NINE MILE CANYON, Carbon County — The crew members were down on all fours, working with hand tools in the dirt, as the double-tanker truck rolled by on the single-lane road just a few feet away.
Their trowels loosened up the hard soil, which was carried to a sifting screen where small artifacts from what was once a Fremont Indian pit house were separated out and placed in neatly labeled paper bags.
"We rarely, rarely get to excavate in the canyon," said Jody Patterson, principal investigator for Montgomery Archaeology Consultants Inc.
"Being able to look at some of these sites — being able to excavate — we're finding out stuff we had no idea existed out here, in places where we didn't know they would be," he said.
The pit house Patterson's crew is excavating is the first of its kind to be found so far up Nine Mile Canyon, he said. It's also the first to be found with a burnt roof, which means the site could provide "a snapshot of daily life" once it's completely unearthed, Patterson said.
"It's extremely exciting," he said.
The structure was discovered during the construction of a new low-water crossing on the Nine Mile Road. Work on that crossing was halted as soon as evidence of the prehistoric site was spotted, and won't resume until the find can be documented and processed.
It's something that has happened at least a dozen times since the reconstruction of the road in Nine Mile Canyon began in April 2011, and project managers say they planned for it.
"There were protocols set in place to take care of all that, so that as we built the road, we didn't lose that history and anything that was discovered, we could learn from and protect," said Carbon County engineer Curtis Page.
Road crews from Carbon and Duchesne counties, along with employees from Jones & Demille Engineering, W.W. Clyde and all of its subcontractors are required to attend training on the identification of sensitive cultural sites, Page said. Archaeological monitors have also been present whenever new earthwork is being done.
"It's been a real collaborative effort," Page said.
Nine Mile Canyon has been dubbed "the longest art gallery in the world." It's steep walls are home to at least 1,000 rock art sites, which contain more than 10,000 individual images that date back to the Fremont Indians. There are also Native American granaries and dwellings, as well as ranch houses built by the area's earliest pioneers.
"It more or less contains a continuous record of human occupation (from the Archaic period) all the way through to today," Patterson said.
The canyon's uniqueness draws tourists from around the world.
The plentiful reserves of natural gas that can be accessed from the plateaus above have also attracted attention from energy developers.
In 2010, Bill Barrett Corp. secured federal approval to drill more than 600 wells on the plateau. As part of the approval process, the Denver-based company agreed to put up $10 million for the reconstruction of the road through the canyon and the protection of cultural sites.
Carbon County, Duchesne County and the Utah Permanent Community Impact Fund Board — which receives royalties paid to the state for oil and gas development, and disburses the money to impacted counties — are covering the remaining $12.5 million for the project.
"For years we knew we needed to do something with this road," Page said. "We made efforts each year to try to improve it the best we could with the budgets we that we had, but 38 miles is a lot of road."
"This project addresses all the major concerns we had with the road," he said.
Flooding has been the primary concern. In 2008, flash floods stranded people in the canyon and did major damage to the road surface.
Engineers and hydrologists on the project studied the problem and have reconfigured the profile of the road to keep it from being "a channel that carries the water," Page said. They've also increased the number of culverts from 50 to 250 and added 24 concrete low-water crossings.
"When it's all said and done, we'll have a road that's maintainable," Page said. "We'll have a road that's a lot easier to take care of for the counties and a lot safer for the public."
To date, about $10 million has been spent on the project. Ten percent of that has gone to cultural site monitoring and preservation and to the suppression of dust in the canyon, which has the potential to harm the delicate rock art.
Road work is expected to be completed in December, but Patterson said the discoveries that have been made in the process will continue to shed new light on the canyon's past for years to come.
"We're getting a whole bunch of new information that's going to open a new chapter on what went on in the canyon, in terms of how the Fremont and other groups were living out here," he said.