I B Reply Refer Tot FO-2-1 April 27, 19*9

Century Offahora HanaBimnt Corporation At tact ion i Mr. Pawl ft. Rervath Lakeuay 1, Sul to 900, Neaienlne Level 3900 Worth Ceueevay Boulevard MoUlrla, Louiaiana Ttftftfl BEST AVAILABLE COPY

Oentleaaui

Rerorenoe la aade to your Ini t ia l Development Oparatlona Coordination Doeument 'DOCD) and •••oBnaojlBi ^formation rooo ivad April 25, 19*9, for Laaaa OCS-Q 6640, Blook 24, Cnoncalaw Aroa. TMa DOCD includea too aot U l t iaa propoaad for Platfora A aad woll No. 1.

IM aooordanoe wtth 30 CTl 250.3«<f>. thla DOCD la hereby deemed •ubedtted and ia BOW he inc aunaldered for approval.

Tour ooatrol Meatier la M-3290 and ahould ao referenoad in your ouiamil-oation and oorroopondonoe oonoomln« thie DOCD.

Sinearaly youra,

7m D. J . Bouraeela Ha, ional Supervisor Plaid Oparatlona

I vJTol bert t ock 104/26/89* doodeon Office of Pi oaj am Services

MAY 01 1989

Information Servtee* t i f M n n

CENTURY OFFSHORE MANAGEMENT CORPORATION tt! HtJJ HAI ©NAI MOMC mf WMT MAIN STBH U0PNC1DN UMTIXKT mor •an HUttD MaemilM-'*"

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Apr i l 24, 1989

Mr. Daniel J . Bourgeois Regional Supervisor Of f ice of Field Operations U.S. Department of the Inter ior Minerals Management Service 1201 Elmwood Park Boulevard New Orleans, LA 70123-2394

RE: Development Operations Coordination Document OCS-G 6840, Chandeleur Are; Block 24 Offshore, Louisiana

Gentlemen:

In accordance wi th the provisions of T i t l e 30 CFR 250.34, Century Offshore Management Corporation (Century) hereby submits for your review and approval nine (9) copies of a Development Operations Coordination Document (DOCO) for Lease OCS-G 6840, Chandeleur Area Block 24, Offshore, Louisiana. Five (5) copies are "Proprietary Information" and four (4) copies are "Public Information".

Excluded from the Public Information copies are certain geologic discussions, depth of wells and structure map.

Centur> Offshore Management Corporation anticipates commencing ac t i v i t i es under this proposed Development Operations Coordination Document on or before July 15, 1989.

Should additional information be required, please contact J . P. Slattery at (504) 832-3750.

Sincerely,

CENTURY OFFSHORE MAHAGEMENT CORPORATION

Paul S. Horvath Senior Vice President

PSH:CJG Enclosures "Public Infernal-ion"

CENTURY OFFSHORE MANAGEMENT CORPORATION

DEVELOPMENT OPERATIONS COORDINATION DOCUMENT

CHANDELEUR AREA BLOCK 24

OCS-G 6840

Ctntury Offshort Management Corporation (Century), as designated operator of the subject lease, submits this proposed Development Operations Coordination Document (DOCD) In accordance with the regulations contained in Title 30 CFR 250.34 and more specifically defined In the Minerals Management Service Letter to Lessee's and Operators dated October 12, 1988.

BRIEF HISTORY TQ PATE

Under Initial and Supplemental Plans of Exploration, Vanguard Offshore Management Companv proposed the dri l l ing of Well Locations A through D. Vanguard dr i l led and temporarily abandoned OCS G 6840, Well No. I.

Century Offshore Management Corporation, as designated operator of the lease, drilled and temporarily abandoned OCS-G 6840, Well No. 2, and subsequently completed and shut-in OCS-G 6840, Well No. 1.

Lease OCS-G 6840 has a primary term ending date of May 31. 1989. Century will be requesting a Suspension of Production in order to maintain the lease for development activit ies leading to the commencement of production.

DESCRIPTION Qf DEVELOPMENT ACTIVITIES

A total of one (1) well will be involved In the envelopment of this lease. A Plat and Well Location Table detailing locations, total depths, and water depths of the wells are Included as Attachment A.

Century has no immediate plans for OCS-G 6840, Well No. 2.

Cen:ury will instal l a minimum support type structure wits production equipment to be designated as Platform "A". A pipeline will be installed to transport produced gas at proposed Production Platform "A" in Block 24, to a subsea tie-in point in Block 25, all being located in the Chandeleur Area. Condenstate production will N stored at thc proposed platfom and barged to shore.

Activities proposed under this DOCD for Chandeleur Block 24 will commence in July. 1989 with commencement of production. The following schedule details the chronological order of lhe proposed events leading to full start up of production act iv i t ies.

Activity Approximate Start-UP Datt

1. Ci Commence Installation of Platfona and Fac i l i t ies

-ay, 1989

2. Cotjatnct Installation of Piptlint Junt, 1989

3. Commence Production July, 1989

DESCRIPTION Qf PLATFOIM

Ctntury proposts to Install a minimum support typt structurt with production facil H i t s and will bt dtslgnattd as Platfona "A". A typical schenatic of tht propostd structure Is Included as Attachment B.

Al l hydrocarbon handling equipment for testing and production such as stparators, tanks, and trtattrs shall be designed, Installed, and operated to prtvtnt pollution.

Maintenance or rtpalrs which art necessary to prevent pollution of offshore waters shall bt undtrtaktn Immediately.

