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Building with Concrete
May 9, 1997

DuPont aggregate plant out to rock the world

By LUCY BODILLY
Special to the Journal

Lone Star Northwest has built its new aggregate mining facility at DuPont. Now company officials are hoping the customers will come. Not only from the West Coast -- where concrete made with the gravel from its Steilacoom facility is prized for its ability to reach high compressive strengths -- but from around the Pacific Rim.

Company officials had little doubt they would build a new facility at DuPont when the supplies at the nearby Steilacoom plant started running out. "We knew the supplies were finite," said Tom Mason, sales manager for aggregates. Planning for a new mine began about 12 years ago, with 18 months of exploration to identify the site and for testing.

Before the project could be built, the company had to agree to 114 environmental mitigation requirements, and a host of monitoring practices.

"We had our permit from the city of DuPont," said Ron Summers, general manager for aggregates. "But the Department of Ecology appealed it because they wanted to negotiate a settlement agreement which would affect the entire Nisqually Delta area."

Negotiations with the state and about a dozen environmental groups took almost nine months. But in all, the permitting process took 10 years, Summers said. Because the facility is close to a National Wildlife Refuge, close monitoring of noise and water quality is required. And complete site restoration is expected when the supplies run out.

At first the company considered building a less complex facility, which primarily would be used to blend the most commonly used mixtures of aggregates. With hopes of reaching more customers, it went for a more complex design, which allows it to make almost an infinite variety of mixes.

Different size aggregates sit in piles on top of gates at Lone Star's DuPont plant. When a special mix is required, a gate opens and feeds a specific size of aggregate onto a conveyor belt in a tunnel below. Custom mixes can be blended from different aggregate piles.
Photo by Lucy Bodilly


"The advantage is that we can meet specifications from California, Oregon and Alaska," Summers said. Other companies can also meet the specifications, but not as easily. Like Steilacoom, the DuPont site also has a barge facility, which allows for low transportation costs, even to sites in the Pacific Rim.

A recent project required a U.S. contractor working on federal property in the Marshall Islands to ship all the materials from one site. He chose aggregates from Steilacoom because they could be shipped out of Seattle and because their strength required less cement to be used, saving money in the long run. Now the company is negotiating with a company from Russia to ship its product there, Mason said.

Like the Steilacoom plant, the DuPont site is a fracture plant, where all the sizes of aggregate and types of sand are graded separately. Each pile, which can be as high as 76 feet (the piles can't be higher than the surrounding trees), sits on top of a gate. When a special mix is required, that specific size is fed onto a conveyor belt in a tunnel underneath the site and blended with other necessary sizes. Commonly requested mixes are stockpiled separately.

The aggregate arrives at the blending area from the mine along a 4,000-foot-long conveyor belt. After being run through a series of screens to determine the right size, from 11/2 -7/8 to 50/200 (which is a fine sand), the product is washed. Water from the wash plant is recycled, with about 6 percent evaporating or going out with the product. Mud and material too fine to use is stored on the site. "We are looking at using it for some kind of topsoil product," Mason said.

The entire system is computerized and run by two people in a central control tower. The computer system is tied together by a fiber optic and camera system. It took employees 18 months to learn the new system.

"Essentially the end product does not exist until it goes onto the barge, or into a truck of stockpile," Mason said.

The new plant has a capacity of 4 million tons of aggregate sales per year, 80 percent of which will leave the site by barge. Construction cost was not disclosed. The company owns 250 acres of the facility and leases 250 from Weyerhaeuser. The facility sits on 55 acres. It was built and designed by a team of companies, Lone Star Northwest, Baugh Industrial and The Harris Group.

"We took a team approach because it made it much easier to address problems," Mason said. He would not discuss details of the construction, except to say that the fine tuning process was still taking place. "We are working out the bugs, which happens in any project."

Lone Star shipped the first load of aggregate out of DuPont Feb. 14. Products are still available at Steilacoom. Truckloads of sand will be sold there for a number of years, Mason said.

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