r the propagation of wildlife, fish and aquatic life, and for domestic, agricultu ral, industrial, recreational and other legitimate beneficial uses.

Goal 4 is addressed in Section B, Gene ral Information, Sectio n G, Air Emissions Information, and Section N, Environmental Impact Analysis.

### Goal 5: To put to be neficial use to the fullest extent of which they are capable the water resources of the state, and to prev ent the waste, unreasonable use, or unreasonable method of use of water.

The activities proposed in this plan are based in Fourchon, Louisiana. As such, Mississippi’s water resources should not be impacted by the proposed activities. Activities occurring at the sites in the OC S will be conducted in accordance with our Regional Oil Spill Response Plan refere nced in Section H of this plan.

Goal 6: To preserve the stat e’s historical and archaeological resources, to prevent their destruction, and to enhance these resources wherever possible.

Goal 6 is addressed in Section E, Biologica l, Physical and Socioeconomic Information, and Section N, Environmental Impact Analysis.

Goal 7: To encourage the preservation of na tural scenic qualities in the coastal area.

Goal 7 is addressed in Section F, Waste Discharges Information, Section H, Oil Spill Information, Section G, Air Emissions In formation, and Section N, Environmental Impact Analysis.

Goal 8: To assist local governments in the pr ovision of public facilities services in a manner consistent with the coastal program.

As the proposed activit ies are located 210 miles from the Mississippi coast and are based out of a shorebase in Fourchon, Louisiana, local governments should not be affected.

### N ENVIRONMENTAL IMPACT ANALYSIS

# Environmental Impact Analysis

SUPPLEMENTAL EXPLORATION PLAN

for Green Canyon Blocks 859 and 903 (OCS

- G 24197)

Offshore Louisiana

October 2013

Prepared for:

Jill Fowler Regulatory Analyst Anadarko Petroleum Corporation
1201 Lake Robbins Drive The Woodlands, Texas 77380

Telephone: (832) 636

- 1554

Prepared by:

CSA Ocean Sciences Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997 Telephone: (772) 219

- 3000Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page ii 

## Contents

Page



### Introduct ion

................................................................................................................ 1

A. Impact

- Producing Factors

....................................................................................... 5

A.1 Drilling Rig Presence (including noise and lights)

........................................................................... 5

A.2 Physical Disturbance to the Seafloor

.............................................................................................. 5

A.3 Air Pollutant Emissions

................................................................................................................... 8

A.4 Effluent Discharges

......................................................................................................................... 8

A.5 Water Intake

................................................................................................ ................................... 8

A.6 Onshore Waste Disposal

................................................................................................................. 9

A.7 Marine Debris

................................................................................................ ................................ . 9

A.8 Support Vessel and Helicopter Traffic

............................................................................................ 9

A.9 Accidents

................................................................................................ ........................................ 9

A.9.1 Types of Accidents Evaluated

............................................................................................. 9

A.9.2 Small Fuel Spill

.................................................................................................................. 10

A.9.3 Crude Oil Spill (Worst Case Discharge)

............................................................................. 11

A.9.4 Other Accidents Not Analyzed in Detail

............................................................................ 16



### B. Affected Environment

........................................................................................... 17

C. Impact Analysis

..................................................................................................... 17

C.1 Physical/Chemi cal Environment

................................................................................................... 17

C.1.1 Air Quality

......................................................................................................................... 17

C.1.2 Water Quality

.................................................................................................................... 20

C.2 Seafloor Habitats and Biota

.......................................................................................................... 22

C.2.1 Soft Bottom Benthic Communities

................................................................................... 23

C.2.2 High

- Density Deepwater Benthic Communities

............................................................... 25

C.2.3 Designated Topographic Features

.................................................................................... 27

C .2 .4 Pinnacle Trend Area Live Bottoms

.................................................................................... 28

C.2.5 Eastern Gulf Live Bottoms

................................................................................................ . 28

C.3 Threatened, Endangered, and Protected Species and Critical Habitat

........................................ 28

C.3.1 Sperm Whale (Endangered)

.............................................................................................. 30

C.3.2 West Indian Manatee (Endangered)

................................................................................. 34

C.3.3 Endangered Mysticete Whales

......................................................................................... 35

C.3.4 Non

- Endangered Marine Mammals (Protected)

.............................................................. 35

C.3.5 Sea Turtles (Endangered/Threatened)

............................................................................. 39

C.3.6 Piping Plover (Threatened)

............................................................................................... 42

C.3.7 Whooping Crane (Endangered)

........................................................................................ 44

C.3.8 Gulf Sturgeon (Threatened)

.............................................................................................. 45

C.3.9 Smalltooth Sawfish (Endangered)

..................................................................................... 45

C.3.10 Beach Mice (Endangered)

................................................................................................ . 46

C.3.11 Elkhorn Coral (Endangered)

.............................................................................................. 47

## Contents
(C ontinued)

Page

Green Canyon Bl ocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page iii C.4 Coastal and Marine Birds

.............................................................................................................. 47

C.4.1 Marine Birds

...................................................................................................................... 47

C.4.2 Shorebird s and Coastal Nesting Birds

............................................................................... 49

C.5 Fisheries Resources

...................................................................................................................... 51

C.5.1 Pelagic Communities and Ichthyoplankton

...................................................................... 51

C.5.2 Essential Fish Habitat

........................................................................................................ 53

C.6 Archae ological Resources

............................................................................................................. 56

C.6.1 Shipwreck Sites

................................................................................................................. 56

C.6.2 Prehistoric Archaeological Sites

........................................................................................ 57

C.7 Coastal Habitats and Protected Areas

.......................................................................................... 58

C.8 Socioeconomic and Other Resources

........................................................................................... 62

C.8.1 Recreational and Commercial Fishing

.............................................................................. 62

C.8.2 Public Health and Safety

................................................................................................... 64

C.8.3 Employment and Infrastructure

....................................................................................... 65

C.8.4 Recreation and Tourism

.................................................................................................... 66

C.8.5 Land Use

............................................................................................................................ 67

C.8.6 Other Marine Uses

............................................................................................................ 67



### D. Environmental Hazards

......................................................................................... 68

D.1 Geologic Hazards

.......................................................................................................................... 68

D.2 Severe Weather

............................................................................................................................ 68

D.3 Currents and Waves

..................................................................................................................... 68



### E. Alternatives

.......................................................................................................... 68

F. Mitigation Measures

............................................................................................. 68

G. Consultation

......................................................................................................... 69

H . Preparers

.............................................................................................................. 69

I. References

............................................................................................................. 69Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page iv 

## List of Tables

Table Page

1 Notices to Lessees and Operators (NTLs) applicable to this Envi ronmental Impact Analysis (EIA)

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

2 Matrix of impact

- producing factors and affected environmental resources

......................... 6

3 Conditional probabilities expressed as percent chance that an oil spill starting at Launch Point 3 will contact a certain parish, county, or coastline within 120 days (Modified from: BOEM, 2012b, Appendix C)

........................................................................ 13

4 Benthic community data from stations near the lease area and in similar water depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted from: Wei, 2006; Rowe and Kennicutt, 2009)

........... 23

5 Federally listed endangered and threatened species potentially occurring in the lease area and along the northern Gulf Coast

...................................................................... 29

6 W ildlife refuges, wilderness areas, and State and National parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEM, 2012b)

................................................................................................ ................................... 59



## List of Figures

Figure Page

1 Location of Green Canyon Blocks 859 and 903

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

2 Bathymetric map of the lease area showing the surface hole loca tions of the proposed wellsites

................................................................................................................ 18

3 Location of selected environmental feature s in relation to the lease area

......................... 43Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page v 

## Acronyms and Abbreviations

Anadarko Anadarko Petroleum Corporation

ADIOS 2 Automated Data Inquiry for Oil Spills 2
bbl barrel

BHL bottom hole location

BML below mud line

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Managem ent, Regulation and Enforcement

BOP blowout preventer

B.P. Before Present

BSEE Bureau of Safety and Environmental
Enforcement

CFR Code of Federal Regulations

CH 4 methane

CO carbon monoxide

CO 2 carbon dioxide

CGA Clean Gulf Associates

DP dynamic position ing

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

EP Exploration Plan

ESA Endangered Species Act

FAD fish

- attracting device

FR Federal Register Fugro Fugro Geoconsulting, Inc.

GC Green Canyon

GMFMC Gulf of Mexico Fishery Management
Council

GPS global positioning system

H 2 S hydrogen sulfide

HAPC Habitat Area of Particular Concern

HOSS high

- volume open sea skimmer

IPF impact

- producing factor

MARPOL International Convention for the Prevention of Pollution from Ships MMC Marine Mammal Commission

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MSRC Marine Spill Response Corporation

MWCC Marine Well Containment Company
NAAQS National Ambient Air Quality
Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric
Admi nistration

NO 2 nitrogen dioxide

NO x nitrogen oxides

NPD ES National Pollutant Discharge Elimination System

NPS National Park Service

NRDA Natural Resource Damage Assessment

NTL Notice to Lessee s and Operators

NWR National Wildlife Refuge

OBM oil

- based mud

OCS Outer Continental Shelf

OSAT Operational Scientific Advisory Team

OSRA Oil Spill Risk Analysis

OSRP Oil Spill Response Plan

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

SBM synthetic

- based mud

SHL surface hole location

SO x sulfur oxides

SWSS Sperm Whale Seismic Study

USCG U .S . Coast Guard

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

VOC volatile organic compound

WCD worst case dischargeGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 1 

## Introduction

Anadarko Petroleum Corporation ( Anadarko ) is submitting a Supplemental Exploration Plan ( EP) for Green Canyon (GC) Blocks 859 (GC 859) and 903 (GC 903). The EP includes 10 exploratory
well locations: GC 859

- F, GC 859

- G, GC 859

- H, GC 859

- I, GC 859

- FF, GC 859

- GG, GC 859

- HH

, GC 859

- II

, GC 903 -D , and GC 903

- DD . All surface hole locations (SHLs) and bottom hole locations (BHLs) will be located in GC 859 or GC 903. T his Environmental Impact Analysis (EIA) provides
information on the exploratory wells based on the SHLs.

Anadarko will also conduct top

- hole drilling on two additional wells with SHLs in GC 903 (EP
locations GC 859

- J and GC 903 -E)

. Waste discharges and air emissions associated with drilling these two wells to the final total depth

, as well as completion operations

, will be addressed in a future EP. The remaining drilling operations to total depth and completion operations will be conducted using a different drilling vessel to be discussed in the subsequent EP submittal. Only waste discharges and air emissions associated with the top

- hole drilling of GC 859

- J and GC 903

- E have been included in this plan.

The lease area is 13 5 miles ( 21 7 km) fr om the nearest shoreline

, 144 miles (232 km ) from the onshore support base at Port Fourchon, Louisiana, and 17 2 miles (27 7 km) from the helicopter
base at Houma, Louisiana ( Figure 1 ). Water depth s at the wellsites range from 5,2 68 to 5,355 ft (1,60 6 to 1,632 m ). The drilling rig is yet to be determined

, but will be either a dynamic positioning (DP) drillship or a DP semisubmersible rig. Drilling is expected to commence in early 2014 and be completed in mid 2020.

This EIA was prepared for submittal to the Bureau of Ocean Energy Management (BOEM) in accordance with applicable regulations, including 30 Code of Federal Regulations (CFR) 550.212(o) and 550.227 . The EIA is a project - and site

- specific analysis of Anadarko ’s planned activities under this EP. This EIA complies with guidance provided in existing Notices to Lessees and Operators (NTLs) issued by the former Minerals Management Service (MMS) and Bureau of Ocean Energy Management, Regulation and Enforcement ( BOEMRE ) , including

NTL 2008

- G04 and NTL 2013

- G02

. Potential impacts have been analyzed at a broader level in the Programmatic Environmental Impact Statement (EIS) for the Outer Continental Shelf (OCS) Oil and Gas Leasing Program (MMS, 2007a; BOEM

, 2012a) and in multi

- lease

- sale EISs for the
Western and Ce ntral Gulf of Mexico Planning Areas (MMS, 2007b; BOEM, 2012b). The analyses from these documents are incorporated here by reference.

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for evaluating oil spill risk during exploratory drilling. According to Holand (1997), the average frequency of a loss of well control incident or “ blowout ” during exp loratory drilling in the

U.S. Gulf of Mexico is 0.00593 blowouts per well drilled, or one blowout per 169 exploration wells drilled. Similarly, the MMS Safety and Environmental Management Program blowout incident rate for 1996 to 1999 was approximately fi ve blowouts per 1,000 well starts, or one blowout per 200 well starts (MMS, 2000). More recently, in its Final Supplemental EIS for the Central Gulf of Mexico Planning Area, BOEM confirmed that “ significant changes to the spill rates for the entire OCS are not anticipated ” (BOEM, 201 2b ).Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 2

Figure 1

. Location of Green Canyon Blocks 859 and 903

.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Suppleme ntal Exploration Plan Page 3 Historically, most blowouts have not resulted in oil spills. Of 151 well blowouts in the Gulf of Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills, with a total combined volume of 1,000 barrels (bbl) of crude oil and condensate released (MMS, 2000). Between 1964 and 1999, almost all offshore spills (94%) from drilling and production

- related operations on the OCS were less than or equal to 1 bbl in size (Anderson and LaBelle, 2000). According to the Bureau of Safety and Environmental Enforcement’s (BSEE’s) Final Drilling Safety Rule (75 Federal Register [FR] 63365) issued following the Macondo incident, the baseli ne risk of a catastrophic blowout is estimated to be about once every 26 years.

All the proposed activities and facilities discussed in this EP are covered by the Regional Oil Spill Response Plan (OSRP) last approved on 17 April 2013 for Anadarko and its subsidiaries, Anadarko U.S. Offshore Corporation, and Anadarko E&P Company L.P. (Company Numbers 00981, 02219, and 00148, respectively) in accordance with 30 CFR Part 254. The biennial update was submitted on 30 June 2013, and an amendment was submitted on 18 July 2013.

The OSRP details Anadarko’s plan to rapidly respond to and effectively manage oil spills that may result from drilling and production operations. Anadarko has designed its response program based on a regional capabili ty of response to spills

, ranging from small operational spills to a worst case discharge (WCD) from a well blowout. Anadarko’s spill response program meets the response planning requirements of the relevant coastal states and applicable Federal oil spill planning regulations and also includes information regarding Anadarko’s regional oil spill organization and dedicated response assets, potential spill risks, and local environmental sensitivities. The OSRP describes personnel and equipment mobilization, the incident management team organization, and an overview of actions and notifications to be taken in the event of a spill.

This EIA is organized into Sections A through I corresponding to the information required by

NTL 2008

- G04. The main impact

- related discussions are in Section A (Impact

- Producing Factors)
and Section C (Impact Analysis ). Table 1 lists and summarizes the NTLs applicable to this EIA.

Table 1. Notices to Lessees and Operators (NTLs) applicable to this Environmental Impact Analysis ( EIA ).

NTL Title Summary

2013- G02 Extension of Prior Notices to

Lessees Extends the effective date of NTL 2008- G04 (and two other NTLs) until the end of the 2013 calendar year

.

2012- N06 Guidance to Owners and Operators
of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans Provides clarification, guidance, and information for preparation of regional Oil Spill Response Plans. Recommends description of response strategy for worst case discharge (WCD) scenarios to ensure capability to respond to oil discharges is both efficient and effective.

2012- BSEE

- G01 Marine Trash and Debris
Awareness and Elimination Instructs operators to exercise caution in the handling and disposal of small items and packaging materials; requires the posting of placards at prominent locations on offshore vessels and structures; and mandates a yearly marine trash and debris awareness training and certification process.

2012- JOINT

- G01 Vessel Strike Avoidance and Injured/Dead Protected Species Reporting Recommends protected species identification gu ides be carried on all Gulf of Mexico petroleum vessels and that vessel operators and crews maintain a vigilant watch for
marine mammals . Vessels are to slow down or stop to avoid striking protected species, and operators are required to report sightings of any injured or dead protected species.Table 1. (Continued).

Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 4 NTL Title Summary

2011- JOINT

- G01 Revisions to the List of OCS Blocks Requiring Arch a eological Resource Surveys and Reports Provides new information of which Outer Continental Shelf (OCS) blocks require arch a eological surveys and re ports and required survey line spacing in each block. This NTL
augments NTL 2005

- G07.

2010- N10 Statement of Compliance with Applicable Regulations and
Evaluation of Information Demonstrating Adequate Spill Response and Well Containment

Resources Informs operators using subsea blowout preventers (BOPs) or surface BOPs on floating facilities that applications for well permits must include a statement signed by an authorized company official stating that the operator will conduct all activities in compliance with all applicable regulations, including the increased safety measures regulations (75 FR 63346). Informs operators that BOEM will be evaluating whether each operator has submitted adequate information demonstrating that it has access to and can deploy containment resources to promptly respond
to a blowout or other loss of well control.

2010- N06 Information Requirements for Exploration Plans, Development and Production Plans, and Development Operations
Coordination Documents on the

OCS Rescinds the limitations set forth in NTL 2008- G04 regarding a blowout scenario and worst case discharge scenario, and provides guidance regarding the information required in blowout scenario and worst case discharge scenario descriptions.

2009- G40 Deepwater Bent hic Communities Provides g uidance for avoiding and protecting high

- density deepwater benthic communities (including chemosynthetic and deepwater coral communities) from damage caused by

OCS oil and gas activities in water depths greater than 300 m (984 ft). Prescribes separation distances of 610 m (2,000 ft) from each mud and cuttings discharge location and 76 m (250 ft) from all other seafloor disturbances.

2009- G39 Biologically Sensitive Underwater
Features and Areas Provides g uidance for avoiding and protecting biologically sensitive features and areas (i.e., topographic features, pinnacles, low relief live bottom areas, and other potentially sensitive biological features) when conductin g OCS operations in water depths less than 300 m (984 ft) in the
Gulf of Mexico.

2009- G06 Military Warning and Water Test

Areas Provides contact links to individual command headquarters for the military warning and water test areas in the Gulf of

Mexico. Lease stipulations require lessees or designated
operators to enter into an agreement with the appropriate individual military command headquarters concerning the control of electromagnetic emissions and use of boats and aircraft in the applicable warning area or water test area before commencing such traffic.

2008- G04 Information Requirements for Exploration Plans and Development Operations Coordination

Documents Provides g uidance on the information requirements for OCS plans, including EIA requirements and information regarding compliance with the provisions of the Endangered Species
Act and Marine Mammal Protection Act.