Curbs, gutttrs, drip ptns, and drains shall bt Installed in deck areas In t manner necessary to colltct all contaminants not authorized for discharge. 011 drainage *sa11 bt piped to a properly designed, operated, •nd maintained sump system which will automatically maintain the «11 at a level sufficient to prevent discharge of oil Into offshort wattrs. All gravity drains shall be equipped with a wattr trap or othtr means to prevent gas 1n the «i«p system from escaping through tht drains. Sump plies shall not bt ustd as processing dtvlcts to trtat or skim liquids, but may bt ustd to col l tct trr ated-produced wattr, treated-produced sand, or liquids from drip pans and deck drains and as a final trap for hydrocarbon liquids in tht tvtnt of equipment upsets. Improperly designed, operated, or maintained sump piles which do not prevent the discharge of oil Into offshore waters shall be replaced or repaired.

There shall be no disposal of equipment, cables, containers, or other materials Into offshort wattrs.

STRUCTURE MP

A currtnt structurt map of tht txptcted productive formation Is included as Attachment C.

BATHYMETRY HAP

A bathymetry Mp showing the locat 1o.. of Platfora "A" Is Included as Attachment 0.

SHALLOW HAZARDS

An analysis of any seafloor and subsurface geologic and manmade features and conditions which may have an adverse effect on the proposed operations was Included In the Supplemental Plan of Exploration for Chandeleur Bloclc 24.

OIL SPILL CONTINGENCY PLAN

All construction and production operations shall be performed In accordance with Industry standards to prevent pollution of the environment. Century Offshore Management Corporation's Oil Spill Contingency Plan has been approved by the MMS. This plan designates an 011 Spill Team consisting of Century's personnel and contract personnel. This team's duties are to eliminate the source of any s p i l l , remove all sources of possible Ignition, deploy the most reliable means of available transportation to monitor the movement of a s l ick, and contain and remove the slick I f possible.

Century Is a member of Clean Gulf Associate* (CGA). The CGA has two permanent equipment bases in Texas, at Rockport and Galveston, and four bases in Louisiana, at Venice, Grand Is le , Intracoastal City and Cameron. Each base 1s equipped with fast response skimmers and there 1s a barge mounted high volume open sea skimmer based at Grand Is le , Louisiana. In addition to providing equipment, the CGA also supplies advisors for clean-up operations. Equipment available from CGA and the base It is located at Is l isted in the CGA Manual, Volume I, Section I I I .

Estimated response time for a spill In Chandeleur Block 24 could vary from 6 to 8 hours minimum based on:

1. Procure a boat and deploy to nearest CGA Base In Venice, Louisiana

2. Load out Fast Response Unit and oil spi l l containment equipment

3. Travel time to lease site (35 miles 9 10 MPH)

Estimated Total Tine

2.0 Hours

2.0 Hours

3,5 Hovrs

7.5 Hours

Equipment located in Venice, Louisiana would be utilized f i rst with additional equipment transported from the nearest equipment base as requ1 red.

In tht tvtnt a s p i l l occurs froa Chandeleur Block 24, our coapany has projected trajectory of a spill ut i l iz ing Information in tht Envlronaental Impact Statement (EIS) for OCS Lease Sales 118 and 122.

The EIS contains oi l spi l l trajectory simulations using seasonal surface currents coupled with wind data, adjusted every 3 hours for 30 days or until a target Is contacted.

Hypothetical spi l l trajectories were simulated for each of the potential launch sites across tht entire Gulf. These simulations presume 500 spi l ls occurring In each of the four seasons of the year. The results In the EIS were presented as probabilities that an oil spill beginning from a particular launch s i te would contact a certain land segment within 3, 10, or 30 days. Ut i l iz ing the summary of the trajectory analysis (for 10 days) as presented on pages IV-40 through IV-45, the probable projected land fall of an oil sp i l l Is as follows. Also listed Is the CGA Nap Nuaber corresponding to tht land segaent which will bt util ized to determine environmentally sensitive areas that may be affected by a s p i l l .

AREA

Chandeleur 24

LAND SEGNENT CONTACT

Plaquemines Parish, LA St. Bernard Parish, LA etal Hancock County, NS etal Mob.le County, AL

%_ CGA MAP NUMBER

18% 23% 10% 1%

LA Map No. LA Map No. LA Map No. LA Map No.

& 8

Section V, Volume II of the CGA Manual containing maps as l isted above, also Includes equipment containment/cleanup protection response modes for tht sensitive artas.

Section VI, Volume I I of the CGA Operations Manual depicts the protection response modes that are applicable for oi l spi l l clean-up operations. Each response mode is schematically rtprtstnted to show optimum deployment and operation of tht equipment in areas of environmental concern. Implementation of the suggested procedures assures the most effective use of the equlpmtnt and will result In reduced adverse Impact of oil spills on the environment. Supervisory personnel have the option to modify the deployment and operation of equipment to more effectively respond to s i te-speci f ic circumstances.

NEW QR UNUSUAL TECHNOLOGY

No new techniques or unusual technology will be required for this operation.

LEASE STIPULATIONS

In accordance with Lease Stipulation No. 1 Is attached to this lease; a Archaeological Study assessing the potential existence of any cultural resources In Chandeleur Block 24 was conducted anf previously subnltted with the Init ial Exploration Plan.

Lease Stipulation No. 4 requires Century Offshore Management Corporaton to coordinate lease activity with the Commander, 159th Tactical Fighter Group (ANG), Naval Air Station, New Orleans, Louisiana, concerning the control of electromagnetic emissions and use of boats and aircraft In Military Warning Area W-453.

DISCHARGES

All discharges from proposed Platform A" will comply with the Environmental Protection Agency NPDES General Permit for the Gulf of Mexico.

Discharges will be free of oil and will be In compliance with an monitored as required by the permit. Any dri l l ing fluid contaminated with oil will be transported to shore for proper disposal at an authorized disposal s i t e .

