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LiDAR data on gas line routes released Aerial laser survey can detect faults, other features important for making design and permitting decisions along pipeline corridors Wesley Loy For Petroleum News
The Alaska Department of Natural Resources has released the first batch of LiDAR survey data along proposed natural gas pipeline routes.
LiDAR is an acronym for light detection and ranging. It’s a laser-powered technology deployed from the air to survey terrain for faults and other features.
DNR’s Division of Geological & Geophysical Surveys announced Oct. 10 it was releasing the first of several high-resolution LiDAR datasets for two proposed gas line projects, one known as the Alaska Pipeline Project and the other as the Alaska Stand Alone Pipeline.
The Alaska Pipeline Project, a partnership of TransCanada Corp. and ExxonMobil, proposes to build a large-diameter gas line from the gas-rich Prudhoe Bay field on Alaska’s North Slope to either Alberta or Valdez.
The Alaska Stand Alone Pipeline is a state-sponsored effort proposing to build a smaller-diameter gas line from the North Slope to Cook Inlet.
The survey areas A contractor, Watershed Sciences Inc. of Corvallis, Ore., conducted the airborne LiDAR survey over proposed transportation and infrastructure corridors from Prudhoe Bay to the Canada border, Delta Junction to Valdez, and Livengood to the Point MacKenzie area at Cook Inlet.
The project covered a total area of about 3,000 square miles.
Funding came from three sources: the Alaska Gas Pipeline Project Office; the Alaska Gasline Development Corp., which is proposing the Alaska Stand Alone Pipeline; and the Office of the Federal Coordinator for Alaska Natural Gas Transportation Projects.
The Oct. 10 DNR press release did not specify the cost of the LiDAR survey.
Survey corridors were a minimum of one mile wide along proposed pipeline routes, but much wider in some areas of known potential hazards such as active faults and slope instability, the release said.
A map accompanying the press release shows the areas surveyed and the location of the first LiDAR data release of approximately 660 square miles.
DGGS plans to release data for the remaining areas over the next few months following delivery from the contractor.
The data products are available for download by quadrangle from the DGGS website, www.dggs.alaska.gov.
LiDAR’s advantage LiDAR is a technology developed over the past 20 years or so. It’s similar to radar but uses light energy instead of radio waves.
To acquire LiDAR data, aircraft fly over the study area with equipment that fires rapid laser pulses to scan the ground. The reflected signals can be used to create high-resolution imagery of the land surface, including “bare-earth” terrain models with trees, brush and manmade structures edited out.
The beauty of LiDAR is that it can see faults in the land surface better than other technologies such as satellite imaging or aerial photography. LiDAR can penetrate thick vegetative cover to map the ground, and it can handle very steep or rough terrain than can hamper human investigators.
“LiDAR data can be used to generate detailed bare-earth digital elevation models (DEMs) and hillshade images, which allow geologists and engineers to view and analyze the earth’s surface as if all vegetation were stripped away,” the DNR press release said. “These products make it possible to identify hazards such as active faults and landslides that may otherwise be undetectable, especially in areas of dense vegetation. This type of information is critical for making permitting and design decisions along these corridors. Because the LiDAR data also contain above-ground points representing vegetation, power lines, pipelines, bridges, and other features, many other uses are also possible, such as vegetation biomass studies and structure inventories.”
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