2005- G07 Archaeological Resource Surveys and Reports Provides guidance on regulations regarding archaeological discoveries, specifies requirements for archaeological resource surveys and reports, and outlines options for protecting archaeological resources.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Suppleme ntal Exploration Plan Page 5 

## A. Impact

- Producing Factors

Table 2 is a matrix of impact

- producing factors (IPFs) and potentially affected environmental resources adapted from Form BOEM -0 142. An “X” indicates that an IPF could reasonably be expected to affect a certain resource, and a dash (

-- ) indicates no impact or negligible impact. Where there may be an effect, an analysis is provided in Section C

. Potential IPFs for the proposed activity are l isted below and briefly discussed in the following sections.

• Drilling rig presence (including noise and lights)

• Physical disturbance to the seafloor

• Air pollutant emissions

• Effluent discharges • Water intake

• Onshore waste disposal

• Marine debris

• S upport vessel and helicopter traffic

• Accidents



## A.1 Drilling Rig Presence (including noise and lights)

The wells proposed in this EP will be drilled using either a DP drillship or a DP semisubmersible rig. DP drillships and DP semisubmersible rig s use a global positioning system (GPS), specific computer software, and sensors in conjunction with and their own propellers and thrusters to maintain position. Essentially, through satellite navigation, the location of the vessel is precisely

monito red, and thrusters positioned at various locations about the vessel’s hull are activated to provide any required station

- keeping adjustment. This allows operations at sea where mooring or anchoring is not feasible.

The drilling rig for the well s proposed in this EP will be on site for an estimated total of 2, 266 days ( ranging from 92 to 140 days per well for drilling and completion ). Drilling the
top

- hole section s of GC 859

- J and GC 903

- E will take approximately 20 days total. The physical presence of th e drilling rig in the ocean can attract pelagic fishes and other marine life

, as discussed in Section C.5.1

.
Drilling operations produce noise that includes strong tonal components at low frequencies and

, in some cases

, infrasonic frequencies (MMS, 2000). Drilling noise from DP drillships and

DP semisubmersible rigs is not particularly intense and is strongest at low frequencies, averaging

10 to 500 Hz (Richardson et al., 1995). From a drilling rig , sound and vibration paths to the
water flow either throu gh the air or through the risers (MMS, 2000). Drilling rigs also maintain exterior lighting for navigational and aviation safety in accordance with applicable Federal safety regulations.



## A.2 Physical Disturbance to the Seafloor

In water depths of 600 m (1 ,969 ft) or greater, DP drillships and DP semisubmersible rigs d isturb only a very small area of the seafloor around the wellbore (SHL) where the bottom template and blowout preventer (BOP) are located. Depending on the specific well configuration, this area is generally about 0.25 ha (0.62 ac) (MMS, 2007a).Green Canyon Bloc ks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 6 Table 2. Matrix of impact

- producing factors and affected environmental resources. X = potential impact; dash (

-- ) = no impact or negligible impact.

Environmental Resources Impact

- producing F actors Drilling Rig Presence (incl. noise & lights) Physical Disturbance to Seafloor Air Pollutant Emissions Effluent Discharges Water Intake Onshore Waste Disposal Marine Debris Support Vessel/Helo

Traffic Accidents Small Fuel Spill Oil Spill (WCD) Physical/Chemical Environment Air quality and greenhouse gases

-- -- -- X ( 9 )

-- -- -- -- -- X (6) X (6) Water quality

-- -- -- X

-- -- -- -- X (6) X (6) Seafloor Habitats and Biota Soft bottom benthic communities

-- X

-- X

-- -- -- -- -- X (6) High

- density deepwater benthic communities

-- -- (4)

-- -- (4)

-- -- -- -- -- X (6) Designated topographic features

-- -- (1)

-- -- ( 1)

-- -- -- -- -- -- Pinnacle trend area live bottoms

-- -- (2)

-- -- (2)

-- -- -- -- -- -- Eastern Gulf live bottoms

-- -- (3)

-- -- (3)

-- -- -- -- -- -- Threatened, Endangered, and Protected Species and Critical Habitat Sperm whale (endangered) X (8 )

-- -- -- -- -- -- X (8) X (6,8) X (6,8) West Indian manatee (endangered)

-- -- -- -- -- -- -- X (8)

-- X (6,8) Endangered mysticete whale s

-- -- -- -- -- -- -- -- -- -- Non

- endangered marine mammals (protected) X

-- -- -- -- -- -- X X (6) X (6) Sea turtles (endangered/threatened) X (8)

-- -- -- -- -- -- X (8) X (6,8) X (6,8) Piping Plover (threatened)

-- -- -- -- -- -- -- -- -- X (6) Whooping Crane (endangered)

-- -- -- -- -- -- -- -- -- X (6) Gulf sturgeon (threatened)

-- -- -- -- -- -- -- -- -- X (6) Smalltooth sawfish (endangered)

-- -- -- -- -- -- -- -- -- X (6) Beach mice (endangered)

-- -- -- -- -- -- -- - - -- X (6) Elkhorn coral (endangered)

-- -- -- -- -- -- -- -- -- X (6) Coastal and Marine Birds

Marine birds X

-- -- -- -- -- -- X X (6) X (6) Shorebird s and coastal nesting birds

-- -- -- -- -- -- -- X

-- X (6) Fisheries Resources Pelagic communities and ichthyoplankton X

-- -- X X

-- -- -- X (6) X (6) Essential Fish Habitat X

-- -- X X

-- -- -- X (6) X (6) Archaeological Resources Shipwreck sites

-- -- (7)

-- -- -- -- -- -- -- X (6) Prehistoric archaeological sites

-- -- (7)

-- -- -- -- -- -- -- X (6) Coastal Habitats and Protected Areas

Beaches

-- -- -- -- -- -- -- -- -- X (6) Wetlands and seagrass beds

-- -- -- -- -- -- -- -- -- X (6) Coastal wildlife refuges and wilderness areas

-- -- -- -- -- -- -- -- -- X (6) Socioeconomic and Other Resources

Recreational and commercial fishing X

-- -- -- -- -- -- -- X (6) X (6) Public health and safety

-- -- -- -- -- -- -- -- -- X (6) Employment and infrastructure

-- -- -- -- -- -- -- -- -- X (6) Recreation and tourism

-- -- -- -- -- -- -- -- -- X (6) Land use

-- -- -- -- -- -- -- -- -- X (6) Other marine uses

-- -- -- -- -- -- -- -- -- X (6)

WCD = worst case discharge.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 7 Table 2 Footnotes and Applicability: (1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any anchors will be on the seafloor within the following: (a) 4- mi le zone of the Flower Garden Banks, or the 3

- mi le zone of Stetson Bank; (b) 1,000

- m, 1

- mi le , or 3

- mi le zone of any topographic feature (submarine bank) protected by the Topographic Features Stipulation attached to an Outer Continental Shelf (OCS) lease; (c) Essential Fish Habitat (EFH) criteria of 500 ft from any no

- activity zone; or (d) Proximity of any submarine bank (500

- ft buffer zone) with relief greater than 2 m that is not protected by the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or

no

- activity zone. There are no submarine banks in the blocks.

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom (Pinnacle Trend) Stipulation attached to an OCS lease.

• The Live Bottom (Pinnacle Trend) Stipulation is not applicable to the lease area.

(3) Activities within any Eastern Gulf OCS block where seafloor habitats are protected by the Live Bottom (Low

- Relief) Stipulation attached to an OCS leas e.

• The Live Bottom (Low

- Relief) Stipulation is not applicable to the lease area.

(4) Activities on blocks designated by the BOEM as being in water depths 4 00 m or greater.

• No impacts on high

- density deepwater benthic communities are anticipated. There ar e no features indicative of high

- density chemosynthetic communities or coral communities within 610 m (2,000 ft) of any drilling mud/cuttings discharge location.

(5) Exploration or production activities where H 2 S concentrations greater than 500 ppm might be encountered.

• Green Canyon Blocks 859 and 903 were classified as H 2 S absent under the Initial Exploration Plan.

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you determine would impact these environmental resources. If the proposed action is located a sufficient distance from a resource that no impact would occur, the EIA can note that in a sentence or two.

• Accidental hydrocarbon spills could af fect the resources marked (X) in the matrix, and impacts are analyzed in Section C

. (7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated by the BOEM as having high

- probability for the occurrence of shipwrecks or prehistoric sites, including such blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would occur, the EIA can note that in a sentence or two.

• No impacts on archaeological resources are expected . The lease area is not on the list of archaeology survey blocks (BOEM, 2012c) and is well beyond the 6 0- m depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. T he site clearance

surveys detected no man

- made features within 610 m ( 2,000 ft) of any of the proposed wellsites . A dynamic positioning ( DP ) drillship or DP semisubmersible rig will be used; therefore, seafloor disturbances due to anchoring will not occur.

(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals
or sea turtles or their critical ha bitats.

• I mpact

- producing factors (I PFs ) that may affect marine mammals, sea turtles, or their critical habitats include drilling rig presence, support vessel and helicopter traffic, and accidents. See Section C

. (9) Production activities that involve transportation of produced fluids to shore using shuttle tankers or barges.

• Not applicable.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 8 

## A.3 Air Pollutant Emissions

Air pollutant emissions are calculated in EP Section G and are estimated to be insignificant. Offshore air pollutant emissions will result from drilling rig operations , as well as service vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. The combustion
of fuels occurs on diesel

- powered generators, pumps, or motors and from lighter fuel motors.

Prim ary air pollutants typically associated with OCS activities are suspended particulate matter (PM), sulfur oxides (SO
x ), nitrogen oxides (NO
x ), volatile organic compounds (VOCs), and carbon monoxide (CO).

The Air Quality Emissions Report prepared in accorda nce with BOEM requirements
demonstrates that the projected emissions are below exemption levels set by the applicable regulations in 30 CFR 250.303 . Based on this and the lease area’s distance from shore, it can be
concluded that the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required.



## A.4 Effluent Discharges

Effluent discharges are summarized in EP Section F

. All offshore discharges will be in
accordance with requirements of the National Pollutant Discharge Elimination System (NPDES)
General Permit No. GMG 290000 issued by the U.S. Environmental Protection Agency ( USEPA )

. Any d ischarges will be in compliance with the permit terms and monitored as required by the permit.

Water

- based drilling muds and cuttings will be released at the seafloor during the initial well
intervals before the marine riser that allows their return to the surface is set. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Synthetic

- based drilling muds (SBMs) will be collected on the rig and either reused by the vendor, or transported to Port Fourcho n , Louisiana

, for recycling and/or disposal at an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit.

Other effluent discharges in accordance with the NPDES permit will include excess cement

,
n on

- contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, uncontaminated freshwater and seawater, and ballast water.



## A.5 Water Intake

Seawater will be drawn from the ocean for once

- through, non

- contact cooli ng of machinery on the drilling rig. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impact from impingement and entrainment of aquatic organisms. The current NPDES General P ermit No. GMG 290000 does not specify requirements for existing facilities (those that started construction before

16 July 2006)

. The drilling vessel ultimately selected for this project will be in compliance with all cooling water intake structure requirements.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 9 

## A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Section F

. A total of a pproximately 3,777 bbl of trash will be generated over the life of this project. The trash will be transported in disposal bags to shore where it will be picked up by municipal operators for final disposal in accordance with applicable regulations

.


## A.7 Marine Debris

Anadarko will comply with a ll regulations relating to solid wastes handling and disposal, including the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V requirements and USEPA and U.S. Coast Guard ( USCG ) regulations, as
well as those of the BOEM

. For example, BOEM regulations at 30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately discharging containers and other similar materials (i.e., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable identification markings on equipment, tools

, and containers (especially drums), and other
material. USEPA and USCG regulations require operators to become proactive in avoiding accidental loss of solid waste items by developing waste management plans, pos ting informational placards, manifesting trash sent to shore, and using special precautions such as covering outside trash bins to prevent accidental loss of solid waste. In addition to the regulations in 30 CFR 250

, BSEE issued NTL 2012

- BSEE -G01, which i nstructs operators to exercise caution in the handling and disposal of small items and packaging materials, requires the posting of placards at prominent locations on offshore vessels and structures, and mandates a yearly marine trash and debris awareness training and certification process.



## A.8 Support Vessel and Helicopter Traffic

Anadarko will use existing shorebase facilities at Port Fourchon, Louisiana

, for onshore support for vessel activities. Air transportation (helicopters) will be based at facilities in Houma, Louisiana.

No terminal expansion or construction is planned at either location

.
The project will be supported by one crew boat and one supply vessel . The crew boat will make
three round trips per week, and the supply vessel will make two round trips per week. The boats typically will move to the project area via the most direct route from the shorebase.

A helicopter will make an estimated 10 round trips per week between the drilling vessel and the heliport. The helicopter will be used to transport personnel and small supplies and will normally
take the most direct route of travel between the shorebase and the lease area when air traffic and weather conditions permit. Helicopters typically maintain a minimum altitude of 213 m (700 ft) whi le in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines,
and 610 m (2,000 ft) over populated areas and sensitive habitats

, such as wildlife refuges and park properties. Additional guidelines and regulations specify that helico pters maintain an
altitude of 305 m ( 1,000 ft) within 91 m ( 300 ft) of marine mammals (BOEM, 2012 d ).



## A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential accidents:

• a small fuel spill, which is the most likely type of spill during OCS exploration activities; and

• t he WCD for this EP, which is an oil spill resulting from an uncontrolled blowout.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 10 The following subsections summarize assumptions about the size s and fate s of these spills, as
well as Anadarko’ s spill response plans. Impacts are analyzed in Section C

.

MMS ( 2007b) and BOEM (2012 b ) analyze d three other types of accidents: chemical spills, vessel collisions, and loss of well control. These types of accidents are discussed briefly in
Section A.9.4

.



### A.9.2 Small Fuel Spill

Spill Size . According to the analys e s in MMS (2007b ) and BOEM (201 2a ), the most likely type of small spill (<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills have been < 1 bbl, and this size is predicted to be the most common in ongoing and
future OCS activities in the Western and Central Gulf of Mexico Planning Areas. As the spill size increases, the incident rate declines dramatically (MMS, 2007b; BOEMRE, 2011a; BOEM, 201 2b ).
The median size for spills < 1 bbl is 0.0 24 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl ( BOEM, 2012a ). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate

. The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as the effectiveness of spill response activities. However, g iven the open ocean location of the lease area and response actions, it is expected
that impacts from a small spill would be minimal ( BOEMRE, 2011a; BOEM, 201 2b).

The water

- soluble fractions of diesel are dominated by two - and three

- ringed polycyclic aromatic hydrocarbons (PAH s ), which are moderately volatile (National Research Council,

2003 a ). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Due to its light density, diesel will not sink to
the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coa stal areas with high suspended solids loads (National Research Council, 2003 a ) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring micr obes ( National Oceanic and Atmospheric Administration [ NOAA ] , 2006).

For purposes of this EIA, t he fate of a small diesel fuel spill was estimated using NOA A’s Automated Data Inquiry for Oil Spills 2 (ADIOS2) model. This model uses the physical properties of oils in its database to predict the rate of evaporation and dispersion over time, as well as changes in the density, viscosity, and water content of the product spilled. I t is estimated that over 90% of a small diesel spill would be evaporated or disp ersed within 24 hours. The sea
surface area with diesel fuel on it during this 24

- hour period would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

The ADIOS2 results, coupled with spill trajectory information discusse d below for a large spill,
indicate that a small fuel spill would not have any impacts on coastal or shoreline resources.
The lease area is 13 5 miles (21 7 km) from the nearest shoreline. Modeling results discussed below indicate that a spill in the lease area w ould have a 4% or less probability of reaching the
coastal areas of Louisiana within 10 days after a spill

. By that time, essentially 100% of a small fuel spill would have been dispersed or evaporated by natural processes, without taking into
account Anadarko ’s response measures. Slicks from spills are expected to persist for relatively short periods of time ranging f rom minutes (<1 bbl) to hours (<10 bbl) to a few days (10 t o 1,000 bbl) and rapidly spread out, evaporate and disperse into the water columnGreen Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 11 (BOEM, 2012b). Because of the distance of these potential spills on the OCS and the ir lack of persistence, it is u nlikely that a spill would make landfall prior to dissipation (BOEM, 2012b).

Spill Response . In the unlikely event the shipboard prevention procedures fail to prevent a fuel spill, response equipment and trained personnel would be activated so that any sp ill effects would be localized and would result only in short

- term environmental consequences.

EP Section 9b provides a detailed discussion of Anadarko’ s response to a spill.



### A.9.3 Crude Oil Spill (Worst Case Discharge)

Spill Size

. Anadarko prepared this blowout scenario pursuant to guidance provided in

NTL 2010

- N06. GC 859 -J is addressed in this blowout scenario since it is the location with the highest potential WCD rate for Green Canyon Blocks 859 and 903. A similar approach would be
taken in the event of a blowout for the other wells ites in GC 859 and 903. Based on

NTL 2010

- N06 guidance, the maximum hydrocarbon dischar ge for GC 859 and 903 is calculated to be 263,660 bbl of oil per day

.
Time taken to mobilize a rig and drill a relief well

. An e stimated 7 to 21 days is required to

suspe nd operations on a deepwater Gulf of Mexico well and begin drilling the relief well. This

assumes 0 to 14 days to suspend current operations on an existing well and 7 days to mobilize and be ready to spud the reli ef well. The estimated time to drill the relief well is 100 days

, which includes 20 days for additional directional work

, for a total estimated time of 107 to
121 days from time of blowout to finishing the relief well. The drilling days were based on the proposed days to drill GC 859 -J through the objective sand s (interval of WCD)

, with additional time added for ranging.

The maximum total volume during a blowout could potentially be 31,902,860 bbl assuming

121 days for the maximum duration of a blowout, m ultiplied by the worst case daily uncontrolled blowout volume of 263,660 bbl. The detailed analysis of this calculation can be
found in EP Section H

.
Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a p robability of 0.0021 for a deep drilling blowout during exploration drilling based on U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per exploratory well for non

- North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEM is in the process of updating these spill fre quency estimates to include the Macondo event; however, significant changes to the spill rates for the entire OCS are not anticipated ( BOEMRE, 2011 a ; BOEM, 2012 d ). As noted in the Introduction , the baseline risk of a catastrophic blowout is
estimated to b e once every 26 years ( BSEE Final Drilling Safety Rule, 75 FR 63365).

Included in EP Section H are Anadarko’s calculations and information as required by

NTL 2010

- N06, including descriptions of measures to prevent a blowout, reduce the likelihood of
a blow out, and conduct effective and early intervention in the event of a blowout. Anadarko will also comply with NTL 2010 -N 10 and the Final Drilling Safety Rule, which specif ies additional safety measures for OCS activities.

