Our Seabed Frontier Challenges and Choices (1989) / Chapter Skim
Currently Skimming:
3. Present and Potential Uses of the Seabed
3. Present and Potential Uses of the Seabed
Pages 20-59
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From page 20... ...
Problems and issues associated with each resource or activity are analyzed, particularly existing or potential conflicts among different uses. Resources and uses examined include oil and gas exploration and development, mineral exploration and development, waste disposal, cables and military uses, biological resources, ocean energy resources, and cultural and recreational resources.
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From page 21... ...
In the future, subsea production systems of the dry type will be used more widely in water depths from 1,000 to 2,000 m, especially for satellite reservoirs. Improvements in deepwater Bowline installation and artificial lift technology should allow the system to be economically attractive for water depths out to 3,000 m.
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From page 22... ...
. Scope of Development Future offshore oil and gas activities will include development of presently unleased areas of the outer continental shelf (OCS)
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From page 23... ...
The primary technical constraints facing designers will be depth limits of current platform and pipeline technology; lack of knowledge about new seafloor sediment types; and lack of understanding of geological, biological, and oceanographic processes that control seafloor conditions that impact platform and pipeline design and operation. Development Constraints Many technical and economic constraints face the offshore oil and gas industry as it moves farther onto the continental slope and into unexplored arctic regions.
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From page 24... ...
A related problem is that existing bathymetric maps for EEZ continental slopes are not accurate enough to develop site-specific oil production systems. Considerably more detailed information on water depths and gradients is needed for potential development sites.
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From page 25... ...
(More detailed discussion of engineering properties and problems of acquiring reliable data are presented in Chapters 2 and 4.) Several important geotechnical problems arise when developing oil and gas production facilities for deep water and the Arctic.
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From page 26... ...
But, historically, pipeline ruptures have released far less petroleum into the marine environment than other transport systems, such as coastal tankers and barges (NRC, 1985~. Any natural phenomenon that presents a potential hazard to a pipeline must be considered, however, and protective measures taken.
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From page 27... ...
disagreement with Law of the Sea provisions over ocean mineral rights, caused the fledgling marine mining industry to shelve deep ocean mining exploration and systems development at a point where proof of concept and site reconnaissance were accomplished. In 1983, interest in offshore minerals was again stimulated by the EEZ proclamation, combined with the Reagan administration's expressed concern over dependence on foreign sources for strategic minerals.
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From page 28... ...
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From page 29... ...
The standard marine mining system has been the dredge, which has proven adequate for unconsolidated or weakly consolidated ore bodies in water depths to 60 m and in relatively calm seas. Major advances in methods and mining systems will be required to recover much of the EEZ deepwater deposits previously described.
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From page 30... ...
One factor in predicting long-term development time frames for EEZ mining is that the U.S. marine mining industry is not competitive with nations such as Japan, France, the United Kingdom, and West Germany.
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From page 31... ...
If there is a perceived national need within the 10- to 15 year time frame for critical minerals available from the seabed, it may be necessary for the federal government to intercede and assist the mining industry (e.g.,- protection measures and cooperative research and development programs)
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From page 32... ...
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From page 33... ...
Even though impressive advances were made in developing prototype mining equipment during the 1960s and 1970s to recover deep ocean manganese nodules, present market conditions, the limited financial strength of the U.S. offshore mining industry and its poor competitive position internationally suggest that it will be many years before the U.S.
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From page 34... ...
Leasing Policy and Regulation The present U.S. marine hard minerals regulatory situation is at best controversial and at worst inadequate to encourage development of EEZ mineral resources and deposits.
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From page 35... ...
As a result, most companies involved in offshore mining operations and development have reduced their activities or closed, and experienced marine mining personnel have retired or left the industry (DOI, 1987~. The technologies and capital investment required to map and evaluate many EEZ minerals (especially in deep water)
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From page 36... ...
Wastes discharged from pipelines tend to result in more localized accumulation of contaminants because the point of release is feed and generally near the seabed. This report considers the principal types of solid wastes disposed beyond coastal waters~redged material, sewage sludge, and industrial wastes-and potential new sources of wastes that might be considered for ocean disposal in the future.
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From page 37... ...
Sludge is a major source of DDT and PCBs, and contaminants have become incorporated into the sediments near previously used disposal sites off New York and Delaware Bay (Lear and O'Malley, 1983; Sawyer and Bodammer, 1983; Stanford et al., 1981~. Organic contaminants in New York Bight sediments attributed to sludge dumping are summarized in Table 3-5.
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From page 38... ...
Over the long term, the volumes of contaminated material may be minimized as source reduction practices lessen the industrial and municipal waste input into coastal waters. Land application and incineration of sewage sludge face increasing public opposition and limitations caused by contaminant levels.
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From page 39... ...
Isolating Contaminated Materials Identifying and isolating contaminated from uncontaminated material is a major constraint for ocean dumping of materials such as dredged sediments. One of the first issues to address is the extent and nature of contaminants present.
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From page 40... ...
Isolation methods within the marine environment, such as mound capping, borrow pit capping, or engineered structures should be used for contaminated material. Improved understanding leading to prediction of erosional processes on the EEZ seabed is needed for longterm prediction of the suitability of such disposal sites.
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From page 41... ...
