The U.S. Army Corps of Engineers has agreed to review the denial of ConocoPhillips Alaska’s permit for CD-5 Alpine satellite development at the Colville River Unit on Alaska’s North Slope.
An appeal review officer has been named and a tentative site visit date set for June 25.
Alaska Gov. Sean Parnell said May 3 the state has requested to be allowed to participate in the administrative appeal.
A request for participation in the appeal conference and further proceedings was sent to the Corps by the Alaska Department of Law on April 30.
The department noted that federal regulations permit participation by third parties in administrative appeals from a Corps permit denial, specifically adjacent property owners or state agency personnel to clarify elements of the administration record.
Since the state is the landowner of the river bed of the Nigliq Channel, over which ConocoPhillips proposed to build a bridge, and under which the Corps proposed a horizontal directional drilling alternative, the department said the state has a direct interest in the Corps’ decision, as well as an economic interest in CD-5 Alpine satellite development. The department said the state also has a valid interest in the potential impacts of CD-5 development on local subsistence users, fish, wildlife and water quality in Alaska.
The department said the Corps’ record of decision failed to give deference to the state’s interests as a landowner of the affected property, and instead ignored the state’s careful review and approval of ConocoPhillips’ proposed bridge crossing in deciding that HDD provided a less environmentally damaging practicable alternative.
Scour issuesThe department attached memos by Louis Kozisek, PE, chief engineer with the State Pipeline Coordinator’s Office, on the scour report on the Nigliq Channel and on aboveground vs. HDD waterway crossings on the North Slope.
On the scour analysis, Kozisek said Baker Engineering used software developed by the Hydrologic Engineering Centers River Analysis System, a part of the Corps. He said in estimating scour, Baker also used other algorithms and a Federal Highway Administration standard, HEC-18, “all well established methodologies that are utilized in a number of applications, including Federal design, such as the Corps of Engineers and the Federal Highway Administration.”
In addition to HEC-18, Baker used another methodology — a widely accepted alternative to HEC-18 — to cross check the calculations.
Kozisek said if the design Baker produced were presented to the State Pipeline Coordinator’s Office for a technical review, “I would recommend that the SPCO accept the design with no modifications. The work performed by the engineer utilized standard analysis methods and software.”
While the analysis predicted only nominal amounts of in-channel scour for the site, “Had the analysis shown excessive scour, I would have looked at other options, rather than recommend horizontal directional drilling” because there are “simple and proven countermeasures” available. Kozisek said he saw “nothing in the report that does not conform to generally accepted engineering methodology or god design practice for mitigation and control of bridge scour.”
On aboveground vs. HDD crossings, Kozisek said while HDD crossings offer better resistance to flooding and ice breakup, “an aboveground crossing offers better opportunities for corrosion control and integrity monitoring. These two aspects become increasingly important as pipelines age, and should be given prominence in selection criteria.”
He said the Alpine Colville River crossing is a unique example of a North Slope HDD installation, with the vast majority of crossings in the region aboveground, “demonstrating that this is the tried and true method.”
There are fundamental differences between the Colville crossing and the Nigliq Channel, Kozisek said, since the Alpine pipeline transports sales quality oil with limited sediment and water, while the CD-5 pipeline will transport unprocessed three-phase fluid — oil, gas and water. “The corrosion rates are typically much higher in this type of service,” he said.
A three-phase HDD pipeline would be “unprecedented on the North Slope,” he said. “Any pioneering engineering design introduces special risks, some not fully appreciated until after considerable operating experience.”
Kozisek said that North Slope experience with three-phase lines shows that where the lines have changes in elevation, water and sediment — and where conditions allow, wax and scale — “accumulate, creating conditions conducive to increased corrosion, especially microbially induced corrosion.”
An HDD crossing of the Nigliq would have a large change in elevation, he said, with “potentially greater risks.”
“In my opinion, the technical feasibility of a HDD crossing of Nigliq is indeterminate,” Kozisek said, with more work needed “to determine feasibility in the area of flow assurance.”
“Where technically and financially feasible and where there are no special design considerations, aboveground pipelines are to be preferred for a variety of maintenance, monitoring, integrity and repair reasons.”
He noted the state’s long experience with Arctic and subarctic Alaska oil facilities and pipelines, and said: “As a broad principle, aboveground modes have demonstrated their advantages and are, in my opinion, the preferred choice for long-term maintenance and integrity of pipelines.”