Spill Trajectory

. The fate of a large oil spill in the lease area would depend on meteorological and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a computer simulation of oil spill transport that uses realistic data for winds and curren ts toGreen Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 12 predict spill fate. Although this model has received some criticism (Earthjustice, 2011), it is still the most widely scientifically accepted model for estimating the fate of small fuel spills. The primary criticism of the OSRA model results as pro vided in Ji et al. (2004) was that the model did not evaluate the fate of a spill over time periods longer than 30 days, nor d id it predict the fate
of a release continu ing over a period of weeks or months, as in the Macondo incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill size

, but has generally been used by the

BOEM to evaluate contact probabilities for spills greater than 1,000 bbl.

To address this criticism

, a special OSRA run was conducted for the recent BOEM Western and
Central Gulf of Mexico Planning Area Supplemental EIS s ( BOEMRE

, 2011 a ; BOEM, 2012 b ) in order to estimate the impacts of a possible future catastrophic long

- duration oil spill. In this
OSRA model run

, a hypothetical high

- volume, long

- duration oil spill was assumed to have occurred, and the analysis emphasized modeling a spill that continued for 90 consecutive days, with each traject ory tracked for up to 120 days.

The OSRA model run for this revised analysis was conducted for five hypothetical launch points
in the Central a nd Western Gulf o f Mexico Planning Areas

. These launch point s were deliberately located in area s identified as having a high possibility of containing large oil

reserves.

The five launch point areas were as follows:

1. Central Gulf of Mexico shelf are a west of the Mississip pi River (28.98660° N latitude,

92.17851 ° W longitude);

2. Central Gulf of Mexico shelf area east of the Mississippi River ( 29.91388 ° N latitude,

88.15338 ° W longitude);

3. Central Gulf of Mexico slope area ( 27.31998 ° N latitude, 90.22203 ° W longitude);

4. Western Gulf of Mexico shelf area ( 27.55423 ° N latitude, 96.76627 ° W longitude); and

5. We stern Gulf of Mexico slope area ( 27.51367 ° N latitude, 94.51836 ° W longitude).

The results for Launch Point 3 , the launch point nearest to the project area, are presented in
Table 3

.
OSRA is a preliminary risk assessment model. In the event of an actual oil spill, real

- time monitoring and trajectory modeling would be conducted using current and wind data available from the rigs and permanent production structures in the area

. Satellite and aerial monitoring

o f the plume and real

- time trajectory modeling using wind and current data would continue on a daily basis to help position equipment and human resources throughout the duration of any major spill or uncontrolled release

.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 13 Table 3. Conditional probabilities expressed as percent chance that an oil spill starting at
Launch Point 3 will contact a certain parish, county, or coastline within 120 d ays (Modified from: BOEM, 201 2b , Appendix C).

Season Winter Spring Summer Fall

Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120 County or Parish , State Percent Chance
Cameron, TX

-- -- -- 2

-- -- -- -- -- -- -- 2

-- -- -- 2 Willacy, TX

-- -- -- 3

-- -- -- -- -- -- -- 2

-- -- -- 3 Kenedy, TX

-- -- -- 8

-- -- -- 1

-- -- -- 9

-- -- -- 5 Kleberg, TX

-- -- 1 6

-- -- -- -- -- -- -- 4

-- -- 1 6
Nueces, TX

-- -- 1 6

-- -- -- -- -- -- -- 2

-- -- 1 2
Aransas, TX

-- -- -- 5

-- -- -- 1

-- -- -- 3

-- -- -- 2 Calhoun, TX

-- -- 1 6

-- -- -- -- -- -- -- 6

-- -- 1 4 Matagorda, TX

-- -- 2 17

-- -- 3 4

-- -- -- 11

-- -- 1 6
Brazoria, TX

-- -- 3 12

-- -- 1 3

-- -- 2 8

-- -- 1 5 Galveston, TX

-- -- 3 10

-- -- 3 6

-- -- 2 5

-- -- 1 4 Jefferson, TX

-- -- 1 4

-- -- 7 9

-- -- 1 1

-- -- -- 2
Cameron, TX

-- -- 1 4

-- -- 11 12

-- 1 1 4

-- -- -- 4 Vermilion, LA

-- -- 1 2

-- -- 5 6

-- 1 1 2

-- -- -- -- Iberia, LA

-- -- -- 1

-- -- 4 4

-- -- -- -- -- -- -- -- Terrebonne, LA

-- 1 2 3

-- 4 12 14

-- -- -- 2

-- -- -- -- Lafourche, LA

-- -- 1 1

-- 2 8 10

-- -- 1 2

-- -- -- -- Jefferson, LA

-- -- -- 1

-- -- 2 2

-- -- 1 1

-- -- -- -- Plaquemines, LA

-- -- -- 1

-- 2 10 12

-- -- 1 2

-- -- -- -- Jackson, MS

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Baldwin, AL

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Bay, FL

-- -- -- -- -- -- -- 1

-- -- -- -- -- -- -- -- Franklin, FL

-- -- -- 1

-- -- -- -- -- -- -- -- -- -- -- -- Monroe, FL

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- 1

Miami

- Dade, FL

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- --
“—“ = Values < 1.0% . A reas where there is <0.5% chance of contact within 120 days are not shown.

Weathering . Following an oil spill, several physical, chemical, and biological processes, collectively called weathering, interact to change the physical and chemical properties of the oil, influencing potential effects to marine organisms and ecosystems. The most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water

- in

- oil emulsions, photochemical oxidation, microbial degradation, adsorpt ion to suspended particulate matter, and stranding on shore or sedimentation to the seafloor (National Research Council, 2003 a ).

Weathering decreases the concentration of oil and produces changes in its chemical composition, physical properties, and toxicity. The more toxic, light aromatic and aliphatic hydrocarbons are lost rapidly by evaporation and dissolution from a slick on the water surface. Evaporated hydrocarbons are degraded rapidly by sunlight. Biodegradation of oil on the water surface and in the water column by marine bacteria removes first the n

- alkanes and then the light aromatics from the oil. Other petroleum components are biodegraded more slowly.
Photo

- oxidation attacks mainly the medium and high molecular weight PAHs i n the oil on the
water surface.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 14 Spill Response

. BOEM has issued re c ent NTLs following the Macondo spill that clarify additional
oil

- spill prevention and response planning requirements. These NTL s are summarized in Table 2

, and additional BOEM (2012 b) guidance is provided below.

NTL 2012

- N06 – Guidance to Owners and Operators of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans : This NTL, effective 10 August 2012, provides clarification, guidance, and information on the preparation and submittal of regional OSRPs for owners and operators of oil handling, storage, or transportation facilities, inclusive of pipelines, located seaward of the coastline. It states that lessees, designated operators, and pipeline right

- of

- way holders are responsible for preparation and submission of these plans. Some of the clarifications and recommended practices in the NTL are based
on lessons learne d from the Macondo oil spill response.

NTL 2010

- N10 – Statement of Compliance with Applicable Regulations and Evaluation of Information Demonstrating Adequate Spill Response and Well Containment Resources : This NTL, effective 8 November 2010, applies only to operators conducting operations using subsea or surface BOPs on floating facilities. It requires that lessees and operators must submit a statement signed by an authorized company official with each well permit application indicating that they will conduct all of their authorized activities in compliance with all applicable regulations, including the Increased Safety Measures Regulations at

75 FR 63346. The NTL also informs lessees that BOEMRE will evaluat e whether the operator has submitted adequat e information demonstrating that it has access to and can deploy surface and subsea containment resources that would be adequate to promptly respond to a blowout or other loss of well control. The NTL notifies the operator that BOEMRE intends to evaluate the adequacy of each operator to comply in the operator’s current OSRP; therefore, there is an incentive for voluntary compliance.

NTL 2010

- N06

– Information Requirements for Exploration Plans, Development and Production Plans, and Development Operations Coordination Documents on the OCS : This NTL, effective 18 June 2010, explains the procedures for the lessee or operator to submit supplemental information for new or previously submitted EPs, Development and
Production Plans , or D evelopment O perations C oor dination D ocument s. The required supplemental information includes the following: ( 1) a description of the blowout scenario as required by 30 CFR 254(b) and 254(h) ; ( 2) a description of their assumptions and calculations used in determining the volume of the WCD required by 30 CFR 254.26 ; and ( 3) a description of the measures proposed that would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early intervention in the event of a blowout, includi ng the arrangements for drilling relief wells and any other measures proposed. The early intervention methods of the third requirement could actually include the surface and subsea containment resourc es that
BOEM announced in NTL 2010

- N10, which states th at BOEM will review to ensure that the measures are adequate to promptly respond to a blowout or other loss of well control.

Anadarko ’s Regional OSRP was last approved on 17 April 2013

. The biennial update was
submitted on 30 June 2013, and an amendment was submitted on 18 July 2013. The OSRP provides a detailed plan for Anadarko to rapidly respond to and effectively manage oil spills that may result from drilling and production operations. The OSRP co ntains detailed information on “Quick Response” proc edures

, including:Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 15 • responsibilities of all Anadarko and contract personnel to report any observed discharge from known or unknown sources;

• procedures to locate and determi ne the size of a discharge; and

• contact information for alerting the spill management team

, complete with names, phone numbers, and locations.

In the event of a WCD, Anadarko has access to surface and subsea response/containment capabilities that could be implemented through various organizations under contract

. Anadarko’s primary spill response equipment provider is Clean Gulf Associates (CGA).

CGA has four skimming vessels capable of operating in shallow waters and offshore/nearshore

areas. These vessels have o leophilic brush pack skimming systems operating in troughs built
into the hulls

, below

- deck storage

, and marine electronics packages that includ e marine, aircraft and company

- frequency radios ; radar ; moving map plotters ; GPS; satellite phone s; and depth
finders. CGA also offers nine fast

- response systems staged throughout the G ulf of Mex ico
available for offshore use.

The CGA high

- volume open sea skimmer ( HOSS ) barge consists of a skimming system built into an oil recovery barge. There are four 1,000

- bbl recovered oil storage tanks built into the hull where oil can be separated and offloaded. Skimming operations are conducted from the control room overlooking the skimmer deck. The estimated daily recovery capacity for the HOS S barge is approximately 43,000 bbl

.
CGA is currently adding to its equipment stockpile and has acquire d 11 sets of Koseq skimming arms and two Aqua Guard skimmers. In addition, an x

- band radar/infrared tracking system is installed on the HOSS barge. Additional CGA equipment can be referenced on the ir website at http://www.cleangulfassoc.com/

.

Anadarko also has a contract with the Marine Spill Response Corporation (MSRC) for additional spill response equipment. MSRC has a dedicated fleet for the Atlantic/ Gulf of Mexico region and additional available equipment staged throughout the U

. S. MSRC equipment in the Gulf of
Mexico includes seven oil spill response vessels, two fast

- response vessels, five oil spill response barges, five platform supply vessels, and 15 shallow water barges. Various equipment is
outfitte d with x

- band and infrared technology.

MSRC recently completed a large expansion of its resources and capability in the Gulf of Mexico,
with a particular focus on deepwater. The expansion is known as “ Deep Blue. ” Additional MSRC capabilities and a comple te equipment listing are available on their website at http://www.msrc.org/

.

Anadarko is also a member of the Marine Well Containment Company (MWCC). In the event of an incident, MWCC can provide a 15,000

- psi single ram capping stack and dispersant injection capability. MWCC can also install and operate the interim containment system, including subsea flowlines, manifold, and risers. The interim system is engineered to be used in depths up to 3,048 m (10,000 ft) and has the capacity to contain 60,000 barrels of liquid per day (and 120 million standard cubic feet per day of gas) with potential for expansion.

See EP Section H f or a detailed description of Anadarko ’s site

- specific response to the WCD for this plan.Green Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 16 

### A.9.4 Other Accidents Not Analyzed in Detail

BOEM (2012b) discusses three other types of accidents: chemical spills, vessel collisions, and
loss of well control. The information from the EIS on these topics remains valid and is incorporated by reference into th is document. These accidents are discussed briefly below along with a hydrogen sulfide ( H 2 S) release . T here are no other site

- specific issues for the drilling of the well s proposed in this EP.

Chemical Spills

. Chemicals are stored and used to condition drillling muds and during production and in well completions, stimulation, and workover procedures. The relative quantity of their use is reflected in the largest volumes spilled. Completion fluids are the largest quantity used and comprise the largest r eleases. Between 5 and 15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The most common chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production chemicals are needed in deepwater operations where gas hydrates tend to form. Spill volumes are anticipated to remain about the same, but spill frequency can be expected to decrease because of advances in subsea processing ( BOEMRE, 2011 a ; BOEM, 2012 b).

Riser Disconnect SBM Spills

. In deepwater drilling, SBMs a re preferred over petroleum oil

- based muds (OBMs) due to the superior environmental properties of SBMs

. The synthetic base fluid s used in SBMs are less toxic to the marine environment and have the potential to biodegrade.

S BMs have been used in the Gulf of Mexico since the mid

- 1990 s , and between 5 and 20 SBM releases are anticipated each year as a result of offshore drilling programs. The majority of these releases are <50 bbl in size, but accidental riser disconnects may r esult in the release of medium (238 to 2,380 bbl) to large (>2,38 0 bbl) quantities of dril ling fluids. Riser disconnect accidents are of particular concern when SBM s are in use ( BOEMRE , 201 1b ).

Vessel Collisions

. BOEM data show that from 1996 to 2009 the re were 226 OCS

- related
collisions. Most collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline risers. Approximately 10 % of vessel collisions with platforms in
the OCS resulted in diesel spills , a nd in several collision incidents , f ires resulted from hydrocarbon releases. To date, the largest diesel spill associated with a collision occurred in
1979 when an anchor

- handling boat collided with a drilling platform in the Main Pass leas e area, spillin g 1,500 bbl. Diesel fuel is the product most frequently spilled

, but oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result of vessel
collision s

. Human error account ed for approximately half of all reported vessel collisions from

2006 to 2009. As summarized in MMS (2007b ) and BOEM (201 2b ), vessel collisions occasionally occur during routine operations. Some of these collisions have caused spills of diesel fuel or
chem icals. Anadarko will comply with all USCG and BOEM mandated safety requirements to minimize the potential for vessel collisions.

Loss of Well Control . A loss of well control is the uncontrolled flow of a reservoir fluid that may
result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is a broad term that includes very minor up to the most serious well control incidents, while blowouts are considered to be a subset of more serious incidents with greater risk of oil spill or human injury (MMS, 2007b). Loss of well control may result in the release of synthetic drilling
fluid or loss of oil. Anadarko has a robust system in place to prevent loss of well control.

M easures to prevent a blowout

, reduce the likeliho od of a blowout, and conduct effective and early intervention in the event of a blowout are described in the NTL 2010

- 06 packageGreen Canyon Blo ck s 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 17 submitted with the exploration plan, as required

. The potential for a loss

- of

- well

- control event will be minimized by adhering to the requirements of applicable regulations such as the Final Drilling Safety Rule and NTL 2010

- N10 , which specify additional safe ty measures for

OCS activities.

H 2 S Release

. GC 859 and GC 903 were classified as H 2 S absent under the Initial EP.



## B. Af fected Environment

Based on the site clearance survey conducted by Fugro Geoconsulting, Inc. (Fugro)

, water depth s at the wellsites are anticipated to range from 1,60 6 to 1,632 m ( 5, 2 68 to 5,355 ft ) ( Figure 2 ). The seafloor at the proposed wellsites is smooth, featureless, and appears stable.
The wellbore at GC 903

- D will intersect a fault at 935 ft (285 m) below mud line ( BML) ; GC 903

- E will intersect a fault at 990 ft (302 m) BML; and GC 859

- J will intersect a fault at 938 ft (286 m)

BML. None of the other wellbores at the proposed wellsites will penetrate subsea faults. There
is no evidence of fluid expulsion featu res, or high

- density deepwater benthic communities near
the wellsites ( Fugro, 2013 ). A detailed description of the regional a ffected environment, including meteorology, oceanography, geology, air and water quality, benthic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses is provided in MMS ( 2007b ) and BOEM ( 2012b ). These regional descriptions remain valid and are incorporated by reference. General background information is presented below, and brief descriptions of each potentially affected resource, including site

- specifi c and/or new information if available

, are presented in Section C

.



## C. Impact Analysis

This section analy z es the potential direct and indirect impacts of routine activities and accidents. Impacts have been analyzed extensively in multi

- lease

- sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b ; BOEM, 2012b )

. The information in these documents is incorporated by reference. Potential s ite

- specific issues are addre ssed in this section.



## C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site

- specific air quality data for the project area due to the distance from shore

. Because of the distance from shore

- based pollution sources and the lack of sources o ffshore

, air quality at the wellsites is expected to be good. The attainment status of Federal OCS waters is unclassified because there is no provision in the Clean Air Act for classification of areas outside

State waters (MMS, 2007b)

.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 18

Figure 2. Bathymetric map of the lease area showing the surface hole location s of the proposed wellsites.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 19 As noted earlier, based on calculations made pursuant to applicable regulations, emissions from drilling activities are not expected to be significa nt as they are below exemption levels. Therefore, the only potential effects to air quality would be from routine air pollutant emissions,

a small fuel spill , and a large oil spill (WCD).

BOEM has reexamined the analysis for air quality presented in MMS (2007b, 2008) based on
additional information and in consideration of the Macondo oil spill event

. No substantial new
information was found that would alter the potential impact s on air quality presented in BOEMRE (2011a) and BOEM (2012b).



### Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant emissions will result from the drilling rig operations and helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel

- powered generators, pump s, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended PM, SO
x , NO
x , VOCs,
and CO. Emissions of pollutants into the atmosphere from these activities are not projected to have significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates and heights, and resulting pollutant concentrations. T he incremental
contribution to cumulative impacts from activities similar to Anadarko’s proposed activitie s is not significant and will not cause or contribute to a violation of any N ational A mbient A ir Q uality

S tandard (NAAQS) (MMS, 2007b

, 2008). Since the BOEM completed the lease sale EISs, the USEPA has adopted a new short

- term NAAQS for nitrogen dioxide ( NO 2 ) . The standard has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project area from shore, emissions from the activities described in
Anadarko’ s propose d EP are not likely to contr ibute to violations of any NAAQS onshore.