Sci Id wastes wil l be transported to shore for proper disposal at an authorized disposal s i te .

Sewage will be treated on location.

HYDROGEN SULfIDE

Century has reviewed available data (geologic and geophysical data and correlations, well logs, formation tests, cores, and analyses of format Mn fluids) conducted on OCS-G 6840, Wells No. I and 2, Chandeleur Block 24, and has classif ied Chandeleur Block 24 as a zone where 4 iie absence of hydrogen sulfide has been confirmed. No additional dri l l ing 1s proposed in this Development Operations Coordination Document, therefore a request for classification is not required.

PROJECTED EMISSIONS

Projected Air Quality Emissions are included as Attachment E.

ENVIRONMENTAL REPORT

An Environmental Report is included as Attachment F.

COASTAL ZONE CONSISTENCY CERTIFICATIONS

Consistency Certif Ication Statement? for the States of Louisiana and Mississippi are Included as Attachment H.

OHSHORE SUPPORT BASE

Chandeleur Block 24 Is located approximately 35 miles from the nearest Louisiana coastline, In water depths ranging from approximately 60 feet to 76 feet. A map showing the location of Block 24 relative to the shoreline and onshore base Is Included as Attachment H.

Century will u t i l i ze existing onshore faci l i t ies located in Venice, Louisiana. This wi l l serve as port of debarkation for supplies and crews. No onshore expansion or construction Is anticipated with respect to this activity.

Th.s base 1s capabi i f providing the services necessary for the proposed act iv i t ies. It has 24-hour service, a radio tower with a phone patch, dock space, equipment and supply storage base, drinking and dr i l l water, e tc . During production activities one helicopter will be making three (3) trips per week.

The onshore act iv i t ies associated with Chandeleur Block 24 should not result In any Increase In the size and number of onshore support and storage faci l i t ies or land and personnel reoulrements.

AUTHORIZED REPRESENTAT UdL

Inquiries may be made to the following authorized representative of Century Offshore Management Corporation.

Mr. J . P. Slattery Vice President • Engineering Century Offshore Management Corporation 3900 North Causeway Boulevard Lakeway I, Suite 500 Metairie, Louisiana 70002 (504) 832-3750

LIST OF ATTACHMENTS

A Well Location Table and PUt B Schematic of Platform C Structure Map D Bathymetry Map E Projected Air Emissions F Environmental Report G Consistency Certifications H Vicinity Map

1

•.

c

i

) 5152

•

i

CENTURY OFFSHORE Aj MANAGEMENT CORP.

N CHANDELEUR AREA BLK. 24 L OCS Q 6840

DEVELOPMENT OPERATIONS COORDINATION DOCUMENT

ATTACHMENT A

1" - 2000*

N

CENTURY OFFSHORE MANAGEMENT COR n .

CHANDELEUR AREA BLK. 24 OCS-G 6840

DEVELOPMENT OPERAT ."ONS COORDINATION DOCUMJTT

BATHYMETRY MAP

C . I . - 2 1 " - 2 0 0 0 '

ATTACHMENT 0

•itfiiiiiiiiaHiiiniirmi P.O. Box 218753 Houston. Texas 77218 713-558-0807

April 24, 1989

PROJECTED AIR EMISSION SCHEDULE FOR [)€VELOPMENT/PROOUCTION PROJECT

GENERAL INFORMATION

Location of Faci l i ty :

Distance Offshore: Naae of Rig/Structure: Operator:

Contact Person: Dat- Production to C nee:

Chandeleur Block 24 OCS-G 6840 35 ailes «>1 atform "A" Century Offshore Manageaent Corp. 3900 N. Causeway Blvd.. Suite 500 Metairie, Louisiana 70002 Mr. J. P. Slattery July. 1989

MAJOR SOURCES (OFFSHORE)

Power used aboard drilling vessel; approximately footage drilled N/A.*

Emitted Substance Projected Emissions

( t o n | & ' r '

8 2

S TSP

R N/A

Table) 3.2.1-3, 3.2.3-1 and 2.1-1, "Compilation of Air Pollutant Emission Factors", Third Edition, EPA Report AP-42, August, 1977.

Based on 60 hphr/ft from Table 4-3, "Atmospheric Emissions from Offshore Oil and Gas Development and Production", EPA No. 450/3-77-026, June. 1977

Emission Factors from Table 3.3.3-1, "Compilation of Air Pollutant Emission Factors", Third Edition, EPA Report AP-42, August, 1977

ATTACHMENT E

I

Projected A1r Emissions Chandeleur Block 24 April 24, 1989

Page Two

MINOR SOURCES

Including helicopter landing and take-off (3 trips/week during production) end supply boat (1 trip/week during production).

Projected Emissions (Tons/Year)

Emitted Substance

CO 1.25 so .03

2 NOX .55 VOC .28 TSP .12

ONSHORE SOURCES

These should be about the same t minor sources unless new faci l i t ies are Installed at the onshore base. No additional fac i l i t ies are reguired or planned at this time.

