Cheyenne Dam Safety Inspection and Surveying
Trihydro provided surveying, monitoring, and geotechnical reporting services to help optimize the structural integrity, longevity, and operations and maintenance of six dams in southeast Wyoming.
The City of Cheyenne Board of Public Utilities (BOPU) contracted Trihydro in 2016 to provide ongoing surveying, monitoring, and geotechnical reporting services for six dams in southeast Wyoming: Rob Roy, Hog Park, Crystal, Granite, North Crow, and North Crow Diversion. The project’s goal was to maintain the structural integrity of the dams and reservoirs, optimize their longevity, meet reporting requirements, and identify opportunities to improve operations and maintenance (O&M).
Data Review and Inspections
Trihydro’s role in the 6-year project entailed reviewing existing data, performing routine inspections, and collecting field data to meet the Wyoming Safety of Dams reporting requirements.
Two dams require annual inspections, one is inspected biannually, and three will only be inspected once during the contract. Our team generated reports with information regarding the condition of the dams and related facilities, as well as targeted recommendations that allowed BOPU to make timely, informed O&M decisions.
Field activities for this project included dam inspection observations, monument surveying, piezometer and inclinometer measurements, and toe drain flow recording. Our team evaluated data from the comprehensive dam inspections to assess dam performance and maintenance needs. In addition, Trihydro completed a hydrologic analysis and spillway review of the North Crow spillway.
Reporting
Based on historical data and findings, Trihydro developed annual reports encompassing observations, field data, and graphs showing movement monuments, embankment lateral movement, dam structure water levels, inclinometer verticality, and supervisory control and data acquisition toe drain flow. The reports meet Wyoming State Engineer’s Office and US Forest Service requirements and present recommendations for improvement.
