Exxon Mobil Corporation

Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

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Revision 7 Appendix H – 110 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

Revision 7 Appendix H – 111 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

Revision 7 Appendix H – 113 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

Revision 7 Appendix H – 115 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

Revision 7 © The Response Group 6/2011

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Regional Oil Spill Response Plan –

Offshore Operations

Appendix H

Worst Case 

Discharge Scenarios

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SECTION 10: Environmental Monitoring Information 

Monitoring Systems 

A rig based Acoustic Doppler Current Profiler (ADCP) is used to continuously monitor the current beneath the Rig. 

Metocean conditions such as sea states, wind speed, ocean currents, etc. will also be continuously monitored 

Incidental Takes 

No incidental takes are anticipated. ExxonMobil implements the mitigation measures and monitors for incidental takes of 

protected species according to the following notices to lessees and operators from the Minerals Management Service: 

 NTL 2007-G03 “Marine Trash and Debris Awareness and Elimination”

 NTL 2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting”

 Flower Garden Banks National Marine Sanctuary 

The operations proposed in this REP will not be conducted within the Protective Zones of the Flower Garden Banks and 

Stetson Bank. 

SECTION 11: Lease Stipulations Information 

Lease OCS-G 21447 is not part of a Biological Sensitive Area, known Chemosynthetic Area, or Shipping Fairway. It is not on the 

list of areas that the BOEM has identified as having a high probability for archeological resources. 

 Stipulation 8: Protected Species 

This Lease Stipulation assigned to Keathley Canyon Block 919 is to reduce the potential taking of federally protected species 

(e.g., sea turtles, marine mammals, Gulf sturgeon and other listed species). See Sections 6 and Section 12 of this REP. 

 Marine Protected Species 

BOEM has issued Notice to Lessees NTL 2007-G02 “Implementation of Seismic Mitigation Measures and Protected Species 

Observer Program”, NTL 2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting” and NTL 2007-

G03 “Marine Trash and Debris Awareness and Elimination” to reference measures to minimize or avoid potential adverse 

impacts to protected species (sea turtles, marine mammals, gulf sturgeon, and other federally protected species). See 

Sections 6 and Section 12 of this REP. 

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SECTION 12: Environmental Mitigation Measure Information 

Impacts to Marine and Coastal Environments 

The proposed action will implement mitigation measures required by laws and regulations, including all applicable Federal 

& State requirements concerning air emissions, discharges to water, and solid waste disposal, as well as any additional 

permit requirements and ExxonMobil policies. Project activities will be conducted in accordance with the Regional Oil Spill 

Response Plan. The EIA in Section 18 discusses impacts and mitigation measures. 

Incidental Takes 

We do not anticipate any incidental takes related to the proposed operations. ExxonMobil implements the mitigation 

measures and monitors for incidental takes of protected species according to the following notices to lessees and operators 

from the Minerals Management Service: 

NTL 2007-G03 “Marine Trash and Debris Awareness and Elimination”

NTL 2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting”

Note: ROV Mitigation was placed in the approval of Plan S-7330 to take ROV surveys for the next well drilled in the 

field. ExxonMobil has complied with this mitigation while drilling well F (Hadrian 5) in 2011. 

SECTION 13: Related Facilities and Operations Information 

Information regarding Related Facilities and Operations Information, transportation systems, & produced liquid hydrocarbon 

transportation vessels are not included in this REP as such information is only necessary in the case of DOCDs. 

 

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SECTION 14: Support Vessels and Aircraft Information 

General 

Type Maximum Fuel Tank 

Storage Capacity (Gals)

Maximum No. In Area at 

Any Time

Trip Frequency or 

Duration

Crew Boats 8,000 2 Twice per week

Offshore Support Vessels 120,000 3 Twice per week

Tug Boats 100,000 2 Once per rig move

Helicopter 764 1 Once per day

Diesel Oil Supply Vessels 

Size of Fuel Supply 

Vessel

Capacity of Fuel 

Supply Vessel

Frequency of Fuel 

Transfers

Route Fuel Supply Vessel Will 

Take

280 foot length 100,000 gals. 1 week Port Fourchon to KC 919

Drilling Fluids Transportation 

This information is only required for Eastern Gulf of Mexico. 

Solid and Liquid Wastes Transportation 

 See Table 7B. 

Vicinity Map 

See Attached. 

Public Information Copy
Lund

East Breaks Atwater Valley Garden Banks

Alaminos Canyon Keathley Canyon

Henderson

Mississippi Canyon

Lloyd Ridge

Destin Dome

De Soto Canyon

Amery Terrace Lund South Florida Plain

Mobile

Figure 14

Vicinity Map - Block Keathley Canyon 919

Fourchon

Range: 237mi

Bearing 27

Nearest Shoreline

Range: 216 mi

Bearing 19

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SECTION 15: Onshore Support Facilities Information 

General 

Name Location Existing/New/Modified

Fourchon Port Fourchon, LA Existing

The proposed surface disturbances in Keathley Canyon Block 919 for this Plan will be located approximately 216 miles from 

the nearest Louisiana shoreline, and approximately 237 miles from the onshore support base. ExxonMobil will use the Port 

Fourchon existing dock as support base. The Fouchon facility is located on Bayou Lafourche, south of Leesville, LA 

approximately 3 miles from the Gulf of Mexico. 

Support Base Construction or Expansion 

This Section does not apply to this EP as ExxonMobil does not plan to construct a new onshore support base or expand 

an existing one to accommodate the activities proposed in this EP. 

Support Base Construction or Expansion Timetable 

This Section does not apply to this EP as ExxonMobil does not plan to construct a new onshore support base or expand 

an existing one to accommodate the activities proposed in this EP. 

Waste Disposal 

See Tables 7A and 7B. 

Air emissions 

Not required by BOEMRE GOM. 

 Unusual solid and liquid wastes 

Not required by BOEMRE GOM. 

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SECTION 16: Sulphur Operations Information 

Information regarding Sulphur Operations is not included in this REP as such information is only necessary in the case of 

DOCDs. 

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SECTION 17: Coastal Zone Management Act (CZMA) Information 

LOUISIANA 

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

Revised EXPLORATION PLAN 

Type of Plan 

 

KEATHLEY CANYON BLOCK 919 (OCS-G 21447) 

 

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal Resources 

Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies. 

We have considered all of Louisiana's Enforceable Policies in making this certification of consistency. 

EXXON MOBIL CORPORATION

Operator 

_____________________________________________ 

Bryan L. Chapman 

Certifying Official 

 08/29/2011

Date 

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Page 40

SECTION 17: Coastal Zone Management Act (CZMA) Information 

LOUISIANA 

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

Revised EXPLORATION PLAN 

Type of Plan 

 

KEATHLEY CANYON BLOCK 919 (OCS-G 21447) 

 

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal Resources 

Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies. 

