Communication, innovation lead to project completion
The extension of Eastgate Road in the southeast quadrant of the Las Vegas metropolitan area required a grade separation bridge over railroad tracks that serve 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.
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 and 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 either removing at least 65,000 cu yd of the material and replacing it with imported fill that met contract requirements or sourcing an alternative MSE wall system that complied with aesthetic facing criteria and incorporated non-corrodible reinforcement.
Design engineer G. C. Wallace, Inc., contacted representatives of Tensar International 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 Associate Engineer Matthew Meyer, P.E. Engineers from both companies worked closely and quickly to develop alternate specifications. The City of Henderson issued an addendum that removed the requirement for the use of metallic soil reinforcement and replaced it with a requirement for polymer geogrid reinforcement.
The installation of the ARES walls was a first for the design engineer and the contractor. “Construction went better than expected,” said Joe Riggs, construction manager with Capriati Construction. “We had a good crew, and we beat our budgets. …Whenever we had field changes, Tensar technical representatives were on site to advise us within 24 hours.” Crews erected the four approach walls, each of which featured 5-ft-by-5-ft panels that were cast with a fractured fin (ribbed) finish. City of Henderson Construction Manager Scott Fiedler, P.E., noted that the MSE walls are the first built by the city as well and credited Tensar representatives’ “expertise” for their successful completion.