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BP plans maintenance at West Dock
Petroleum News Alaska
BP Exploration (Alaska) Inc. has applied for permits for maintenance dredging at West Dock at Prudhoe Bay.
BP has applied to the U.S. Army Corps of Engineers for permits for 10 years of maintenance dredging to a 6.5 foot water depth at dock heads No. 2 and No. 3, and is also proposing to dredge a shoal northeast of dock head No. 3.
The corps said that BP has been developing a coordination plan for the West Dock causeway and has designated Jason Moncrieff as West Dock planning manager. BP is discussing both short- and long-term needs with West Dock users and federal and state agencies.
Recent work and activity at West Dock includes a small boat mooring area on the west side of the causeway north of the 650-foot breech for spill response equipment and boats; a seasonal floating dock at dock head No. 3 for the Northstar crew transport boat; loading of Northstar supplies and drilling equipment from barges at dock head No. 2.
Northstar also uses the West Dock staging area as a helipad and for staging supplies to be shipped to the island. The Point McIntyre No. 2 production pad is at dock head No. 3. Crowley Alaska Inc. operates boats and barges out of dock heads No. 2 and No. 3, including a spill response barge for Alaska Clean Seas, Northstar project crew boats and supply barges and sea lift barges for oilfield activities. About 10 days of dredging a year Dredging would be conducted immediately prior to use of the docks by the barges requiring the 6.5 foot water depth and may not be needed annually. Estimates for volumes of dredged sediments are: 9,100 cubic yards at dock head No. 3; 1,900 cubic yards at dock head No. 2 and 1,500 cubic yards from the shoal. Dredging may be conducted by backhoe from the dock (45 foot horizontal reach), drag line from the dock (130 foot horizontal reach) or by screed barge. Dredging would require up to 10 days per year to complete, weather permitting.
Clean and gravelly dredged material would be hauled by dump trucks to fill the eroding northwest corner of the causeway by the seawater treatment plant, the east side of the causeway from Point McIntyre No. 2 drill site to the seawater treatment plant; eroded areas south of dock heads No. 2 and No. 3. If fine materials are dredged, they would be stockpiled on the causeway above the waterline, drained and then bladed into the roadbed.
The corps said that an erosion control study was prepared for BP by Coastal Frontiers Corp. to evaluate options for short- and long-term erosion of the causeway. The current proposal incorporates recommendations for the one- to two-year and five-year time periods. BP proposed to construct one groin this summer just north of the dock head No. 3 retaining wall. One groin is already in place and capture of gravel and sediments by the groins is intended to reduce or eliminate the need for maintenance dredging at dock head No. 3. Two additional groins may be added in 2003 or 2004 if monitoring shows the two groins are not adequate to control sediment transport.
Within the next two years, decisions are expected about projects that could extend the need for the West Dock causeway for 10 years or more. Once a longer lifetime is known, a long-term erosion control plan may be implemented.
Mitigation measures include re-use of gravel accumulated at dock heads or groins rather than mining new gravel from onshore sites, and erosion control along the causeway to reduce or prevent the need for dredging.
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