Seattle Stadium, a.k.a. Lumen Field, has taken on a wholly different look for the world soccer games. The Stadium is hosting six matches before the final world soccer matchup in New Jersey on July 19th. Two games have already been played with four left to go.
The Seahawks’ home turf is currently buried beneath a sandwich of geogrid, sand, and natural grass. The conversion from synthetic turf to natural grass field was a must to bring the stadium up to the world soccer organization’s strict standards.
The process was rigorous but worth the effort. The Athletic, a sports platform owned by The New York Times, recently ranked Seattle Stadium the #1 venue for the world soccer games based on “atmosphere, location, and suitability for soccer.” It even gave the field a 10/10 in the “suitability for soccer” category.
Read on to learn about how the natural grass system was installed and how Washington Rock’s sand played a role.
The “Perfect Hybrid Grass Surface”
The world soccer organization knows what they like. And it’s not synthetic turf.
To meet the organization’s standards, eight out of sixteen world soccer stadiums had to convert their synthetic turf fields to natural grass fields. All eight of these stadiums are NFL fields, including Seattle Stadium.
Designing the grass overlay for Seattle Stadium and the other seven fields began nearly ten years ago. According to the Associated Press, teams at the University of Tennessee and Michigan State University worked together to grow the perfect grass that would sit on top of the perfect foundation.
The system that the two universities devised consists of several layers:
- an impermeable landscape fabric that covers the synthetic turf;
- a polypropylene grid that provides drainage and ventilation to the grass;
- a layer of permeable landscape fabric that covers the grid;
- 6+ inches of sand;
- pipes for water and air; and
- specially grown sod strips blended with 5–10% artificial fibers.
This system eliminates many of the issues experienced on past synthetic turf conversions, like a lack of ball bounce.
The Perfect Soccer Sand
The sand layer is a key component of the natural grass system because it provides stability as well as drainage.
“What we know is that as long as we have six inches of sand over the top of the artificial turf, the player will not feel anything but a natural turf reaction,” Michigan State professor and turfgrass expert Trey Rogers told The Seattle Times. Rogers is part of the research team who advised the world soccer organization.
The sand used for the world soccer pitch has to hold up from March until July through a total of 17 games, including the world soccer games, Major League Soccer games, and National Women’s Soccer League games.
Seattle Stadium hired Walrath Soil Technologies to procure and install the sand for the field conversion. Walrath specializes in soil and sand for specialty surfaces. Their blending yard in Frederickson, Washington, enables them to homogenously mix products with proprietary and hard-to-source ingredients.
Walrath soil consultant Jami Burke managed the project. It was one of the most challenging projects she has worked on due to the world soccer organization’s high standards. Jami worked closely with three organizations to choose the perfect sand: general contractor FieldTurf Northwest, landscape architect D.A. Hogan & Associates, and soil-testing firm A. McNitt & SerenSoil Testing.
D.A. Hogan acted as the voice of the world soccer organization, while FieldTurf Northwest managed the installation of the new natural grass system. A. McNitt & SerenSoil Testing tested sand samples to determine whether or not they met the world soccer organization’s strict gradation requirements. All three agencies were looking for the Goldilocks of sand: not too fine and not too coarse.
Washington Rock’s Fine Sand (above, left) served as the main medium for the field. Washington Rock’s Fairway Top Dressing Sand (above, right) was tilled in after the entire field was laid out.
Walrath worked with Washington Rock Quarries in the past to create a custom soil mix for the Seattle Sounders FC training fields. Jami was familiar with Washington Rock’s products and their ability to meet strict specifications.
“The material specifications were difficult to achieve due to the nature of the project,” Jami explained. Organizers opted for a base of Washington Rock’s Fine Sand with Fairway Top Dressing Sand tilled in.
Once the sand was chosen, Jami coordinated the process of bringing approximately 1,500 tons of sand to Seattle Stadium.
First, the sand was trucked from Washington Rock’s King Creek Pit facility in Orting to Walrath’s blending yard in Frederickson. At the blending yard, the sand was re-blended to ensure particle sizes were evenly dispersed. Then the sand was trucked to Seattle Stadium.
“Access into the stadium was very tight, so we had to run all the material in super solo loads,” Jami explained. Super solo trucks are dump trucks with an extra axle, which allows them to carry heavier loads than normal dump trucks.
By the time the sand was brought into Seattle Stadium, the drainage layer and second layer of landscape fabric had already been installed. Laying down the irrigation line and installing the sand on top was a careful dance. Trucks had to drive around and next to closely positioned irrigation lines. After sand was dumped on top of the lines, more irrigation line could be laid out in anticipation of the next loads of sand. Tight security meant that truck drivers couldn’t leave their vehicles, which made deliveries and vehicle handling more challenging.
As sand was stockpiled over top of the irrigation lines, bulldozers carefully spread the sand outward and graded the sand into a level plane. Lumen Field shared a timelapse video of the installation on their social media, which can be viewed below.
The process of laying down the sand took 10 working days. The process was nail-biting at times. After all of the sand had been installed, organizers watered it with the sprinkler system and observed drainage. One patch wasn’t draining as well as the rest of the field, so Walrath replaced about 150 cubic yards of sand with new sand. Then Fairway Top Dressing Sand was tilled into the sand layer.
After the sand layer got the green light, sod was installed on top.
Worldwide Approval
The Seattle Stadium team was satisfied with the end result, but what about the soccer players?
The Seattle Sounders, the Seattle Reign, and the U.S. Women’s National Team played a combined eleven matches on the newly converted field prior to the world soccer games.
The U.S. Women’s National Team hadn’t played at Seattle Stadium since 2017 due to the artificial turf. In an interview with the Associated Press, team captain Lindsey Heaps gave the new grass field a great review: “I didn’t notice it at all, so that means it was a good thing.”
The best testament to Walrath’s work came when Jami’s daughter attended a Sounders game at Seattle Stadium and texted Jami a photo of the completed field. It looked incredible.
As the world games have begun, Jami has been hearing and reading comments from locals and international visitors. “People are having such positive experiences,” Jami said.
Driving home from work, Jami has been listening to interviews on the radio. Many people have praised how smooth the grass field is. Seeing players and fans alike enjoying the field brings home the importance of her small part in the field conversion.
“I feel inspired by humanity coming together in such a positive way,” Jami said. “Let’s face it, there is so much ugliness in the world right now, but the [world soccer games are] showing all of us that our best authentic selves are the majority.”
Check out other articles about the Seattle Stadium natural grass conversion:
- “Lumen Field is already unrecognizable — and Seattle’s World Cup makeover isn’t done yet” (King 5 News)
- “It took years to engineer the right grass for World Cup fields” by Anne M. Peterson (Seattle Sports/AP News)
- “2026 FIFA Men’s World Cup: How Lumen Field will transition to grass” by Tim Booth (The Seattle Times)
- “How NFL stadiums are transforming for the 2026 World Cup” by Henry Bushnell (The New York Times)
- “How the 2026 World Cup is tackling its turf problem with the ‘most micromanaged grass in the world’” by Henry Bushnell (Yahoo! Sports)
- “World Cup grass in NFL stadiums stirs debate over field surface” by Jordan Raanan (ESPN)
Check out our Sports Field project page to see other fields we’ve contributed materials to.
Washington Rock Quarries is a family-owned business that produces rock, sand, and soil products at Kapowsin Quarry and King Creek Pit in Orting, Washington.