We have considered all of Louisiana's Enforceable Policies in making this certification of consistency. 

EXXON MOBIL CORPORATION

Operator 

_____________________________________________ 

Bryan L. Chapman 

Certifying Official 

 08/29/2011

Date 

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Section 18 - Environmental Impact Analysis (EIA) 

A. Impact-Producing Factors 

This Environmental Impact Analysis (EIA) evaluates the potential impacts of exploratory drilling in Keathley 

Canyon (KC) Block 919. The activities proposed in this Plan will be a DP semi-submersible (rig). 

Water depths in KC 919 range from about 6,900 to 7,400 ft. The lease is approximately 216 statute miles from 

the nearest shoreline (Louisiana). The air onshore support base for helicopters will be located in Port Fourchon, 

Louisiana, and the marine onshore support base for the work and crew boats will be the C-Port base in Port 

Fourchon, Louisiana. No new facilities or workers will be needed for the proposed activities. Helicopters and 

boats will move supplies and personnel between the offshore and onshore locations. Helicopters will make 

approximately 30 round trips per month. Work boats will make approximately 15 round trips per month, and crew 

boats will make approximately 5 round trips per month. Helicopters and boats will normally take the most direct 

route, traffic and weather conditions permitting. 

Table 1 is a matrix of impact-producing factors (IPFs) and potentially affected environmental resources. The 

table is based on the matrix provided by the Minerals Management Service (MMS). An “X” in a table cell indicates 

that an IPF could affect a certain resource, and a dash (--) indicates no impact or negligible impact. Where there 

may be an effect, an analysis is provided in EIA Section B. For those cells that are footnoted, a statement has been 

provided after the table as to the applicability of the proposed operations. 

The following IPFs applicable to the proposed activity have been identified: 

 Rig presence, noise, and lights; 

 Air pollutant emissions (from rig, support vessels, and helicopters); 

 Effluent discharges (drilling fluids and cuttings, sanitary and domestic wastes, deck drainage, etc.); 

 Marine debris; 

 Support vessel and helicopter traffic; and 

 Accidents (oil spills). 

Physical disturbance to the seafloor was determined not to be a relevant IPF for the proposed action because 

a DP semi will be used, with no anchoring or rig emplacement on the seafloor. This IPF was included in the matrix, 

but all of the entries in the column indicate no impact. 

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Table 1. Matrix of impact-producing factors and environmental resources. 

Environmental Resources

Impact-Producing Factors

Rig 

Presence, 

Noise, and 

Lights

Air 

Pollutant 

Emissions (rig, 

support vessels, 

and helicopters)

Effluent Discharges 

(drilling fluids and cuttings, 

sanitary and domestic 

wastes, deck drainage, etc.)

Physical 

Disturbances to 

the Seafloor a

Marine 

Debris

Support 

Vessel and 

Helicopter 

Traffic

Accidents 

(oil spills)

Site-specific at Offshore Location

Designated topographic features -- -- --(1) --(1) -- -- --(1)

Pinnacle trend area live bottoms -- -- --(2) --(2) -- -- --(2)

Eastern Gulf live bottoms -- -- --(3) --(3) -- -- --(3)

Chemosynthetic communities -- -- -- --(4) -- -- --

Water quality -- -- X -- -- -- X

Fisheries X -- -- -- -- -- X

Marine mammals X(8) -- -- -- X X X(8)

Sea turtles X(8) -- -- -- X X X(8)

Air quality -- X(9) -- -- -- -- X

Shipwreck sites (known/potential) -- -- -- --(7) -- -- --

Prehistoric archaeological sites -- -- -- --(7) -- -- --

Vicinity of Offshore Location

Essential fish habitat X -- X -- -- -- X(6)

Marine and pelagic birds X -- -- -- X -- X

Public health and safety -- -- -- -- -- -- --(5)

Coastal and Onshore

Beaches -- -- -- -- -- -- --(6)

Wetlands -- -- -- -- -- -- --(6)

Shore birds and coastal nesting birds -- -- -- -- -- X --(6)

Coastal wildlife refuges -- -- -- -- -- -- --(6)

Wilderness areas -- -- -- -- -- -- --(6)

Other Resources

Non-chemosynthetic benthic communities -- -- X -- -- -- X

Pelagic communities X -- X -- -- -- X

a

 This column is included for completeness; however, because a DP semi-submersible (rig) will be used, there will be no anchoring. 

Table Footnotes and Applicability: 

(1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well or platform site or any anchors will be on the seafloor within the: 

(a) 4-mile zone of the Flower Garden Banks, or the 3-mile zone of Stetson Bank; 

(b) 1000-m, 1-mile or 3-mile 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. 

– This footnote does not apply because the lease is not within or near any marine sanctuary, topographic feature, or no-activity zone. There are no submarine banks in the lease. There will be no 

anchoring in the lease. 

(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. 

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(3) Activities within any Eastern Gulf OCS block where seafloor habitats are protected by the Live Bottom (Low-Relief) Stipulation attached to an OCS lease. 

– The Live Bottom (Low-Relief) Stipulation is not applicable to the lease. 

(4) Activities on blocks designated by the MMS as being in water depths 400 m or greater. 

– The lease is in water depths greater than 400 m, but the chemosynthetic community review indicates that there are no areas that could support high-density chemosynthetic communities within 

1,500 ft of the proposed surface locations. There will be no anchoring. 

(5) Exploration or production activities where H2S concentrations greater than 500 ppm might be encountered. 

– This footnote is not applicable to the proposed activities because H2S concentrations greater than 500 ppm are not expected to be encountered. 

(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 spills could affect the resources marked (X) in the matrix, and impacts are analyzed in EIA Section B. Due to spill response measures, weathering, and the distance from shore, 

impacts on coastal resources and biota are highly unlikely. 

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

– The lease is not on the BOEMRE list of blocks determined to have a high probability of archaeological resources. Moreover, there will be no anchoring. Therefore, no impacts on historic or 

prehistoric sites are expected. 

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

– IPFs that may affect endangered or threatened marine mammals, sea turtles, or their critical habitats include rig presence, noise, and lights; marine debris; support vessel and helicopter traffic; 

and accidents. Impacts are analyzed in EIA Section B. 

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

– This footnote is not applicable. The proposed activity does not involve transportation of produced fluids using shuttle tankers or barges.

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B. Analysis 

B.1 Site-Specific at Offshore Location 

B.1.1 Designated Topographic Features 

There are no IPFs that could cause impacts to designated topographic features. The block is not within or 

near a BOEMRE-designated topographic feature or no-activity zone. The nearest designated topographic 

feature is over 100 miles away. 

