| MMS ENVIRONMENTAL STUDIES PROGRAM: ONGOING STUDIES | ||||||
| MMS OCS Region: | Headquarters |
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| Title: | Environmental Investigation of the Long-Term Use of Ship Shoal Sand Resources for Large-Scale Beach and Coastal Restoration in Louisiana (NT-03-04) | |||||
| Total Cost: | $600,000 | Period of Performance: | FY 2004 - 2007 | |||
| Conducting Organization: | Coastal Marine Institute, Louisiana State University | |||||
| MMS Contact: | Colleen Finnegan | |||||
| Description: | ||||||
| Background | ||||||
| Geological and geophysical studies of Ship
Shoal, offshore the central coast of Louisiana, have determined that the
shoal’s sand is an ideal source of material to place on the rapidly eroding
Louisiana barrier islands. MMS is currently negotiating leases with the
State of Louisiana and several other Federal Agencies for planned barrier
shoreline/barrier island restoration projects. Many large-scale Louisiana
coast projects are in the planning stages, some of which will require
enormous amounts of nourishment material. Resource estimates for the volumes
of sand comprising the Ship Shoal structure are 1.2 billion cubic meters
(m3) ranging from very fine to medium sand. One complicating factor,
however, is the magnitude of oil and gas structures, platforms and
pipelines, which are located on the shoal. This necessitates that only areas
free of pipelines and structures serve as sand borrow areas. Thus, large
volumes of material may ultimately be removed from certain blocks or zones.
In addition to the existence of numerous oil and gas-related structures, site-specific biological information is scarce and sketchy at best. In a Southwest Research study conducted by Baker and others in 1981, samples from the Louisiana continental shelf (LCS), including Ship Shoal, were studied to determine the ecological effects of petroleum production platforms in the central Gulf of Mexico. The sampling stations for Ship Shoal, located in the vicinity of one platform, were located roughly 27km (17 miles) from the shore, in approximately six meters of water depth. Results from this study indicated that the benthic communities of the Ship Shoal varied from that found throughout the LCS. This data is not sufficient to properly assess impacts to the local biology given the probable long-term use of the shoal as a sand resource area. Physical field and numerical modeling studies conducted on Ship Shoal indicate that it exerts a significant influence on regional hydrodynamics, reducing wave energy and modulating current velocity, particularly during storm events (Stone and Xu, 1996; Stone et al, 2001). Although wave modeling results show favorable results relative to potential effects of sand extraction on the local wave climate, Stone (2001) recommends site-specific numerical modeling, using state-of-the-art models such as SWAN when the precise volumes and dimensions of borrow sites are finalized, particularly for large-scale, cumulative events. |
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| Objectives | ||||||
| The objectives of the study are to provide
biological, physical, and other pertinent information which can be used by
MMS analysts during the evaluation of impacts associated with large-scale,
cumulative extraction of sand from blocks which located on Ship Shoal. |
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| Methods | ||||||
| The study will involve the collection of
site-specific biological information (infauna and epifauna) from within
blocks identified as the most likely areas to be used as a source of sand on
a long-term basis. Site-specific numerical wave modeling, using fine-mesh
sub-grids, will also be performed using a state-of-the-art model such as
SWAN or the enhanced version of STWAVE to evaluate the cumulative effects of
large-scale sand extraction from within the most likely targets. An
evaluation of the potential areas which can be exploited give the complexity
of oil and gas structures (pipelines, platforms, etc.) will also be
accomplished, given the geology of the shoal and usable sand thicknesses in
site-specific areas. |
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| Importance to MMS | ||||||
| The collection and assessment of
biological information, as well as very site-specific numerical modeling in
the areas most likely to be utilized is critical if MMS is to assess the
potential consequences of long-term use of the shoal. During the preparation
of previous environmental assessments for Ship Shoal, MMS analysts have
found very little information relative to benthic biology for the shoal and
have used information from either closer to shore or offshore of the shoal
proper. Numerical modeling has also only been performed on a regional,
shoal-wide basis. |
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| Current Status: |
All bottom boundary layer instrumentation has been prepared and re-fabricated for deployment at Ship Shoal. Deployment of the instrumentation, as well as the conduct of the biological sampling cruises was hindered by the occurrence of several major GOM storms. However, site surveys were conducted to ensure the instrumentation could be tethered to platform infrastructure at the study site. Preparation for the meio- and macro-benthic focus of the project has also been completed and surveys will occur in Spring 2006. |
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| Final Report Due: | November 2007 | |||||
| Publications: | ||||||
| Affiliated WWW Sites: | http://www.mms.gov/sandandgravel/Louisianastudies.htm | |||||
| Revised date: | February 2006 | |||||
| ESPIS |
ESPIS - All completed
ESP Studies: |
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