May 10, 2022

Already Active Rock Quarry, Material Processing Operations Entering New Phases

Rock quarrying and material processing are among the most essential aspects of dam construction, and those operations at the Chimney Hollow Reservoir site – already extremely active through the first nine months of construction – entered into news phases in recent weeks. 

Aggregate processing equipment went into action in late April. The aggregate processing equipment includes a jaw crusher, a cone crusher, a vertical shaft impact crusher and a wash plant. Crews can now begin producing the specific crushed rock and aggregate materials needed for construction of many key pieces of the main dam, including different zones of the rockfill embankment, the aggregates for the asphalt core, and hydraulic filters and aggregates for structural concrete. Additionally, WALO, a Switzerland-based company that has constructed asphalt-core dams all over the world, set up its asphalt batch plant at the Chimney Hollow site. It will soon begin utilizing the aggregate produced by the crushers and processing it into the material mixes needed to build the main dam’s asphalt core. While there are about 200 asphalt-core dams worldwide, the main dam at Chimney Hollow Reservoir will be only the second one built in the United States, and will be by far the tallest once it’s constructed.  

Prior to these recent developments, rock quarry and materials processing operations had already been a focal point of activity at the Chimney Hollow Reservoir construction site. As of April, crews had stripped about 80 percent of the overburden (or upper layers) within the site’s 80-acre rock quarry. Crews are now excavating the more competent granite rock needed for construction of the dam that starts about 60-feet below the preconstruction ground surface.  

As construction continues, the quarry’s equipment and crews will produce about 2-foot and smaller rock that will either be sent to the rock crushers (and then processed by WALO for the asphalt-core of the dam) or to the rock-fill portions of the main dam that will surround and support the asphalt core. Once dam construction kicks into full swing, the rock quarry and processing crews will be producing about 63,000 tons of material per day, making it one of the largest mining operations in Colorado.