An oil spill is unlikely to occur during the proposed activities. Because of spill response measures described 

in the ExxonMobil Corporation Gulf of Mexico Regional Oil Spill Response Plan (OSRP) as well as natural 

weathering processes, significant quantities of oil would be unlikely to reach the vicinity of any topographic 

feature. Since the crests of designated topographic features in the northern Gulf are at least 10 m below the 

sea surface, concentrated oil would not be expected to reach their sessile biota. No impacts would be 

expected. 

B.1.2 Pinnacle Trend Area Live Bottoms 

There are no IPFs that could cause impacts to pinnacle trend live bottoms. The Live Bottom (Pinnacle 

Trend) Stipulation does not apply to the lease. The pinnacle trend is located along the shelf edge offshore of 

the Mississippi River delta, several hundred miles from the lease area. 

An oil spill is unlikely to occur during the proposed activities. Because of spill response measures described 

in the Regional OSRP as well as natural weathering processes, significant quantities of oil would be unlikely to 

reach the vicinity of the pinnacle trend area. Further, since the crests of pinnacle features are more than 50 m 

below the sea surface, concentrated oil would not be expected to reach their sessile biota. No impacts would 

be expected. 

B.1.3 Eastern Gulf Live Bottoms 

There are no IPFs that could cause impacts to low-relief Eastern Gulf live bottoms. The nearest Eastern 

Gulf live bottom areas as defined by MMS stipulation (Eastern Planning Area leases in water depths of 100 m or 

less) are several hundred miles from the project area. 

An oil spill is unlikely to occur during the proposed activities. Because of spill response measures described 

in the Regional OSRP as well as natural weathering processes, significant quantities of oil would be unlikely to 

reach the vicinity of Eastern Gulf live bottom areas. Further, since these are low-relief features on the seafloor, 

concentrated oil would not be expected to reach these communities. No impacts would be expected. 

B.1.4 Chemosynthetic Communities 

The chemosynthetic community review indicates that there are no areas that could support high-density 

chemosynthetic communities within 457 m (1,500 ft) of the proposed surface locations. There will be no 

anchoring and there are no IPFs likely to cause impacts to chemosynthetic communities. It is possible that 

undiscovered chemosynthetic communities exist in nearby lease blocks. However, a subsurface spill (e.g., a 

blowout) would be unlikely to affect benthic communities beyond a few hundred meters from the wellsite. 

Therefore, no impacts on chemosynthetic communities would be expected. 

B.1.5 Water Quality 

IPFs potentially affecting water quality include: 

 Effluent discharges; and 

 Accidents (oil spills). 

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Effluent Discharges. Effluents to be discharged will include water-based drilling fluids and associated 

cuttings; cuttings with adhering synthetic drilling fluids; sanitary and domestic wastes; deck drainage; 

desalinization unit brine, and uncontaminated bilge and ballast water. Since all routine discharges from the rig 

will be made in accordance with the general National Pollutant Discharge Elimination System (NPDES) permit 

issued by the U.S. Environmental Protection Agency (USEPA), they are not expected to cause significant impacts 

to water quality. Discharges of sanitary and domestic wastes from support vessels will be in accordance with 

U.S. Coast Guard (USCG) regulations and also would not cause significant impacts on water quality. 

Accidents (oil spills). It is unlikely that an oil spill would occur from the proposed activities. If a spill were 

to occur, marine water quality would be temporarily affected by the dissolved components and small oil 

droplets. Spill response measures detailed in the Regional OSRP as well as natural weathering processes would 

remove the oil from the water column and dilute the constituents to background levels. 

B.1.6 Fisheries 

The main commercial fishing activity in deepwaters of the northern Gulf of Mexico is pelagic longlining for 

tuna, swordfish, and other billfishes (Continental Shelf Associates, Inc., 2002). While most recreational fishing 

activity occurs in depths less than about 200 m, deepwater petroleum platforms attract considerable 

recreational fishing activity offshore of Louisiana and Texas. 

IPFs potentially affecting fisheries include: 

 Rig presence, noise, and lights; and 

 Accidents (oil spills). 

Rig Presence, Noise, and Lights. Rig presence is the only routine IPF that may have an impact on 

commercial fishing. There is a slight possibility of pelagic longlines becoming entangled in the rig; however, 

longline fishers use radar and generally are aware of offshore structures when placing their sets. Therefore, 

little or no impact on pelagic longlining is expected. Other routine 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. 

Accidents (oil spills). In the event of a large oil spill, fishing activities near the project area could be 

temporarily disrupted. The area affected would be relatively small, and the duration presumably would be a 

few days. Due to spill response measures and natural weathering processes, little or no disruption of fishing 

activities in coastal waters would be expected. 

B.1.7 Marine Mammals 

The only endangered marine mammal likely to be present near the project area is the sperm whale (Davis 

et al., 2000). Five endangered baleen whales (northern right whale, blue whale, fin whale, sei whale, and 

humpback whale) have been reported from the northern Gulf but are either extralimital or uncommon 

(Jefferson and Schiro, 1997) and are not discussed further. Another endangered marine mammal, the West 

Indian manatee, is a coastal species that does not occur in or near the project area, although manatees 

occasionally occur in Louisiana and Texas coastal waters during summer months. The most common 

nonendangered cetaceans in the deepwater environment are odontocetes such as pantropical spotted dolphin, 

spinner dolphin, and clymene dolphin. Other odontocetes that may be present include dwarf and pygmy sperm 

whales, four species of beaked whales, and 14 species of dolphins and porpoises (Jefferson and Schiro, 1997). 

IPFs potentially affecting marine mammals include: 

 Rig presence, noise, and lights; 

 Marine debris; 

 Support vessel and helicopter traffic; and 

 Accidents (oil spills). 

Other factors such as effluent discharges are likely to have negligible impacts on marine mammals due to 

rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. 

Rig Presence, Noise, and Lights. The behavior of marine mammals could be affected by noise and light 

emitted from the rig, as well as the presence of fish populations associated with the rig. Drilling-related noise is 

of relatively low frequency (Richardson et al., 1995). The sperm whale appears to have good low frequency 

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hearing, but the available data do not indicate a consistent response to anthropogenic noise (National Marine 

Fisheries Service [NMFS], 2001). The other marine mammals commonly seen in deepwater are odontocetes, 

which have their best hearing in high frequencies and are less likely to be disturbed by low frequency noise. 

Little is known of the effects of offshore structures and activities on marine mammals, but in any case, such 

effects would likely consist of short-term behavioral changes and would not be expected to harm the animals. 