Carbon dioxide (CO 2 ) and methane ( CH 4 ) emissions from the project would constitute a small incremental contribution to greenhouse gas emissions from all OCS activities. According to the Programmatic EIS (MMS, 2007a), estimated CO 2 emissions from all OCS activities in the

2007

- 2012 leasing program are about 0.08% to 0.016% of the global CO 2 emissions from fossil fuel combustion. Greenhouse gas emissions may contribute to climate change, with important effects on temperature, rainfall, frequency of severe weather, ocean acidification, and sea l evel rise (Intergovernmental Panel on Climate Change, 2007). Greenhouse gas emissions from this proposed project represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in MMS ( 2007 a, b)

. Because of the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, includi ng nonattainment areas. As noted in MMS ( 2007b) , emissions of air pollutants from routine activities in the Central and Western Gulf of Mexico Planning Area are projected to have minimal impacts to onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance of these emissions
from the coastline

. The Air Quality Emissions Report ( see EP Section G ) prepared in accordance
with BOEM requirements shows that the projected emissions are below exemption levels; therefore, according to 30 CFR 250.303

, the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required

.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 20 The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air quality area. BOEM is required to notify the National Park Service (NPS) and the U.S. Fish and Wildlife Service ( USFWS ) if emissions from proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be required for sources within 186 miles (300 km) o f the Breton Class I area that exceed emission limits agreed upon by the administering agencies (NPS, 2010). The lease area is approximately 189 miles (304 km) from the Breton
Wilderness Area

, and no air quality impacts on the Wilderness Area are expected

. Anadarko will comply with all BOEM r equirements regarding air emissions.



### Impacts of a Small Fuel Spill

Potential impacts o f a small spill on air quality are expected to be consistent with th os e analyzed
and discussed in MMS ( 2007b ) and BOEM ( 2012 b ,d ). The probability of a small spill would be minimized by Anadarko’ s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation of Anadarko’ s OSRP could reduce the potential impacts

. EP Section H includes a detailed discussion of the spill response measures that would be employed

. Given the open ocean location of the lease area, the extent and duration of air quality impacts from a small spill would not be significant.

A small fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The ADIOS2 model ( see Section A.9.2 ) indicates that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

A small fuel spill would not affect coastal air quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up ( see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on air quality are expected to be consistent with th os e analyzed and discussed in MMS ( 2007b ) and BOEM ( 2012 b ,d).

A large oil spill (WCD) could potentially affect air quality by introducing VOCs through evaporation from the slick. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response

measures. Real

- time wind and cu rrent data from the project area would be available at the time of a spill and would be used to assess the fate and effects of VOCs released. Additional air quality impacts could occur if response measures included in situ burning of the floating oil.

Bu rning would generate a plume of black smoke and result in emissions of NO x , SO
x , CO, and PM, as well as greenhouse gases. However, in situ burning would occur only after authorization
from the USEPA.

Due to the lease area’s distance from the nearest shoreline, most air quality impacts would
occur in offshore waters with minimal chance s to affect onshore air quality.



### C.1.2 Water Quality

There are no site

- specific water quality data for the lease area. Due to the lease location in deep, offshore waters , water quality is expected to be good, with low levels of contaminants.

As noted in MMS ( 2007b), deepwater areas in the northern Gulf of Mexico are relativelyGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 21 homogeneous with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that
the deepwater region has little evidence of contaminants in the dissolved or particulate phases of the water column. However, there are localized occurrences of natural seepage of oil, gas,
and brines in near

- surface sediments and up through the water column

.
The lease area is located approximately 185 miles (298 km) fr om the Macondo spill site . Based on the general circulation pattern seen in the Gulf of Mexico and satellite imagery, the surface
slick from that discharge did no t extend over the lease area during the spill

, and it is unlikely
that water quality in the lease area was affected.

IPFs potentially affecting water quality are effluent discharges and two types of accidents –

a small fuel spill and a large oil spill (WCD).



### Impacts of Effluent Discharges

In general, turbid water can be expected to extend between a few hundred meters and several kilometers down current from the discharge point for water

- based drilling muds and cuttings. SBMs will be collected on the rig and either reused b y the vendor or transported to

Port Fourchon , Louisiana

, for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit. All NPDES permit limitations and requirements will be met. There will be no persistent impacts on water quality in the lease area ( National Research Council , 1983; Neff, 1987 ; Neff et al., 2000 ).

Treated sanitary and domestic wastes , including those from support vessels, may have a slig ht transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements and USCG regulations (as applicable) will be met , therefore, l ittle or no impact on water quality is anticipated.

Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, and drains, including drip pans in work areas. Rainwater that falls on uncontaminated areas of the drilling rig will flow overboard without treatment. However, rainwater that falls on the drilling rig deck and other areas such as chemical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements. Based on adherence to permit limits and app licable regulations, little or no impact on water quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water are expected to be diluted rapid ly

, resulting in little or no impact on water quality.



### Impacts of a Small Fuel Spill

Potential impacts of a small spill on wate r quality are expected to be consistent with th os e analyzed and discussed in MMS ( 2007b ) and BOEM ( 2012 a, b ). The probability of a small spill would be minimized by Anadarko ’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of Anadarko’s OSRP could potentially help mitigate and reduce the impa cts

. EP Section H provides detail on spill response

measures in addition to the summary information provided in this EIA

. Given the open ocean location of the lease area, the extent and duration of water quality impacts from a small spill
would not be si gnificant.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 22 A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. However, it is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours (see Section A.9.2 ).
The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending
on sea state and weather conditions.

The water

- soluble fractions of diesel are dominated by two - and three

- ringed PAH s , which are moderately volatile (National Research Council, 2003 a ). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Because the density of diesel is less than the density of seawater, diesel will not sink and pool on
the seafloor. Di esel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solid loads (National Research Council, 2003 a ) and would not be expected to occur to any appreciable degree in offshor e waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

A small fuel spill would not affect coastal water quality because the spill would not be expected

to make landfall or reach coastal waters due to both response efforts that would be undertaken

, as well as natural attenuation (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on wate r quality are expected to be consistent with th os e analyzed and discussed in MMS ( 2007b ) and BOEM ( 2012b,d ). A large spill w ould affect water quality by producing a slick on the water surface and increasing the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at the surface, although new information from the Macondo spil l indicates that plumes of submerged oil droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants would be applied only after approval fr om the USEPA. Small droplets in the water may adhere to suspended sediment s and be removed from the water column (Operational Scientific Advisory

Team [ OSAT ], 2010).

Because of the lease area ’s distance to the nearest shoreline , it is expected that most w ater quality impacts would occur in offshore waters, especially in the event of a spill lasting less than 30 days ( Table 3 ).



## C.2 Seafloor Habitats and Biota

W ater depth s at the proposed project area range from 1,60 6 to 1,632 m ( 5, 2 68 to 5,355 ft)

. The seafloor at the proposed wellsites is smooth, featureless, and appears stable . One fault intersects the proposed G C 903

- D wellbore at 935 ft BML. Several seafloor scarps are present from 500 to 1,000 ft southwe st of the GC 903

- D wellsite, but the scarps dip away from the wellsite and will not be intersected by the wellbore ( Fugro, 2013 ).Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 23 Based on the absence of hard bottom areas detected by side

- scan sonar during the site
clearance s urvey, the seafloor within 610 m (2,000 ft) of the wellsites is expected to consist mainly of soft bottom communities. The site clearance survey did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the wellsites. No areas of gaseous sediments or possible hydrocarbon seepage were defined within

610 m (2,000 ft) of the wellsites , and the presence of chemosynthetic communities is considered negligible ( Fugro, 2013 ).



### C.2.1 Soft Bottom Benthic Communities

There are no site

- specific benthic community data from the lease area. However, data from the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Wei, 2006;

Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in the area.
Table 4 summarizes data collected at stat ions in water depths similar to the proposed drilling

area.

Table 4. Benthic community data from stations near the lease area and in similar water depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted f rom: Wei, 2006; Rowe and Kennicutt, 2009).

Station Water Depth (m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna (individuals/m 2 ) Megafauna (individuals/ha)

NB3 1,875 165,245 1,342 191

NB5 2,065 117,263 706 1,600

Meiofaunal and megafaunal abundances from Rowe and Kennicutt (2009); macroinfaunal abundance from

Wei (2006).

Densities of meiofauna (animals passing through a 0.5

- mm sieve but retained on a 0.062

- mm sieve) in water depths representative of the lease area ( 1,60 6 to 1,632 m ) typically range from approximately 190,000 to 343,000 individuals/ m 2 (Rowe and Kennicutt, 2009 ). Nematodes, nauplii, and harpacticoid copepods were the three dominant meiofaunal groups, accounting for
about 90% of total abundance.

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both of which reflect the meager primary production in Gulf of Mexico surface waters (Wei, 2006). Densities decrease exponentially with water depth. Based on an equat ion presented by Wei (2006), macroinfaunal densities in the water depths of the lease area are expected to be about 2,062 individuals/m 2

.
Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of

Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four depth

- dependent faunal zones (1 through 4), two of which are divided
ho r izontally. The lease area is in Zone 3W, which includes the most complex bathymetric
features in the northern Gulf of Mexico, including the Alaminos Canyon and the base of the Sigsbee Escarpment (Wei, 2006). The most abundant species in Zone 3W were the polychaetes

Levinsenia uncinata

, Paraonell monilaris , and Tachytrypane sp. A; the bivalve Heterodonta sp. B; and the isopod Macrostylis 256.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 24 Megafaunal densities from nearby s tations ranged from 0 to 1,600 individuals/ha

. Common megafauna included motile groups such as decapods, ophiuroids, holothurians, and demersal
fishes as well as sessile groups such as sponges and anemones.

Bacteria also are an important component in terms of biomass and cycling of organic carbon (Cruz

- Kaegi, 1998). Bacterial biomass at the depth range of the lease area typically is about

1 to 2 g C/m 2 in the top 15 cm (6 in.) of sediments (Rowe and Kennicutt, 2009).

IPFs potentially affecting benthic communities are physical disturbance to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowout
at the seafl oor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.



### Physical Disturbance to the Seafloor

In water depths such as those encountered in the lease area, the areal extent of seafloor impacts will be small compared to the lease area itself

. T hese type s of s oft bottom communities are ubiquitous along the northern Gulf of Mexico continental slo pe (Gallaway, 1988; Gallaway

et al., 2003; Rowe and Kennicutt, 2009 ) and i mpacts from the physical disturbance of the seafloor during this project should have no significant impact on soft bottom benthic communities in the region.



### Impacts of Effluent Discharges

Drilling muds and cuttings are the only effluents that are likely to affect bent hic communities. During initial well interval(s) before the marine riser is set, cuttings and seawater

- based “spud mud ” will be released at the seafloor. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Cement slurry components typically include cement mix and some of the same chemicals used in water

based drilling muds (Boehm et al., 2001). The main impacts will be burial and smothering of benthic organisms withi n several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by cuttings, drilling muds, and cement slurry will eventually be recolonized through larval settlement and migration from adjacent areas. Because some deep

- sea biota grow and reproduce slowly, recovery may require several years.

Discharges of washed SBM cuttings from the rig may affect benthic communities, primarily
within several hundred meters of the wellsite s . The fate and effects of SBM cuttings have been
reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of Mexico by Continental Shelf Associates, Inc. (2004, 2006). In general, washed cuttings with adhering SBMs tend to clump together and form thick cuttings piles close to the d rillsite. Areas of SBM cuttings deposition may develop elevated organic carbon concentrations and anoxic conditions (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate in concentrations of approximately 1,000 mg/kg or higher, benthi c infaunal communities may be adversely affected due to both the toxicity of the base fluid and organic enrichment (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 S predominate (Continental Shelf Associates, Inc., 2006). As the base synthetic fluid is decomposed by microbes, the area will gradually return to pre

- drilling conditions. Disturbed sediments will be recolonized through larval settlement and migration from adjacent areas.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 25 T he areal extent of impacts from drilling discharges will be small. Assuming a typical effect
radius of 500 m (1,640 ft), the affected area around the wellsite s would represent about 3% of
the seafloor within a le ase block. Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project should have no significant impac t on soft bottom benthic communities in the region.



### Impacts of a Large Oil Spill (WCD)

The most likely effects of a subsea blowout on benthic communities would be within a few
hundred meters of the wellsite s

. The MMS (2007b) estimat ed that a severe subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius. While coarse sediments (sands) would probably settle at a rapid rate within 400 m (1,312 ft) from the blowout site, fine sediments (silts and clays) c ould be resuspended for more than 30 days and dispersed over a much wider area. Based on previous studies, surface sediments at the project area are assumed to largely be silt and clay ( Rowe and Kennicutt, 2009 ).

Discussions in MMS ( 2007a, 2008) in dicat ed that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, du ring the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resul ted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300

- m (984

- ft) r adius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. This contact could result in smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic organisms over a period of months to years (National Research Council, 2003 a ).



### C.2.2 High

- Density Deepwater Benthic Communities

As defined by NTL 2009

- G40, high

- density deepwater benthic communities are f eatures or areas that could support high

- density chemosynthetic communities or feature s or areas that could support high

- density deepwater corals and other associated high

- density hard bottom

communities. Chemosynthetic communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald, 2002). D eepwater coral communities are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007;

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities.

The nearest known chemosynthetic community site is approximately 38 miles (61 km) north of
the lease area in GC 287. The nearest identified deep water coral communities are in GC 866,

21 miles (34 km) east of the lease area

.

The site clearance survey did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling mud /cuttings discharge locations ( Fugro, 2013 ).Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 26 IPFs potentially affecting high

- density deepwater benthic communities include physical
disturbance to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor. A small fuel spill would not affect benthic
communities because the diesel fuel would float an d dissipate on the sea surface.



### Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships or DP semisubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are l ocated. Depending upon the specific well configuration, this area is gene rally about 0.25 ha (0.62 ac).

T he areal extent of these impacts from the DP drilling vessel will be small , and NTL 2009

- G40 requires that high

- density deepwater benthic communities and f eatures o r areas that could support high

- density chemosynthetic communities, or deepwater corals communities be
avoided

. Based on the Fugro ( 2013 ) r eport, there should be no impacts on chemosynthetic or deepwater coral communities from this project.



### Impacts of Effluent Discharges

The site clearance survey ( Fugro, 2013 ) did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling locations, and the presence of chemosyntheti c communities in the lease area is considered negligible

. Mo nitoring programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft )
of the wellsite , althou gh detectable deposits may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 2005). Because of the water depth of the lease area, drilling discharges would be expected to result in thinner, more diffuse accumulation s on the seafloor than those documented in the literature. Although small amounts of cuttings particles may reach areas inhabited by high

- density deepwater benthic communities, the discharges are not expected to result in significant impacts to these communities.



### Impacts of a Large Oil Spill (WCD)

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact hig h- density deepwater benthic communities beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. Oil plumes that contact sensitive benthic communities before degrading could potentially impact the resource (BOEM, 2012b). Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants , and such approval would be obtained from the USEPA prior to the use of dispersants

.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 27 The biologi cal effects and expected fate of the oil remaining in the Gulf of Mexico from the blowout are still unknown due to the depth and the magnitude of this event. Hazen et al. (2010) reported changes in plume hydrocarbon composition with distance from the sour ce . I ncubation experiments with environmental isolates demonstrated faster than expected hydrocarbon biodegradation rates at 5°C. Based on these results, Hazen et al. (2010) suggested the potential exists for intrinsic bioremediation of the oil plume in the deep water column without substantial oxygen drawdown.

Potential impacts of oil on high

- density deepwater benthic communities are discussed in

MMS (2007b). Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very const ant and occurs at low rates compared to the potential rates of oil release from a blowout. In addition, seep organisms also require unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organisms or deepwater corals. As discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; chang e in sediment characteristics; and reduction or loss of one or more commercial and recreational fishery habitats. Sublethal effects could be long

- lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water temperature and diseases) (BOEM

, 2012d)

.
The potential for a spill to affect deepwater corals is indicated by preliminary findings from a recent (October 2010) survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010). Government and academic researchers were working at a site 1,400 m (4,600 ft) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead when they observed dead and dying corals with sloughing tissue and discoloration. Much of the soft
coral observed in an area measur ing about 15 by 40 m (50 by 130 ft) was covered by what appeared to be a brown flocculent substance (floc). Out of 40 large corals, 90% were heavily affected and showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) farther away had a colony of stony corals similarly affected and partially covered with a similar brown substance. Based on hopanoid petroleum biomarkers from the floc, researchers concluded that it contained oil from the Macondo spill. The injured and dead corals were in an area where a subsea plume of oil had been documented during the spill in June, 2010; corals elsewhere in the Gulf of Mexico outside the area affected by the plume did not appear to be experiencing higher mortality. The research team concluded that the observed coral injuries likely resulted from exposure to the subsurface oil plume (White et al., 2012).



### C.2.3 Designated Topographic Features

The block is not w ithin or near a designated topographic feature or a no

- activity zone as
identified in NTL 2009

- G39 . The nearest designated topographic feature is Ship Shoal South, in Ewing Bank Block 945, 63 miles (101 km) north of the lease area

.
There are no IPFs associated with either routine operations or accidents that could cause impacts to designated t opographic features due to the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region areGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 28 predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf edge

.



### C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Botto m (Pinnacle Trend) Stipulation. As defined by

NTL 2009

- G39, the nearest pinnacle trend is in Ma in Pass Block 290, 205 miles (330 km)
northeast of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the lease area. A small
fuel spill would float on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf edge

.



### C.2.5 Eastern G ulf Live Bottoms

The lease area is not covered by the Live Bottom (Low

- Relief) Stipulation, which pertains to seagrass communities and low

- relief hard

- bottom reef within the Eastern Gulf of Mexico Planning Area blocks in water depths of 100 m (328 ft) or l ess and portions of Pensacola and

Destin Dome Area b locks in the Central Gulf of Mexico Planning Area . The nearest block covered by the live bottom stipulation, as defined by NTL 2009

- G39, is Destin Dome Block 573,

244 miles (393 k m) northeast of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to eastern Gulf live bottom areas due to the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due
to the distance and the di fference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf

.



## C.3 Threatened, Endangered, and Protected Species and Critical Habitat

This section discusses species listed as endangered or threatened under the Endangered Species Act ( ESA ) . In addition, it includes all marine mammal species in the region, which are protected
under the Marine Mammal Protection Act ( MMPA ).

Endanger ed or threatened species that may occur in the project area and/or along the northern
Gulf C oast are listed in Table 5 . The table also indicates the location of critical habitat (if designated in the Gulf of Mexico). Critical habitat is defined as (1) sp ecific areas within the geographical area occupied by the species at the time of listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and (2) spe cific areas outside the geographical area occupied by the species if the agency determines that the area itself is essential forGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 29 conservation. The National Marine Fisheries Service ( NMFS ) has jurisdiction for ESA

- listed cetaceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction for

ESA

- listed birds and the West Indian m anatee.

Table 5. Federally listed endangered and threatened species potentially occurring in the lease area and along the northern Gulf C oast.

