UNITED STATES DEPARTMENT OF THE INTERIOR
MINERALS MANAGEMENT SERVICE
GULF OF MEXICO OCS REGION

NOTICE TO LESSEES AND OPERATORS OF FEDERAL OIL, GAS, AND SULPHUR
LEASES IN THE OUTER CONTINENTAL SHELF, GULF OF MEXICO OCS REGION

Deepwater Chemosynthetic Communities

This Notice to Lessees and Operators (NTL) supersedes NTL No. 98-11, effective August 10, 1998, and is being issued to make technical amendments.

Purpose

The purpose of this NTL is to provide a consistent and comprehensive approach to protecting high-density chemosynthetic communities from damage caused by oil and gas activities.

Introduction and Background

Deepwater (water depths greater than 400 meters) chemosynthetic communities were discovered in 1984 in the central Gulf of Mexico and have been studied extensively in recent years. Chemosynthetic communities include assemblages of tubeworms, clams, mussels, bacterial mats, and a variety of associated organisms. They are remarkable in that they use a carbon source independent of photosynthesis and the sun-dependent photosynthetic food chain that supports all other life on earth. Many of the species, while similar to those of other chemosynthetic communities, including vent communities of the Galapagos Ridge, are new to science. While most communities are represented by low densities, there are examples of very high densities of organisms in small isolated areas. Features or areas that could support high-density chemosynthetic communities include hydrocarbon-charged sediments associated with surface faulting, acoustic void zones associated with surface faulting, anomalous mounds or knolls, and gas or oil seeps. Damage to these communities will result from oil and gas activities that disturb the seafloor in the immediate vicinity of these communities. Such activities include (but are not limited to) drilling, anchoring, placing seafloor templates, discharging muds and cuttings, and installing pipelines.

Regulatory authority to require avoidance or protection of chemosynthetic communities and avoidance of shallow hazards, such as gaseous sediments, appears at several places in 30 CFR 250. General provisions concerning protection of the environment are at 30 CFR 250.106(c). Specific provisions concerning sea-bottom hazards at particular sites are at 30 CFR 250.203(b)(1)(ix) for exploration plans, 30 CFR 250.204(b)(1)(vii) for development and production plans, 30 CFR 250.909(b)(2) for platform foundations, and 30 CFR 250.1007(a)(5) for pipelines.

Detailed data regarding the extent, location, structure, and relationship of these communities to the local geophysical environment are sparse. This information is particularly lacking for potential chemosynthetic community sites believed to exist in water depths beyond 1,000 meters (3,281 feet).

Policy

If you propose activities that could disturb seafloor areas in water depths 400 meters (1,312 feet) or greater, maintain the following separation distances from features or areas that could support high-density chemosynthetic communities:

1. At least 1,500 feet from each proposed muds and cuttings discharge location; and

2. At least 250 feet from the location of all other proposed seafloor disturbances (including those caused by anchors, anchor chains, wire ropes, seafloor template installation, and pipeline construction).

Refer to Attachment A for a list of known chemosynthetic communities. Note that the location of each known chemosynthetic community is delineated by only a single point (latitude and longitude). Use your judgement to determine the boundary of the known chemosynthetic community. The separation distances given in Items 1 and 2 above apply to the boundary.

Procedure

So that the Minerals Management Service (MMS), Gulf of Mexico OCS Region (GOMR) can make determinations regarding the possibility of chemosynthetic communities being present and the potential of their being harmed by exploration, development, and pipeline construction activities, provide the following information:

1. If you propose activities in an Exploration Plan (EP) or Development Operations Coordination Document (DOCD) that could disturb seafloor areas in water depths 400 meters or greater, include the information outlined in Attachment B to this NTL in one copy of your EP or DOCD.

2. If you propose activities in a pipeline application that could disturb seafloor areas in water depths 400 meters or greater, include the information outlined in Attachment C to this NTL in one copy of your pipeline application.

The MMS GOMR will analyze the above information during its review of your OCS plan or pipeline application. If the MMS GOMR determines that features or areas that could support high-density chemosynthetic communities are present and could potentially be harmed by your proposed activities, the MMS GOMR will instruct you to:

1. Amend the OCS plan or pipeline application to relocate the proposed activities to avoid impacting possible high-density chemosynthetic communities;

2. Amend the OCS plan or pipeline application to provide additional information (perhaps including a photo-survey, a video-survey, or already available information) that documents whether high-density chemosynthetic communities exist in the areas of concern; or

3. Adhere to certain conditions of OCS plan or pipeline application approval such as using a remotely operated vehicle to set anchors precisely or taking other measures to ensure that the proposed anchor pattern does not impact high-density chemosynthetic communities, monitoring impacts caused by the proposed activities, or adhering to any other condition deemed necessary by the MMS GOMR.

Paperwork Reduction Act Statement

The information collection provisions of this NTL are intended to provide clarification, description, or interpretation of requirements contained in 30 CFR 250, Subparts B and J. The Office of Management and Budget (OMB) has approved the information collection requirements for these regulations and assigned OMB Control Numbers 1010-0049 and 1010-0050, respectively. This NTL does not impose additional information collection requirements subject to the Paperwork Reduction Act of 1995.

Chris C. Oynes
Regional Director

Attachments

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