TOTAL ALL SOURCES (Tons/Year)

CO S02 NOX VOC TSP

Major

Minor L25 J» JB AZ

Total 1.25 .03 .55 .28 .12

EMISSION EXENPTION DETERMINATION

2/3 2/3 For CO: E - 1400 - 3400 (35) • 36,380 tons/year For NOx, VOC, TSP & SO : E • 33.30 - 33.3 (35) - 1166 tons/year

2

Projected Air Emissions Chandeleur Block 24 Apr i l 24, 1989

Page Three

PREDICTED PROOUCTION AHO DRILLING ACTIVITY AT PLATFORM

Gas Production -Condensate Production -Oete Production Will Begin - July, 1989

TRANSPORTATION SERVICES

Crew Boats (3000 hp) Trips Per Week During Production - 0

Supply Boats (3000 hp) Trips Per Week During Production - 1

HelIcopters Trips Per Week During Production - 3

METHODOLOGY

Platforn: Horsepower - hour method Boats: Horsepower - hour method Helicopters: Landing/Takeoff (LTO) cycle method

REFERENCES

Production - EPA 450/3-77-026 (June, 1977) - "Atmospheric Emissions from Offshore Oil and Gas Development and Production", pp. 81-116.

- EPA Rei Boats - EPA Report AP-42 - "Compilation of Air Pollutant Emission Factors", 3rd Edition, (August, 1977), pp. 116, 125 and 127

FINDINGS OF AIR QUALITY REVIEW

As per DOI/NMS regulations, this facil i ty is exempt from further air quality review as i t has been determined that Its operations will not have a significant adverse environmental impact on air quality.

EW I RONMENTAL REPORT

FEDERAL LEASE OCS-G 6840

CHANDELEUR AREA BLOCK 24

OFFSHORE PLAQUEMINES AND ST. BERNARD PARISHES, LOUISIANA

AND

HANCOCK, HARRISON ANO JACKSON COUNTIES, MISSISSIPPI

Prepared by:

J . Connor Consulting P.O. Box 218753

Houston, TX 77218 713/558-0607

A p r i l , 1989

ATTACHMENT F

r TABLE QP CONTENTS

TITLE PAGE 1

TABLE OF CONTENTS 11

I. DESCRIPTION OF PROPOSED ACTION 1

A. DESCRIPTION OF PROPOSED TRAVEL MOOES, ROUTES ANO FREQUENCY 1

I . NSHORE SUPPORT BASE 1 C. "EW OR UNUSUAL TECHNOLOGY 1 0. VICINITY NAP 1 E. PROPOSED MEANS TO TRANSPORT OIL ANO GAS TO SHORE,

ROUTES, QUANTITIES 2

I I . OESCRIPTION OF AFFECTED ENVIRONMENT

A. COMMERCIAL FISHING 2 B. SHIPPING 2 C. PLEASURE BOATING, SPORT FISHING ANO RECREATION 3 D. POTENTIAL OR KNOWN CULTURAL RESOURCES 4 E. ECOLOGICALLY SENSITIVE FEATURES 5 F. PIPELINES ANO CABLES 6 6 . OTHER NINERAL USES $ H. OCEAN DUMPING 6 1 . ENDANGERED AND THREATENED SPECIES ANO CRITICAL HABITAT 7

I I I . UNAVOIDABLE ADVERSE ENVIRONMENTAL IMPACTS

A. WATER QUALITY 8 B. EFFECTS ON MARINE ORGANISMS 8 C. WETLANDS AND BEACH 8 D. AIR QUALITY 8 E. COMMERCIAL FISHING 9 F. SHIP NAVIGATION 9 G. CULTURAL RESOURCES 9

H. RECREATION AND AESTHETIC VALUES 10

IV. SUMMARY 11

REFERENCES 12

LIST OF ATTACHMENTS

ATTACHMENT A - VICINITY MAP

DESCRIPTION QF PROPOSED ACTIOM

Century Offshort Management Corporation (Century) proposes to conduct dtvelopment act iv i t ies on least OCS-G 6840, Chandeleur Block 24 as outlined In the Development Operations Coordination Document.

Tht proposed act iv i t ies leading to the commencement of production will Include the Installation of a elnimum support type structure to be designated as Platform "A"; and placing one (1) well on production.

The approximate start-up date for development activit ies will be on or before July IS, 1989.

A. DESCRIPTION Qf PROPOSED TRAVEL MODES, ROUTES AND FREQUENCY

A supply boat wi l l be dispatched from a support base located In Venice, Louisiana. The boat will normally move to the block via the most direct route from Venice, Louisiana, howtvtr, boats operating In the field may travel from other faci l i t ies nearby. Following is an tstimatt of trips to the proposed operation.

Productlun Operations

Supply Boat 1 Trip Per Week Helicopter 3 Trips Per Week

B. ONSHORE SUPPORT BASE

The proposed act iv i t ies will ut i l ize a support base located at Venice, Louisiana. This base provides 24-hour service, a radio tower with phone patch, dock space, office space, parking lot, equipment and supply storage space, drinking and dr i l l water, etc. The proposed development act ivi t ies will htlp to maintain this bast at i t s prtstnt level of act ivi ty. No txpansion of tht physical f a c i l i t i e s or the creation of new jobs Is txptcted to result from the work planned in conjunction with this block.

C. NEW OR UNUSUAL TECHNOLOGY

No new or unusual technology will be required for this operation.

0. VICINITY MAP Chandeleur Block 24 is located approximately 35 miles from the nearest Louisiana coastline, in water depths ranging from approximately 60 feet to 76 feet. A nap showing the location of Block ?4 relative to the shoreline is enclosed as Attachment A.

E. PROPOSED MEANS TO TRANSPORT OIL AMD CAS TQ SHORE. ROUTES QUANTITIES

Gts Production will bo transported via a proposed right-of-way pipeline to an existing pipeline lit Chandeleur Block 25. Condensate production will be stored on the proposed Platfona, and barged to shore.

I I . DESCRIPTION OF AFFECTED ENVIRONMENT

A. COMMERCIAL FISHING

The Gulf of Mexico Is the single most important area for fisheries production in the United States. Louisiana with Its extensive coastal marshes and nutrient Input froa the Mississippi and Atchafalaya Rivers Is the most productive State In terms of commercial f isheries. Sixty-four (64%) of the tidal marshes along the entire Gulf Coast are found In Louisiana.