Marine Debris. Ingestion of, or entanglement with, accidentally discarded debris can kill or injure marine 

mammals. The disposal of solid waste from drilling rigs and vessels is prohibited by the MMS and the USCG 

under MARPOL regulations. In addition, MMS has issued Notice to Lessees (NTL) 2003-G11, which instructs 

operators to exercise caution in the handling and disposal of small items and packaging materials, requires 

posting of placards at prominent locations on offshore vessels and structures, and requires a marine trash and 

debris awareness training and certification process. Compliance with this NTL and any related MMS 

requirements is assumed to be effective in minimizing the potential for debris-related impacts on marine 

mammals. 

Support Vessel and Helicopter Traffic. Vessel and helicopter traffic may startle or disturb marine 

mammals. Reactions may range from apparent indifference to evasive moves (e.g., turns, diving, etc.) 

(Richardson et al., 1995). Many of the reactions of marine mammals to vessel traffic appear to be primarily a 

result of noise, though there may be visual or other cues as well. 

There is a small risk of a supply or crew boat striking a sperm whale. To reduce the potential for vessel 

strikes, the MMS has issued NTL 2003-G10, which recommends protected species identification training, 

specifies ways for vessel operators and crews to avoid vessel strikes, and requires operators to report sightings 

of any injured or dead protected species. Compliance with this NTL and any related MMS requirements is 

assumed to be effective in minimizing the likelihood of vessel strikes. 

Accidents (oil spills). The sperm whale is the only endangered marine mammal likely to come into contact 

with an oil spill at the project area. Sperm whales are widely distributed in the Gulf of Mexico, but 

concentrations occur in the Mississippi Canyon area south of the Mississippi River Delta (Davis et al., 2000). 

Common nonendangered cetaceans in the deepwater environment, such as pantropical spotted dolphin, 

spinner dolphin, and clymene dolphin, also could come into contact with spilled oil. However, the total area of 

a slick would be small relative to the available deepwater habitat. Oil exposure would not persist in the open 

ocean, and the animals could avoid oiled areas. Although individual marine mammals may be affected if 

exposed to oil, no significant population-level impacts on any marine mammal species would be expected. 

The West Indian manatee occasionally occurs in Louisiana, Texas, and other northern Gulf states during 

summer months. It is assumed that natural weathering processes and spill response measures as detailed in 

the Regional OSRP would remove most or all of the spilled oil before it could contact manatee habitats. The 

historical spill data and trajectory/risk calculations referenced in a recent Environmental Impact Statement (EIS) 

(MMS, 2002) indicate there is little risk of contact or impact to the coastline or associated environmental 

resources. Therefore, no significant impacts on manatees are expected. 

B.1.8 Sea Turtles 

Five species of endangered or threatened sea turtles may be found near the project area. Endangered 

species are the leatherback, Kemp's ridley, and hawksbill sea turtles. The loggerhead sea turtle is a threatened 

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

as endangered. Leatherbacks and loggerheads are the most likely turtles to be present as adults near the 

project area. Green, hawksbill, and Kemp’s ridley turtles are typically inshore species that are unlikely to occur 

near the project area as adults. Hatchlings or juveniles of any of the sea turtles may be present in deepwater 

areas, where they may be associated with sargassum and other flotsam. 

Loggerhead turtles nest in significant numbers along the Florida Panhandle and to a limited extent in other 

northern Gulf coast states. Green turtles infrequently nest on Florida Panhandle and Alabama beaches. Very 

few leatherback nests have been documented along the northern Gulf coast (e.g., Florida Panhandle). Kemp’s 

ridley turtles nest mainly near Rancho Nuevo in northeastern Mexico and also in South Texas (Padre and 

Mustang Islands). Hawksbill turtles do not nest anywhere near the project area. Due to the distance from 

shore, nesting beaches are highly unlikely to be affected by the project. 

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IPFs potentially affecting sea turtles include: 

 Rig presence, noise, and lights;

 Marine debris; 

 Support vessel and helicopter traffic; and 

 Accidents (oil spills). 

Other factors such as 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. 

Rig Presence, Noise, and Lights. Little is known of how turtles may respond to noise from offshore drilling 

activities. Helicopters and service vessels also may affect sea turtles due to machinery noise and/or visual 

disturbances. The most likely impacts would be short-term behavioral changes such as diving and evasive 

swimming, disruption of activities, or departure from the area. 

Turtle hatchlings may be attracted to brightly lit offshore platforms, where they may be subject to 

increased predation by birds and fishes that are also attracted to offshore structures. However, NMFS (2001) 

states that attraction to offshore platforms is unlikely to appreciably reduce the reproduction, numbers, or 

distribution of sea turtles in the wild. 

Marine Debris. Ingestion of, or entanglement with, accidentally discarded solid debris can kill or injure sea 

turtles (Lutcavage et al., 1997). Some adult sea turtles such as loggerheads and leatherbacks may ingest plastic 

debris. The disposal of solid waste from drilling rigs and vessels is prohibited. Also, MMS has issued NTL 

2003-G11, which instructs operators to exercise caution in the handling and disposal of small items and 

packaging materials, requires posting of placards at prominent locations on offshore vessels and structures, and 

requires a marine trash and debris awareness training and certification process. Compliance with this NTL and 

any related MMS requirements is assumed to be effective in minimizing the potential for debris-related impacts 

on sea turtles. 

Support Vessel and Helicopter Traffic. There is a chance of collision between service vessels and sea 

turtles. While adult 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 or during nighttime or periods of inclement 

weather. To reduce the potential for vessel strikes, the MMS has issued NTL 2003-G10, which recommends 

protected species identification training, specifies ways for vessel operators and crews to avoid vessel strikes, 

and requires operators to report sightings of any injured or dead protected species. Compliance with this NTL 

and any related MMS requirements is assumed to be effective in minimizing the likelihood of striking sea 

turtles. 

Accidents (oil spills). Sea turtles could be affected by an oil spill in offshore waters. Leatherbacks and 

loggerheads are the most common adult turtles in offshore waters and the most likely to be affected. They are 

regularly sighted within deepwater areas. In addition, juvenile turtles of any species may be found within 

convergence zones in deepwater areas. While some turtles may come into contact with spilled oil, the total 

area affected would be small relative to the available deepwater habitat, and the viability of sea turtle 

populations as a whole would not likely be threatened. 

It is assumed that most or all of the spill volume would be removed due to weathering and spill response 

measures prior to reaching turtle nesting beaches. The historical spill data and trajectory/risk calculations 

referenced in a recent EIS (MMS, 2002) indicate there is little risk of contact or impact to the coastline or 

associated environmental resources. Therefore, no significant impacts on turtle nesting beaches would be 

expected. 

B.1.9 Air Quality 

There are no site-specific air quality data for the project area. The attainment status of Federal OCS waters 

is unclassified due to the lack of representative air quality data. Due to the distance from shore-based pollution 

sources, offshore air quality is expected to be good. 