Species Scientific Name Status Potential Presence Critical Habitat Designated
in Gulf of Mexico Lease
Area Coastal

Marine Mammals

Sei whale Balaenoptera borealis E X a

-- None

Blue whale Balaenoptera musculus E X a

-- None

Fin whale Balaenoptera physalus E X a

-- None
North Atlantic right whale Eubalaena glacialis E X a

-- None
Humpback whale Megaptera novaeangliae E X a

-- None
Sperm whale Physeter macrocephalus E X

-- None

West Indian manatee Trichechus manatus latirostris E

-- X Florida (Peninsular)

Sea Turtles

Loggerhead turtle Caretta caretta T X X None

Green turtle Chelonia mydas T, E b X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys imbricata E X X None
Kemp ’ s ridley turtle Lepidochelys kempii E X X None

Birds

Piping Plover Charadrius melodus T

-- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E

-- X Coastal Texas (Aransas National Wildlife Refuge )

Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T

-- X Coastal Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Smalltooth sawfish Pristis pectinata E

-- X Southwest Florida and the Florida Keys

Invertebrates

Elkhorn coral Acropora palmata E

-- X Flower Garden Banks

Terrestrial Mammals

Beach mice (A labama, Choctawhatchee, Perdido Key,
St. Andrew) Peromyscus polionotus E

-- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = e ndangered; T = t hreatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be present in the lease area.

b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

As mandated by the ESA, MMS consulted NMFS and the USFWS on possible and potential impacts from the proposed leasing in the Gulf of Mexico on endangered/threatened species and their designated critical habitat (MMS

, 2007a

, b)

. A B iological A ssessment was prepared for each consultation. The formal ESA consultation with NMFS was concluded with receipt of theGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 30 Biological Opinion on 3 July 2007 (NMFS, 2007). The Biological Opinion concludes that the proposed lease sales and associated activities in the Five

- Year Leasing Plan for Western and Central Planning Areas 20 07

- 2012 are not likely to jeopardize the continued existence of threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded with a
letter dated 14 September 2007. The USFWS concurred with MMS’s determination that proposed actions of the Five

- Year Leasing Plan were not likely to adversely affect threatened/endangered species or designated critical habitat under U SFWS jurisdiction. Following the Macondo spill

, BOEMRE requested to reinitiat e an ESA consultation with both
NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on

24 September 2010 , and t he USFWS responded with a letter to BOEMRE on 27 September 2010. At present, the NMFS and US FWS have placed th e consultation process on hold because they
feel the environmental baseline information needs to be updated for the post

- Macondo spill
environment based on the results of the Natural Resou rce Damage Assessment ( NRDA ) process. The NRDA data have yet to be released , and the existing consultation remain s in effect (BOEM, 2012b)

. The existing consultation recognizes that BOEM

- required mitigations and other reasonable and prudent measures shou ld reduce the likelihood of impacts from all

BOEM

- authorized activities in the Gulf of Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include
the West Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of
beach m ouse . Critical habitat has been designated for all of these species as indicated in Table 5
and discussed in individual sections.

Two other coastal species (Bald Eagle and Brown Pelican) discussed in MMS (2007b) and BOEM (2012b) are no longer federally listed as endangered or threatened . T hese are discussed in
Section C.4.2

, Shorebirds and Coastal Nesting Birds

.
There are five sea turtle and six marine mammal species that are currently listed as endangered and threatened by the ESA and known to occur within OCS and slope waters of the Gulf of
Mexico. The listed sea turtles include the l eatherback turtle , Kemp’ s ridley turtle , hawksbill turtle, loggerhead turtle, and green turtle. Listed marine mammal species includ e one odontocete (toothed) whale ( sperm whale ) and five mysticete (baleen) whales ( blue whale,
fin whale, humpback whale, North Atlantic right whale, and sei whale)( Pritchard, 1997; Würsig

et al., 2000 ). No critical habitat has been designated for these s pecies in the Gulf of Mexico.

The sperm whale and five species of sea turtles are the only endangered or threatened species likely to occur at or near the lease area. No critical habitat has been designated for these species in the Gulf of Mexico.

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico

, but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.



### C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the pro ject area is the sperm whale ( Physeter macrocephalus )

. Resident populations of s perm whales occur within the
Gulf of Mexico ; a species description is presented in MMS ( 2007b). Gulf of Mexico spermGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 31 whales are classified as an endangered species and a “str ategic stock ” (defined as a stock that may have unsustainable human

- caused impacts) by NOAA Fisheries (Waring et al., 2012 ). No
critical habitat for the sperm whale has been designated in the Gulf of Mexico.

The distribution of sperm whales in the Gulf of Mexico is correlated with mesoscale physical features such as eddies associated with the Loop Current (Jochens et al., 2008). Sperm whale populations in the north

- central Gulf of Mexico are present there throughout the year (Davis et al., 2000). Results of a multi

- year tracking study show female sperm whales typically concentrated along the upper continental slope between the 200 - and 1,000

- m (656 - and 3,280

- ft) depth contours ( Jochens et al., 2008 ). Male sperm whales were more variable in their

movemen ts and were documented in water depths greater than 3,000 m (9,843 ft). Generally, groups of sperm whales sighted in the Gulf of Mexico during the MMS

- funded Sperm Whale Seismic Study (SWSS) consisted of mixed

- sex groups comprising adult females and immat ures, and groups of bachelor males. Typical group size for mixed gro ups was 10 individuals (Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the
lease area. Movements of satellite

- tracked individuals suggest tha t this area of the Gulf continental slope is within the home range of the Gulf of Me xico population (within the

95% utilization distribution) (Jochens et al., 2008).

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the in termittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on sperm whales

.

C urrent threats to sperm whale populations worldwide are discussed in a final recovery plan for the sperm whale r ecently published by NOAA (NMFS, 2010 a ). Threats are defined as “ any factor that could represent an impediment to recovery ,” and include fisher ies interactions, anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from marine debris, research, predation and natural mortality, direct harvest, competition for resources, loss of prey base due to climate change and e cosystem change, and cable laying.

In the Gulf of Mexico , the impacts from many of these threats are identified as either low or
unknown ( BOEMRE, 2011 a ; BOEM, 2012 b).



### Impacts of Drilling Rig Presence, Noise, and Lights

Noise generated from the drilling ri g and from routine drilling activities may be audible to sperm
whales and so has the potential to disturb individuals near the lease area

. The drilling rig used during the proposed activity will be located within a deepwater, open ocean environment and

wi ll remain stationary during drilling operations. Sounds generated by the rig and by drilling operations will be generally continuous (with some variability in sound level, considering thruster activity)

. This analysis assumes that the continuous nature of sounds produced by the drilling rig will provide individual whales with cues relative to the direction and relative distance (sound intensity) of the sound source, and the fixed position of the drilling rig will provide multiple options for active avoida nce of potential physical impacts. NMFS analyzed the potential for impacts of drilling

- related noise on sperm whales in its Biological Opinion for the
Gulf of Mexico Oil and Gas Activities: Five

- Year Leasing Plan for Western and Central Planning

Areas 2007

- 2012 (NMFS, 2007)

. The analysis noted that semisubmersible drilling rigs emit lowGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 32 sound source levels and concluded that drilling is not expected to produce amplitudes sufficient to cause hearing or behavioral effects in sperm whales; therefore, these effects are insignificant (NMFS, 2007 ).

In addition, there are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar noise sources. Drilling

- related noise associated with this project will contr ibute to increases in the ambient noise environment of the Gulf of Mexico, but it is not expected in amplitudes sufficient to cause either hearing or behavioral effects to sperm
whales.

Drilling rig lighting and rig presence are not identified as IPFs for sperm whales (MMS, 2007b ; BOEM, 2012a, b ,d ; NMFS, 2007 ).



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a ). Data concerning the frequency of vessel strikes are presented in MMS ( 2007b). To reduce the potential for vessel strikes, the BSEE and BOEM issued NTL 2012

- JOINT

- G0 1 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected spe cies. When whales are sighted, vessel operators and crews are required to attempt to maintain a
distance of 91 m (300 ft) or greater whenever possible. Vessel operators are required to reduce vessel speed to 10 knots or less

, when safety permits

, when mo ther/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm
whales.

NMFS (2007) analyzed the poten tial for vessel strikes and harassment of sperm whales . With implementation of the mitigation measures in NTL 2012

- JOINT

- G01 , NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant
levels. NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not expected to result in any significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to individuals, or have any consequences at the population level

. With implementation of the vessel strike avoidance measures requirement to maintain a distance of 9 1 m ( 300 ft) from sperm whales, the NMFS concluded that the potential for harassment of sperm whales would be reduced to
discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) documented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an
altitude of 245 m (800 ft). A reaction to the initial pass of the aircraft was observed during

3 (12%) of 24 sightings. All three reactions consisted of a hasty dive and occurred at less than

360 m (1,180 ft) lateral distance from the aircraft. Additional reactions were seen when aircraft
circled certain whales to make further observations. Based on other studies of cetacean responses to sound, the authors concluded that the observed reactions to brief overflights by
the aircraft were short

- term and probably of no long

- term biological significance.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 33 W hile flying offshore in the Gulf of Mexico , helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In the event that a whale is seen during transit, the helicopter will not approach or circle the animal. Although responses are possible (Smultea

et al., 2008), the NMFS (2007) and BOEM (2012 d ) concluded that t his altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expected

.


### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in MMS ( 2007b ), BOEM ( 2012 a, b ,d ), and NMFS (2007) . Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals that were not analyzed in the previous documents

.
The probability of a fuel spill will be minimized by Anadarko’ s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko’ s OSRP could mitigate and lessen the potential for impacts on sperm whales. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorolog ical and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (Marine Mammal Commission [ MMC ] , 2011 ). However,
du e to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of sperm whales, no significant impacts would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mamma ls including sperm whales are discussed in MMS ( 2007b ), BOEM ( 2012 a,b, d), and NMFS (2007)

. For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

Impacts of oil spills on sperm whales can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, no ise, and dispersants) (MMC, 2011 ). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft. Complications of the above may l ead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime
habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or
patterns

, changing reproductive behavior/productivity, and changing movement patterns orGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 34 migration (MMC, 2011 ). Ackleh et al. (2012) hypothesized that sperm whales may have temporarily relocated away from areas near the Mac ondo spill in 2010.

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels woul d operate in accordance with NTL 2012

- JOINT

- G01 to reduce the potential for striking or disturbing these animals.



### C.3.2 West Indian Manatee (Endangered)

M ost of the Gulf of Mexico manatee population is located in peninsular Florida (USFWS, 2001).

Manatee sightings in Louisiana have increased as the species extends its presence farther west of Florida in the warmer months (Wilson, 2003). A species description is presented by MMS ( 2007b) and in the recovery plan for this species (USFWS, 2001).

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees due to the
distance to the nearest shoreline. As explained in Section A.9. 2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

. Compliance with

NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on manatees.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001).

To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species

, and requires operators to report sightings of any injured or dead protected species. Compliance with this NTL will minimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

Helicopter traffic also has the potential to di sturb manatees. Rathbun (1988) reported that manatees were disturbed more by helicopters than by fixed

- wing aircraft; however, the helicopter was flown at relatively low altitude s of 20 to 160 m (66 to 525 ft). Helicopters used in support operations main tain a minimum altitude of 213 m (700 ft) while in transit offshore,

305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park properties. In addition, guidelines and regulations specify that helicopters maintain an altitude of 305 m ( 1,000 ft)
within 91 m ( 300 ft) of marine mammals (BOEM, 2012a, d ). This mitigation measure will minimize the potential for disturbing manatees, and no significant impacts ar e expected.



### Impacts of a Large Oil Spill (WCD)

In the event that manatees were exposed to oil, effects could include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic,

no ise, and di spersants) (MMC, 2011 ). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via con taminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immuneGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 35 and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of
social structure

, changing prey availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 201 1 ).

In the event that a large spill reached coastal waters where manatees were present , the level of vessel and aircraft activity associated with spill respo nse could disturb manatees and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate
in accordance with NTL 2012

- JOINT

- G01 to reduce the potential for striking or disturbing these
animals , and theref ore no significant impacts are expected

.



### C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico

, but are consider ed rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.

Because of the rare occurrence of these whales in the Gulf of Mexico and the limited sco pe and duration of the project, i t is highly unlikely that any endangered mysticete whale would come into contact with any project activities – either routine operations or accidents . NMFS did not include any of these mysticete whales as affected species in its Biological Opinion (NMFS, 2007)

. Potential impacts are analyzed in MMS ( 2007b ) and BOEM ( 2012a,b, d), and those analyses are incorporated by reference. If any of these whales were present in the area, potential impacts
would be the same as those discussed below in Section C.3.4

.



### C .3.4 Non

- Endangered Marine Mammals (Protected)

Excluding the seven endangered species that have been cited previously, there are 22 additional species of marine mammals that may be found in the Gulf of Mexico

, includ ing 2 species of mysticete whales, dwarf and pygmy sperm whales, 4 species of beaked whales, and 1 4 species
of delphinids . All marine mammals are protected species under the MMPA. The most common

non

- endangered cetaceans in the deepwater environment are odontocetes

, such as the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin. A brief summary is presented below, and a dditional information on these groups is presented in MMS ( 2007b).

Mysticete whale s . Two species of non

- endangered mysticete whales a re known from the Gulf
of Mexico. The Bryde’s whale ( Balaenoptera edeni ) has been sighted most frequently along the

100

- m (328

- ft) isobath (Davis and Fargion, 1996; Davis et al., 2000). Most sightings have been made in the DeSoto Canyon region and off we stern Florida, although there have been some in
the west

- central portion of the northeastern Gulf. The minke whale ( Balaenoptera

acutorostrata ) is considered rare in the Gulf of Mexico, with the only confirmed records coming from strandings (Würsig et al. , 2000). Based on the available data, it is possible that Bryde’s
whales could occur in the lease area.

Dwarf and pygmy sperm whales

. At sea, it is difficult to differentiate dwarf sperm whales ( Kogia sima ) from pygmy sperm whales ( Kogia breviceps ), and sightings are often grouped together as Kogia spp. Both species have a worldwide distribution in temperate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge andGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 36 in deeper waters off the continental s helf (Mullin et al., 1991). Either species could occur in the
lease area.

Beaked whales . Four species of beaked whales are known from the Gulf of Mexico. They are Blainville’s beaked whale ( Mesoplodon densirostris ), Cuvier’s beaked whale ( Ziphius cavirostris ), Sowerby’s beaked whale ( Mesoplodon bidens ), and Gervais’ beaked whale ( Mesoplodon

europaeus ). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked whale is the

most common

, and Sowerby’s is extralimital. Due to the difficulties of at

- sea identification,
beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked whales or are grouped into an undifferentiated complex ( Mesoplodon spp. and Ziphius spp.). In the northern Gulf of Mexico, they are broadly distribu ted in water depths greater than 1,000 m (3,281 ft) over lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in the
lease area.

D elphinids . Fourteen species of delphinids are known from the Gulf of Mexico, including Atlantic spotted dolphin ( Stenella frontalis ), bottlenose dolphin ( Tursiops truncatus ), Clymene dolphin ( Stenella clymene ), f alse killer whale ( Pseudorca crassidens )

, Fraser’s dolphin ( Lagenodelphis hosei ) , k iller whale ( Orcinus orca ) , m elon

- headed whale ( Peponocephala electra )

, p antropical spotted dolphin ( Stenella attenuata )

, p ygmy killer whale ( Feresa attenuata )

, short

- finned pilot whale ( Globicephala macrorhynchus ) , R isso’s dolphin ( Grampus griseus )

,
r ough

- toothed dolphin ( Steno bredanensis ) , s pinner dolphin ( Stenella longirostris ) , and s triped dolphin ( Stenella coeruleoalba ). Any of these species could occur in the lease area. The most

common non

- endangered cetaceans in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin.

Bottlenose dolphins

. The bottlenose dolphin ( Tursiops truncatus ) is a common inhabitant of the northern Gulf of Mexico, particularly within continental shelf waters. There are two ecotypes of bottlenose dolphins, a coastal form and an offshore form, which are genetically isolated from each other ( Waring et al., 2012 ). The offshore form of the bottlenose dolphin may occur within
the lease area. Inshore populations of coastal b ottlenose dolphins in the northern Gulf of

Mexico are sepa rated into 37 geographically distinct population units, or stocks, for management purposes by the NMFS (Waring et al.

, 201 2) . NMFS (2013) has proposed to classify the Gulf of Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of the Bay, Sou nd, and Estuarine Stocks as strategic stocks. A “strategic ” stock is defined by the MMPA as a marine
mammal stock

• for which the level of direct human

- caused mortality exceeds the potential biological removal level;

• which, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the ESA within the foreseeable future; or

• which is listed as a threatened or endangered species under the ESA, or is designated as depleted under the MMPA.

The strateg ic stock designation in this case was based primarily on the occurrence of an “unusual mortality event” of unprecedented size and duration that has affected these stock areas. This unusual mortality event began in February 2010 and is ongoing. Carmichael et al. (2012) hypothesized that the unusual number of bottlenose dolphin strandings in the northern Gulf of Mexico during this time may have been associated with environmental perturbationsGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 37 including sustained cold weather and the Macondo spill in 2010 as well as large volumes of cold freshwater discharge in the early months of 2011.

IPFs potentially affecting non

- endangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents

– a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these marine mammals. Compli ance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts.



### Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use higher frequency sounds than those produced by OCS drilling activities (Richardson et al., 1995). Noise generated durin g drilling operations is generally continuous and fixed in location. Noise intensity associated with these operations is relatively weak . Stronger noise levels will occur during thruster use in dynamic positioning. Thruster noise impacts would be expected at greater distances than vessel noi se alone (LGL Ecological Research Associates, Ltd.

, 2006)

, but are dependent on variables relating to thruster type and usage. It is expected that marine mammals within or near the lease area
would be able to detect the presence of the drilling rig and avoid exposure to higher energy sounds, particularly within an open ocean environment. Some odontocetes have shown increased feeding activity around lighted platforms at night (Todd et al

. , 2009). Even temporary
drill ing rigs present an attraction to pelagic food sources that may attract both cetaceans and sea turtles. Therefore, prey congregation could pose an attraction to protected species that exposes them to higher levels or longer durations of noise that might o therwise be avoided.
There are other OCS facilities and activities near the lease area

, and the region as a whole has a large number of similar sources. Species in the northern Gulf of Mexico have been exposed to noise from anthropogenic sources for a lo ng period of time and over large geographic areas and likely do not represent a naïve population with regard to sound (National Research Council, 2003b). T his project would represent a temporary contribution to the overall noise regime
within the lease ar ea, and potential impacts are expected to be biologically in significant to marine mammal populations.

Drilling rig lighting and rig presence are not identified as IPF s for marine mammals (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a,b ).



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals

, and there is also a risk of
vessel strikes. Data concerning the frequency of vessel strikes are presented in MMS ( 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Vessel operators and crews are required to attempt to maintain a distance of

91 m (300 ft) or greater when whales are sighted and 45 m (150 ft) when small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt changes in direction until the cetacean has left the area. Vessel operators are required to reduce vessel speed toGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 38 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel

, when safety permits. Compliance with NTL 2012

- JOINT

- G01 will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine
mammals , and therefore no significant impacts are expected

.

