Feb 15, 2012
Challenge
Sea-Tac International Airport in Seattle, WA has grown to become the 18th busiest airport in the country and the need for convenient parking is a growing concern. To help provide needed parking, one of the area’s leading parking services, MasterPark Inc., sought to turn unusable land near the airport into a valuable $20-per-night parking lot. Five retaining walls up to 33 feet in height reinforced with geogrid were needed to build up the site and create a level and stable area for the parking lot.
Solution
Goodfellow Bros. of Maple Valley, WA, the general contractor, and Sound Retaining Walls of Tacoma, WA, selected Strata Systems to provide the geogrid reinforcement for the complex array of walls. The retaining wall design specified Stratagrid with embedment depths up to 26 feet. Goodfellow Bros. had to excavate 35-foot tall back-cuts and haul the soil off site to allow for the reinforcement and the construction of the walls. Then, as Sound Retaining Walls constructed the segmental walls, the soil was brought back to the site for reinforced backfill. Segmental retaining wall construction, backfill and compaction of the reinforced fill are always a coordinated effort. Since the backfill was stored offsite, both contractors had to make concerted efforts to coordinate the construction of the walls to optimize construction efficiency.
A total of 18,000 square yards of Stratagrid SG200, SG500 and SG600 was installed behind the 19,000 square feet of segmental retaining walls. The installation was completed by the contractor without any special equipment saving time and money.
Result
This site was once considered unusable because of the dramatic grade change and the cost of development was not feasible. Today, with the economy of utilizing soil reinforcement technology, this site is now a very valuable asset to MasterPark, Inc.