IPFs potentially affecting air quality include: 

 Air pollutant emissions; and 

 Accidents. 

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Air Pollutant Emissions. Routine offshore air pollutant emissions will result from rig operations and from 

helicopters and service vessels. These emissions occur mainly from combustion or burning of fuels and natural 

gas and from venting or evaporation of hydrocarbons. The combustion of fuels occurs primarily on 

diesel-powered generators, pumps, or motors and from lighter fuel motors. Air pollutants associated with OCS 

activities are nitrogen oxides, carbon monoxide, sulfur oxides, volatile organic compounds, and suspended 

particulate matter. 

Due to the distance from shore, routine operations in the project area will have no impact on air quality 

conditions along the coast. Based on the air quality screening in EP Appendix G, no detailed analysis of 

emissions is required by MMS. 

Accidents (oil spills). An oil spill would affect air quality in the vicinity of the oil slick by introducing volatile 

organic compounds through evaporation. The emissions would not last long due to rapid volatilization of 

hydrocarbons. Evaporation is greatest within the first 24 hours. The extent and persistence of impacts would 

depend on the meteorological and oceanographic conditions at the time. Little or no impact on air quality in 

coastal areas would be expected. 

B.1.10 Shipwreck Sites (known or potential) 

There are no IPFs that are likely to cause impacts to shipwreck sites. There will be no anchoring around the 

wellsites, and the lease is not on the MMS list of blocks determined to have a high probability of archaeological 

resources. Therefore, no impacts on shipwreck sites are expected. Further, due to natural weathering 

processes and spill response measures as detailed in the Regional OSRP, it is highly unlikely that significant 

quantities of oil from a spill in the project area would reach coastal areas and contaminate shipwreck sites. 

B.1.11 Prehistoric Archaeological Sites 

There are no IPFs that are likely to cause impacts to prehistoric archaeological sites. There will be no 

anchoring around the wellsites, and the lease is not on the MMS list of blocks determined to have a high 

probability of archaeological resources. Therefore, no impacts on prehistoric archaeological resources are 

expected. Further, due to natural weathering processes and spill response measures as detailed in the Regional 

OSRP, it is highly unlikely that significant quantities of oil from a spill in the project area would reach coastal 

areas and contaminate prehistoric sites. 

B.2 Vicinity of Offshore Location 

B.2.1 Essential Fish Habitat 

The Gulf of Mexico Fishery Management Council (GMFMC) has prepared fishery management plans (FMPs) 

identifying EFH for corals and coral reefs, shrimp, stone crab, spiny lobster, reef fishes, coastal pelagic fishes, 

and red drum, none of which occur in waters overlying the lease area. 

Another group of exploited species, the highly migratory pelagic fishes, are managed by NMFS. NMFS 

(1999) defined EFH for managed highly migratory species, which include 10 shark, 3 tuna, and single swordfish 

species of concern. These species may occur as transients in the project area. EFH includes most of the 

substrate and water column of the Gulf of Mexico where the managed species commonly occur. Although 

billfishes are now managed as highly migratory species, there were no EFH designations given in NMFS (1999). 

Spatially limited EFH called habitat areas of particular concern (HAPC) have been identified in the Gulf of 

Mexico by the GMFMC. These include the Flower Garden Banks National Marine Sanctuary, Florida Middle 

Grounds, Florida Keys National Marine Sanctuary, and Dry Tortugas (Fort Jefferson National Monument). The 

nearest of these, the Flower Garden Banks, is about 80 miles from the lease area. 

IPFs potentially affecting EFH include: 

 Rig presence, noise, and lights; 

 Effluent discharges; and 

 Accidents (oil spills). 

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Rig Presence, Noise, and Lights. The rig will attract fishes, particularly epipelagic fishes such as tunas, 

dolphin, billfishes, and jacks (e.g., Holland et al., 1990; Higashi, 1994). This effect could enhance feeding of 

epipelagic predators by attracting and concentrating smaller fish species. Because the rig is a single, temporary 

structure, impacts on EFH, whether beneficial or adverse, are considered minor. 

Effluent Discharges. Discharges of water-based drilling fluids and associated cuttings will produce 

temporary, localized increases in suspended solids in the water column around the rig. Turbid water will persist 

for minutes to a few hours during and after each discharge and will have a negligible impact on EFH. Other 

effluent discharges such as sanitary and domestic wastes, deck drainage, desalinization unit brine, and 

uncontaminated bilge and ballast water will have negligible impacts on ambient water quality. No significant 

impacts on EFH are expected from these discharges. 

Accidents (oil spills). An oil spill in offshore waters would produce a slick and temporarily increase 

hydrocarbon concentrations. Given that EFH includes most of the substrate and water column of the Gulf of 

Mexico where highly migratory managed species commonly occur, some impact on EFH would be unavoidable. 

However, the area affected would be a small percentage of the EFH in the Gulf of Mexico, and the duration 

would be brief (few hours to a few days). 

A large spill could affect biota including phytoplankton, zooplankton, and nekton. Eggs and larvae of fishes 

will die if exposed to certain toxic fractions of spilled oil. Most of the fishes inhabiting shelf or oceanic waters 

of the Gulf of Mexico have planktonic eggs and larvae. However, due to the wide dispersal of early life history 

stages of fishes in the surface waters of the Gulf of Mexico, an oil spill is not expected to have significant 

impacts at the population level. 

B.2.2 Marine and Pelagic Birds 

A variety of seabirds such as terns, storm-petrels, shearwaters, and jaegers occur in the deepwater 

environment (Peake, 1996; Hess and Ribic, 2000). Powers (1987) indicates that seabird densities over the open 

ocean typically are <10 birds/km2. Seabirds spend much of their lives offshore over the open ocean, except 

during breeding season when they nest along the coast. Other birds such as waterfowl, marsh birds, and shore 

birds may occasionally be present over open ocean areas, but no endangered or threatened birds are likely to 

occur at the project area due to the distance from shore. EIA Section B.3.3 discusses Shore Birds and Coastal 

Nesting Birds. 

IPFs potentially affecting marine and pelagic birds include: 

 Rig presence, noise, and lights; 

 Marine debris; and 

 Accidents. 

Other factors such as effluent discharges are likely to have negligible impacts on marine birds due to rapid 

dispersion, the small area of ocean affected, and the intermittent nature of the discharges. 

Rig Presence, Noise, and Lights. Pelagic seabirds and trans-Gulf migrant birds may be present at the 

project area. Birds may use offshore drilling rigs and platforms for resting, feeding, or as temporary shelter 

from inclement weather (Russell, 2001). Some birds may be attracted to offshore structures because of the 

lights and the fish populations that aggregate around these structures. Birds that frequent platforms may be 

exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely 

due to rapid dispersion of effluents. Birds migrating over water at night have been known to strike offshore 

structures, resulting in death or injury (Russell, 2001; Wiese et al., 2001). 

