Geogrid to the rescue at Sea-Tac Intl.

Airport parking is added using grid-reinforced soil

By Jessica Bies

Serving nearly 33 million passengers annually, Seattle-Tacoma International Airport is the 17th busiest airport in the U.S. It is also a difficult place to park.

With rates ranging anywhere from $4 to $35 a day, the parking scene is a fairly competitive one.

That’s one reason MasterPark Inc., one of the area’s leading parking services, sought to transform a site, once considered unusable due to the dramatic grade change and development costs, into a $20-per-night parking lot.

Using geogrid, a low-cost development solution, and a complex system of segmental retaining walls, the land was landscaped into a level and stable area suitable for parking.

The five retaining walls are backed by 18,000 square yards of geogrid, embedded at depths up to 26 feet. The soil, excavated from 35-foot-tall backcuts and stored offsite, in combination with the geogrid, provided a reinforced backfill.

The final retaining wall system required a relatively short time to construct and did not require the use of special equipment, making it an economically viable option. The lot, just a shuttle ride away from the airport, is a valuable asset for MasterPark and for Sea-Tac customers.

Jessica Bies is an editorial intern at IFAI.