A project to determine the locations of abandoned mines in the Willamette National Forest could help firefighters and others avoid injuries.
The Statesman Journal reports in a story on Saturday that the four-year project initiated by the U.S. Forest Service found 226 features of abandoned mines in the North Santiam Mining District. Those features include mine entrances, exploration pits and waste rock areas.
The Oregon Department of Geology and Mineral Industries used an airborne LiDAR to scan the Earth’s surface in a technology known as lidar. Combining the results with other information created a three-dimensional map that workers used to go into the field to pinpoint abandoned mining areas.
This LiDAR image shows a canopy height profile across. (Image courtesy of Tom Spies and Keith Olsen, OSU College of Forestry)
“Lidar aids in the inventory and closure of abandoned mine features with the aim to protect public safety,” said Ruth Seegar, a U.S. Forest Service spokeswoman. “Lidar is an effective tool in advance of a ground survey because it increases the efficiency and labor of a time-consuming abandoned mine survey.”
The mountains in the region are rugged, steep and densely forested, said Clark Niewendorp, industrial minerals geologist with the Oregon Department of Geology and Mineral Industries.
“We can now see an incredibly detailed image of the earth’s surface,” he said. “Lidar imagery has real value for inventorying abandoned mine land because it can show mine openings that weren’t well documented, or that were even completely unknown.”
Mining in the area dates back to 1860, although records indicate the area never produced much.
But the abandoned mines can be dangerous, and the Forest Service has had particular concerns as dry conditions could cause a fire and put at risk firefighters who might encounter a mine.
“USFS was particularly interested in knowing where mine openings had been closed with foam, because it accelerates fires,” said Ali Ryan, information officer for the Oregon Department of Geology and Mineral Industries.
