Throwback Thursday: Soil Nail Shoring System – Canyon Crossing Center
The Canyon Crossing project is located in Frederickson,
WA, a rapidly growing suburb of the town of Tacoma, south
of Seattle. The project site is approximately 592,000 ft² and
will include the construction of a supermarket; six out-parcel
buildings and a fueling center. The topography of the site
prohibited a project of this size from being constructed
without a vertical shoring system. A permanent soil nail
shotcrete shoring system was selected to stabilize and
tieback the east and south sides of the project site. The
site conditions required the average height of the soil nail
wall to be 45 feet.
The eastern slope of the project site was stabilized with
approximately 709 EA – epoxy coated soil nails and
southern slope was stabilized with approximately 543 EA
- galvanized soil nails. The average drill depth of the soil
nails was 30 feet. The difficult ground conditions required
the soil nails to be drilled using “Rotary Percussive Duplex”
drilling techniques in order to advance the inner drill steel
and casing simultaneously.
The two retaining walls have a surface area of approximately
26,000 ft². The construction procedure started with the
installation and grouting of the soil nails. After each row
of soil nails was installed and grouted, a 4-inch thick
temporary shotcrete facing was placed in 6-foot vertical lifts.
The final step of the construction sequence was to place
an 8-inch thick permanent shotcrete face over the entire
wall surface. The permanent facing was then architecturally
carved and textured to resemble natural granite stone.
Numerous shoring system options were explored during the
preliminary phases of the project. The most feasible and
economical solution due to the erratic nature of the subsurface
conditions throughout the project site was determined to be a
soil nail / shotcrete system. The versatility of this shoring system
also offered the owner an option to architecturally carve the
shotcrete facing to provide future tenants of the property with
an appealing natural looking rock wall versus an unattractive
grey concrete wall.
The project was an overall success. We were able to reshape the landscape
of the area and provided a new landmark to the neighborhood.