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AGDC has potentially costly to-do list Some issues, particularly those from US Pipeline and Hazardous Materials Safety Administration, could require costly design changes TIM BRADNER For Petroleum News
Federal agencies have handed Alaska Gasline Development Corp., the state’s gas corporation, a long to-do list for final preparations of an application to the Federal Energy Regulatory Commission to build the Alaska LNG Project.
Some of the issues raised by the agencies, particularly the U.S. Pipeline and Hazardous Materials Safety Administration, or PHMSA, could require costly design changes in the project.
State agencies are also requesting more research on permafrost thawing and how that will affect integrity of the buried pipeline.
AGDC is in the process of taking over Alaska LNG, previously led by ExxonMobil Corp. on behalf of a consortium of the three North Slope producers and the state.
The state corporation must now answer questions submitted through FERC by federal and state agencies on the 12 resource reports prepared by Alaska LNG as a part of the pre-application process for a FERC certificate.
The 56 pages of questions submitted through FERC on Dec. 14 are in addition to 362 pages of questions submitted earlier.
Rosetta Alcantra, AGDC’s spokeswoman, said the corporation is developing cost estimates for doing the work but those have not yet been presented to the corporation’s board. “We’re doing as much as we can with in-house staff in answering the questions,” although contractors will eventually be brought in to deal with some issues. Discussions with potential contractors are now underway, she said.
Costly PHMSA concerns PHMSA’s questions total 38 of the 56 pages referred by the FERC and deal mainly with federal safety codes and specifications for pumps, equipment pressures, fluids and spill-containment systems.
One significant issue raised by the agency involves the proposed 50-mile spacing between mainline block valves along the 800-mile pipeline. The valves, which can be closed to isolate sections of pipeline, “would probably have to be 35 miles or less,” PHMSA said.
Also, “Mainline valve spacing and the crack-arrestor spacing changes would require a special permit,” from PHMSA, the agency said. Crack arrestors are placed on pipelines to limit and contain stress cracks.
The agency said a special permit would also be required to approve Alaska LNG’s plans to use multi-layer coatings on the pipeline that are installed to shied cathodic protections that limit corrosion.
A request from a state agency asks Alaska LNG to do further investigation of permafrost thaw, which will affect the stability of piles and gravel pads installed to support the pipeline over its projected 30 years of life. The draft resource report submitted by Alaska LNG refers to 1- to 2-foot layers of active permafrost on the North Slope during summer. “Some evidence indicates that permafrost warming has increased the active layer … and designs should account for the trends during the facility’s design life of 30 years.”
Other federal agencies asked for a marine vessel simulation study for LNG ship traffic at the marine terminal at Nikiski and to identify the number of tugs that will be needed based on the study.
Safety, subsistence issues There were safety-related issues raised, such as a request for information on maximum distances for safety during possible toxic chemical releases at the North Slope gas treatment plant and the LNG plant at Nikiski. Agencies asked for data on three levels of severity of exposure (the Acute Exposure Guideline Levels) with points on plot plans and with property lines and occupied buildings identified.
A “comprehensive discussion” was also requested of safety measures employed to protect the public, workers and wildlife during construction, including measures like traffic control and above-ground and underground utility crossings.
Federal agencies also asked for more information on subsistence activities along the pipeline and the project areas and the effects on communities due to increased payroll spending, with corresponding effects on the mix of cash-earning and subsistence in rural villages.
On more specific plant safety issues, agencies noted that several impoundment areas for ignitable fluids, if they were ignited, could cause heat impacts over 3,000 British thermal units per hour over equipment areas. More information was requested on fire water and cooling volumes for each ignitable fluid impoundment and how these were arrived at in the sizing of the impoundment.
Questions were also asked about the estimated soil settlement of 10 inches at the LNG storage tanks along with 5 inches of differential settlement. Information was requested on the calculations and assumptions used in arriving at these. The agency also noted that, “the levels of settlement seem high and may warrant either additional ground improvement or use of deep foundations.”
Other questions dealt with estimated effects on facilities of high winds. Parts of the LNG plant designed for liquefying, storing and vaporizing LNG would be designed to withstand sustained winds of 150 miles per hour but other parts of the plant would be designed to withstand three-second gusts of 110 mph winds.
Alaska LNG was asked which facilities that handle hazardous fluids, or are control buildings or emergency facilities, are not designed to withstand l50 mph winds and to provide a justification as to why they are not.
Another comment noted that the facility fire protection system was not fully developed at the time the report was submitted. Alaska LNG was requested to provide an updated description of the fire protection system and to explain how indoor and outdoor equipment, including the outdoor liquid propane system, would be kept cool in the event of a fire.
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