Adam Spencer, The Triplicate

Access to the upper reaches of South Fork Smith River has a long and storied past, harking back to Del Norte's boot-strapping days of miners, loggers and mule trains.

Until bridges were built across large creeks and South Fork Road was extended past Rock Creek in the 1950s, it took almost three hours to reach the upriver community of Big Flat from Hiouchi using French Hill Road out of Gasquet.

Another milestone of infrastructure improvement to the scenic South Fork Road is being completed at this moment with the replacement of the Steven Memorial Bridge and Hurdy Gurdy Creek Bridge, projects expected to be completed this fall. The existing bridges and roadways will be demolished next year, after a winter break to avoid the rain and high-water season.

The $8.6 million project for both bridges is entirely covered with funding from the Federal Highway Administration and creates at least 21 temporary jobs.

"We're getting two new bridges and it's not costing the community any money," said Jeff Daniels, county roads superintendent. "The two that were there were definitely in need of replacement."

The improvements are part of a larger project to upgrade all of the one-lane sections on South Fork Road.

In 2009 and 2010, four one-lane sections were widened and one-lane bridges over Rock Creek and Boulder Creek were replaced with new two-lane structures, costing almost $14 million.

Wider replacements

The existing Steven Memorial Bridge is a one-lane, 14-foot-wide, 325-foot-long structure. The replacement bridge will be a steel plate girder structure with reinforced concrete decks and steel safety railings at 370 feet long and 31 feet wide, accommodating a two lane road.

The existing Hurdy Gurdy Creek Bridge is a single span structure with a length of 170 feet and a one-lane width of 14 feet.   The new bridge will be a 190-foot-long single span of steel, 31 feet wide to accommodate two cars.

The approaches to the new StevenMemorial Bridge have been cleared of timber by a local company and graded. The logs are now for sale by the Forest Service, a necessary task as the new bridge will be 70 feet downstream of the existing one.

There will be two 84-inch-wide, steel-reinforced, concrete drilled shafts supporting the bridge. The pier on the east side has already been drilled 15 feet into the bedrock, poured with 57 cubic yards of concrete and has a few more days of curing before the casing is removed.

Two-foot wide concrete abutments drilled 45 feet into the ground on the east side of the river have also been completed.

Drilling for "pier one" on the west side of South Fork Smith River was delayed by minor equipment failure, but the crews are now drilling 24 hours a day to catch up.

"If everything works out alright and nothing breaks down, we'll be back on schedule by Monday," said Chuck Laws, project engineer for the two bridge replacements, as he stood on the existing bridge watching the drilling from above.

Laws, an engineer with RockSol Consulting Group, is familiar with South Fork Road after also working on the Rock and Boulder Creek bridge projects. He remembers his crew filling canteens at the popular Steven spring next to the bridge during those projects. His crew has maintained public access to the spring during construction.

No sediment will enter the river from drilling, which will occur during the low-water season using aggregate bags that let water pass through but not fine particles, Laws said.

Not as much has been done on the new Hurdy Gurdy Creek Bridge.

Steven Memorial Bridge, as a popular whitewater boating put-in, will receive a new bathroom, parking lot and trail to the river as part of the project.

Drilling in unique soil

Among all the drilled shafts at the Steven Memorial Bridge site, the type of rock is roughly the same, but "the degree to which they have been altered and deformed is highly variable," said Dylan Caldwell, the on-site geologist for drilling operations.

Caldwell, a staff geologist with Busch Geotechnical Consultants, said that the variability is due to the history of the rock found in the Smith River drainage: serpentinized ultramafic rocks typically found in the Earth's mantle.

"It's rare to see these rocks on the surface of the Earth's crust. It's unique globally," Caldwell said. "These are very hard rocks that belong miles below the Earth's surface."

For an igneous-type rock to reach the surface would mean the rock has gone through a number of chemical and weathering processes before it got there. The possible variation in those processes is what makes drilling into the rock a bit of a surprise; you never know exactly how the rock might react when an 84-inch-wide drill starts ripping it apart.

Electronic systems in the drill rig ensure that drilling is being conducted in the exact place, alignment, and angle needed at all times. Workers also constantly pause to manually measure and make sure the drilling is on track.

"This operator is very good, because he takes his time to get started," Laws said of the drill rig operator from Inland Engineering, while watching from above.

South Fork history

When Del Norte County sheriff's Commander Bill Steven looks at the county seal with a mule pack train in the mountains and St. George Reef Lighthouse in the background, he thinks of his family's predecessors.

His grandfather, Robert Raymond Steven, and great-uncle William Steven bought the Steven Ranch property in Big Flat in the 1920s from a man, coincidentally named Phil Stevens - with an "S" at the end.

At that time, Big Flat was like a weigh station for stage coach travel between Del Norte County and Jacksonville. William, Robert and Robert's wife Marguerite Steven, were like the "anchors of Big Flat for decades," before the community had hardly any full-time residents, Steven said.

Robert Steven, as a reserve sheriff's deputy and reserve fish and game officer, would check in with the Sheriff's Office via radio every night at 5 p.m. to provide the status of Big Flat.

Primarily due to timber interests, South Fork Road was extended to Big Flat and the two bridges currently being replaced were built in the 1950s. Before that, Big Flat was hard to access. The only thing crossing the South Fork River at the current Steven Bridge site was an old cable car that could transport two people at a time, dangling 100 feet above the river.

"The only previous access to Big Flat was a long, rough journey up French Hill across Coon and Gordon mountains passing landmarks with names like Cedar Springs and Zeke's Saddle, and finally dropping into the Hurdy Gurdy Creek drainage passing the giant flume line, which supplied water to the Oro Grande Mine and Boston Bedrock Workings, and China Camp," said an account by Barney McClendon Jr. filed away at the Del Norte County Historical Society.

"In the wintertime when the road over French Hill was blocked by snow, the few residents of Big Flat had to walk down the river on a trail to Rock Creek and hope that they could catch a ride on into town," reads a historical account by Carol McClendon. The McClendon family has long, strong ties to South Fork communities.

Recognizing the Steven family's long ties to Big Flat, Bill Byers, an in-law to the family, asked the county Board of Supervisors to name the bridge after the family, making it Steven Memorial Bridge.

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