Aircraft traffic also has the potential to disturb marine mammals (W ü rsig et al., 1998). However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In addition, guidelines and regulations spe cify that helicopters maintain
an altitude of 305 m ( 1,000 ft) within 91 m ( 300 ft) of marine mammals (BOEM, 2012a, d ). Maintaining this altitude will minimize the potential for disturbing marine mammals , and no significant impacts are expected ( BOEM, 2012 a, d ).



### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in MMS ( 2007b ) and BOEM ( 2012a,b ); oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For this

EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Anadarko ’s OSRP is expected to
lessen the potential for impacts on marine mammals

. EP Section H provides detail on spill

response measures , along with a summary of those measures in this EIA

. Given the open ocean location of the lease area, the limited duration of a small spill and re sponse efforts, it is expected that any impacts would be brief and minimal

.
A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and a ircraft (MMC, 2011 ). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of marine mammals, no significant impacts would be expected.



### Impacts of a Large Oil Spill (WCD)

Pote ntial spill impacts on marine mammals are discussed in MMS ( 2007b ) and BOEM ( 2012a,b )

. For this EP , there are no unique site

- specific issues

. Impacts of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect impact s due to response activities and materials (e.g., vessel traffic , noise, and dispersants) (MMC, 201 1 ). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or co ntaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the aboveGreen Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 39 may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 201 1 ).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb marine mammals and potentially result in vessel strikes, entanglement, or other injury or str ess. Response vessels would operate in accordance with NTL 2012

- JOINT -G01 to reduce the potential for striking or disturbing these animals , and therefore no significant impacts are expected

.



### C.3. 5 Sea Turtles (Endangered/Threatened)

F ive species of endang ered or threatened sea turtles may be found near the lease area.
L eatherback turtle ( Dermochelys coriacea ), Kemp’ s ridley turtle ( Lepidochelys kempii ), and
hawksbill turtle ( Eretmochelys imbricata ) turtles are endangered . The loggerhead turtle ( Caretta c aretta ) is currently a threatened species ; however, in March 20 10 , NMFS and USFWS proposed to list the Northwest Atlantic Ocean population of loggerhead turtles as endangered (75 FR 12598) . The green turtle ( Chelonia mydas ) is listed as threatened, except for the Florida
and Pacific c oast of Mexico breeding population s , which are listed as endangered. Species descriptions are presented in MMS ( 2007b).

Leatherback and loggerhead turtle s are the most likely species to be present near the lease area as adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and near shore species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea
turtle species may be present in deepwater areas, including the lea se area, where they may be
associated with Sargassum and other flotsam.

Sea turtle nesting on the northern Gulf of Mexico coast can be summarized by species as follows:

• Loggerhead turtles – Loggerheads nest in significant numbers along the Florida Panhandle and, to a lesser extent, from Texas through Alabama (MMS, 2007b). The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR;

• Green and leatherback turtles – Green and leatherback turtles i nfrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 201 2 );

• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo B each,

Tamau lipas, Mexico (NMFS et al., 2011 ). Kemp’s ridley turtles typic ally do not nest anywhere near the project area, although there have been occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area.

IPFs potenti ally affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on sea turtles.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 40 

### Impacts of Drilling Rig Pr esence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include behavioral disruption and temporary or pe rmanent displacement from the area near the sound source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures (Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced during routine oper ations. The most likely impacts would be short

- term behavioral changes such as diving and evasive swimming, disruption of activities, or departure from the area. Due to the limited scope and short duration of drilling activities , these short

- term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are insignificant.



### Impacts of Support Vessel and Helicopter Traffic

Noise generated from support vessel traffic has the potential to disturb sea turtles

, and there is
also a risk of vessel strikes. Data show that vessel strike is one cause of sea turtle mortality in
the Gulf of Me xico (Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in clear weather, they can be difficult to spot from a moving vessel when resting below the water surface, during nighttime, or during periods of inclement weather. To reduce the potent ial for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for sea turtles and slow down or stop their vessel to avoid striking

p rotected species, and requires operators to report sightings of any injured or dead protected species. When sea turtles are sighted, vessel operators and crews are required to attempt to
maintain a distance of 45 m (150 ft) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Noise generated from support helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are expected.



### Impacts of a Small Fuel Spill

Pot ential spill impacts on sea turtles are discussed in MMS ( 2007b ), BOEM ( 2012a,b ), and the

NMFS Biological Opinion (NMFS, 2007)

. For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko’ s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Anadarko’ s OSRP is expected to

minimize potential impacts on sea turtles

. EP Section H provides detail on spill response

measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 41 A small fuel spill in offshore waters would produce a slick on the water surface and incr ease the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state a nd weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMS, 2007b; NMFS, 2010b; BOEM, 2012b ,d ) . However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, no s ignificant impacts would be expected.

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches due to
the distance from nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make l andfall or reach coastal waters prior to breaking up

.


### Impacts of a Large Oil Spill (WCD)

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and smoke (e.g., from in situ burning of oil) ; ingestion of oil (and dispersants) directly or via contaminated food; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of social structure

, changing food availability and foraging distribution and/or patterns

, changing reproductive behavior/prod uctivity, and changing movement patterns or migration. In the unlikely event of a spill, implementation of Anadarko’ s OSRP is expected to minimize the potential for these types
of impacts on sea turtles. EP Section H provide s detail on spill response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest that
sea turtles show no avoidance behavior w hen they encounter an oil slick, and any sea turtle in
an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface

over time , which may result in repeated exposure to volatile vapors and oiling (NMFS, 2 007).

Spilled oil reaching sea turtle nesting beaches could have e ffects on nesting sea turtles and egg development (NMFS, 2007). An oiled beach could affect nest site selection or result in no nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired movement and normal bodily functions (NMFS, 2007).Green Canyon Blo cks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 42 In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury or stress. Response ves sels would operate in accordance with NTL 2012

- JOINT

- G01 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected

.
The extent and scope of the Macondo spill represents new information not assessed in the existing ESA Section 7 consultation under the current Five

- Year Program. As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing Gulf of Mexico lease
sale EIS with NMFS and the US FWS on 30 July 2010. The NMFS responded with a letter to

BOEMRE on 24 September 2010 , and the US FWS responded with a letter to BOEMRE on

27 September 2010. However, NMFS and the US FWS have placed the consultation process on hold pending the results of the NRDA post

- Macondo spill data review, which has yet to be
released. The existing consultation currently remain s in effect (BOEM, 2012b)

.
BOEMRE (2011a) and BOEM (2012b) reexamined the impacts analys es presented in MMS (2007b, 2008) for the five sea turtle species that inhabit the Gulf of Mexico based on additional information and in consideration of the Macondo spill. No new information was found that
would alter the potential impact s on sea turtles described in previous EISs . In most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles.



### C.3. 6 Piping Plover (Threatened)

The Piping Plover ( Charadrius melodus ) is a migratory shorebird that overwinters along the southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of hunting, habitat loss and modification, predation, and disease (USFWS, 2003) . Critical overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, Alabama, and Florida ( Figure 3 ) . Piping Plovers inhabit coastal sandy beaches and mudflats, feeding by probing for invertebrates at or just below the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in

MMS ( 2007b).

A large oil spill (WCD) is the only IPF potentially affecting Piping Plovers. There are no IPFs

associa ted with routine project activities that could affect these birds. A small fuel spill in the lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 ).Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 43

Figure 3. Location of selected environmental features in relation to the lease area.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 44 

### Impacts of a Large Oil Spill (WCD)

Th e lease area is 133 miles (214 km) from the nearest shoreline s inhabited by Piping Plovers ( Figure 3 ). The revised OSRA results (BOEMRE, 2011a; BOEM, 2012b) summarized in
Section A.9.3 ( Table 3 ) predict that there is a 4 % probability that an oil spill from the lease area would reach a shoreline designated as critical habitat for the Piping Plover within 10 days. Plovers could ph ysically oil themselves while foraging on oiled shores or secondarily
contaminate themselves t hrough ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and feed along tidally exposed banks and shorelines, following the tide out and foraging at the water’s edge. It is possible that some deaths of Piping Plovers could occur, especially if spills occur during winter months when p lovers are most common along the coastal Gulf or if spills contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other activities associated with spill clea nup. Anadarko has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as
detailed in the OSRP.



### C.3.7 Whooping Crane (Endangered)

The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild populations in North America (Whooping Crane Eastern Partnership, 2010). One population winters along the Texas coast at Aransas NWR and
summers at Wood Buffalo National Park in Canada ; t his population re presents the majority of the world’s population of free

- ranging Whooping Cranes and reached a record population of
270 at Aransas NWR in December 2008 (Whooping Crane Eastern Partnership, 2010).

A non migrating population has been reintroduced in central F lorida, and another reintroduced population summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species

. A species description is presented in MMS ( 2007b ) and BOEM (2012a ). A large oil spill (WCD) is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would be unlikely to affect Whooping Cranes, due to the
distance from Aransas NWR. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

.


### Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately

356 miles (573 km) from its critical habitat designated in the Aransas NWR . T he revised

OSRA modeling (BOEM, 2012b) predicts that there is a 0.5 % or less probability that an oil spill originating in the lease area would reach the Aransas NWR within 30 days and a 5% probability of oil reaching that area in 120 days.

In the event of oil exposure, Whooping Cranes could physically oil themselves while foraging in oiled areas or secondarily contaminate themselv es through ingestion of contaminated shellfish, frogs, and fishes . It is possible that some Whooping Crane deaths could occur. In the event of a spill, Anadarko would work with the applicable State and Federal agencies to prevent impacts from a spill

.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 45 

### C. 3. 8 Gulf Sturgeon (Threatened)

The Gulf sturgeon ( Acipenser oxyrinchus desotoi ) is a threatened fish species that inhabits major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida (Barkuloo, 1988; Wakeford, 2001). An a nadromous fish that migrates from the sea upstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Sulak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from Lake Borgne, Louisiana (St. Bernard Parish) , t o Suwannee Sound, Florida (Levy County) (NMFS, 2010 b) ( Figure 3 )

. A species description is presented MMS ( 2007b) and in the recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995)

.
A large oil spill (WCD) is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to make landfall or reach coastal waters prior to brea king up (see explanation in

Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on Gulf sturgeon are discussed in MMS ( 2007b ) and BOEM ( 2012 a, b ) and by NMFS (2007)

. For this EP , there are no unique site

- specific issues with respect to this species.

The lease area is approximately 202 miles (325 km) from the nearest Gulf sturgeon critical
habitat. The revised OSRA modeling (BOEM, 2012b) predicts tha t a spill in the lease are a has

1% or less probability of contacting any coastal areas inhabited by Gulf sturgeon within

30 or 120 days.

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills.
Based on t he life history of this species, subadult and adult Gulf sturgeon would be most vulnerable to an estuarine or marine oil spill, and would be vulnerable only from

1 September through 30 April when this species is foraging in estuarine and shallow marine
hab itats (NMFS, 2007).



### C.3.9 S malltooth S awfish (Endangered)

Smalltooth sawfish ( Pristis pectinata ) are found in the tropical and subtropical Atlantic Ocean.
In the W estern Atlantic they have historically ranged from New York to Brazil, including the Gulf of Mexico and Caribbean Sea. This sawfish primarily occurs in estuarine and coastal habitats such as bays, lagoons, and rivers. The smalltooth sawfish was listed as endangered under the

ESA on 1 April 2003. Its critical habitat consists of two units: the Charlotte Harbor Estuary Unit, which comprises approximately 89,621 ha (221,459 ac ) of coastal habitat; and the Ten Thousand Islands/Everglades Unit, which comprises approximately 250,506 ha ( 619,013 ac ) of coastalGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 46 habitat. The two units are located along the southwestern coast of Florida between Charlotte Harbor and Florida Bay.

A large oil spill (WCD) is the only IPF potentially affecting smalltooth sawfish

. Ther e are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect smalltooth sawfish because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine species in MMS ( 2007b ), BOEM ( 2012a )

, and by the NMFS (2007) in its Biological Opinion. For this EP , there are no unique site

- specific issues with respect to smalltooth sawfish

.
In the event of oil reaching smalltooth sawfish habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the a bsorption of dissolved petroleum products through the gills.



### C.3. 10 Beach Mice (Endangered)

Four subspecies of endangered beach m ouse ( Peromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctaw h atchee,
Perdido Key, and St. Andrew beach mice. Critical habitat has been designated for all four subspecies ; Figure 3 shows the critical habitat combined for all four subspecies . Species descriptions are provided in MMS ( 2007b).

A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs associated with routine project activities that could affect these animals due to the distance from shore and the lack of any onshore support activities near their habitat. A small fuel spill in
the lease area would not affect beach mice because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on beach mice are discussed in MMS ( 2007b, 2008 ), BOEMRE ( 2011a ),
and BOEM ( 2012a ). For this EP , there are no unique site

- specific issues with respect to these species that were not analyzed in these documents

.

The beach mouse habi tat is 273 miles (439 km) from the lease area. The revised OSRA modeling
summarized in Section A.9.3 predicts that a spill in the lease area has a 1 % or less probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 1 20 days.

In the event of oil contacting these beaches, beach mice could experience several types of direct and indirect impacts. Contact with spilled oil could cause skin and eye irritation and subsequent infection; matting of fur; irritation of sweat gla nds, ear tissues, and throat tissues; disruption of sight and hearing; asphyxiation from inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fo uling of nests. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup. However, any such impacts are unlikely due to the distance from shore and response actions that would occur in the event of a spill.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 47 

### C.3.1 1 Elkhorn Coral (Endangered)

Elkhorn coral ( Acropora palmata ) is found primarily in shallow waters with temperatures ranging
between 26°C and 30°C (79 °F and 86°F) and significant water movement. Elkhorn coral was

once one of the most abundant coral species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep in tropical and subtropical waters. In the northern Gulf of Mexico , e lkhorn coral has been found within the coral cap region of the Flower Garden Banks National Marine Sanctuary ( Flower Garden B anks National Marine Sanctuary , 2011).

There are no IPFs associated with routine project activities that could affect this species in the
northern Gulf of Mexico

. A small fuel spill would not affect elkhorn coral colonies because the oil would float and dissipate on the sea surface. A WCD would be unlikely to affect the coral cap region of the Flower Garden Banks because of the water depth of the area. A lthough subsurface plumes were reported following the Macondo spill, these plumes resulted from the

us e of subsea dispersant s at the seafloor.



## C.4 Coastal and Marine Birds

C.4.1 Marine Birds

Marine birds include seabirds and other species that may occur in the pelagic environment of the project area (Clapp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives offshore over the open ocean, except during breeding season when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and shorebird s may occasionally be present over open ocean areas. No endangered or threatened bird species are likely to occur at the project area due to the distance from shore. For a discussion of sh orebird s and coastal nesting birds, see Section C.4.2

.
Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that terns, storm

- petrels, shearwaters, and jaegers were the most frequen tly sighted seabirds in the deepwater area. From these surveys, f our ecological categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants (shearwaters, storm petrels, boobies); summer residents that breed in the Gulf (Soot y Tern, Least Tern, Sandwich Tern, Magnificent Frigatebird); winter residents (gannets, gulls, jaegers); and permanent resident species (Laughing Gulls, Royal Terns, Bridled Terns) (Hess and Ribic, 2000). The GulfCet II study did not estimate bird densiti es; however, Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2

.
The distributions and relative densities of seabirds within the deepwater areas of the Gulf of

Mexic o, including the project area, vary temporally (i.e., seasonally) and spatially. In GulfCet II studies, species diversity and densities varied by hydrographic environment and by the presence and relative location of mesoscale features such as Loop Current eddies that may enhance nutrient levels and pr oductivity of surface waters where these seabird species forage ( Hess and
Ribic

, 2000 ).

Trans

- Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be present in the lease area. Migrant birds may use offshore structures and rigs for resting, feeding, or as temporary shelter from inclement weather (Russell, 2005). Some birds may be attracted to offshore structures because of the lights and the fish populations that aggregate
around these structures.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 48 IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on t he birds due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these animals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for
marine debris

- related impacts on birds.



### Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent rig s may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over
water have been known to strike offshore structures, resulti ng in death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant birds at tall towers and other land

- based structures has been reviewed extensively, and the mechanisms involved in rig collisions appear to be similar. In some cases, migrants simply do not see a part of the rig until it is too late. In other cases, navigation may be disrupted by noise (Russell, 2005). On the other hand, offshore structures are suitable stopover habitats for most trans

- Gulf migrant species, and most of the migrants that stop over on rigs probably benefit from their stay, particularly in spring (Russell, 2005). Due to the limited scope and short duration of drilling activities described in this EP, any impacts on p opulations of either seabirds or trans

- Gulf migrant birds are not expected to be significant.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open,
offshore waters. It is likely that individual birds would experience, at most, only short

- term behavioral disruption

, and the impact would not be significant.



### Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in MMS ( 2007b ) and BOEM ( 2012 a,b ,d ).

F or this EP , there are no unique site

- specific issues with respect to spill impacts on these
animals.

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could reduce the potential for impacts on marine and pelagic birds.

EP Section H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of
toxic fumes. Due to the limited areal extent and short dura tion of water quality impacts from aGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 49 small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abundance are unlikely. Due to the low densities of birds in open ocean areas, the small area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine and pelagic birds are discussed in MMS ( 2007b ) and BOEM ( 2012 a,b ,d ). For this EP , there are no unique site

- specific issues with respect to spill impacts on
these animals.

BOEM has reexamined the analys e s for coastal and marine birds presented in MMS (2007b, 2008) and determined that no new information was found that would alter the potential imp act s on marine and pelagic birds ( BOEMRE, 2011 a ; BOEM, 2012 b ).

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) reported that terns, storm

- petrels, shearwaters, and jaegers were the most frequently sighted

s eabirds in the deepwater Gulf of Mexico (>200 m [<656 ft] ). Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2 . The number of pelagic birds that could be affected in open, offshore waters would depend on the extent and persistence of
the oil slick.

Data collected following t he Macondo spill provide d relevant information about the species of pelagic birds that may be affected in t he event of a large oil spill . Birds that have been treated for oiling include several pelagic species such as the Northern Gannet

, Magnificent Frigatebird,
and Masked Booby ( USFWS, 2011 ). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.



### C.4.2 Shorebird s and Coastal Nesting Birds

Threat ened and endangered bird species (Piping Plover and Whooping Crane) have been discussed previously in Section C.3 . Various species of non

- endangered birds are also found along the northern Gulf C oast, including diving birds, shorebird s, marsh birds, wadin g birds, and
waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that breed on beaches, flats, dunes, bars, barrier islands, and similar habitats include the Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull

- Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in MMS ( 2007b ) and BOEM ( 2012a ).