Shrimp (primarily brown and white) are by far the most valuable component of the Louisiana landings. Production of shrimp depends largely on environmental conditions In the estuaries during postlarval recruitment. Production Is good when there Is a warm, dry spring.

Menhaden are the state's largest fishery In terms of pounds landed and ranks second In value. Unlike the shrimp fishery, this fishery operates exclusively ofTshore. Menhaden are found primarily In shallow waters with about 93% of the fishing effort occurring with In 10 miles of shore.

Oysters constitute the third most valuable commercial fishery in Louisiana. The most Important areas for oyster production are Terrebonne Parish, Barataria Bay, and the Lake Borgne-Breton Sound System.

The blue crab 1s Louisiana's fourth most valuable commercial fishery species. Estuarine waters produce over 90% of this catch.

Other important Louisiana fisheries Include the food finfish and those for Industrial purposes, such as pet food. Approximately 50 spec.es of food finfish are harvested in the Gulf. Some of the more important are croakers, snappers, groupers, black mullet, red and black drums, spotted and silver seatrout, Spanish mackerel, spots, pompano, flounder, crevalles. Gulf kingfish. sheepshead, and king mackerel. The majority of food finfish are caught in coastal waters wilh the exception of snappers, groupers, mackerel, tuna, and b i l l f ish.

In 1986, tht commercial fishing Industry landed Louisiana 1,700 million pounds valued at $322 million. LoulsUna ranked f i rs t In tht United States in pounds landed and second In value.

B. SHIPPING Fairways play an Important role In the avoidance of collisions on the OCS, particularly 1n the case of the large oceangoing vessels, but not al l vessels stay within the fairways. Many othtrs, such as fiehing boats and OCS support vessels, travel through areas with high concentration of fixed structures. In such cases the most Important mitigation factor 1s the requirement for adtquatt marking and lighting of structures. Afttr a structurt has bttn in pi act for a while, It often becomes a landmark and an aid to navigation for vessels that operate In tht arta on a rtgular basis.

Chandeleur Block 24 1s clear of al l shipping fairways and anchorage artas. Tht platform and each of the marine vessels servicing this operation will be equipped with all U.S. Coast Guard required navigational safety aids.

A number of ports In the Central and Western Gulf havt developed Into Important ctnttrs for offshort support. Tht most active of these In Louisiana are (from tast to wtst) Venice. Morgan City, Intracoastal Ci ty , and Cameron, Louisiana.

C. PLEASURE BOATING. SPORT FISHING ANO RECREATION

The northern Gulf of Mexico coastal zone Is one of the major recreational regions of the United States, particularly in connection with marine fishing and beach-related act ivi t ies. The shorefronts along the Culf Coasts of Alabama, Mississiopi, Louisiana, and Texas offer a diversity o' natural and developed landscapes and seascapes. The coastal beaches, barrier Islands, estuarine bays and sounds, river deltas, and tidal marshes are extensively and intensively utilized for recreational activity by residents of the Gulf South and tourists from throughout the Nation, as well as from foreign countries. Publicly-owned and administered areas such as National seashores, parks, beaches, and wildlife lands, as well as specially designated preservation areas such m$ historic and natural sites and landmarks, wilderness artas, wildl1ft sanctuaries, and scenic rivers attract residents and visitors throughout the year. Commercial and private recreational faci l i t ies and establishments, such as resorts, marinas, amusement parks, and ornamental gardens, also serve as primary interest areas and support services for people who seek enjoyment from the recreational resources associated with the Gulf.

•MMMM

Thc two maior recreational areas most directly associated with the offshore leasing and potentially affected by It are the offshore marine environment and the v as tal shorefront of the adjoining stetes. Thc only major recreational activity occurring on thc OCS Is offshore marine recreational fishing and diving. Studies, reports, and conference proceedings published by MMS and others have documented a substantial recreational fishery Including scuba diving, directly associated with oil and gas production platforms. The recreational fishing associated with oil and gas structures stems from their function as high profile art i f ic ia l fishing reefs. A report on the 1964 Marine Recreational Fishery Statistics Surveys presented by NMFS at the Sixth Annual Gulf of Mexico Information Transfer Meeting Indicates a majority of the offshore recreational fishing In the Central and Western Gulf of Mexico Is directly associated with the oil and gas structures. There are currently about 4,000 offshore oi l and gas structures In the Central and Western Gulf of Mexico. Many other studies have demonstrated that when oil and gas structures are accessible tomarine recreational fishermen and scuba divers they are a major attraction for marine recreational act ivi t ies and a positive Influence on tourism and coastal economics.

With the exception of Grand Isle and vicinity and a stretch of beach area In Cameron Parish, (Peveto/Constance/Ocean View Beaches, Holly Beach, Hackberry Beach) Louisiana has very limited beach area suitable for recreation. Nost of it Is very narrow, of poor recreational quality and generally Inaccessible by automobile. Some of the highest quality beach areas In coastal Louisiana are found along the barrier Islands chainoff Terrebonne Parish. Several additional significant recreational resources are found along the Gulf Coast. Louisiana has ornamental gardens, scenic roads, rivers, and t ra i ls .

POTENTIAL OR KNOWN CULTURAL RFSOURCES

Archeological resources are any objects or features which are man-made or modified by human activity. Significant archeological resources are either historic or prehistoric and, as defined by 36 CFR 60.6, generally include properties greater than 50 years old which are associated with events that have made a significant contribution to the broad patterns of our history; are associated with the lives of persons significant in the past; embody the distinctive characteristics of a type, period, or method of construction; represent the work of a master; possess high a r t is t ic values; represent a significant and distinguishable entity whose components may lack individual distinction; or have yielded, or may be likely to yield, information important in prehistory or history.

