Project Overview
PND was responsible for several key elements of BP Exploration Alaska’s (BPXA) ambitious artificial gravel island project to support petroleum production north of Prudhoe Bay. PND has been involved in this project from its inception, including design engineering for a module offload dock, pipeline transitions, ARKTOS ramp, heliport, seawater intake system, and foundations for the processor, compressor, turbine, and fuel tank module buildings. PND also provided budgetary, administrative, project management, and alliance support, as well as design services for temporary island access during the first year of a two-year construction program.
PND designed a 360-foot by 140-foot OPEN CELL SHEET PILE™ (OCSP™) dock with fenders, foundations, and various structural elements at the south end of Northstar Island―located in 40-foot water depths―all capable of withstanding multiyear ice impacts and overtopping while supporting 4,000-ton sealift modules, building/pipeline foundations, seawater intake system/sump, helipad, and various structural elements. The OCSP dock was critical for the pipeline installation.
The man-made gravel island, more than 6 miles offshore, was the first arctic oil and gas production island of its kind in the United States.
Our Role
- Coastal Engineering: conducted metocean and sea ice encroachment studies and evaluated several slope protection options, including numerical modeling of the options for both wave and ice events
- Arctic Engineering: engineered all-season seawater intake systems and solutions to withstand 18-foot wave events, multiyear ice events, wind chill reaching -75 degrees Fahrenheit, strong winds, frozen terrain, freeze/thawing cycles, and large volumes of sea ice and ice runs
- Geotechnical Engineering: developed foundation design and settlement analysis for a module offload dock capable of supporting 4,000-ton modules, including subsurface thermal analysis
Conquering Arctic Challenges to Support Petroleum Infrastructure
By developing robust yet rapidly constructable and prefabricated design elements, PND overcame a number of unusual challenges during design and construction at the offshore project site, including its remote arctic location; frozen soils; seasonal thaw/settlement; continuous darkness during winter months; temperatures far below zero; snow; frequent high winds; up to 6 feet of first-year sea ice; massive multiyear ice runs; polar bears; and unusually large load requirements due to the extremely heavy oil production modules and drilling rigs.
PND also expanded Northstar Island to accommodate updated personnel living quarters and designed an ARKTOS emergency exit ramp. These efforts were integrated into a general improvement effort to improve the existing slope protection. The project involved installation of a sheet-pile retaining wall and numerous pipe piles for site facilities. PND provided construction support personnel for all of the above phases of construction. PND was also involved in peer review and field modifications during pile installation to support the personnel living quarters.
Since construction was completed and production began in 2001, Northstar Island has produced over 100 million barrels of oil.
Feet Deep
PND designed the OCSP™ dock in a water depth of over 12 meters
Tons
PND’s OCSP dock can support thousands of tons
Barrels of Oil
Since 2001, Northstar Island has produced 100 million barrels of oil
