This $14-million project is located between St. George and Hurricane, Utah, and includes a 50,000 acre-foot off-stream reservoir which is contained by two dams with heights up to about 100 feet. RB&G performed reservoir site selection studies at the start of the project and then performed conceptual designs and estimated volumes and potential costs for earthfill, rockfill and roller compacted concrete (RCC) embankments. Borrow investigations were performed to identify sources and characteristics of construction materials. RB&G teamed with Alpha Engineering to design the project. RB&G was responsible for the reservoir and embankment design. Following additional foundation and borrow investigations, detailed designs were completed for RCC, earthfill, rockfill and combined earth-rockfill embankments. Although it was determined that any of the embankment types could be safely constructed, a rockfill embankment with a central clay core and internal filters and drains best suited the site, due primarily to the foundation conditions and availability of materials. This type of structure was also the most cost efficient.
Services: All engineering services during construction of the 2.5 million cubic yard project, including construction engineering, quality control inspection and testing. Personnel from the Washington County Water Conservancy District were trained to assist with testing.