00-14738. Completion of an Environmental Assessment on Exploration, Development, and Production Operations and Activities in the Deepwater Gulf of Mexico Outer Continental Shelf

AGENCY:

Minerals Management Service, Interior.

ACTION:

Completion of an environmental assessment.

SUMMARY:

The Minerals Management Service (MMS) has completed an environmental assessment (EA) on exploration, development, and production activities in the deepwater areas (generally beyond 1,000 feet water depth) of the Gulf of Mexico (GOM) Outer Continental Shelf (OCS). The MMS is mandated to manage the development of OCS oil and natural gas resources, while also ensuring safe operations and protection of the human and natural environment. To meet these objectives, MMS has used the National Environmental Policy Act (NEPA) process as a planning tool to assist in managing these activities and assure appropriate environmental reviews. The findings of the EA are summarized below.

Based on the information and analyses in the EA, MMS has determined that a programmatic Environmental Impact Statement (EIS) on regional deepwater activities on the Gulf of Mexico OCS is not required. Most deepwater operations and activities are substantially the same as those associated with conventional operations and activities on the continental shelf. These deepwater components and activities include anchoring, mooring, stationkeeping, most drilling and well completion activities (the exceptions are discussed below), well test and cleanup operations, flaring/burning, facility installation and production operations, host facilities, pipeline installation and operations, alternative transportation options, operational emissions, routine produced-water discharges, support service activities, decommissioning, and site clearance. Existing NEPA documents, established project-specific and programmatic NEPA review processes, and established mitigation measures are fully sufficient to address these deepwater components and associated activities.

Specific deepwater operations and activities that are substantially different from those associated with conventional operations and activities on the continental shelf have been addressed by requiring specific mitigation measures, initiating a more in-depth EA, and initiating an EIS.

Seafloor discharges from pre-riser and riserless drilling operation, and the discharge of synthetic-based drilling fluids (SBF) and cuttings wetted with SBF may pose potentially significant localized impacts to chemosynthetic communities. An appropriate mitigation measure has been developed to avoid or reduce the potential for significant impacts from these factors. Deepwater wells must be at least 1,000 ft away from any potential high-density chemosynthetic communities. Notice to Lessees (NTL) 98-11 is being modified to include this 1,000 ft buffer zone around all deepwater well sites. As the NTL goes through the formal review and implementation process, this mitigation is currently being applied on a site-by-site basis. Accidental spills of chemical products and the subsea release of oil are low-probability events. Extensive mitigation measures for spill prevention and response are currently required.

Deepwater seismic surveying operations are essentially the same as seismic surveying operations on the continental shelf. Historically, the potential impacts of noise associated with seismic surveying have been considered insignificant, and the EA supports this view. As this position has recently become controversial, the potential impacts of geological and geophysical (G&G) activities, including seismic surveying operations, on the GOM OCS are currently being analyzed in detail in a separate EA. The decision on the need to prepare an EIS on seismic surveying operations is pending completion of the G&G EA.

The use of floating production, storage, and offloading (FPSO) systems represents new and unusual technology for the GOM OCS and may pose potentially significant impacts to the marine and coastal environments. The need for an EIS was recognized early during the preparation of this EA. A Notice of Intent to Prepare an EIS was published in the Federal Register on June 10, 1999.

Copies of the EA are available from the Public Information Office (MS 5034), Minerals Management Service, Gulf of Mexico OCS Region, 1201 Elmwood Park Boulevard, New Orleans, Louisiana 70123-2394 by asking for publication MMS 2000-001. Copies of the Technical Report (OCS Report MMS 2000-015) prepared in support of the EA will also be available in mid-July 2000. Both the EA and the Technical Report will eventually be available on CD and will be placed on the MMS website http://www.mms.gov.

FOR FURTHER INFORMATION:

Questions regarding the EA should be directed to Ms. Deborah Cranswick, Leasing and Environment, at [phone]. Questions regarding deepwater operations should be directed to Mr. Jim Regg, Field Operations, at [phone]. The mailing address is Minerals Management Service, Gulf of Mexico OCS Region, 1201 Elmwood Park Boulevard, New Orleans, Louisiana 70123-2394.

Dated: June 6, 2000.

J. Hammond Eve,

Acting Regional Director, Gulf of Mexico OCS Region.