Pierce County mine under fire for proposed expansion. We took a look inside the operation
Behind the gate of the Pioneer Aggregates Mine in DuPont, mountains of sand and gravel stand against the sky. Workers in neon vests and hardhats cut grooves into the ground with heavy machinery, and a network of conveyor belts hum through the facility, transporting tons of construction material to a waiting barge on the Puget Sound.
Since the 1890s, Glacier Northwest, a CalPortland company, has mined sand and gravel near Steilacoom, turning rock into concrete for projects like the Tacoma Narrows Bridge, both of Seattles’ sports stadiums and miles of Interstate 5.
Now, the company hopes to expand its existing mine at 4301 Pioneer Ave. into previously undisturbed areas of southwestern Pierce County as demand for aggregate rock grows with population increases.
The expansion project has come under fire from environmentalists and neighbors who fear it would do irreparable harm to the flora and fauna nearby. They’re also concerned the company’s plan to drain the Vashon Aquifer would kill off vegetation along the popular Sequalitchew Trail.
DuPont city officials are in the midst of drafting a final environmental-impact statement, which will include a recommendation to the city’s hearing examiner on whether the project should move forward. If the appropriate permits aren’t approved, the denial could be appealed to the Superior Court, the city’s community development director Barb Kincaid told The News Tribune last month.
The News Tribune took a tour of the Pioneer Aggregates Mine on Friday to see how the mining process works and learn more about why the company believes it should be allowed to expand.
The ‘Steilacoom standard’
Pioneer Aggregates Mine is on an ancient river delta where rich rock was deposited after glaciers receded, said Pete Stoltz, senior manager of permitting and government affairs of CalPortland.
“We’re mining what they call the ‘Steilacoom gravels.’ And the ‘Steilacoom gravels’ are really well known in the industry, among the gravel geeks, for being extremely hard and durable,” he said. “At one point the Department of Transportation used what they called the ‘Steilacoom standard.’ So Steilacoom gravel basically became the standard for the quality of material.”
Stoltz says the strength of concrete comes from the strength of the rock. Their company has supplied concrete for big technical projects like the Seattle’s State Route 99 tunnel, various floating bridges and the Tacoma Narrows Bridge, in addition to supplying material to other concrete providers in the region via barge.
Now CalPortland wants to mine the southern part of the site and dig deeper into the area they’re in now. They’ve been pushing to do that for decades, engaging with the state Department of Ecology, DuPont officials, Joint Base Lewis-McChord and other environmental stakeholders to develop a restoration plan to restore historic water flows to Sequalitchew Creek, which would be funded by CalPortland if the mining expansion progresses.
“This is not a typical development project,” Stoltz said. “I don’t know any other project that has gone through this kind of a process to address potential concerns and identify ways to go forward.”
Stoltz acknowledged CalPortland is a corporation operating under a for-profit model and the mining issue is “politically controversial.” But he sees the project as a necessity given limited resources.
The number of permitted gravel mines in Washington state is decreasing at a rate of about 14 per year, Stoltz said. A big factor is identifying new resources, in addition to the time and resources necessary to get a permit, he said. With increased population and more demand for sand and gravel, existing mines are more quickly depleted, and they aren’t being replaced, Stoltz said.
“We endeavor to be a good corporate citizen. We support the community, we work in the community, the community is our customers. More than 50% of our material goes to public projects,” Stoltz said. “In order for us to continue to build and maintain our public infrastructure, in order for us to accomplish all the things we want, like fish habitat restoration and affordable housing and transportation … you’re going to need a lot of concrete and a lot of rock.”
Even if CalPortland isn’t approved to build on the site, other developers will.
“The only reason this forest and this property is here the way it is today is because we’ve had a proposal for the last 25 years to mine it,” Stoltz said. “If we went away, the next day there would be a proposal to build, probably warehouses.”
From mine to sea
So how does this mine operate? Vice president and general manager for Glacier Northwest, Sean Smith, explained the process to The News Tribune on Friday’s tour.
After the rock is mined, bulldozers push material down to loaders, which load the crushed rock onto a conveyor belt that brings the material to a plant.
There it is separated by size through a series of screens with different-sized holes and pressure washed. Larger sized rocks are crushed down first to smaller sizes depending on what it will be used for and what customers want, Smith said. Conveyor belts then carry thousands of tons of washed material to barges on Puget Sound to be transported to their next destination, usually a concrete or construction company.
This story was originally published September 11, 2024 at 5:15 AM.