No tentative shipwreck locations have been assigned to th is block. The block Is located within Zone 1 (High Probabil i ty) of the Cultural Resources Evaluation of the Northern Gulf of Mexico Continental Shel f . The water level curve in the "Evaluation" indicates that the area has been submerged fcr approximately six thousand years, well within the theoretical range of human occupation along the Gulf Coast.

No evidence of archaeological features was seen in the remainder of the data presented for this block as evidenced in the Cultural Resource Evaluation prepared and previously submitted.

ECOLOGICALLY SENSITIVE FEATURES

Barrier beaches are a common landform along the Gulf Coast and stretch In an Irregular chain from Florida to Texas. These elongated, narrow landforms are composed of sand and other loose sediments transported >y waves, currents, storm surges, and wind. In geologic terms, barrier Islands are a young phenomenon, being formed only In the last 5,000 to 6,000 years. The term "barr ier" Identif ies the structure as one that protects other features, such as bays, estuaries, and marshes, from direct wave attack of the open ocean. The waters in these bays and estuaries are a blend of the te r res t r ia l - f resh water systems of the mainland and the saltwater system of the ocean, and among the richest ecosystems known. Many of the species that Inhabit the bays, estuaries, and adjacent marshes use these areas as spawning, nursery, and feed grounds. I t Is estimated that two-thirds of the top value At lant ic and Uulf Coast species of f ish are direct ly dependent In some stages of U f e on conditions in these estuaries.

Another benef i t of both the islands and the i r adjacent marshes and bays Is that of providing habitats for a large number of birds and other animals. The islands also provide habitat for several thousand threatened or endangered species, for example, the loggerhead t u r t l e , the southern bald eagle, a l l i ga to rs , and b own pelicans.

Louisiana has the most rapidly retreat ing beaches in t f« nation. The average re t rea t for the Fourchon beach over the « t 100 years has been In excess of 60 f t / y r . The statewide average according to Dolan et a l . (1982) Is in excess of 12 f t / y r . The consequences of barr ier island retreat are observed at Isles Derniers in Terrebonne Parish and at the Chandeleur Islands in St. Bernard Parish. These barrier islands once flanked central headlands l i ke the central headland at Fourchon. but both have subsequently become separated from the mainland.

There are no known ecologically sensit ive features located in Chandeleur Block 24. The closest sensit ive feature is lovated approximately ten (10) miles west of Block 24 along the shores of the Breton National Wildl i fe Refuge.

The importance of the coastal wetlands to f i sh and w i l d l i f e resources i s wel1-documented. FWS studies Indicate that Louisiana contains 40% of the vegetated coastal wetlands in the conterminous United States id 64% of the t ida l marshes along the Gulf of Hexlco. The Louisiana coastal wetlands support over two-thirds of the Mississippi Flyway wintering waterfowl population (Including 20-50% of North America's puddle duck population) and the largest fu r harvest In North America (from 40-65% of the Nation's t o t a l per year).

Wetlands In coastal Louisiana are usually established on a substrate of a l l uv i a l sediment that is subject to high, natural subsidence ra tes . The effects of natural subsidence are compounded by sea level r ise , which has been occurring during the past several mi l lennia. Under natural conditions, sedimentation encourages ve r t i ca l accretion of wetland areas and may of fset the submergence and Inundation that resul t from subsidence and sea level r i se . The deterioration of coastal wetlands, par t icu lar ly In Louisiana, Is an Issue of concern; i t has been estimated that the state Is losing up to 50 square miles of wetlands every year. Wetlands loss in coastal Louisiana 1s most severe in that area of the State that Is to the east of the Atchafalaya River and Is commonly re fer red to as the Mississippi River Deltaic Plain region.

A recent study funded by MMS ent i t led "Causes of Wetland Loss in the Coastal Central Gulf of Mexico", examined coastal ecosystems of the Northern Gulf of Mexico region and how wetland habitats have .hanged as a result of natural processes and man's act ivi ies thereon. The study's primary focus was on assessing and quant i fy ing the direct and Indirect impacts of OCS-related ac t iv i t ies on wetland areas. OCS-related ac t i v i t i es began in the Gulf region in the early 1950's and based on the study's f indings, of the tota l direct impacts to the areas we., lands (which equate to 74,000ha), OCS-related impacts have contributed to only 4-5% (11,000-14,000ha) of Louisiana's to ta l wetlands loss during the period 1955/56 to 1978 and some 26% of d i rect impacts there.

The shelf and shelf edge of the Central and Western Gulf are characterized by topographic features which are inhabited by benthic communities. The habitat created by the topographic features i s Important because they support hard-bottom communities of high biomass, high d ivers i ty , and high numbers of plant and animal species; they support, either as shelter, food, or both, large numbers of commercially and recreationally important f i shes ; they are unique to the extent that they are small isolated areas of communities in the vast Gulf of Mexico; they provide a re la t ive ly pr ist ine area suitable for sc ien t i f i c research; and they have an aesthetical ly a t t rac t ive in t r ins ic value.

Tht Central Gulf of Mexico l i s t s 16 topographic f t t t u r t s . None of tiiose l i s t e d art in or ntar th t v i c in i t y of th t propostd operations In Char,deleur Block 24.

F. PIPELINES AND CABLES

There are no existing pipelines and/or cables within Chandeleur Block 24.

As a prudent operator, Century w i l l avoid a l l pipelines and cables In th i s block during development ac t i v i t i e s .