Marine Debris. Debris lost overboard from offshore operations can injure or kill birds that ingest or 

become entangled in it. MMS regulations and Federal law prohibit disposal of trash and debris in the ocean. In 

addition, MMS has issued NTL 2003-G11, which instructs operators to exercise caution in the handling and 

disposal of small items and packaging materials, requires posting of placards at prominent locations on offshore 

vessels and structures, and requires a marine trash and debris awareness training and certification process. 

Compliance with this NTL and any related MMS requirements is assumed to be effective in minimizing the 

potential for debris-related impacts on birds. 

Accidents (oil spills). Pelagic seabirds could be exposed to oil from a spill at the project area. Presumably, 

birds such as terns, storm-petrels, shearwaters, and jaegers would be the most likely to be present, but in low 

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densities. Due to these low densities and the relatively small percentage of deepwater habitat that would be 

affected by a spill, total numbers of birds affected would be small, and no significant population-level impacts 

on any bird species would be expected. 

B.2.3 Public Health and Safety 

There are no IPFs associated with routine operations that are expected to affect public health and safety. 

In the event of a major spill, the main safety and health concerns are those of the offshore personnel 

responding to the spill. The proposed activities will be covered by the Regional OSRP, and in addition, the rig 

maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL. Based on the spill volumes, 

weathering rates, and response measures as detailed in the Regional OSRP, it is expected that most or all of the 

spilled oil would be removed before reaching coastal waters or shorelines. Therefore, no impacts on public 

health and safety would be expected. 

B.3 Coastal and Onshore 

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities are 

described in a recent Gulf EIS (MMS, 2002). Sensitive coastal habitats are also tabulated in the Regional OSRP. 

Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged 

seagrass beds. Generally, most of the northern Gulf is fringed by barrier beaches, with wetlands and/or 

submerged seagrass beds occurring in sheltered areas behind the barrier islands and in estuaries. 

B.3.1 Beaches 

There are no IPFs associated with routine activities that could affect beaches due to the distance from 

shore. 

Accidents (oil spills). A large oil spill is unlikely, and it is assumed that most or all of the spill volume would 

be removed due to weathering and spill response measures, as detailed in the Regional OSRP, before reaching 

the coast. The historical spill data and trajectory/risk calculations referenced in a recent EIS (MMS, 2002) 

indicate there is little risk of contact or impact to the coastline or associated environmental resources. 

Therefore, no significant impacts on beaches are expected. 

B.3.2 Wetlands 

Coastal wetlands are unlikely to be affected by any routine IPF due to the distance from shore. Support 

operations including crew boats and supply boats may have a minor incremental impact on coastal wetlands. 

Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and 

harbors. Impacts are assumed to be minimized by following the speed and wake restrictions in harbors and 

channels. 

Accidents (oil spills). A large oil spill is unlikely, and it is assumed that most or all of the spill volume would 

be removed due to weathering and spill response measures, as detailed in the Regional OSRP, before reaching 

the coast. The historical spill data and trajectory/risk calculations referenced in a recent EIS (MMS, 2002) 

indicate there is little risk of contact or impact to the coastline or associated environmental resources. 

Therefore, no significant impacts on wetlands are expected. 

B.3.3 Shore Birds and Coastal Nesting Birds 

Bird species of concern in inshore waters or onshore areas include the bald eagle, brown pelican, piping 

plover, and western snowy plover. Various species of nonendangered birds are also found along the northern 

Gulf coast, including diving birds, shore birds, marsh birds, wading birds, and waterfowl (MMS, 2002). 

IPFs potentially affecting shore birds and coastal nesting birds include: 

 Support vessel and helicopter traffic; and 

 Accidents (oil spills). 

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Support Vessel and Helicopter Traffic. Due to the distance from shore, the only routine IPF that may affect 

shore birds and coastal nesting birds is support operations. Support vessels and helicopters will transit coastal 

areas in Louisiana where shore birds and nesting birds may be found. Helicopter and vessel traffic could 

periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may 

support feeding, resting, or breeding birds). However, existing mitigation measures requiring aircraft to 

maintain minimum altitudes over sensitive habitats such as wildlife refuges and park properties would minimize 

any potential impacts. Similarly, vessel operators are required to use designated navigation channels and 

comply with posted speed and wake restrictions while transiting sensitive inland waterways. With these 

measures in effect, it is likely that individual birds would experience at most only short-term, behavioral 

disruption. 

Accidents (oil spills). Coastal bird species could be affected if a large oil spill reached coastal waters and 

shorelines. Brown pelicans typically do not venture offshore of the inner continental shelf. Piping plovers or 

western snowy plovers could encounter the spill only if it reached coastal habitats. A spill would not be 

expected to contact or otherwise impact bald eagles unless contamination and subsequent cleanup activities 

occurred near eagle nesting or roosting sites. However, it is assumed that most or all of the spill volume would 

be removed due to weathering and response measures, as detailed in the Regional OSRP, prior to reaching 

coastal waters. The historical spill data and trajectory/risk calculations referenced in a recent EIS (MMS, 2002) 

indicate there is little risk of contact or impact to the coastline or associated environmental resources. 

Therefore, no significant impacts on shore birds or coastal nesting birds are expected. 

B.3.4 Coastal Wildlife Refuges 

Coastal national wildlife refuges (NWRs) include Breton, Delta, and Shell Keys in Louisiana and Anahuac, 

Aransas, Big Boggy, Brazoria, McFaddin, San Bernard, Texas Point in Texas. In addition, there are various state 

wildlife management areas and private refuges in coastal areas. 

Due to the distance from shore, there are no IPFs associated with routine activities that are likely to affect 

coastal wildlife refuges. 

Accidents (oil spills). A large spill is unlikely, and it is assumed that most or all of the spill volume would be 

removed due to weathering and spill response measures, as detailed in the Regional OSRP, before reaching the 

coast. The historical spill data and trajectory/risk calculations referenced in a recent EIS (MMS, 2002) indicate 

there is little risk of contact or impact to the coastline or associated environmental resources. Therefore, no 

significant impacts on coastal wildlife refuges are expected. 

B.3.5 Wilderness Areas 

There are no IPFs associated with routine activities that are likely to affect wilderness areas in Louisiana, 

Texas, or other coastal states. 

Accidents (oil spills). A large spill is unlikely, and it is assumed that most or all of the spill volume would be 

removed due to weathering and spill response measures, as detailed in the Regional OSRP, before reaching the 

coast. The historical spill data and trajectory/risk calculations referenced in a recent EIS (MMS, 2002) indicate 

there is little risk of contact or impact to the coastline or associated environmental resources. Therefore, no 

significant impacts on coastal wilderness areas are expected. 

