The I-580 freeway extension between Reno and Carson City has been “on the books” in one form or another since 1957. This new segment extends the freeway from the Mt. Rose Highway (State Route 431) to the Bowers Mansion cutoff, completing the freeway in southern Washoe County. The new roadway includes nine bridges and 8½ miles of freeway, winds through remote canyons in Pleasant Valley, and involves numerous unique features, including the longest, highest arch supported bridge in Nevada. NDOT Contract 3292 also includes sculpting of the rock cuts, revegetating slopes, and construction of retaining walls on the downhill slopes. Due to the high winds and safety concerns voiced by the prior contractor, Fisher Industries decided to use a different approach to build the arch at the Galena Creek Bridge. The decision was made to temporarily fill Galena Creek Canyon to a maximum height of 140 feet and build the arch on top of the temporary fill. The fill was approximately 210 feet wide at the top and 385 feet wide at the base of the creek. In order to construct the fill, Fisher had to move 380,000 cubic yards of material. Once the fill was in place, falsework was built on top of the fill to support the arch during construction. A temporary culvert was constructed to allow Galena Creek to pass under the temporary fill. Lumos served as a subcontractor to primary contractor Fisher Industries on this contract. Lumos provided ageotechnical investigation, expert analysis, materials testing, construction inspection, and concrete mix design testing on this $393 million dollar contract. Our Geotechnical Engineer, Mitch Burns performed the geotechnical site investigation and recommendations for foundation of the arch structure and earth fill. He also provided QA/QC during the construction of the temporary fill to assure settlement would be maintained within allowable limits.Construction Services Engineer, Mike Brown assisted Fisher Industries by providing the High Performance Concrete mix design for the bridge decks for this project including the Galena Creek Arch Bridge.