G. OTHER MINERAL USES

The a c t i v i t i e s proposed for Chandeleur Block 24 w i l l have no d i rect or Indirect Impact on other mineral uses.

Ocean dumping is prohibited in th is area.

FNDANGERED AND THREATENED SPECIES AND CRITICAL HABITAT

Six Federally l i s t e d endangered whale species may occur in the Gulf of Mex1co--the b lue, f i n , humpback, r i gh t , sle, and sperm whales. Generally, these 1*rge cetaceans inhabit the continental slope and deep oceanic waters; ocass'onally, they are sighted nt rshore.

Endangered red wolf hybrids occur along the Gulf Coast in Cameron Parish, Louisiana.

Federally l i s t e d endangered sea tur t les (Kemp's r id ley , green, hawksbill, and leatherneck t u r t l e s , and the threatened loggerhead tu r t le ) occur In the Gulf of Mexico. The green t u r t l e 1s l i s ted as threatened 1r. Louisiana. The Kemp's r id ley t u r t l e Inhabits shallow coastal and estuarine waters and commonly occur in shallow water areas from Marsh Island to the Mississippi Delta in Louisiana (Hildebrand, 1982). The green tu r t le 1s found throughout the Gulf, where i t s favored habi tats are lagoons and shoals providing an abundance of narine grass and algae on which i t feeds. No recent green t u r t l e nesting has been reported along Gulf beaches. The hawksbill t u r t l e inhabits reef hallow coastal areas, and p<t ses in water deoths of less than 20 ». jeep. Hawksbill nesting has not been reported along the coast «f Louisiana. The leatherback tur t le may be found near the continental . h e l f edge. Sightings have been reported along the Gulf Coast, but no recent nesting has been reported. The loggerhead tu r t le occurs throughout the Gulf and has been observed as far as 500 miles out in the open sea. Infrequent nesting occurs on the Northern Gulf Coast. In addi t ion to their usual habitat area, tu r t les are sometimes seen around offshore oi l /gas platforms.

Tht American al l igator occurs generally throughout tht Gulf Cctst region In fresh to brackish water areas. Tht alligator 1s Hsted as "threatened by similarity of appearanct" throughout its range.

The endangered red-cockaded woodpecker occurs primarily in mature open pine forests throughout the Eastern and Central Gulf area and Into eastem Texas.

Endangered American and threatened art ic peregrine falcons migrate along the Gulf Coast, and some peregrine falcons overwinter In Gulf coastal areas. The ar t ic peregrine falcon migration route occurs along the entire Central and Eastern Gulf of Mexico coasts. The endangered piping plover's winter range Is along the Gulf Coast.

Brown pelicans renain l isted as endangered in Louisiana. Three brown pelican rookeries (about 2,500 birds) occur at North Island, Northern St. Bernard Parish, and Queen Bess Island In Louisiana. The habitat of these colonial nesters Is snail coastal Islands In salt and brackish water areas.

These species may be affected by the developnent of coastal lands and/or the occurrence of oil spi l ls which amy affect the species directly or through thei- food sources. Since the proposed activities include no plans for the developnent of tte coastal lands, the inpact on tndangered and threatened species s primarily based on the occurrence of oil s p i l l s .

As a prudent optrator, Ctntury will ttkt all ntctsstry measures to reduce the probaoility of oil spi l ls . Century's proposed development operations on Block 24 should not pose a threat to any endangered or threatened species.

UNAVOIDABLE ADVERSE ENVIRONMENTAL EFFECTS

A. WATER QUALITY

Production act iv i t ies will temporarily reduce water quality adjacent to the location. This will Increase turbidity in a plume down-current from the work s i te . Released waters and a minor oil sp i l l could also contribute to water quality degradation.

B. EFFECTS ON MARINF ORGANISMS

Some organisms will be kil 1 ed and some will be temporarily functionally impaired as a result of development operation*. The most affected groups will be plankton and benthos immediately around the platform. Damage will be both mechanical and toxlcological. These impacts are considered to be localized, short term and reversible at the population level.

An oil sp i l l could affect a broad spectrum of marine organisms. However, most effects would be localized and short term. Any effects on mammals and turtles would be significant.

MTLAHK AMD BEACH In the unlikely event of a spi l l occurring and reaching siore, organisms in wetland and beach habitats could be k l l l e l or functionally Impaired. Human community disruption could also occur. Although all such effects would be localized, any effects on endangered species and/or cr i t ica l habitats would be significant.

AIR QUALITY The a i r quality at the lease site will be degraded temporarily during operations, but should return to normal once operations are measurably completed. Offshore activit ies probably will not affect onshore air quality. Air quality at the onshore base will be o"ly Insignificantly reduced by onshore act iv i t ies. Any such effect wil l be temporary.

COMMERCIAL FISHING The major Impact on fishing activit ies from the proposed operations 1s production platform placement, oil sp i l l s , and underwater OCS obstructions such as pipelines and debris. Other Impact producing factors Include discharge of dri l l ing muds and removal of structures.

Oil s p i l l s that contact the coastal marshes, bays, estuaries, and open Gulf areas with high concentrations of floating eggs and larvae have the greatest potential for damage to commercial f isheries. An oil spill could seriously affect the shrimp, oyster, and finfish catches In Louisiana as these fishes are estuarine dependent. One production platform removes approximately 4 acres of trawling space, and underwater OCS obstructions cause gear conflicts which result in such losses as trawls, shrimp catch, business downtime, and vessel damage. Gear conflicts caused by underwater OCS obstructions are mitigated by the Fisherman's Contingency Fund.

The installation of pipelines will contribute to fishery habitat loss and, therefore, negatively impact fishery resources.