B.4 Other resources 

B.4.1 Non-Chemosynthetic Benthic Communities 

Benthic communities in the project area are expected to consist of soft bottom infauna and epifauna. No 

chemosynthetic communities are expected in the lease area (see Section B.1.4). Drilling activities and 

anchoring will affect a small area of seafloor around the wellsite. Disturbed bottom sediments will be 

recolonized through larval settlement and migration from adjacent areas. Because some deepsea biota grow 

and reproduce slowly, recovery may require several years. 

Water depths are approximately 2,226 m (7,304 ft) at the surface location for KC 919-1 and KC 919-2, and 

approximately 2,219 m (7,279 ft) at the surface location for KC 919-3. Therefore, the wellsites fall within the 

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Upper Abyssal Zone (1,650 to 2,250 m) defined by Gallaway (1988). Macroinfaunal densities for this depth are 

likely to be about 3,000 individuals/m2 (Rowe and Kennicutt, 2002). There are no individual dominant species 

in the deepsea macroinfauna, but polychaetes are the most abundant and diverse group (Pequegnat et al., 

1990). Meiofauna and microbiota are also important components of the deepsea benthos. Rowe (2000) 

indicates that little information is available on either group for the deep Gulf. A deep Gulf of Mexico benthos 

program is now underway that expands upon the depth range and geographic coverage of the previous MMS 

continental slope study (Rowe and Kennicutt, 2002). 

Under NTL 2003-G03, the MMS requires remotely operated vehicle (ROV) surveys in deepwater blocks in 

the Central and Western Planning Areas. If required by the MMS, an ROV survey will be conducted as specified 

under this NTL. ROV surveys provide information about the extent of drilling-related impacts on deepwater 

benthic communities. 

The IPFs potentially affecting benthic communities are 

 Effluent discharges; and 

 Accidents (seafloor blowout). 

Effluent Discharges. Cuttings associated with both water-based and synthetic drilling fluids will be 

discharged from the rig. All discharges will be in accordance with the NPDES general permit. Cuttings from 

synthetic drilling fluid systems tend to clump together and form cuttings piles close to the discharge point (Neff 

et al., 2000). Where these cuttings accumulate in concentrations of about 1,000 mg/kg or higher, benthic 

infaunal communities may be adversely affected (Neff et al., 2000). Some benthic organisms will be buried or 

smothered by cuttings accumulations. Infaunal numbers may increase, and diversity may decrease as 

opportunistic species that tolerate low oxygen and high H2S predominate. Neff et al. (2000) estimated the area 

affected around a drilling rig on the Gulf of Mexico continental slope to be about 1 hectare (10,000 m2), or 

about 0.04 percent of a lease block. As the base synthetic fluid is decomposed by microbes, the area will 

gradually return to pre-drilling conditions. Disturbed soft bottom sediments will be recolonized through larval 

settlement and migration from adjacent areas. 

Accidents (seafloor blowout). A seafloor blowout resulting in an oil spill could affect benthic communities 

within a few hundred meters of the wellsite. While some oil could initially adhere to surface sediments 

surrounding the wellsite, resulting in smothering and/or toxicity to benthic organisms, most of the oil is 

assumed to rise rapidly through the water column. The physical impacts of a seafloor blowout are also a 

consideration. The MMS (2002) estimates that a seafloor blowout could resuspend and disperse sediments 

within a 300-m radius. While coarse sediments (sands) would probably settle at a rapid rate near the blowout 

site, fine sediments (silts and clays) could be resuspended for more than 30 days and dispersed over a much 

wider area. Surface sediments at the project area are assumed to be largely silt and clay. The affected area 

would be recolonized by benthic organisms over a period of months to years. 

B.4.2 Pelagic Communities 

IPFs potentially affecting pelagic communities include: 

 Rig presence, noise, and lights; 

 Effluent discharges; and 

 Accidents (oil spills). 

Rig Presence, Noise, and Lights. The rig will attract epipelagic fishes such as tunas, dolphin, billfishes, and 

jacks (e.g., Holland et al., 1990; Higashi, 1994). This effect might enhance feeding of epipelagic predators by 

attracting and concentrating smaller fish species. Because the rig is a single, temporary structure, impacts on 

fish populations, whether beneficial or adverse, are considered minor. 

Effluent Discharges. Discharges of drilling muds and associated cuttings are likely to have little or no 

impact on pelagic biota due to the low toxicity and rapid dispersion of these discharges (National Research 

Council, 1983; Neff, 1987; Hinwood et al., 1994). Other effluent discharges in accordance with the NPDES 

permit, such as sanitary and domestic wastes, deck drainage, desalinization unit brine, and uncontaminated 

bilge and ballast water, are expected to be diluted and mixed rapidly with ambient waters and would have little 

or no impact on water column biota. 

Accidents (oil spills). A large spill could affect water column biota including phytoplankton, zooplankton, 

and nekton. While adult and juvenile fishes may actively avoid a large spill, the planktonic eggs and larvae 

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would be unable to avoid contact. Eggs and larvae of fishes will die if exposed to certain toxic fractions of 

spilled oil. Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae. 

However, due to the wide dispersal of early life history stages of fishes in the Gulf of Mexico, a large spill would 

not be expected to have significant impacts at the population level. 

C. Impacts on Proposed Activities 

A shallow hazards assessment was prepared in accordance with Appendix C of NTL 2003-G17, and 

NTL 98-20. The analysis concluded that the drillsites are free of any major constraints to drilling. 

Under most circumstances, meteorological and oceanographic conditions are not expected to have any 

effect on the proposed activities. Extreme weather, including high winds, strong currents, and large waves, has 

been taken into account in the design criteria for the rig. High winds, waves, and limited visibility during a 

severe storm could disrupt support activities (vessel and helicopter traffic) and might make it necessary to 

suspend some activities for safety reasons until the storm or weather event passes. 

D. Alternatives 

Various technical and operational options have been considered in developing the proposed action, 

including the selection of a drilling unit, the selection of drilling fluids, and the drilling locations required to 

meet the objectives. No formal alternatives to the proposed action were evaluated. 

E. Mitigation Measures 

The proposed action does not involve any mitigation measures other than those required by laws and 

regulations, including all applicable Federal, State, and local requirements concerning air emissions, discharges 

to water, and solid waste disposal, as well as any additional permit requirements. All project activities will be 

conducted under the ExxonMobil Corporation Gulf of Mexico Regional OSRP. 

Note: Mitigation placed on Plan S-7330 approval letter -- "In accordance with Notice to Lessees and Operators No. 

