• Arizona Contractor & Community

Digging Through the Archives: Union Rock & Materials Company

By William Horner


One of the largest midcentury construction rock and sand providers was started by a businessman who knew more about manure than materials.

Arizona was still a territory when Walter T. Bartol arrived in Phoenix in 1907. He landed a job at a Phoenix livery stable for $50 a month before starting his own, the Golden Eagle Livery Stable at 217 North Central Avenue in 1910. The site later became the Vista Theater and is currently the 40-story Chase Tower, the state’s tallest building.


Bartol enlisted in the U.S. Army in 1917 during World War I and returned a few years later to open Cement Products, Inc., a cement block plant, on West Buchanan Street located just south of Downtown. The plant remained in operation at that location until 1933.


In 1928, Bartol acquired 100 acres at the southern end of the Central Avenue bridge at the Salt River. He started Union Rock, a materials operation, by excavating sand using mules and selling it to local contractors. The mules also towed vehicles across the flowing Salt River to provide additional revenue, according to Kieways published by Peter Kiewit & Sons in 1979.

The plant expanded to ready-mix mortar, cement blocks, and rock. A dragline was used to excavate the materials, which were then crushed, screened, and washed. In 1939, Bartol incorporated the business and renamed the operation Union Rock and Materials Company. The company’s "Omaha orange" colors made its vehicles easily recognizable, and its slogan was "In Union There Is Strength.”


Bartol continued expanding Union Rock & Materials, adding a lime mortar plant in 1939 and doubling its output three years later. The entire operation was overhauled and upgraded in 1945 with a Cedar Rapids 15 x 24-foot crushing unit, which had two double-deck vibrating screens and a secondary Simons-Cone 2-foot crushing unit. New conveyors and concrete loading bins were also installed. In 1948, Bartol obtained an automatic block machine for the plant that produced “Dunbrick” brand blocks.


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This article originally appeared in the bimonthly Arizona Contractor & Community magazine, Mar/Apr 2021 issue, Vol. 10, No. 2.


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