How do you rehabilitate nearly 30 miles of historic highway at more than 7,000 feet above sea level on the caldera rim of a dormant volcano?

How do you rehabilitate nearly 30 miles of historic highway at more than 7,000 feet above sea level on the caldera rim of a dormant volcano?

Very carefully, according to Ray Moore, chief of maintenance at Crater Lake National Park.

"The road up here was built on a volcanic cone, on pumice, not necessarily the most stable bedrock around," he said. "The challenge is getting the road base solid."

The National Park Service, working with the Federal Highway Administration, has just completed its anticipated environmental assessment of proposed alternatives to shore up the 72-year-old highway, resurface sections and reduce the rockfall hazard along the picturesque route.

The 133-page document includes three action alternatives, with the preferred alternative including different measures to shore up rockfall at selected sites to determine which is most effective.

Deadline for public comments on the document is Jan. 28.

Cost of the entire project is estimated to be about $17 million. Road work would begin in 2015 at the earliest.

The West Rim Drive is 5.9 miles long and begins at the junction with Munson Valley Road, ending at the junction with the North Entrance Road. The 23.5-mile East Rim Drive completes the loop around Crater Lake from the North Junction to its intersection with the Munson Valley Road at Park Headquarters.

Both the east and west sections of Rim Drive are listed on the National Register of Historic Places.

Work on building Rim Drive began in June 1931. Up to 125 workers and four steam shovels were employed that first summer to remove more than 50,000 cubic yards of rock per mile, according to park records. An estimated 150,000 pounds of explosives were used to blast rock out of the way.

Because of the geological challenges coupled with a tight four-month work window because of weather, Rim Drive wasn't completed until 1941.

Rim Drive is now closed and usually remains closed because of snow until June. The park receives an average 533 inches of snow each year. There is currently an 80-inch snowpack at the park headquarters.

Nearly half a million people visit the park each year, many of them traveling on Rim Drive. The wear and tear over the years, coupled with severe winter weather conditions, have taken a toll on the road.

"Portions of the existing pavement on both east and west rim drives have exceeded their service life and have developed ruts, lateral cracking and severe raveling of the road pavement edge," wrote park Superintendent Craig Ackerman in announcing the completion of the environmental assessment.

"The roads have suffered from incremental erosion of the road bench supporting the pavement," he added, also citing the problem of having a road base that includes pumice.

The goals of the project are to improve safety, reduce maintenance requirements and protect the parks' scenic, natural and cultural resources, he said.

In addition to the roadwork, the project would repair and restore stone masonry retaining walls and guard walls that are failing in some areas because of erosion and age, officials said. Some parking area work would also be included.

However, the work won't alter the historic aspects of the road or other features, Moore said.

"For instance, we won't widen or change the drive from its historic width," he said. "It is considered a cultural landscape. We can't do a lot of adjustments you would normally do on most major roads to adjust for the wider vehicles used today."

If the funding is available when the planning is completed, Moore said the work on preventing the rockfall would be done in 2014, with the West Rim Drive road base work conducted in 2015-16. Work on the East Rim Drive, mainly overlay and surface repair, would be done in 2017-20, he said.

"We're trying to be good stewards of the park," Moore said. "There are no frills in these projects."

Crater Lake was created by the eruption of Mount Mazama some 7,700 years ago. Rain and snow eventually filled the caldera, creating the lake with its famous blue surface.

Comments regarding the proposed work can be made at or via mail to: Superintendent at Crater Lake National Park, P.O. Box 7, Crater Lake, OR 97604.

Reach reporter Paul Fattig at 541-776-4496 or email him at