The Brown Pelican ( Pelecanus occidentalis ) was delisted from Federal endangered stat us in 2009 (USFWS, 2010c). However, this species remains listed as endangered on the Louisiana list of Endangered Species (Louisiana Department of Wildlife and Fisheries, 2013), is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 20 05 ), and a s a species of special concern by the State of Florida (Florida Fish and Wildlife Conservation Commission, 2011). Brown Pelicans inhabit coastal habitats and forage within b oth coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, including GulfCet and GulfCet II, indicate that Brown Pelicans do not occur in deep offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans live s in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010 b ).Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 50 The Southern Bald Eagle ( Haliaeetus leucocephalus ) was delisted from its threatened status in
the lower 48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed across the southern U.S., including coastal habitats along the Gulf of Mexico. The Gulf C oast is inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 19 90; Ehrlich et al., 1992).

IPFs potentially affecting shorebird s and coastal nesting birds include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely
to affect shorebird s or coastal ne sting birds , due to the lease area’s distance from the nearest
shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on shorebirds.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas n ear Port Fourchon and Houma, Louisiana, where shorebird s and coastal nesting birds may be found. These activities could periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).

Vessel traffic may disturb some foraging and re sting birds. Flushing distances vary between species and between individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds away from vessel pathways; known distances are from 20 to 49 m (65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 ft) for an outboard

- powered boat (Rodgers and Schwikert, 2002). Flushing distances may be similar or less for the support
vessels to be used for Anadarko ’s project, and some species such as gulls are attracted to boats.

S upport vessels will not approach nesting or breeding areas on the shoreline, so disturbances to nesting birds, eggs, and chicks are not expected. Vessel operators will use designated navigation channels and comply with posted speed and wake restrictions w hile transiting sensitive inland
waterways. Due to the limited scope and short duration of drilling activities, any short

- term impacts are not expected to be biologically significant to coastal bird populations.

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly dependent on the type of aircraft, the bird species, the activities that animals were previously engaged in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most intense responses over other human disturbances for some species (Bélanger and Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91

- 36D recommends that pilots maintain a minimum altitude of 610 m (2,000 ft) when flying o ver noise

- sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. This is greater than the distance (slant range) at which aircraft overflights have been reported to cause behavioral effects on most species of birds stu died (Efroymson et al., 2000). With these guidelines in effect, it is likely that individual birds would experience, at most, only short

- term
behavioral disruption.



### Impacts of Large Oil Spill (WCD)

Coastal birds can be exposed to oil as they float on the water surface, dive during foraging, or wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 2010 e ). Oil interferes with the water repellency
of feathers and can cause hypothermia in the right conditions. As birds groom themselves, theyGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 51 can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be exposed to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an oiled adult sits on the nest.

As noted above, the Brown Pelican was recently removed from the Federal en dangered species list. Brown Pelicans are especially at risk from direct and indirect impacts from spilled oil within inner shelf and inshore waters, such as embayments . The range of this species is generally limited to these waters and surrounding coast al habitats. Brown Pelicans feed on mid

- sized fish that they capture by diving from above (“plunge diving”) and then scooping the fish into their expandable gular pouch. This behavior makes them susceptible to plumage oiling if they feed in areas with surface oil or an oil sheen. They may also capture prey that has been physically contaminated with oil or has ingested oil. Issues for Brown Pelicans include direct contact with oil, disturbance by cleanup activities, and long

- term habitat contamination. The Bald Eagle may also be at risk from direct and indirect impacts from spilled oil. This species often captures fish within shallow water areas (snatching prey from the surface or wading into shallow areas to capture prey with their bill) and so may be susceptible to plumage oiling and, as with the Brown
Pelican , they may also capture prey that has been physically contaminated with oil or has ingested oil.



## C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) revi ewed the biology of pelagic communities in the deepwater environment of the northern Gulf of Mexico. The biological oceanography of the region is dominated by the influence of the Loop Current, whose surface waters are among the most oligotrophic in the w orld’s oceans. Superimposed on this low

- productivity condition are productive “ hot spots ” associated with entrainment of nutrient

- rich Mississippi River water and mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an

i mportant role in determining biogeographic patterns and controlling primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the planktonic community for various lengths of time (10 to 100 days, depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents –a small fuel spill and a large oil spill ( WCD).



### Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish

- attracting device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfi shes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994 ; MMS, 2000, 2007b,

2008 ). This FAD effect could possibly enhance the feeding of epipelagic predators by attrac tingGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 52 and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or adverse, are considered minor.



### Impacts of Effluent Discharges

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic matter, and chlorine, but should be diluted rapidly to undetectable levels within tens to
hundred s of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. Deck drainage from contaminated areas wi ll be passed through an
oil

- and

- water separator prior to release, and discharges will be monitored for visible sheen. The discharges may have slightly elevated levels of hydrocarbons but should be diluted rapidly to
undetectable levels within tens to hund reds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water

, are expected to be diluted rapidly and have little or no impact on water column biota.



### Impacts of Water Intakes

Seawater will be drawn from the ocean for once

- through, non

- contact cooling of machinery

on the drilling rig. The drilling rig ultimately chosen for this project will be in compliance with all

coo ling water intake requirements.

The intake of seawater for cooling water will entrain plankton. The low

- intake velocity should allow most strong

- swimming juvenile fishes and smaller adults to escape entrainment or impingement. However, drifting plankton would not be able to escape entrainment with the exception of a few fast

- swimming larvae of certain taxonomic groups. Those organisms entrained may be stressed or killed, primarily through changes in wa ter temperature during the route from cooling intake structure to discharge structure and mechanical damage (turbulence in pumps and condensers). Due to the limited scope and short duration of drilling activities , any short

- term impacts of entrainment are not expected to be biologically significant to plankton or ichthyoplankton populations.



### Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resource s are discussed in MMS ( 2007b ) and

BOEM ( 2012a, d). F or this EP , there are no unique site

- specific issues with respect to spill impacts.

The probability of a fuel spill will be minimized by Anadarko’ s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP co uld mitigate the potential for impacts on pelagic communities

, including ichthyoplankton. EP Section H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 53 A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 ho urs. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton.

Due to the limited areal extent and short duration of water quality impacts, a small fuel spill would be unlikely to produce detectable impacts on pelagic communities.



### Impacts of a Large Oil Spill (WCD)

A large oil spill could affect water column biota

, including phytoplankton, zooplankton, ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more likely to affect these communities. While adult and juvenile fishes may actively avoid a large spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes are especially vulnerable to oiling because they inhabit the upper layers of the water column and will die if exposed to certain toxic fractions of spilled oil. Impacts potentially would be greater if
local

- scale currents retained planktonic larval assemblages (and the floating oil slick) within the

same water mass.



### C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for spawning, breeding, feeding, and growth to maturity. Under the Magnuson

- Stevens Fishery Conservation and Management Act, as amended, Federal agencies are required to consult on activities that may adversely affect EFH designated in Fishery Management Plans developed by the regional Fi shery Management Councils.

The BOEM (201 2b ) has reexamined the analysis for fish resources and EFH presented in MMS ( 2007a,b) in consideration of the Macondo event. No substantial new information was found that would alter the impact conclusions for fish resources and EFH presented in MMS (2007a,b)

.
The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Mana gement Plans for corals and coral reefs, shrimp s , stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). T he EFH
for most of these GMFMC

- managed species is on the continental shelf in waters shallower than

183 m (600 ft). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, and shrimps

. EFH for coral s and coral reefs includes some shelf

- edge topographic
features on the Texas

- Louisiana OCS, the nearest of which are

, located approximately 61 miles (98 km) northwest of the lease area

.
Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the lease area include the following species and life stages (NMFS, 2009):Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 54 • Atlantic bluefin tuna (spawn, eggs, larvae, adults)

• Bigeye tuna (juveniles, adults)

• Bigeye thresher shark (all)

• Blue marlin (juveniles, adults)

• Longbill spearfish (juveniles, adults)

• Longfin mako shark (all)

• Oceanic whitetip shark (all) • Sailfish (adults)

• Silky shark (all)

• Skipjack tuna (spawn, adul ts)

• Swordfish (larvae, juveniles, adults)

• Whale shark (all)

• White marlin (juveniles, adults)

• Yellowfin tuna (spawn, juveniles, adults)

Recent research indicates the central and western Gulf of Mexico may be important spawning
habitat for Atl antic bluefin tuna, and NMFS (2009) has designated a Habitat Area of Particular Concern (HAPC) for this species. The HAPC covers much of the deepwater Gulf of Mexico, including the lease area ( Figure 3 ). The areal extent of the HAPC is approximately 300, 000 km 2 (15,000 mi 2 ). The prevailing assumption is that Atlantic bluefin tuna follow an annual cycle of foraging in June through March off the eastern U.S. and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in Apr il, May, and June ( NMFS, 2009).

On 27 May 2011, after an extensive scientific review, NOAA announced that Atlantic bluefin tuna currently do not warrant species protection under the ESA

. However, NOAA did classify
the bluefin tuna as a species of concern, effectively placing the species on a watch list as the agency awaits new data on the impact of a stricter international management regimen

.

A new amendment to the original EFH Generic Amendment was finalized in 2005 (GMFMC, 2005). One of the most significant proposed changes in this amendment reduced the extent of EFH relative to the 1998 Generic Amendment by removing the EFH description and
identification from waters between 100 fathoms and the seaward limit of the Exclusiv e Economic Zone ( EEZ )

. The Highly Migratory Species Fisheries Management Plan was amended

in 2009 to update EFH and HAPC to include the bluefin tuna spawning area ( NMFS , 2009).

There are current NTLs (2009

- G39 and 2009

- G40) that provide guidance and clari fication of the regulations with respect to biologically sensitive underwater features and areas and benthic

communities that are considered EFH (MMS, 2009 a,b ). A new EFH consultation has been initiated between BOEM’s Gulf of Mexico Region and NOAA’s Sout heastern Region. Some

EFH requirements may change with the new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation with the elements described a bove will be followed ( BOEMRE, 2011 a ; BOEM, 2012 b ).

Other HAPCs have been ident ified by the GMFMC (2005). These include the Florida Middle Grounds, Madison

- Swanson Marine Reserve, Tortugas North and South Ecological Reserves, Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The nearest HAPC is Jakkula Bank

, located approximately 74 miles (119 km) from the
lease area

.
IPFs potentially affecting EFH include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents – a small fuel spill and a large oil spill (WCD).Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 55 

### Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a n FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes s uch as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994 ; MMS, 2000, 2007b, 2008 ). This FAD effect would possibly enhance feeding of epipe lagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, any impacts on EFH for highly migratory pelagic fishes are considered minor.



### Impacts of Effluent Discharges

Other effluent dis charges affecting EFH by diminishing ambient water quality include drilling muds and cuttings, treated sanitary and domestic wastes, deck drainage, and miscellaneous discharges such as desalination unit brine and uncontaminated cooling water, fire water, a nd ballast water. Impacts on water quality have been discussed previously. No significant impacts

on EFH for highly migratory pelagic fishes are expected from these discharges.



### Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, including fish eggs and larvae (ichthyoplankton). Due to the limited scope and short duration of drilling activities , any short

- term impacts on EFH for highly migratory pelagic fishes are not expected to be biolog ically significant.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could help diminish the potential for impacts on EFH. EP Section H provides
detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in MMS ( 2007b ) and BOEM ( 2012a, d)

. F or this EP

, there are no unique site

- specific issues with respect to spill impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and incre ase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A .9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The sea surface area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to

12 ac)

, depending on sea state an d weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the
lease area. A spill would also produce short

- term impact on water quality in the HAPC for spawning bluefin tuna, which covers much of the deepwater Gulf of Mexico. The areal extent of the affected area would represent a negligible portion of the HAPC.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 56 A small fuel spill would not affect EFH for corals and coral reefs, the nearest EFH located approximately 61 miles (98 km) from the lease area

. A small fuel spill would float and dissipate

on the sea surface and would not contact these features.



### Impacts of a Large Oil Spill (WCD)

Potential spill impact s on EFH are discussed in MMS ( 2007b ) and BOEM ( 2012a, d ). For this EP

, there are no unique site

- specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially in the subsurface as well. Given the extent of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species

, including shrimp s , stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse impacts on water quality and water col umn biota

, including phytoplankton, zooplankton, and nekton. In coastal waters, sediments could be contaminated and result in persistent degradation of the seafloor habitat for managed demersal fish and shellfish species.

T he lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009). A large spill could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water column, with the potential for lethal or sublethal impacts on spawning tuna. Potential impacts

wou ld depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

The topographic features

, located 61 miles (98 km) from the lease area are designated as EFH
under the corals and cora l reefs management plan. An accidental spill would be unlikely to
affect this area, since a surface slick would not reach these features due to their depth

.



## C.6 Archaeological Resources

C.6.1 Shipwreck Sites

The BOEM (201 2b ) reexamined the analys e s for archaeological resources presented in

MMS (2007b, 2008), b ased on additional information available since the publication of these
two documents and in consideration of the Macondo oil spill

. Substantial new information that alters the impact conclusion for archaeological resources presented in MMS (2007b, 2008) has come to light as a result of BOEM

- sponsored studies and industry surveys. Specifically, evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown to have occurred because of an incomplete knowledge of seafloor conditions in lease areas >200 m (656 ft) deep that have been exempted from high

- resolution surveys. Since significant historic shipwrecks have recently been discovered outside the previously de signated high

- probability areas (some of which show evidence of impacts from permitted activities prior to their discovery), a survey is now required for exploration and development projects.

The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks (BOEM, 2012c) and no man

- made features were identified within 600 m (2,000 ft) of any of the proposed wellsites during the site clearance surveys (Fugro, 2013). Anadarko will abide by t he applicable requirements of NTL 2005

- G07, which stipulate that work be stopped at the projectGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 57 site if any previously undetected archaeological resource is discovered after work has begun until appropriate surveys and evaluations have been completed.

Beca use there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. I mpacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not affect shipwrecks because the oil would float and dissipate on the sea surface.



### Impacts of a Large Oil Spill (WCD)

MMS (2007b) estimate d that a severe subsurface blowout could resuspend and disperse
sediments within a 300

- m (984

- ft) radius. Because there are no historic shipwrecks in the lease

area , this impact would not be relevant.

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact shipwreck sites beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrecks on the se afloor

, it could adversely affect their condition or preservation. Should there be any indication that potential shipwreck sites could be affected, in accordance
with NTL 2005

- G07 Anadarko will immediately halt operations, take steps to ensure that the si te is not disturbed in any way

, and contact the BOEM Regional Supervisor, Leasing and Environment, within 48 hours of its discovery. Anadarko would cease all operations within

305 m (1,000 ft) of the site until the Regional Supervisor provides instruction s on steps to take to assess the site’s potential historic significance and protect it.

A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. A s noted by MMS (2007b), should an oil spill contact a coastal historic site, such as a fort or a lighthouse, the major impact would be a temporary, reversible visual impact from
oil contact and contamination of the site and its environment.



### C.6.2 Prehistoric Archaeological Sites

Available evidence suggests that sea lev el in the northern Gulf of Mexico was at least 9 1 m ( 300 ft), and possibly as much as 130 m (427 ft), lower than present sea level during the period 20,000 to 17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern
Gulf reach ed its present stand around 3,500 years B.P. (Pearson et al., 1986).

During periods that the continental shelf was exposed above sea level, the area was open to habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is

c urrently accepted to be around 12,000 years B.P. (Aten, 1983). The sea

- level curve for the
northern Gulf of Mexico proposed by Coastal Environments, Inc. suggests that sea level at 12,000 years B.P. would have been approximately 45 to 60 m (148 to 197 ft) bel ow the
present

- day sea level (Coastal Environments, Inc.

, 1977

, 1982). On this basis, the contine ntal
shelf shoreward of the 45 - to 60

- m (148 - to 197

- ft) bathymetric contours has potential forGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 58 prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry date of prehistoric man into North America, the MMS adopted
the 60

- m (197

- ft) water depth as the seaward extent for archaeological site potential in Gulf of

Mexico region

.

With water depth s between 1,60 6 and 1,632 m (5, 268 and 5,355 ft)

, the lease area is well beyond the 60

- m (197

- ft) depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric

arc haeological sites are not found in the lease area, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archaeological resources because the oil would float and dissipate on the sea surface.



### Impacts of a Large Oil Spill (WCD)

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the physical effects of a subsea blowout. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius.

Along the northern Gulf C oast, prehistoric sites occur frequently along the barrier islands and mainland coast and along the margins of bays and bayous (MMS, 2007b). If a spill did reach a prehistoric site along these shorelines

, it could coat fragile artifacts or site features and compromise the potential for radiocarbon dating organic materials in a site (although other dating methods are available and it is possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could also be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features).



## C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities
are described in MMS ( 2007b ), BOEM ( 2012a,b, d), and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include barrier beaches and dunes,

wet lands, and submerged seagrass beds. Generally, most of the northeastern Gulf is fringed by barrier beaches, with wetlands and/or submerged seagrass beds occurring in sheltered areas
behind the barrier islands and in estuaries.

Due to the distance from sho re, the only IPF associated with routine activities in the lease area
that potentially may affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area relate to support vessel
traffic . The support bases at Port Fourchon and Houma, Louisiana

, are not in wildlife refuge s or wilderness area s . Potential impacts of support vessel traffic are addressed briefly below.

A small fuel spill in the lease area would be unlikely to affect coastal habitats due to the lease
area’s distance from the nearest shoreline

. A s explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



### Impacts of Suppor t Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inle ts, channels, and harbors. Support operations, including crew boats and supply boats as detailed in EP Section K

, may have a minorGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 59 incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restri ctions in harbors and channels.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on coastal habitats are discussed in MMS ( 2007b ) and BOEM ( 2012a,b, d ). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP , there are no unique site

- specific issues with respect to
coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that there is a 17% probability of oil from a spill in the lease area reaching Texas shorelines within 120 days, a 14% probability of oil from a spill in the lease area reaching Louisiana shorelines within 120 days, and a 1% chance of oil from a spill in the lease area reaching Mississi ppi shorelines within 120 days.

The shorelines within the geographic range predicted by the OSRA modeling ( Table 3 ) include extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered
areas behind the barrier islands and in estuaries. NWRs and other protected areas along the
coast are discussed in MMS ( 2007b ), BOEM ( 2012b ), and Anadarko’ s OSRP. Coastal and near
coastal wildlife refuges, wilderness areas , and State and National parks within the geographic range of the potential shoreline contacts after 120 days are presented in Table 6

.

Table 6. W ildlife refuges, wildernes s areas, and State and National parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEM , 2012 b).

