The occurrence and existence of submarine slides, slumps, debris flows, and related features on the mid-Atlantic slope and rise has been well documented in the literature. McGregor (1977) and McGregor and Bennett (1977, 1979) observed large submarine slides on the slope and rise between Spencer and Wilmington Canyons. Embley and Jacobi (1977) reported the existence of a large slide zone and the occurrence of large slump masses on both the slope and rise southeast of Baltimore Canyon and south of Norfolk Canyon. Knebel and Carson (1979) found evidence of extensive slumping on various intercanyon portions of the mid-Atlantic slope.

More recently Robb et al. (1981a) and Robb et al. (1983a) surveyed the continental slope between Toms and Lindenkohl Canyons. Only 1.3 percent of the entire survey area contained slump or slide features. Robb et al. (1983a) do report, however, that small-scale slumping and sliding does appear to commonly occur within the submarine canyons.

Other slump or slide features have also been identified within the proposed sale area. Keer and Cardinell (1981) identified such features south of Hudson Canyon, near Wilmington and Baltimore Canyons, and south of Baltimore Canyon. Malahoff et al. (1980) reported the occurrence of numerous small sediment slides and slumps on the slope region between Baltimore and Washington Canyons. These and other related features are discussed in detail in Appendix H of this EIS. Appendix H also contains a discussion of debris flows and mass wasting events which some researchers have suggested may pose a hazard to offshore operations, particularly to those areas on the lower slope and upper rise lying at the base of the submarine canyons.

Mitigating Measures and Regulations Pertaining to Geologic Hazards and Siting Considerations

Under OCS Operating Order No. 2, a lessee is required to conduct an independent geological hazards survey on a newly leased block prior to any actual commencement of drilling. The data must be submitted to the RS/FO who will evaluate it for completeness and accuracy and recommend or require that certain operational procedures be followed to safeguard against any hazardous conditions. The general procedures to be followed by the lessee in conducting site-specific geological hazards surveys are set forth in various Notices to Lessees and Operators (NTL) issued by the regional offices of MMS. The NTLs serve as guidance for minimum requirements and do not restrict the authority of the RS/FO to impose additional requirements on the lessee when necessary. Requirements regarding hazards surveys for the Atlantic Region are set forth in Atlantic NTL 83-2. In areas where geohazards are known to be present, DOI may include an Information to Lessees clause within the Notice of Sale.

In the case where a slump body or mass sediment movement feature is identified within a leased block, the lessee will be required to thoroughly analyze the feature as to its foundational stability. OCS Order No. 8 requires that a lessee submit to the RS/FO a soil stability report including a determination, with supporting information, of the susceptibility or nonsusceptibility of an area to sediment movement and, if susceptible to soil movement, a complete analysis of slope and soil stability. Should a block or blocks upslope of a leased block appear to present problems in terms of instability, the RS/FO may require that soil stability studies be undertaken outside of the leased

block. Similar measures would be required, should apparently unstable conditions exist downslope of the immediate vicinity of a leased block. Upon plugging and abandonment, surface plugs may be set deeper than required by the orders if it is determined that there is a possibility of mass movement after abandonment.

Various safety devices to mitigate potential geologic hazards are required under the OCS Operating Orders. OCS Order No. 5 requires that all producing wells have fail-safe surface controlled subsurface-safety valves. valves are extremely effective in preventing uncontrolled flow from wells that have been damaged at the surface. This is particularly relevant in terms of potential submarine slumps or slides where the primary concern is to shut in all producing wells.

The subsurface safety valve (SSSV) is installed in the production tubing of a well at a specified depth beneath the sea floor. It can be installed and retrieved by wireline and pump down methods, or it can be an intergral part of the tubing string.

Such valves remain in an open position only when under hydraulic or other pressure exerted by the control medium and are, therefore, essentially failsafe. When hydraulic pressure is removed, either intentionally or as a result of failure, the valve moves to the closed position, preventing any further flow from the well.

The Minerals Management Service (MMS) requires in OCS Order No. 5 that subsurface safety devices be tested in place for proper operation at intervals not exceeding 6 months. New requirements added to OCS Order No. 5 should lead to further improvements in the reliability of these devices. All SSSVs must now conform to the quality assurance standards of the American National Standards Institute/American Society of Mechanical Engineers (ANSI/ASME, SPE-1 and SPE-2), and the American Petroleum Institute (API) Specification for subsurface Safety Valves (API Spec. 14A).

Existing technology can be utilized in designing SSSVs for the proposed sale area. In areas of potential bottom instability, the valves may have to be set at depths as great as 1,000 ft beneath the sea floor. Such deep setting depths are also required in the Arctic to ensure that the valves are set beneath permafrost zones. SSSVs in Prudhoe Bay wells are set as deep as 2,500 ft beneath the surface. Such valves have proven to be nearly 100 percent reliable. The major manufacturers, operators, and MMS technical personnel all believe that such valves can be set at much greater depths if the decision to do so is made when the well completion is being designed.

Exist

Deep water should not pose a problem in actuating subsurface valves.
ing subsurface valves are almost exclusively actuated by hydraulic systems.
Although total hydraulic systems also could be employed in the proposed
sale area, electrohydraulic techniques would likely be used to minimize the
time required for transmitting signals.

