Survey
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| USGS Survey Marker |
Survey data is vital to the monitoring of a dam and helps to warn dam owners of potential problems occurring in or around the dam over time. Without comparisons between past and current survey, imperceptible changes in the positioning of the dam over time are likely to go unnoticed.
"Dams, locks, levees, embankments, and other flood control structures are subject to external loads that cause deformation and permeation of the structure itself, as well as its foundations. Any indication of abnormal behavior may threaten the safety of the structure. Careful monitoring of the loads on a structure and its response to them can aid in determining abnormal behavior of that structure. In general, monitoring consists of both measurements and visual inspections... To facilitate the monitoring of the structures, they should be permanently equipped with proper instrumentation and/or monitoring points per the goals of the observation, structure type and size, and site conditions"[1]
“Surveys shall be performed at night to avoid troublesome optical distortions due to sunlight and heat radiation. The surveys shall be in accordance with the accuracy with methods established for first-order triangulation measurements as stipulated by the U.S. Coast and Geodetic Survey.”[2]
Best Practices Resources
Structural Deformation Surveying (EM 1110-2-1009) (USACE, 2018)
Survey Markers and Instrumentation (EM 1110-1-1002) (USACE, 2012)
Trainings
On-Demand Webinar: Using Instrumentation for Dam Safety Monitoring
Citations:
Revision ID: 4146
Revision Date: 11/07/2022