In 2018, BNSF Orillia Railway began making extensive upgrades to its automotive distribution facility in Renton, Wash. The upgrades were required to support the increased demand for new automobiles. As new-car sales soared, so did the demand for rail capacity for vehicle shipments arriving from overseas. Part of this $125 million project included expanding the facility’s auto storage yard to accommodate the increasing number of vehicles received from overseas and transferred through the facility.
The 20-acre (8.1-ha) storage yard’s poor subgrade soil consisted of a layer of sand, clay and silt with a portion of the area located over organic fill. The low-strength subgrade required a soil-stabilization solution to reduce over-excavation and control project costs. The engineer chose the Presto Geosystems GEOWEB 3D Soil Stabilization System for its superior load distribution, low maintenance and cost-saving benefits.
When used as a base layer, the GEOWEB system creates a stabilized layer under asphalt, concrete or roller-compacted concrete that holds up under heavy, cyclical loadings. Under cyclical loadings, the GEOWEB system prevents the lateral movement of infill material and dramatically increases its shear resistance. In effect, the GEOWEB system behaves like a semi-rigid slab, which significantly reduces stress reaching the subgrade. A stronger base layer means a more resilient surface layer and a longer pavement life with less maintenance and potential downtimes.
Approximately 900,000 square feet (83,500-m2) of GEOWEB GW30V6 (6-inch [152-mm] deep) panels were installed over an enhanced HP570 woven geotextile, which was filled with recycled, crushed concrete and finished with an asphalt wearing surface. By using the GEOWEB system, the facility was able to reduce the overall cross-section depth, which limited over-excavation by 80,000 cubic yards (61,000 m3) and reduced project costs. The GEOWEB system provides the ability to span unknown pockets of very soft soils, which limits settlement while increasing the pavement life.
Confined aggregate within the GEOWEB 3D Soil Stabilization System (vs. unconfined aggregate):
- requires 50% or less base material to achieve the same load support requirements
- minimizes load-related deformation and settlement, and reduces pavement degradation and cracking common with soft subgrades
- allows the use of lower quality granular infill, even over soft subgrades
Since its installation in 2018, the GEOWEB system has exceeded project expectations and required no maintenance or repairs.