2008-G06, conduct the two Remotely Operated Vehicle surveys you proposed in your plan. The first survey will be for 

the first well location approved under this plan which is actually drilled. The post-drilling survey can be conducted at the 

time you are preparing to leave this location. Submit both your survey reports within 60 days after the rig leaves the 

well location." ExxonMobil drilled KC 919 Location F (Hadrian 5) and has complied with this mitigation. 

ExxonMobil will not implement any mitigation measures to avoid, diminish, or eliminate potential environmental 

resources, other than those required by regulation and policy. 

F. Consultation 

No persons or agencies were consulted during the preparation of this EIA. 

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G. References 

The following references were used in preparing the EIA. 

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the fishing and petroleum industries in deepwaters of the Gulf of Mexico. U.S. Department of the Interior, 

Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 

Davis, R.W., J.G. Ortega-Ortiz, C.A. Ribic, W.E. Evans, D.C. Biggs, P.H. Ressler, J.H. Wormuth, R.R. Leben, K.D. Mullin, and 

B. Würsig. 2000. Cetacean habitat in the northern Gulf of Mexico, pp. 217-253. In: R.W. Davis, W.E. Evans, and 

B. Würsig (eds.), Cetaceans, sea turtles, and seabirds in the northern Gulf of Mexico: Distribution, abundance 

and habitat associations. Volume II: Technical Report. U.S. Geological Survey, Biological Resources Division, 

USGS/BRD/CR-1999-0006 and U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico 

OCS Region, New Orleans, LA, OCS Study MMS 2000-003. 346 pp.

Gallaway, B. (ed.). 1988. Northern Gulf of Mexico continental slope study, final report: Year 4. Vol. II: Synthesis Report. 

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Hess, N.A. and C.A. Ribic. 2000. Seabird ecology, pp. 275-315. In: R.W. Davis, W.E. Evans, and B. Würsig (eds.), 

Cetaceans, sea turtles, and seabirds in the northern Gulf of Mexico: Distribution, abundance and habitat 

associations. Volume II: Technical Report. U.S. Geological Survey, Biological Resources Division, 

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OCS Region, New Orleans, LA, OCS Study MMS 2000-003. 346 pp.

Higashi, G.R. 1994. Ten years of fish aggregating device (FAD) design and development in Hawaii. Bull. Mar. Sci. 

55(2-3):651-666.

Hinwood, J.B., A.E. Potts, L.R. Denis, J.M. Carey, H. Houridis, R.J. Bell, J.R. Thomson, P. Boudreau, and A.M. Ayling. 1994. 

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Offshore Oil and Gas Development in Australia. The Findings of an Independent Scientific Review. Australian 

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Christopher Beck Books, Queensland, Australia. ISBN 0 908277 17 2.

Holland, K.R., R.W. Brill, and R.K.C. Chang. 1990. Horizontal and vertical movements of yellowfin and bigeye tuna 

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Jefferson, T.A. and A.J. Schiro. 1997. Distribution of cetaceans in the offshore Gulf of Mexico. Mammal Rev. 

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Lutcavage, M.E., P. Plotkin, B. Witherington, and P.L. Lutz. 1997. Human Impacts on sea turtle survival, pp. 387-410. In: 

P.L. Lutz and J.A. Musick (eds.), The Biology of Sea Turtles. CRC Press, Boca Raton, FL. 432 pp.

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192, 196, and 200. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, 

New Orleans, LA. OCS EIS/EA MMS 2002-052. 

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Neff, J.M. 1987. Biological effects of drilling fluids, drill cuttings and produced waters, pp. 469-538. In: D.F. Boesch and 

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Neff, J.M., S. McKelvie, and R.C. Ayers, Jr. 2000. Environmental impacts of synthetic based drilling fluids. Report 

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Peake, D.E. 1996. Bird surveys, pp. 271-304. In: R.W. Davis and G.S. Fargion (eds.), Distribution and abundance of 

cetaceans in the north-central and western Gulf of Mexico, Final report. Volume II: Technical Report. Prepared 

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Pequegnat, W., B. Gallaway, and L. Pequegnat. 1990. Aspects of the ecology of the deep-water fauna of the Gulf of 

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Powers, K. 1987. Seabirds, pp. 194-201. In: J.D. Milliman and W.R. Wright (eds.), The Marine Environment of the U.S. 

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Rowe, G.T. 2000. Non-seep benthos, pp. 189-207. In: Continental Shelf Associates, Inc. Deepwater Program: Gulf of 

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of Mexico OCS Region, New Orleans, Louisiana. OCS Study MMS 2002-063. 158 pp.

Russell, R.W. 2001. Platforms for research: The “migration over the Gulf” project, pp. 395-398. In: M. McKay, J. Nides,

and D. Vigil (eds.), Proceedings: Twentieth Annual Gulf of Mexico Information Transfer Meeting, December 

2000. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New 

Orleans, LA. OCS Study MMS 2001-082. 464 pp.

Wiese, F.K., W.A. Montevecchi, G.K. Davoren, F. Huettmann, A.W. Diamond, and J. Linke. 2001. Seabirds at risk around 

offshore oil platforms in the north-west Atlantic. Mar. Poll. Bull. 42(12):1,285-1,290. 

H. List of Preparers 

This EIA was prepared by the following Consultant: 

Neil Phillips, Senior Scientist 

Continental Shelf Associates 

Public Information Copy
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SECTION 19: Administrative Information 

Exempted Information Description (Public Information Copies Only) 

The following attachments were excluded from the public information copies of this plan: 

 Section 1: OCS Plan Information form – Bottom hole locations & proposed total depth 

 Section 2: Blowout Scenario – confidential information for NTL 2010 N06 calculation 

 Section 3: Geologic Description

 Section 3: Structure Contour Maps

 Section 3: Interpreted 2D or 3D seismic line(s) 

 Section 3: Cross Section(s) 

 Section 3: Shallow Hazards Report 

 Section 3: Shallow Hazards Assessment – confidential data 

 Section 3: High-Resolution Seismic Lines & Top Hole Progs

 Section 3: Stratigraphic Column with Time vs. depth table 

Bibliography 

 Gardline Surveys Inc. Geohazards Report No. 8796 for KC874, 875, 918, and 919, June 2011 

 Fugro Geoservices site specific geophysical survey in Keathley Canyon Block 919, August 2008. 

 Sassen et al., 1994 

 Exxon Mobil Corporation Regional Oil Spill Response Plan - Offshore Operations, Appendix H, July 2011 

 OCS EIA/ EA MMS 2007-059

 Geraci and St Aubin, 1980 

 Laist et al, 2001 

 CSA Environmental Impact Analysis for Keathley Canyon, 2004 

Public Information Copy