Cold Regions Projects
   

ARCTIC RIVER OVERFLOOD MAPPING USING REMOTE SENSING TECHNIQUES
 

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Clients: U.S. Department of the Interior, Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE)
 
Each spring, snow melt and the break-up of river ice cause fresh water to arrive at the Arctic coast prior to the break-up of the nearshore sea ice.  If the sea ice is frozen to the bottom, as typically occurs to depths approaching 2 m, the "bottomfast ice" forms a dam that causes the river discharge to flow on top of the sea ice.  The overflow, which can exceed a depth of 1 m, spreads offshore until it drains through holes and cracks in the ice sheet.  This brief but energetic phenomenon constitutes a potential hazard to offshore oil and gas development in that it can impede access to facilities, disperse contaminants, and expose buried subsea pipelines through the phenomenon known as "strudel scouring".

In 2007, a study team led by Coastal Frontiers and DF Dickins Associates was selected by the Minerals Management Service (now BOEMRE) to investigate river overflood in the Alaskan Beaufort Sea.
 
Study Tasks
 
Map the annual river overflood boundaries from 1995 through 2007 using satellite imagery and helicopter-based survey data
 
Assess and compare the utility of imagery from alternative satellite platforms, including those that use the visible spectrum (Landsat 7, SPOT, and MODIS) and those that use SAR (ERS-2 and RADARSAT)
 
Investigate the environmental factors that govern river overflood
 
Assess the hazards associated with overflood (primarily strudel scouring)
 
Compile a database containing approximately 2,000 strudel drainage features and 1,000 strudel scours documented by 19 industry-sponsored studies
 
Incorporate the overflood and strudel data into a GIS database
 
Based on an assessment of strudel scour frequency and severity, the river overflood areas were segregated into Primary, Secondary, and Tertiary zones according to water depth.  The three zones can be used to assess the relative risks associated with prospective pipeline routes.

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COASTAL EROSION STUDIES FOR FACILITIES SITING
 

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Clients:  Various Members of the Petroleum Industry
 
The Beaufort Sea coast is subject not only to wave-induced erosion, but also to thermal erosion.  Wave-induced erosion is most pronounced during westerly storms due to the rise in sea level (storm surge) that accompanies such events.  The uniquely-Arctic phenomenon of thermal bluff erosion can result not only from sea water thawing the base of the bluff, but also from elevated air temperatures thawing ice lenses embedded in the bluff face.  The rate of coastal retreat is governed by a combination of wave and thermal erosion at many Arctic coastal locations, with thawed sediments augmenting the beach before being carried away by waves.

Coastal Frontiers personnel have investigated coastal erosion and the potential for ice encroachment at numerous Arctic sites to determine appropriate setback distances for coastal facilities over their intended service lives.  The facilities have included coastal production pads as well as shore-crossing sites for subsea pipelines.  In those instances where the natural erosion rate is unacceptably high, facilities can be protected by methods that include armoring the shoreline or insulating the bluff face with granular fill material.
 
Representative Study Tasks
 
Analysis of aerial photographs at decadal intervals from the late 1940s to the present
 
Investigation of historical accounts of erosion dating back over 100 years
 
Establishment of permanent survey baselines from which annual changes in bluff and shoreline position can be measured
 
Terrestrial and nearshore bathymetric surveys to quantify profile changes and rates of coastal retreat
 
Prediction of ice encroachment based on historical data acquired in similar Arctic coastal environments
 
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ARCTIC OCEAN DATA COLLECTION
 

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Clients:  Various Members of the Petroleum Industry
 
Ice-infested waters and heavily travelled maritime routes present unique challenges to oceanographic data collection.  Coastal Frontiers has obtained oceanographic data in the Beaufort Sea to support the design, construction, and maintenance of various projects.  The parameters studied include the following:
 
  Wave height, period
  Curren speed and direction
  Water level
  Storm and ice movement conditions
  Time lapse photos of storms and ice events
  Data analysis correlates the wind, wave, storm surge, and current data to better predict extreme ocean events.

Specific deployment and recovery techniques developed to ensure the
long-term safety of data collection systems include:
 
  Ocean instrument deployments using both boats and helicopters
  Bottom-founded tripods to minimize the potential for damage or loss from deep-keeled ice floe or ship impacts
  Instrument recovery through the Arctic ice cover in November- December following stabilization of the winter ice sheet.Recovery after freeze-up ensures complete data collection during severe storms of September-October.
 