State of Class I: nondegrading to water quality and nontoxic to organisms. Connecticut Class Il: moderately polluted, but suitable for island or marsh habitat designation development and for open-ocean disposal.
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From page 42... ...
regulates ocean dumping of dredged material, barged sewage sludge, and industrial waste, and prohibits disposal of HLW and radiological warfare agents in the ocean. · The Clean Water Act, National Pollutant Discharge Elimination Systems (NPDES)
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From page 43... ...
Improved technical understanding and sound regulatory controls could enhance public confidence that some tones of waste can be disposed of in the marine environment without degrading it. Siting -or More resources and technical expertise will be needed if dredged material dumpsites are to be designated and monitored on a more timely basis during the 1990s than they were in the 1980s.
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From page 44... ...
The socioeconomic tradeoffs of disposing of waste on land~vhere it poses a serious hazard to groundwater, freshwater lakes and rivers, and the rich nearshore environment of bays and estuaries-have been given far too little attention in risk assessments of marine waste disposal. Summary Over the past ten years many waste disposal practices in the ocean have been phased out, and while seafloor disposal of dredged materials will continue, public and political opposition is likely to uphold restrictions of ocean dumping of sewage and industrial wastes.
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From page 45... ...
Dual coax cable 1959 48 (3kHz) Single coax cable 1961 80 (3kHz)
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From page 46... ...
In the next 10 years, the development of fiber optic cables with wider transmission bandwidth will reduce the number of active cables in use for a particular link. However, over the next 25 years, the number of cables is likely to increase as links to other continents and islands become more cost effective, due to improved economy per unit length of fiber optic cables.
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From page 47... ...
In the immediate future, fiber optic cable systems will cause coax cables to become obsolete on high traffic density routes, resulting in fewer active cables. However, rapid growth in digital traffic means that more fiber cables are being planned.
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From page 48... ...
· Remotely operated vehicles and autonomous underwater vehicles: The application of ROVs and AUVs to military tasks is in its infancy relative to the potential of these vehicles for solving many problems associated with accomplishing underwater tasks, and military investigation of this potential will yield vehicles capable of performing increasingly complex tasks, some of which will use the seabed as a working surface. Military development of these vehicles for installation and support of complex mechanical structures in deeper water will well outstrip corresponding commercial development.
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From page 49... ...
The bottom trawling fishing industry uses gear that are often incompatible with the protection of ocean cables and sensor/transducer systems. Although ocean cables can be buried, some sensor
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From page 50... ...
Summary Future growth in the number and value of ocean cables is assured by the soaring demand for digital transmission using fiber optics, which have produced more reliable, economical, and secure telecommunications. There is also every reason to believe there will be an increased military presence in the EEZ because the nation's defense depends on military activities carried out in these waters.
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From page 51... ...
Domestic aquaculture operations are generally restricted to coastal waters and significant expansion beyond three miles into the EEZ seabed is unlikely and is therefore not discussed in this report.
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From page 52... ...
~ ~ ~ ~ ~ _ , · oil- and gas-producing regions on the Louisiana continental slope, where methane and hydrogen sulfide are released from the sediment; · the Florida Escarpment, where thermochemical reactions at depth appear to be responsible for producing hydrogen sulfide-rich hypersaline brines; and · the Gorda Ridge off northern California and Oregon, where active hydrothermal vents occur. In these locations, unique animals have been found living symbiotically with bacteria that utilize the chemical energy in hydrogen sulfide.
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From page 53... ...
Additionally, many bacterial species found in chemically unusual marine environments are logical candidates to study for their ability to degrade toxic chemicals (Jannasch, 1989~. Discoveries of microorganisms with the ability to metabolize chemical compounds previously thought to be resistant to biodegradation have stimulated the search for additional microbes with such desirable abilities (Roberts, 1987~.
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From page 54... ...
· Ocean Thermal Energy Conversion (OTEC) requires a substantial temperature difference between warm surface water and cold deeper water and a nearshore steeply sloping seafloor, conditions that are found off Puerto Rico, the Virgin Islands, and Pacific islands (Figure 3-9~.
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From page 55... ...
Scope of Development OTEC involves harnessing the temperature differences between surface and deeper waters and converting them to energy. A closed system version vaporizes a working fluid using warm surface water, which expands under high pressure to run a turbine, and is then recondensed by deep cold water.
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From page 56... ...
to a steeply sloping seafloor will be technically demanding, and will require a wide range of seafloor information (Rogers et al., 1988~. The most important information will pertain to properties of the upper continental slope: strength and stress-strain time parameters, compressibility and stress history, permeability, effects of slope deformation and failure, landslides, turbidity currents, debris flows, faulting, erosion, and scour.
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From page 57... ...
Of the two technologies, OTEC will have more demand for EEZ seafloor information since wave energy systems will almost certainly be located on or near the shore. CULTURAL AND RECREATIONAL RESOURCES Background Cultural and recreational resources of the EEZ include marine archaeology, treasure seeking, and commercial salvage; recreation; and marine sanctuaries.
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From page 58... ...
EEZ. While these activities will create new demands for more detailed seafloor information in selected locations in the foreseeable future, these will fall within the territorial sea.
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From page 59... ...
The identification and designation process will require detailed site-specific information on physical and biological characteristics. Summary Increasing utilization of ocean-related cultural and recreational resources will stimulate demand for better and more detailed seafloor information.
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