Road Warrior

June 17, 2013
Nevada city chooses mechanically stabilized earth retaining walls for road extension project

The extension of Eastgate Road, located in the southeast quadrant of the Las Vegas metropolitan area, required a grade separation bridge over railroad tracks serving an industrial manufacturing facility. Documents issued by the city of Henderson called for the construction of four bridge approach mechanically stabilized earth (MSE) retaining walls over the relatively flat grade.

The Nevada Department of Transportation (NDOT) standards specified the use of metallic soil reinforcement with select backfill for the MSE walls. The city excavated and stockpiled approximately 100,000 cu yd of material from a source adjacent to the project site for use as backfill as well as roadway fill. Subsequent soil tests revealed that the stockpile of select fill did not meet NDOT’s electrochemical requirements for metallic soil reinforcement as specified; the corrosive elements within the fill would have seriously compromised the long-term performance of the reinforcement.

City officials were left with the option of removing at least 65,000 cu yd of the material and replacing it with imported fill that met contract requirements, or with sourcing an alternative MSE wall system that complied with the aesthetic facing criteria and incorporated non-corrodible reinforcement.

G.C. Wallace Inc., design engineer, contacted representatives of Tensar Intl. regarding the Ares retaining wall systems.

“Our Tensar representative really knew the product and provided the information on its structural characteristics that we needed to develop the bid,” said G.C. Wallace’s Matthew Meyer, P.E., associate engineer. Engineers from both companies worked closely and quickly to develop alternate specifications.

The city of Henderson issued an addendum deleting the use of metallic soil reinforcement and replacing it with polymer geogrid reinforcement. Installation of the Ares walls was a first for the design engineer and the contractor.

“Construction went better than expected. We had a good crew, and we beat our budgets,” said Joe Riggs, construction manager with Capriati Construction. “Whenever we had field changes, Tensar technical representatives were on site to advise us within 24 hours.”

Crews erected the four approach walls, each with 5 ft by 5 ft panels cast with a fractured fin (ribbed) finish.

Scott Fiedler, P.E., construction manager with the city of Henderson, noted that the MSE walls are the first built by the city as well and credited Tensar representatives’ “expertise” for their successful completion.

About the Author

Paul Glickstein