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INNOVATIVE SLOPE ARMOR DESIGN FOR ISLANDS AND COASTAL PADS
 

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Clients:  Various Members of the Petroleum Industry
 
Since 1979, our team has developed and evaluated innovative slope protection systems for use in the Arctic offshore.  Innovation is required to deal with the limitations associated with construction materials, construction equipment and methods, and weather limitations in northern coastal zones. These projects include:
 
  Exploration Facilities
Endeavor Island
Resolution Island
Alaska Island Pad
No Name Island Pad
Seal Island
Mukluk Island
Northstar Island
Ellice L-39
Northwest Milne Island
  Production Facilities
Endicott
Northstar
Oooguruk
Nikaitchuq
Pt. McIntyre
 
 
Innovative Materials and Installation Methods
 
2 and 4 cy gravel bags
 
Grout-filled bags
 
Longard tubes
 
Linked concrete matting
 
Sacrificial gravel beaches
 

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SLOPE PROTECTION MONITORING
 

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Clients:  Various Members of the Petroleum Industry
 
Coastal Frontiers personnel have conducted comprehensive inspections of the slope protection systems on nearly all exploratory islands and offshore production facilities in the Alaskan Beaufort Sea, including:
 
  Endeavor Island
Northstar Exploration Island
No Name Island Pad
Alaska Island Pad
Niakuk Drill Pad
F Pad
West Dock Causeway
Northwest Milne Island
  Resolution Island
Mukluk Island
Sag III Island
Seal Island
Tern Island
Northstar Production Island
Oooguruk Production Island
Nikaitchuq Production Island

 
 
Monitoring and Maintenance Services
 
Aerial, ground, and underwater photography
 
Slope profile surveys (above- and below-water)
 
SCUBA diving reconnaissance
 
Assessment of slope armor damage
 
Maintenance recommendations
 
Construction advisory during maintenance activities
 
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WEST DOCK EROSION CONTROL AND SLOPE PROTECTION STRATEGY
 

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Clients:  Various Members of the Petroleum Industry
 
The West Dock Causeway is the marine transportation center for petroleum activities on Alaska's North Slope.  The initial segment was constructed as a dock in 1974-75, followed by extensions in 1976-77 and 1981, the addition of a seawater intake structure in 1983, and the installation of an oil production facility in 1991.  Much of the causeway is protected by sacrificial beaches, but revetments and groins have been added in areas susceptible to accelerated erosion or containing topside facilities of high value.  During the early years, Coastal Frontiers personnel provided inspections and maintenance recommendations as well as coastal engineering design support for the Point McIntyre oil production pad.  In 2004, Coastal Frontiers was selected to develop and implement a comprehensive plan for inspection, maintenance, and improvement of the various slope protection systems.  Since that time, on-going responsibilities have included the following.
 
Erosion Control Activities
 
Annual break-up and freeze-up inspections
 
Annual transect surveys to quantify changes in side slopes
 
Recommendations for replenishment of sacrificial gravel beaches
 
Recommendations for maintenance and improvement of groins and revetments
 
Construction advisory for all maintenance and improvement work
 
Semi-annual presentations to owners and regulatory agencies
 
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RESOLUTION ISLAND: INCEPTION THROUGH ABANDONMENT
 

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Clients:  Various Members of the Petroleum Industry
 
Resolution Island, located in the Sagavanirktok River Delta, was one of the first armored exploration islands to be constructed in the Alaskan Beaufort Sea.  Although the design life was three years, the service life was extended to more than two decades through annual inspections and periodic maintenance.  Coastal Frontiers personnel developed the design of the slope protection system, performed all of the inspection activities, provided construction advisory for the initial construction and all subsequent maintenance work, developed the plan of abandonment, and served as the owner's representative during implementation of the plan of abandonment.
 
Design and Construction (1980)

Prototype testing of candidate Arctic armor systems
- 2-cy gravel bags constructed of different geotextile fabrics
- Concrete-filled geotextile bags
- Gravel-filled tubes
- Precast, linked concrete mat (subsequently adopted for use on the
        Endicott Project)
 
Annual Long-Term Monitoring (1980-1995)
 
Monitoring tools included aerial photography, bathymetric surveys, and dive inspections
 
Results were used to identify and characterize agents of damage for gravel bag armor
 
Abandonment (Summer 2003)
 
Removed all anthropogenic materials
 
Reshaped gravel core to create avian nesting habitat
 
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SLOPE PROTECTION DESIGN FOR THE ENDICOTT PROJECT
 

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Client:   Member of the Petroleum Industry
 
The Endicott Project, consisting of two islands connected to shore by a gravel causeway, represents the first offshore production facility to be constructed in the Alaska Beaufort Sea.  It was completed in 1986 in the shallow waters of the Sagavanirktok River Delta.  Coastal Frontiers personnel have provided coastal engineering support for the project for nearly 30 years, from the preliminary design stage in the early 1980s through present-day maintenance and expansion work.

