Alturas is the largest community in rural Modoc County, California, with 2,500 citizens.
It sits in the northeast region of the Golden State, its county limits bordering Oregon and Nevada. The town is served by U.S. 395 from the south towards Susanville, and S.R. 299 coming in from Reno, Nevada. Both routes intersect in Alturas and head north to Lakeview, Oregon and its pervasive logging and milling industry; east to Cedarville, California; and 145 miles due west to Redding. Couched quietly at the intersection of these two major corridors, Alturas is rural, remote, and pretty much surrounded by Federal Bureau of Land Management administered lands in the form of large-scale livestock grazing regions and various parklands.
This part of California is a difficult one as regards road management and maintenance. It is not uncommon to have frost every month of the year—even in July and August—in consequence of which, S.R. 299 coming out of Alturas was plagued with severe transverse, block, and longitudinal cracking with oxidation due to wide variations in temperature. There is skiing in this area, and thus it is a popular route for tourists, one that much of the local economy hinges on.
In 2018, the California DOT (Caltrans) identified three centerline sections of S.R. 299 and earmarked them for pavement rehabilitation: a 2.3-mile section on the west side of Alturas; 5.5-mile stretch in the mountain region to the east; and another 2.4-mile section on the west end of the town of Cedarville.
Eagle Peak Rock and Paving, a local family-owned company founded in 1995, was brought on to provide asphalt paving and concrete cement services. The $4.2 million contract for this project was awarded on Feb. 21, 2019. Caltrans wanted it done quickly and done right, and ultimately the decision was made that cold in-place recycling (CIR) was the appropriate solution.
Caltrans District 2 Maintenance Engineer Lance Brown explained why cold in-place was chosen for this project: “California uses CIR as an intermediate strategy between minor rehabilitation and highway maintenance overlays. The state dedicates funding to perform CIR in its highway maintenance budget allocation. These cold in-place recycle projects use green technology that recycles partial depth using existing pavement materials. We found that on lower average daily traffic routes in various climates, the CIR strategy is effective for 7-10 years when overlaid with a minimum hot-mix asphalt overlay at a thickness of 0.15 ft. The strategy mitigates minor to moderate cracking in the wheel pass by disrupting the cracking that would typically reflect through the surface when overlaid.”
Coughlin Company, headquartered in St. George, Utah, was subcontracted to do the cold in-place work. And the “interesting” stuff began straight away.
“I supposed it was more interesting than challenging, but when we were out there, the Burning Man Festival was going on right at the same time in Black Rock Desert,” Coughlin Safety Manager Stephen Steed told Roads & Bridges. “We were right smack in the middle of that, and there was a huge amount of traffic with people heading out to that thing. S.R. 299 is a main way out there. There’s also a little ski resort right at the top of the mountain near the project site and a Caltrans maintenance shed about midway through the project limits, where they keep their plow fleet and salt stockpile. The cracking on this road was really severe. So this project was important from multiple perspectives.”
Tony Cruse, president of Eagle Peak Rock and Paving, concurred, saying, “This was a challenging job with a short window to complete. Coughlin was chosen as a partner on this job based on our having done many previous projects with them. This job required flawless planning, execution, and completion, and we knew Coughlin was up for the challenge. Some mechanical issues delayed the start a few days, but the time was made up by the team’s proficiency and hard work. Traffic control on a high-speed mountainous road is always a safety issue, of course. But with our extremely experienced traffic-control team, this never became an issue.”
An uphill battle
Because steep grades and sudden wind-outs caused some issues with the recycled, milled material rolling off the belt conveyors, it was decided to process certain sections of the job going uphill, rather than down.
“Coming out of Cedarville, we ran that section uphill on both lanes, it was so steep,” Steed said. “The material wouldn’t stay on the belts when we ran it downhill; it would actually roll right off the belts and wind up under the tires. That was a little bit of a challenge, but we’ve done a ton of mountain projects so we were prepared to deal with it. When we reversed, even if some material slid back, it landed in the hopper and not on the roadway, so it was manageable.”
The first day (Aug. 15) started out a little slower than everyone would have liked with just 1 mile processed. Crews were milling off and recycling an even 4 in., and luckily the subgrade was relatively stable, making for a reasonably smooth mill-through. Coughlin employed a pair of Roadtec RX-900 roto mills, one of which was equipped with a 7-ft cutter to be used in areas that required some measure of widening; the other sported a 12.5-ft cutter which was used to pull the RT-500 recycling train. Subsequent days would prove progressive: 1.3 miles of production was completed on day 2, and by day 4 the entire first section of the project was completed. Immediately, equipment was transported to the second section where production goals were met or exceeded each day throughout the remainder of the job.
A final lift
A staging area for emulsion transfers was set up in Eagle Peak’s yard just east of Alturas. While there was some concern about getting resupply transfers out to the project due to heavy traffic (e.g., Burning Man) as well as major reconstruction of the mid-section of the highway a few miles west of Cedarville, coordination with traffic control resulted in no delays, which aided crews in keeping to its quick, tight timeline.
A unique mix design was crafted for each of the three respective sections by Professional Assurance and Testing, which called for 3% Pass R engineered emulsion manufactured and supplied by Western Emulsion out of its Redding, California terminal. The mix design also called for 0.5% of portland cement to be used for added strength and to handle anti-stripping concerns.
Paving the final overlay began a few days behind the CIR project with a 0.15 ft overlay of 0.5 in. PG 64-28 hot-mix asphalt produced at Eagle Peak’s Alturas plant. A fog seal was applied to the CIR mat along with a sand spread in order to put traffic back on the road in advance of the final surface lift; soon after, the sand was broomed off and the HMA lift was applied.
“We actually finished up the CIR work a day ahead of schedule,” Steed said. “Caltrans had to get it paved once we were done, and they were trying to beat the cold weather in order to get that done. Eagle was paving the surface lift just as we finished up the CIR. They had plenty of time to get the mat cured. A lot of good coordination; everyone worked well together. No weather delays, which is unusual on these types of projects, but we were able to sail right through it.”
Eagle Peak used a IR 5510 paver with a Weiler pickup machine to pave over the recycled material. A rolling pattern was established using a Volvo DD138 as the breakdown roller behind the paver with five passes followed by a Sakai 160 pneumatic roller equipped with vibratory capabilities. An IR DD-130 was used for smoothness and final rolling.
The specification for compaction was 97-103% for the 2,640-ft lots and 95-105% for an individual test site. Caltrans test method 375 was used to layout and test at 10 random locations in each lot during production. Compaction was verified daily by Caltrans with a nuclear density gauge. The approximate compaction of the mat on average was 99.6%. This was the average on more than half of the lots tested. Once specified conditions were met, supplemental compaction was done, and as moisture evaporated, density increased with additional rolling.
Ryan Silvia with Pavement Management Solutions ran a profilograph, the result of which had him saying, “This was one of the best-quality mountainous CIR jobs I have seen; 4-in. CIR is very hard to get smooth, and this project was very smooth.”
Even with the uphill challenges on the CIR portion of the project, work was completed in under 12 days, making for a great example of well thought-out planning, coordination, and teamwork that resulted in a very successful project—one that has earned the 2020 Roads & Bridges/ARRA Recycling Award for Cold In-Place Recycling.