May and June 2006
 

 

 

Going Outdoors

With a very mild climate, Sierra Pacific's Terra Bella sawmill in Californiasaid
to be the west coast's most southern mill-is able to take advantage of
the balmy weather and has more operations outdoors, including its new
trimmer and lumber sorter.

By Alan Froome

There are benefits to being the most southern sawmill on the west coast of the United Stateslike little rain and doing a lot of work outdoors.

The Sierra Forest Products sawmill is about an hour south of Fresno and, true to California, is surrounded by citrus and pistachio orchards. The mill is something of a showplace with a landscaped main office area, and benefits from the warm southern California climate with only 10” of rain a year. So much so that its new trimmer optimizer and 60-bin lumber sorter were installed with no roof.

The mill recently completed a $2 million upgrade to improve its overall fiber recovery. The new system started up in August 2005.

Besides its location, the mill is unique in some other ways. Its log supply is drawn from the Sequoia National Forest, which covers 1.1 million acres in the Sierra Mountains east of the mill. The logs are selected by the U.S. Forest Service (USFS) and the mill is obliged to take every size and species logged, whether the timber is from thinnings for fire suppression, wind blowdowns or whatever comes its way. As a result, logs range from 6” to 72” in diameter and include white fir, ponderosa, lodgepole and sugar pine plus incense cedar. The sequoia is shorter than the more famous coastal variety but can be as much as 3,000 years old and is protected by law. The mill also takes some logs from private sources.

The mill employs 160 people and includes a co-gen plant and a bark processing plant on the same 80-acre site.

Mill general manager Kent Duysen has been working at the mill for 36 years and is a graduate of Oregon State-in forestry. “I never expected to end up running a sawmill,” he says, smiling.

The mill processes 45 million board feet of logs a year on a one-shift basis and typically produces around 350,000 board feet of pine or 400,000 board
feet of fir per shift. Duysen explains that the new trimmer optimizer and sorter system has not only improved fiber recovery, but also removed a bottleneck at the back of the mill.

Due to the wide range of log sizes, the mill produces a correspondingly wide range of products. In lengths from 6 to 18 feet, 2 x 4 and 2 x 6 fir, 4 x 4 and 6 x 6 pine is shipped mostly to Arizona and New Mexico, but 5/4 and 6/4 shop and moldings are also produced. Recently, incense cedar was being processed that is cut into 3 x 3 squares and shipped to China for pencil stock. This species, however, only accounts for seven percent of the logs handled.

The size of the largest logs coming into the mill dictates that primary breakdown is handled by a headrig/carriage, although there are plans to install a small log side in the future.

The mill processes 45 million board feet a year, primarily fir and pine. Recently they've been processing incense cedar that's sent to China for pencil stock, but that accounts for only 7 percent of the logs.

Raw logs are bought from the USFS and cut by contractors to Sierra FP specs. They are bucked in the woods to lengths ranging from 10 to 18 feet and trucked to the mill yard, where they are stacked and moved by a LeTourneau and five different Caterpillar machines, a 980B, two 966's and two 988's. “We don't haul logs all year round as some logs come from well above the snow line at 9,000 feet elevation,” Duysen says.

Logs are bucked by a manual controlled bucking line and are debarked by one of two debarkers, a 35” Nicholson and an older 60” Salem. They then pass over a deck for loading on the Salem 54” opening three-knee log carriage. An 8-foot Letson & Burpee headrig bandmill makes the first cuts on the logs and is controlled by an Innovec scanner and computer.

The pieces produced are then conveyed downstream to two Albany 6- foot horizontal twin bandmills. Here, the operators feed them one or two at a time on flat slat-bed feed tables to make the secondary cuts. The resulting center cants and jacket boards are then fed through one of two Ukiah combination gang edgers. The mill also has a Schurmann double arbor 48” machine. Side boards are handled by two Ukiah 6” board edgers, one equipped with a USNR scanner/optimizer controlled infeed.

The lumber is then transferred to a grading table, where graders using special markers feed the lumber through a new Coe/Newnes grade mark reader, before the boards enter the new Coe/Newnes trimmer optimizer. This line was only started up in August of last year. Toward the end of last year, it was running at 90 pieces/minute with an eventual target of 120 pieces/minute.

The trimmer has 10 saws and, like the downstream lumber sorter, is actually installed outdoors, with no roof whatsoever. “When we installed the new trimmer optimizer, it was 110 degrees,” says Sam Pope of Coe's Portland office. Pope pointed out the system has the capability for future upgrading to also do automatic defect scanning, which would involve additional hardware and software.

The mill processes a wide range of products, including 2x4s, 2x6s, 6x6s and moldings. Most of the products are destined for Arizona or New Mexico.

After the trimmer, lumber climbs up an incline to the new 60-bin lumber sorter. This replaced the original system, which was in effect two sort lines running in opposite directions. The new three level setup has everything running the same way.

The Sierra Forest operation, like many mills these days, operates a cogeneration plant, which is adjacent to the sawmill. Duysen has some surprising comments about its merits.“For us, co-gen is a necessity to produce steam, but not otherwise. We use it for our dry kilns, which saves us between $70,000 and $100,000 a month compared to using natural gas.” Duysen explains that the environmental and power situation is somewhat different in southern California from other regions. “Strict pollution controls severely restrict emissions and the price the electrical authority will pay for electricity the plant produces is disappointingly low.”

The co-gen plant was installed in 1986 by the Wellons company-100,000 pounds of steam is produced to heat the kilns and to drive a Westinghouse turbine generator. The plant lay idle for some years, but is now operated full time. Electrostatic precipitators are now used to comply with the tighter emission regulations. The plant is fired-like others-by burning mill waste, but not including bark.

Orchard prunings and other farm waste from the surrounding farm areas is also burned. “We feel in many ways we are part of the agricultural community,” says Duysen.

Mill manager, Kent Duysen, says the cogeneration plant next to the mill is a necessity. It saves them between $70,000 and $100,000 a month.

As mentioned, bark is not burned in the co-gen plant, as it is regarded as too valuable. A separate bark plant is operated on-site, where it is sorted and processed into 15 different products, the main one being potting soil. Certain types of bark are used for potting soil, and it is ground down to 1/8” particle size before it is bagged for sale. Colorizing bark for landscape material has been tried but has not been a sales success.

Future plans for the Terra Bella mill might be dictated by environmental concerns. Kent says there are some concerns in the Sierras about the protection of a small nocturnal animal called the Pacific Fisher, and they are hoping it doesn't reach the status of the Spotted Owl further north. In terms of log supply, at one time there were five sawmills operating in the area, but four have since closed. Kent says they have reduced shift time from 12 hours to 8 hours to match the log supply, but the mill is secure. Some further equipment changes are on the way: the company has purchased a used Maximill end-dogger line, which they plan to install at a future date near the headrig to handle an increasing number of smaller logs.

TW

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This page was last updated on Friday, October 20, 2006