The islands and causeways are protected by four different slope protection systems that reflect varying degrees of exposure to wave and ice attack.  Key components include articulated, linked concrete mats; large gravel-filled bags; sacrificial gravel beaches; and both straight and compound profile configurations.  Key contributions from Coastal Frontiers personnel include the following.
 
Areas of Contribution
 
Design of the slope protection systems, including 2- and 3-dimensional hydraulic model testing
 
Optimization of the causeway route based on an analysis of deltaic bathymetry
 
As-built survey of the slope protection systems
 
Periodic bathymetric surveys to evaluate scour in the causeway breaches and sedimentation in a seawater intake channel
 
Design of a sediment barrier and maintenance dredging program for the intake channel (2008-2009)
 
Comprehensive evaluation of slope protection systems with recommendations to permit extension of original design life (2008-2009)
 
Assessment of options for a new marine bypass seawater outfall system (2010)
 
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COASTAL ENGINEERING FOR THE NORTHSTAR DEVELOPMENT
 

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Client:  Member of the Petroleum Industry
 
In 1995, Coastal Frontiers was selected to serve as a member of the Northstar Development Alliance.  The group designed and constructed the first free-standing Arctic offshore production facility requiring a subsea pipeline.  Located to the northwest of Prudhoe Bay, the Northstar Development includes an armored production island in a water depth of 38 ft and a buried pipeline that extends six miles from the island to a shore crossing on the mainland coast.  Coastal Frontiers personnel provided engineering support for the design and construction of the project facilities, and continue to provide post-construction monitoring and maintenance advisory services.  Representative tasks are described below.
 
Coastal Engineering Support
 
Wide-ranging bathymetric surveys to evaluate prospective locations for the production island and routes for the subsea pipeline to shore
 
Annual pre-construction bathymetric surveys in the planned pipeline corridor to quantify ice gouge and strudel scour characteristics
 
Selection of an optimum location for the pipeline shore crossing based on an evaluation of coastal erosion
 
Design of an articulated concrete mat slope protection system for the island, including 2- and 3-dimensional hydraulic model testing
 
Support for permit acquisition and regulatory compliance, including presentations to North Slope Native villagers and regulatory agencies
 
On-site advisory during armor installation
 
Survey support for subsea pipeline installation
 
As-built surveys of the island, pipeline, and shore crossing, along with an underwater inspection of the island slope protection system
 
Annual monitoring of the island and shore crossing in concert with bathymetric surveys of the subsea pipeline right-of-way
 
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COASTAL ENGINEERING FOR THE OOOGURUK DEVELOPMENT
 

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Client:  Member of the Petroleum Industry
 
In 2005, Coastal Frontiers personnel initiated field investigations and coastal engineering analysis for the Oooguruk Development, which represents the third offshore production facility to be constructed in the Alaskan Beaufort Sea.  Although the project site is partially protected from wave and ice attack by virtue of its location in the shallow waters of the Colville River Delta, significant design challenges arose from the financial constraints imposed by the modest size of the oil field and from an exposure to substantial storm surge and vigorous strudel scouring.  Our coastal engineering support has ranged from preliminary design and permit acquisition through construction, post construction monitoring, and maintenance of a production island, buried subsea flowline, and flowline shore crossing.  Key tasks are summarized below.
 
Production Island
 
Assessment of design oceanographic conditions
 
Bathymetric survey of the prospective island site and barge approach route
 
Design and hydraulic model testing of a gravel-bag slope protection system
 
Construction support for slope grooming and gravel bag installation
 
Post-construction inspection and maintenance of the slope protection system
 
Flowline Route and Shore Crossing
 
Bathymetric survey of the prospective flowline route and measurement of strudel scour depressions
 
Analysis of historical air photos to establish the long-term rate of coastal erosion (3.3 ft/yr)
 
On-site surveys to document short-term rates of coastal erosion
 
Construction support for through-the-ice winter flowline installation
 
Annual bathymetric surveys to monitor the flowline depth-of-cover and strudel scour activity in the vicinity
 


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BATHYMETRIC DATA COLLECTION IN ARCTIC WATERS
 

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Clients:  Various Members of the Petroleum Industry
 
The Prudhoe Bay region requires precise bathymetric survey data to plan the construction of offshore islands, support docking of large vessels in shallow nearshore waters, and monitor the sediment cover over subsea pipelines.  Challenges to this work include frequent high winds and waves, ice formation and floe movements, and limited nearshore water depth.  Since the mid-1980s, Coastal Frontiers has developed and perfected survey equipment and methods for efficient use in ice-infested Arctic waters.
 