Orilling mud discharges contain chemicals that are toxic to marine f ishes; however, only at concentrations four or five orders of magnitude higher than those found more than a few meters from the discharge point.

Tht removal of platforms results In habitat loss and can caust fish k i l l s when explosives art ustd.

In conclusion, although th ts t factors Impact th t commercial f isheries industr ies, tht level of impact is expected to bt very neg l ig ib le

F. SHIP NAVIGATION,

Very l i t t I t interference :an bt t xp tc t td bt twttn th t platform and •arine vessels u t i l i zed during production optr t t lons and ships that ust established fairways. However, at night and during rough weather, fog, and heavy seas, ships not using established fairways could co l l ide with the plat form. Approved aids to navigation w i l l be installed on the proposed platform in accordance w i th USCG regulations.

G. CULTURAL RESOURCES

There 1s only a small probabi l i ty that an unknown cultural resource ex is ts in the lease area.

H. RECREATION AND AESTHETIC VALUES

The platform and marine vessels may represent an obstacle to some sport fisherman, but such an ef fect 1s expected to be negligible and not permanent.

Even though ex i s t i ng regu la t ions and orders prohibit indiscriminate l i t t e r i n g of the marine environment with trash, offshore o i l and gas operations involving men, machines, equipment, and supplies is bound to resul t in some l i t t e r i n g of the ocean. Human nature and accidents associated with offshore operations w i l l contribute some f loatable debris to the ocean environment which w i l l eventually come ashort on major recre-ational beaches.

The effects that normal operations or a minor o i l sp i l l would have on any f i sh stocks important to sport fishermen are also considered to be negligible.

A Minor o i l s p i l l and/or non-petroleum f loat ing debris could foul beaches inshore of the lease area. The foul ing of the beaches would be an aesthetic detriment that could adversely affect recreation. Any effects on beach recreation could adversely affect tourism, and consequently, the local economy.

SUMMARY

Tht propostd tc t lv l ty Mill bt carried out tnd completed with guarantee of tht following items.

A. Tht btst available tnd stftst technologies will bt utilized throughout tht project. This Includes meeting al l applicable requirements for equipment types, general project layout, safety systems, and equipment and monitoring systems.

B. All optrttlons trt covered by a Mintrtis Management Service approved 011 Spi l l Contingency Pltn.

C. All applicable Federal, State, and Local requirements regarding air emission and water quality and discharge for the proposed activit ies, as well as any other permit conditions, wi l l be complied with.

D. Tht proposed activities described In detail In the Development Plan will comply with Louisiana's Coastal Maragemtnt Program and will be conducted In a manner consistent with svcn Program.

1 BIFlBLms

l .

2.

3.

4.

5.

6.

7

8.

9.

final Environ—ntal Impact State—nt. Propostd 011 and Gas Ltast Salts 94, 98, and 102, Gulf of Mexico OCS Region, OCS EIS, MMS 84-0057.

Final Environmental lea act Statement. Propostd 011 and Gts Lttst Sales 94, 98, and 102, Gulf of Mexico OCS Region, OCS EIS, MMS 84-0057, visuals.

fisheries of tht Unite, SUtCS, 1985. April, 1986.

Tht Ecology of Petroltum Platforms in '.he Northwestern Gulf of Mexico: A Community Profilt. Bureau of Land Management Open File Report 82-03, July, 1982.

Environmental Report West Cameron Area Blocks 516 and 524. March, 1987.

BLH Draft Environmental Impact Statement. OCS CO and Gas Lease Sales A-62 and 62.

BLM Final Environmental Itm^t Statement. OCS O'i and Gas Lease SHes A-6? and f\i.

BLH Final Environmental Impact Statement. OCS 01 < and Gas Least Salt 47.

Interior. Final Environmental Impact Statement. Proposed Oil and Gas Ltast Silts 110 and 112, Culf of Mexico OCS Region, OCS EIS, MMS 86-0087.

final Environment*! Impact Statement, Proposed 011 and Gas Lease Sales UO and 112, Gulf of Mexico OCS Region, OCS EIS, MMS 86-00*7, visuals.

Final Environmental Impact Statement. Proposed Oil and Gas Lease Sale? 113, 115, and 116, Gulf of Mexico OCS Region, OCS EIS. MMS 87-0077.

Final Environmental Impact Statement. Proposed Oil and Gas Lease Sales 118 and 122. Gulf of Mexico OCS Rerjion. OCS EIS. MMS 88-0044.

COASTAL XOtiE MANAGEMEHT

CONSISTENCY CERTIFICATION

OEvtr^PMBirr OPERATIONS CQQRDINATIQII DOCUMENT

CHAHPELBUR i M l BLOCK 21

OCS-Q 6840

Thm propoaad a c t i v i t i e s described in deta i l ln thla Plan comply w i t h Louisiana'a approved Coaatal Management Program and w i l l ba conducted in a nannar cone la tent with auch Program.

Cmnturv Ofignore Management Corporatio,; Laooaa or Oparator

D. Kirby Mor r i a Cert i fy ing O f f i c i a l

Oata

ATTACHMENT G

COASTAL SONS MANAGKMENT

CONSISTENCY CERTIFICATION

nmmrHiHT OPERATIONS COQRJINATIQH PQCVMBHT

CttANDBLBUR MM BLOCK 24

OCS-0 6840

The propoaed actlvitlea described ln detail In thla Plan comply with Mlealaeippi'e approved Coaatal Manageaent Program and will be conducted in a manner contiatent with tuch Progran.

Century Offahore MAnaaemmnt Porporatlon Leasee or Operator

i. Kirty H^rrl. D. Certifying O f f i c i a l

Date

ATTACHMENT G

r i