County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Kenedy County, Texas Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Nueces County, Texas Laguna Madre Estuarine And Coastal Marine Area Mustang Island State Park Lake Corpus Christi State Park

Port Aransas Park

Mission

- Aransas National Estuarine Research Reserve

Aransas County, Texas Mission

- Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge

Goose Island State Park

Calhoun County, Texas Mission

- Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge Matagorda Island State Park Guadalupe Delta Wildlife Management Area

Welder Flats Coastal Preserve

Matagorda County, Texas Aransas National Wildlife Refuge Mad Island Wildlife Management Area Big Boggy National Wildlife Refuge San Bernard National Wildlife Refuge

Brazoria County, Texas San Bernard National Wildlife Refuge Peach Point Wildlife Management Area

Bra zoria National Wildlife Refuge Christmas Bay State Park Christmas Bay Coastal PreserveTable 6. (Continued).

Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 60 County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Galveston County, Texas Brazoria National Wildlife Refuge

Galveston Island State Park Apffel Park
Seawolf Park

Old Fort Travis Park Atkinson Island Wildlife Management Area

Ft. Anahuac Park Anahuac National Wildlife Refuge McFaddin National Wildlife Refuge Candy Abshier Wildlife Management Area Atkinson Island Wildlife Management Area

Chambers County, Texas Anahuac National Wildlife Refuge McFaddin National Wildlife Refuge

Jefferson County, Texas McFaddin National Wildlife Refuge
Sea Rim State Park Murphree Wildlife Management Area Texas Point National Wildlife Refuge

Cameron Parish, Louisiana Sabine National Wildlife Refuge Cameron Prairie National Wildlife Refuge Lacassine National Wildlife Refuge

Little Pecan Island Natural Area
Peveto Woods Natural Area Lower Neches Wildlife Management Area Rockefeller Wildlife Management Area

Vermilion Parish, Louisiana Rockefeller Wildlife Management Area Paul J. Rainey Wildlife Management Area

Iberia Parish, Louisiana Marsh Island Wildlife Management Area Cypremort Point State Park Shell Keys National Wildlife Refuge

St. Mary Parish, Louisiana Atchafalaya Delta Wildlife Management Area Bayoue Teche National Wildlife Refuge

Terrebonne Parish, Louisiana Atchafalaya Delta Wildlife Management Area Mandalay National Wildlife Refuge

Isles Dernieres Barrier Islands Refuge Point Au Chein Wildlife Management Area

Lafourche Parish, Louisiana Point Au Chein Wildlife Management Area Wisner Wildlife Management Area

Jefferson Parish, Louisiana Grand Isle State Park
Salvador Wildlife Management Area
Jean Lafitte National Historical Park and Preserve

Lafitte Woods Natural Area

Plaquemines Parish, Louisiana Salvador Wildlife Management Area

Jean Lafitte National Historical Park and Preserve Delta National Wildlife Refuge

Pass A Loutre Wildlife Management Area Breton National Wildlife Refuge
St. Bernard State Park

St. Bernard Parish, Louisiana Breton National Wildlife Refuge

St. Bernard State Park Biloxi Wildlife Management Area Bayou Sauvage National Wildlife RefugeTable 6. (Continued).

Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 61 County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Hancock and Harrison Counties, Mississippi Hancock County Coastal Marsh Reserve

Buccaneer State Park

Jourdan River Coastal Reserve
Biloxi River Coastal Reserve
Gulf Islands National Seashore Bayou Sauvage National Wildlife Refuge Big Branch Marsh National Wildlife Refuge Pearl River Wildlife Management Area

Wolf River Coastal Reserve Grand Bayou Coastal Preserve Bayou Portage Coastal Reserve
Biloxi Marshes State Coastal Preserve

Deer Island State Coastal Preserve

Jackson County, Mississippi Gulf Islands National Seashore Davis Bayou Coastal Preserve Mississippi Sandhill Crane National Wildlife Refuge Pascagoula River Coastal Reserve Grand Bay National Estuarine Research Reserve Grand Bay National Wildlife Refuge

Grand Bay Savannah Coastal Preserve

Deer Island State Coastal Preserve Old Fort Bayou Coastal Reserve
Bellefontaine Point Coastal Reserve Graveline Bay Coastal Reserve

Mobile County, Alabama Grand Bay National Wildlife Refuge The Grand Bay Savanna Tract
Penalver State Park Bon Secour National Wildlife Refuge W.L. Holland Wildlife Management Area

Baldwin County, Alabama Bon Secour National Wildlife Refuge

Meaher State Park Weeks Bay National Estuarine Research Reserve
Gulf State Park Lillian Swamp Mitigation Area Tarklin Bayou State Preserve W.L. Holland Wildlife Management Area

Escambia County, Florida Perdido Key State Recreation Area Big Lagoon State Recreation Area Fort Pickens State Park Aquatic Preserve
Gulf Islands National Seashore Pensacola Bay SWIM Area Yellow River Wildlife Management Area

Okaloosa County, Florida Gulf Islands National Seashore Pensacola Bay SWIM Area Choctawatchee Bay SWIM Area

Walton County, Florida Choctawatchee Bay SWIM Area
Henderson State Park Point Washington Outstanding Florida Water

Walton County, Florida (Continued) Deer Lake State Park Grayton Beach State Park Outstanding Florida Water St. Andrew Bay Watershed SWIM AreaTable 6. (Continued).

Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 62 County or Parish, State W ildlife Refuge, Wilderness Area, or State/National Park

Bay County, Florida Point Washington Outstanding Florida Water St. Andrew Bay Watershed SWIM Area St. Andrews State Park Aquatic Preserve
St. Andrews State Park

Gulf County, Florida St. Andrew Bay Watershed SWIM Area St. Joseph Peninsula State Park St. Joseph Bay State Buffer Preserve

Franklin County, Florida St. Vincent National Wildlife Refuge Apalachicola National Estuarine Research Reserve Apalachicola Bay Aquatic Preserve Outstanding Florida Water Apalachicola River and Bay SWIM Area Apalachicola River Wildlife and Environmental Area St. George Island State Park

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil

- and

- water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the time of landfall. Oil that remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths und er the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manually, mechanically, or both. Some oil can rema in on the beach at varying depths and may persist for several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 2.7 ha (6.7 ac ) of wetland vegetation will experience dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the contacted wetlands are expected to be converted permanently to open

- water habitat. The critical concentration of oil is that concentration above which impacts to wetlands will be long

- term and recovery will take longer than two growing seasons, and which causes plant mortality and some permanent wetland loss. Critical
concentrations of various oils are expected to vary broadly for wetland types and wetland plant species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direc t impacts of oil, cleanup activities in marshes may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b ; BOEMRE, 2011a; BOEM, 2012b ).



## C.8 Socioeconomic and Other Res ources

C.8.1 Recreational and Commercial Fishing

BOEM has reexamined the analysis for recreational and commercial fishing presented in

MMS (2007b, 2008) based on additional information and in consideration of the Macondo spill.

N o new information was foun d that would alter the potential impact s on commercial fishing ( BOEMRE, 2011 a ; BOEM, 2012 b).Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 63 The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and

summer

.
Longline gear consists of monofilament line deployed from a moving vessel and generally allowed to drift for 4 to 5 hours (Continental Shelf Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are clipped in place at regular intervals. It takes 8 to 10 hours to deploy a longline and about the same time to retrieve it. Longlines are often set near oceanographic features such as fronts or downwellings, w ith the aid of sophisticated on board temperature sensors, depth finders, and positioning equipment. Vessels typically are 10 to 30 m (33 to 98 ft) long, and their trips last from about 1 to 3 weeks. The main Gulf of Mexico homeports for longlining vessels are in Louisiana (Dulac and Venice) and Florida (Destin, Madeira Beach, and Panama City).

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area . Benthic species targeted by commercial fishers occur on the upper continental slope, well inshore of the project area. Royal red shrimp ( Pleoticus robustus ) are caught by trawlers in water depths of about 250 to 550 m (820 to 1,804 ft). Tilefish es (primarily Lophalotilus chamaeleonticeps ) are caught by bottom longlining in water depths from about

165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).

Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum rig s offshore Texas and Louisiana. Due to the distance from shore, it is unlikely that recreational fishing activity is occurring in the lease area.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and lights)

. T wo types of potential accidents are also addressed below – a small fuel spill and a large oil spill ( WCD).



### Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For example, in January 1999, a portion of a pelagic longline snagged on the acoustic Doppler current profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The line was removed without incident. Generally, longline fishers use radar and are aware of offshore structures and ships when placing their sets. Therefore, little or no impac t on pelagic longlining is expected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts are anticipated. Other factors such as effluent discharges are likely to have negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could potentially mitigate and reduce the potential for impacts

. EP Section HGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 64 provide s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small fuel spill. The sea surfac e area with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of response vessels operating in the lease area. A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on fishing activities are discussed i n MMS ( 2007b ) and BOEM ( 2012b,d ).
For this EP , there are no unique site

- specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spill response measures. Data obtained following the Macondo spill provide d information about the maximum potential extent of fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010 d ). At its peak

on 12 July 2010, closures encompassed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the U.S. Gulf of

Mexico EEZ.



### C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health and safety. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.



### Impacts o f a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could potentially alleviate the potential for impacts. EP Section H provide s detail on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect only a small area of the open ocean 13 5 miles (21 7 km) from the nearest shoreline

, and nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with appropriate safety equipment to avoid injury and health effects.

A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

In the event of a large spill from a blowout, the main safety and health concerns are those of the offshore personnel involved in the incident and those responding to the spill. The drilling rig maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL 73/78.

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, meteorological and oceanographi c conditions at the time, and the effectiveness of spill response measures, the public could be exposed to oil on the water and along the shoreline, includingGreen Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 65 skin contact or breathing VOCs . Crude oil is a highly flammable material

, and any smoke or

vapor s from a crude oil fire can cause irritation, and in large quantities may pose a health
hazard.

Data obtained f ollowing the Macondo spill provide d relevant information about the types of health issues that may occur in the event of a large oil spill (Cente rs for Disease Control and Prevention, 2010a). Wildlife cleaning and rehabilitation workers have reported concerns

, including scrapes and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or b ack pain was also reported by some wildlife

- cleaning workers. Personnel working on offshore vessels or providing direct oversight to o ffshore vessels, including USCG personnel, civilian contractors, and other responders who were exposed to oil and dispers ants

, had a 7 to 12 times higher prevalence of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill response workers in general was heat stress from work in a hot and humid environment. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 S ( e.g., headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest p ain ) (Solomon and Janssen, 2010).



### C.8.3 Employment and Infrastructure

There are no IPFs associated with routine operations that are expected to affect employment and infrastructure. The project involves drilling with support from existing shorebase facilities in

Louisiana . No new or expanded facilities will be constructed, and no new employees are expected to move permanently into the area. The project will have a negligible impact on
socioeconomic conditions

, such as local employment, existing offshore and coastal infrastructure (including major sources of supplies, services, energy, and water), and minority and lower income groups. Impacts of a small fuel spill and a large oil spill (WCD) are addressed
below.



### Impacts of a Small Fuel Spill

The probabili ty of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could potentially mitigate and reduce the potential for impacts

. EP Section H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill that is dissipated within a few days would have little or no economic impact, as the spill response would use existing facilities, resources, and personnel.



### Impacts of a Large Oil Spill (WCD)

Potential socioeconomic impacts of an oil spill are discussed in MMS ( 2007b ) and

BOEM ( 2012a,b ,d ). For this EP , there are no unique site

- specific issues with respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of work; it c ould result in temporary employment as part of the response effort; it could result in adverse publicity that affects employment in coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, including s ervice and support operations that are an important part of local economies.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 66 In addition to the analys e s presented by MMS (2007b, 2008 ) and BOEM (201 2b ), a recent study explored the economic impacts of the Macondo spill on oil and gas industry employment d ue to suspension of deepwater drilling (Inter

- Agency Economic Report, 2010). The study indicates that during the moratorium, the number of oil industry workers in the Gulf of Mexico fell by about 2,000 and may have indirectly caused a temporary loss of 8, 000 to 12,000 jobs along the Gulf Coast. Total spending by drilling operators is estimated to have declined by $1.8 billion

over a six

- month period; this direct reduction in spending affected employment in the industries that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business spending (Inter

- Agency Economic Report, 2010)

.



### C.8.4 Recr eation and Tourism

BOEM has reexamined the analys e s for recreation and tourism presented in MMS (2007b, 2008)
based on additional information and in consideration of the Macondo oil spill event. No new information was found that would alter the potential impact s on recreation and tourism ( BOEMRE, 2011 a ; BOEM, 2012 b ).

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by any routine activities due to the distance from shore.

Co mpliance with NTL 2012

- BSEE

- G01 will minimize the chance of trash or debris being lost overboard from the drilling rig and subsequently washing up on beaches.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s pre ventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP could potentially help mitigate and reduce the potential for impacts.

EP Section H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are no known recreational or tourism activities occurring in the lease area and

, as explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



### Impacts of a Large Oil Spi ll (WCD)

Potential impacts of an oil spill on recreation and tourism are discussed in MMS ( 2007b ) and

BOEM ( 2012a ,b,d ). For this EP , there are no unique site

- specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreation and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourages people to stay away. Based on the revised OSRA modeling (BOEM, 2012b) as summarized in Section A.9.3 ( Table 3 ), there is a

12 % probability of oil from a spill in the lease area reaching shorelines in Louisiana within

30 day s and a 17 % chance of oil contacting shorelines in Texas within 120 days.

In addition to the analysis presented by MMS (2007b ; BOEMa,b,d), recent and ongoing studies have explored the economic impacts of the Macondo spill

, including tourism and “ brand ”Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 67 damage (IEM, 2010; Oxford Economics, 2010). The U.S. Travel Association has estimated the economic impact of the Macondo spill on tourism across the Gulf Coast over a 3- year period at $22.7 billion (Oxford Economics, 2010)

.



### C.8.5 Land Use

Land use along the northern Gulf C oast is discussed in MMS ( 2007b ) and BOEM ( 2012a,b ,d ). There are no routine IPFs potential ly affecting land use. The project will use existing onshore support facilities in Louisiana . The land use at the existing shorebase sites is ind ustrial. The project will not involve any new construction or changes to existing land use and, therefore, will not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal resources, will represent a small fraction of the level of activity occurring at the shorebase s.

A large oil spill (WCD) is the only relevant IPF. A small fuel spill would not have any impacts on land use, as the response would be staged out of existing shorebases and facilities.



### Impacts of a Large Oil Spill (WCD)

The initial response for a large oil spill would be staged out of existing facilities, with no effect on land use. A large spill could have limited temporary impacts on land use along the coast if
additional staging areas were needed. For example, d uring the Macondo spill, temporary staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging areas could be needed. These areas would eventually return to their original use as the response is demobilized.



### C.8.6 Other Marine Uses

The lease area is located within Military Warning Area W

- 92

. Anadarko will comply with BOEM requireme nts and lease stipulations to avoid impacts on uses of the area by military vessels and
aircraft.

There are no IPFs from routine project activities that are likely to affect other marine uses of the lease area. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have any impacts on other marine uses because spill response activities would be mainly within
the lease area and the duration would be brief.



### Impacts of a Large Oil Spill (WCD)

An accidental spill would be unlikely to significantly affect shipping or other marine uses

. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. Anadarko will comply with BOEM requirement s and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be required to ensure that no anchoring or seafloor

- disturbing activities occur near the existing pipelines and flowlines.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 68 

## D. Environmental Hazards

D.1 Geologic Hazards

The site clearance survey s conducted by Fugro (2013) con cluded that the wellsites are free of any significant geological hazards and are suitable for the pr opose d activities. See EP Section C for supporting geological and geophysical information.



## D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed activities. Extreme weather, including high winds, strong c urrents, and large waves, was considered in the design criteria for the drilling rigs under consideration for this project . High winds and limited visibility during a severe storm could disrupt support activities (vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety
reasons until the storm or weather event passes. In the event of a hurricane, procedures as
outlined in the Hurricane Evacuation Plan would be adhered to.



## D.3 Currents and Waves

Metocea n conditions such as sea states, wind speed, ocean currents, etc. will be continuously
monitored. Under most circumstances, physical oceanographic conditions are not expected to have any effect on the proposed activities. Strong currents (e.g., caused by Loop Current eddies and intrusions) and large waves were considered in the design criteria for the drilling rig under consideration for this project. High waves during a severe storm could disrupt support activities (i.e., vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes.



## E. Alternatives

N o formal alternatives we re evaluated in this EIA for an EP . However, various technical and operational opti ons , including the location of the wellsite s and the selection of a drilling unit, were considered by Anadarko in developing the proposed action.



## F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and

BOEM lease stipulations and NTLs. The project will comply with all applicable F ederal, S tate, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under guidance by Anadarko ’s OSRP and will
include the measures described in EP Section H

.Green Canyon Blocks 859 and 903 October 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 69 

## G. Consultation

No persons or agencies were consulted during the preparation of thi s EIA.



## H. Preparers

The EIA was prepared by CSA Ocean Sciences Inc. Contributors included :

• M. John Thompson (Senior Scientist);

• John M. Tiggelaar II (Project Scientist);

• Keith VanGraafeiland (Geospatial Manager) ;

• Kevin Noack (Geospatial Coordinator) ;

• Kristen L. Metzger (Library and Information Services Director);

• Leslie Ann Weekes (Technical Editor) ; and

• Kim Dunleavy (Technical Editor)

.



## I. References

Ackleh, A., G.E. Loup, J.W. Loup, B. Ma, J.J. Newcomb, N. Pal, N.A. Sidorovskaia, and C. Tiemann. 2012. Assessing the Deepwater Horizon oil spill impact on marine mammal population through acoustics: Endangered sperm
whales. J. Acoust. Soc. Am. 131(3) : 2, 306 -2, 314.
Anderson, C.M. and R.P. LaBelle. 2000. Update of comparative occurrence rates for offshore oil spills. In: Spill Science & Technology Bulletin, Vol. 6, No. 5/6, pp. 303

- 321. Elsevier Science Ltd., PII: S1353

- 2561(01)

00049

- 4. U.S. Mineral s Management Service, Herndon, VA. Antonio, F.J., R.S. Mendes, and S.M. Thomaz. 2011. Identifying and modeling patterns of tetrapod vertebrate mortality rates in the Gulf of Mexico oil spill. Aquatic Toxicology 105(1

- 2):177

- 179.
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### O ADMINISTRATIVE INFORMATION

(a) Proprietary Information

Proprietary copies of this plan contain inform ation not available to the public and include structure maps, seismic information, cross sections, depths of wells, etc.

(b) Bibliography

Shallow Hazards Report Final Sale Package for Central Gulf of Mexico Sale Number 182.