Typical Needs
 
Barge routes
 
Pipeline routes and backfill monitoring
 
Island slope armor monitoring
 
Dock approaches
 
Ice gouge and strudel scour mapping and measurement
 
Work Platforms
 
Mid-winter ice sheet
 
Large survey vessels with multi-beam sonar
 
Small inflatable vessels suitable for helicopter transport to remote sites
 
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ARCTIC SUBSEA PIPELINE INSTALLATION SUPPORT
 

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Clients:  Various Members of the Petroleum Industry
 
Arctic production pipelines convey oil and gas from offshore islands to the shore.  The pipelines are buried in the seabed to protect them from forces imposed by ice, waves,   currents, and strudel scouring forces.  The pipelines are installed through a slot in the late-winter ice sheet.  Specialized amphibious wide-track backhoes excavate the subsea trench.  The trench is backfilled following the pipeline installation.  Coastal Frontiers has developed methods to guide the efficient installation of subsea pipelines, including the following tasks:
 
Monitor the depth of the initial trench bottom and note progressive infilling from side wall sloughing
Provide approval to lower the pipeline into the trench once natural sloughing has subsided and trench bottom elevation has stabilized
Organize on-site radio communication between water level and pipeline surveyors and the pipeline installation contractor to allow timely approval for laying in the pipeline
Oversee placement of gravel plugs or gravel-filled bags to improve pipeline stability
Develop instrumentation to measure the flatness and elevation of the trench bottom and roll of the pipeline as it is installed
Monitor the elevation of the trench backfill at the conclusion of installation
Note the formation of ice gouges and strudel scours on or near the pipeline using aerial overflights and summertime bathymetric surveys
 
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ARCTIC PIPELINE ROUTE SURVEYS
 

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Clients:  Various Members of the Petroleum Industry
 
During each open-water season from 1995 to the present, Coastal Frontiers has performed detailed sea floor surveys to obtain bathymetric, ice gouge, and strudel scour data to support the design and performance monitoring of the three subsea production flowlines in the Alaskan Beaufort Sea.
 
Primary Instrumentation
 
Multi-beam sonar to acquire comprehensive bathymetric data
 
Single-beam sonar for bathymetric data collection in shallow waters
 
Side scan sonar to locate ice gouges, strudel scours, and hard bottom (boulder patch) habitats
 
Diving and remotely-operated vehicle (ROV) operations to acquire “ground truth” information for calibration and verification of the side scan sonar data
 
Sub-bottom profilers and magnetometers to locate potential impediments to production flowline installation
 

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LARGE-SCALE MODEL STUDIES OF ARCTIC ISLAND SLOPE PROTECTION
 

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Clients:  Various Members of the Petroleum Industry
 
Arctic offshore construction requires innovation to deal with the limited resources and challenging construction season of the Beaufort Sea.  In order to better predict the performance of various types of innovative slope armor for application to Arctic oil exploration and production islands, Coastal Frontiers has performed numerous large-scale model studies at the Oregon State University Wave Research Facility in Corvallis, Oregon.  Based on these test results, the final designs of a number of offshore structures were optimized.
 
Hydraulic Modeling
 
2-D wave flume: 350 ft long, 12 ft wide wave tank accommodating water depths to 11 ft and wave heights of approximately 4 ft
 
3-D wave basin: 160 ft long by 87 ft wide capable of generating wave heights of approximately 2.5 ft
 
Irregular and monochromatic waves
 
Several hundred tons of gravel fill required to construct model cross-sections
 
Model scale ratios varying from 1:3 to 1:40
 
Large-scale models to minimize distortions of armor behavior and wave run-up and overtopping
 
Model Parameters Tested
 
Armor stability
 
Slope stability
 
Wave run-up
 
Wave overtopping
 
Gravel transport around islands
 
Effect of following wind on wave overtopping
 

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COMMUNITY RELATIONS AND REGULATORY LIAISON, PUBLIC AND AGENCY INVOLVEMENT
 

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Clients:  Various Members of the Petroleum Industry
 
Public and local community awareness, involvement, information transfer, and education are required in order to pursue development plans within all coastal zones.  These needs have become very common for coastal projects within the United States and abroad, and we are committed to participate in these efforts on our clients’ behalf.
 
Tasks Performed
 
Liaison between project owners and Federal and State regulatory agencies in Alaska.
- Environmental Protection Agency (EPA)
- U.S. Army Corps of Engineers
- North Slope Borough, Native Villages
- Department of Environmental Conservation
 
Presentations in the Native villages of Barrow, Nuiqsut, and Kaktovik to explain project plans and technical issues
 
Solicitation of Native Knowledge related to environmental forces (waves, ice, currents, fish and game movements, whale migration and harvesting issues, storm conditions)
 
Organization of a tour of the Prudhoe Bay oil field for a group of Russian engineers and regulatory authorities to familiarize them with coastal engineering and construction practices for possible application to the Russian frontier
 
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