While the original visitor center at Dinosaur National Monument suffered from stability issues, the new facility going up has deep roots -- upwards of six stories' deep into bedrock -- that should provide substantial stability.
Monument Superintendent Mary Risser reports that the foundation for the Quarry Visitor Center is just about complete.
"Although there is still a tremendous amount of work to be done, we think we’re still on target for fall opening of the stabilized Quarry Exhibit Hall and the new Visitor Center," she said the other day in a release.
The old visitor center was shut down in 2006 due to structural problems that left "portions of the building’s foundation twisted" and prone to movement, she said.
"The east curtain wall broke away from the foundation and was suspended only by a few welds. The second floor and roof of the rotunda were no longer structurally attached to the building and were held in place only by the tension caused by the building falling in on itself," Superintendent Risser said. "The east side of the rotunda was 10 inches higher than the west.”
With the new facility, however, engineers "developed a system of micropiles and foundation footings under each of the 10 support columns on the south side of the building. Forty micropiles were drilled an average of 40 to 60 feet down to solid rock," the park said in a release. "Each micropile is an 8-inch hole with a rod in the center surrounded by concrete. Holes were grouted within three hours of being drilled. Extensive load testing of the micropiles was completed. Each of the 10 columns is attached to at least 4 micropiles."
After these micropiles were drilled, workers then attached each of the "10 columns to a temporary steel shoring frame, lifted up the columns and then reset them on the final foundations. The shoring frames were placed on donage and then an air bag system jack carried and distributed the weight. Eight out of the 10 primary support columns were within 1 to 2 inches of each other, but on the east side of the building the ninth column was raised a few inches, and 10th column was between 7 and 10 inches higher than the others. While the columns were supported by the temporary shoring, the existing footings were excavated and demolished. Forms for the new footings were constructed, and the concrete was poured."
To protect the fossil-studded bank that is the hallmark of the visitor center from the construction, crews enclosed it in a protective structure.