Gravel Pad Restoration on Alaska's North Slope
Authors: Herlugson C.J. , McKendrick J.D. , Parnell J.A. 
Published: December 2007

Federal and state permits for North Slope oil development stipulate that sites used for exploration and production operations must eventually be returned to a condition acceptable to the regulating agencies and the landowner. In cooperation with the University of Alaska Fairbanks and regulatory agencies, BP Exploration (Alaska) Inc. (BPXA) has been researching and testing rehabilitation measures for abandoned exploration facilities. Results from these studies are identifying effective ways to assure that disturbed sites will provide usable wildlife habitat after field abandonment.

Introduction

The North Slope of Alaska is a vast area covering more than 88,000 square miles (37 million acres). Nearly the entire region is classed as wetlands. The area is underlain by continuous permafrost extending to depths of 2,000 feet or more beneath the tundra surface. The Arctic coastal plain remains frozen for more than nine months of the year. During the short summer, which lasts from mid-June through mid-August, a shallow active layer of surface soil thaws to a depth of 1 to 3 feet. This arctic coastal plain is dominated by thousands of thaw lakes and tundra ponds.

The region is home to 15 regularly occurring species of terrestrial mammals, six species of marine mammals and more than 250 species of birds. Bird and mammal density is generally low, although regionally the area may support numbers in the millions. Wildlife frequently seen in the North Slope oil fields include caribou, grizzly bears, foxes, and birds.

The presence of permafrost dictates that oil and gas production facilities be placed on gravel pads to protect the underlying frozen soil and to provide a stable surface for equipment and buildings. Approximately five feet of gravel is placed on the tundra for road and pad construction on the North Slope.

Oil production from the Prudhoe Bay field began in 1977 with completion of the Trans-Alaska Pipeline (TAPS). other North Slope fields have come on line since then - Kuparuk, Endicott, Milne Point, Lisburne, Niakuk, Pt. McIntyre - and currently provide approximately 1.6 million barrels of crude per day, approximately 25 percent of U.S. domestic crude production.

This contribution to U.S. energy needs has been achieved with extremely low impact to Alaska's wetlands. Less than 20,000 acres of wetlands have been affected by oil and gas development on Alaska's North Slope, including oil field production facilities and infrastructure, airport support facilities, exploration drill pads, gas production fields, and those portions of TAPS and the Prudhoe Bay Haul Road north of the Brooks Range. In a state with more than 173 million acres of wetlands, that equates to less than 0.1 percent. Less than 0.05 percent of all North 1Slope wetlands have been affected by oil and gas development.

BPXA has developed many ways to avoid important habitats and minimize the area required for new facilities and reduce impact to tundra wetlands on the North Slope. Winter construction techniques utilize ice roads and ice pads which melt in the spring, leaving little trace of exploration activities on the tundra. Advances in directional drilling, elimination of surface reserve pits for drilling waste disposal and continued reduction in well pad size (more than 70 percent in the last two decades) help minimize the land needed for operations. New operating practices have also been developed to minimize the generation of waste and improve waste handling.

BPXA is also working cooperatively with government to explore options for eventual rehabilitation of oil field facilities. Such measures have not yet been applied to production facilities because North Slope oil fields are still operational, and because gravel roads and pads continue to be used. However, at some point in the future, production facilities will be removed, and rehabilitation will be required. Lands currently used for oil and gas development on the North Slope are leased, primarily from the State of Alaska.

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