Electrohydraulic controls are presently used to actuate sea floor blowout preventers during deepwater drilling operations. Exxon successfully utilized electrohydraulic equipment to remotely control and monitor the ocean floor equipment on its prototype Submerged Production System (designed for operation

in 2,000 ft of water). All flow-control valves on the Submerged Production Systems (including subsurface-safety valves) are fail-safe closed and require the presence of hydraulic pressure to remain open. However, to reduce the time required for operation valve actuators, commands are transmitted electrically from the surface to the sea floor.

An added safety factor in the control of blowouts is the installation of blowout preventors (BOP). BOPs are required on all drilling operations by OCS Order No. 2. BOPs must be tested at least once a week and visually inspected once a day. BOP drills are required periodically and reports submitted to MMS. A BOP drill is required to be conducted for each drilling crew in accordance with the well-control drill requirements of the MMS OCS standard entitled "Training and Qualifications of Personnel in Well-Control Equipment and Techniques for Drilling on Offshore Locations," MMS-OCS-T1.

In addition, MMS requires the use of diverter equipment. Should shallow gas be encountered during drilling, the diverter "diverts" gases to the side, downwind and away from the platform. Diverters thus provide additional time for the drilling crew to try control the blowout.

Note: At the present time MMS is studying proposed rules which would consolidate into one document the currently multi-tiered rules of MMS's offshore programs that govern oil and gas operations on the OCS. The proposed rules would merge the various operating requirements now found in the regulations, OCS Operating Orders, and other documents into a single set of requirements to be codified at 30 CFR, Part 250. This reform is directed toward reducing the burden on industry resulting from the regulations while maintaining or increasing the level of safety and the protection provided for the environment. This is being accomplished by addressing issues identified by MMS as well as issues raised by industry in response to a request from the Secretary of the Interior for the identification of burdensome regulations.

The goal of reducing the burden on industry while maintaining levels of safety and environmental protection is proposed to be accomplished through the following specific objectives:

o to consolidate all requirements into a single document, eliminating
the multiple tiers of rules;

to state requirements in terms of performance standards to the extent practicable;

to update rules in areas where warranted by safety or environmental
needs, operating experience, current operational practices, and
advances in technology;

to trim reporting and recordkeeping requirements to the minimum; and

O to remove redundant provisions, generally simplify the language and
clarify the rules.

Sections III.A.2 and III.A.3 describe the oceanographic and meteorologic conditions found in the mid-Atlantic region. Offshore hazardous conditions in the mid-Atlantic area may be comparable to or less severe than those in the existing operating areas in the Gulf of Alaska and in the North Sea (see Figures IV.A.3-1 and 3-2 for a comparison) (Tetra Tech, 1974). In general, the surface wind pattern along the Atlantic coast is controlled by the location and intensity of the Bermuda-Azores high pressure system. The region's major low pressure storm systems sweep through in a north to east-northeast direction. These extra tropical or continental cyclones (nor'easters) are often intense and severe and are generally accompanied by strong, gusting winds and high seas. These storms occur most often during the winter months when the Bermuda-Azores high is located far to the southeast. Winds over the proposed sale area are generally westerly thoughout the year, with some seasonal shifting to the northwest during winter and to the southwest during summer. Of particular concern in offshore areas is the percent frequency of extreme events, in this case winds in excess of 41 kt. On an annual average, such winds occur in the nearshore area of the proposed sale area between 0.5 and 0.7 percent of the time, and up to 1.8 percent of the time in areas farther offshore. Extreme wind speeds are likely to occur during the passage of either tropical or extratropical storms.

Tropical cyclones occur primarily during the period from June through November. They may exhibit winds of up to 100 kt and generate wave heights in excess of 40 ft (12 m). Winds accompanying extratropical cyclones can reach gale and, occasionally, hurricane force. Extratropical storms generally occur between the months of October and April. These storms may be severe, producing prodigious amounts of precipitation, and their high winds generate unusually high waves. The highest incidence of tropical storms occurs during the summer and autumn. Wind speeds as high as 100 kt and wave heights in excess of 40 ft may accompany these storms. Because of the long fetch available to them, these kinds of winds can generate very large waves. If a spill occurs when 'the area is subject to these extreme events, onshore winds could drive the oil close to the coastline. Although transport by waves is minimal in deep water, oil driven into the surf zone could be transported onto the shore by breaking waves. The high winds could produce spray laden with oil droplets which could contact shore vegetation.

It should be noted that the Gulf of Mexico operating area is subject to hurricane winds more often and more intensely than the mid-Atlantic area. Yet, because of the precautionary steps that have been taken in the region, loss of life, destruction of platforms, and oil spills caused by hurricanes have been relatively few. Incidence of high waves is likely to be greater in the proposed lease area than in the Gulf of Mexico because of the large size of extratropical storms in combination with the available fetch, which is rather restricted in hurricanes. When such conditions threaten, the normal procedures would call for operators to shut wells in with storm chokes and to evacuate platforms.

Production platforms which may be used within the proposed lease area are being designed to withstand normal and extreme North Sea wind and wave conditions which are considered more severe than those encountered in the midAtlantic region.

Figure IV.A.3-1 compares the maximum sustained winds* that can be expected in the proposed sale area, the North Sea, and the Gulf of Alaska, This comparison would seem to indicate that the wind designs for Mid-Atlantic structures should be approximately the same as those for North Sea struc

* Maximum sustained wind is defined as the average over a one minute period of the maximum measured wind. Maximum gust velocity is usually about 1.4 times the maximum sustained wind.