Nashville District Structural Deformation Surveys - Cordell Hull & Center Hill Dams
PROJECT DESCRIPTION:
SEAS was contracted by the USACE Nashville District to perform a high accuracy dam deformation/monitoring surveys of Center Hill and Cordell Hull Lock and Dam project sites. SEAS utilized TerraSurv to aid in the project. TerraSurv is a SEAS team member on SEAS Nashville contract that is an expert in Dam Deformations & Geodetic surveying. The survey effort consisted of the following tasks:
• Calibration of Equipment: EDMs were calibrated at a NGS EDM calibration baseline. Digital Levels were initially calibrated by the manufacturer and daily peg tests were performed and recorded.
• Recover and surveyed select existing control monuments. A geodetic quality static GNSS network was performed to establish horizontal coordinates on each site’s reference network. Monuments were selected based on location at the project sites to give the best geometry for the network adjustment.
• Performed geodetic quality vertical leveling throughout the project sites tying all base control monuments together. Trimble DiNi 12 digital level and invar rods were used.
• Survey of all alignment pins using 1” total stations. Each pin was observed in at least four sets of direct and reverse sighting, and from at least two instrument setups. Wherever possible Seco Mini stakeout prisms with a height of 0.1 meters were used to locate the pins. This helps ensure that centering errors over the points is minimized.
• Survey report in compliance with the format defined in Chapter 12 of EM 1110-2-1009, including overall positional accuracy statements for each data set (alignment, settlement, gauges, etc.) equipment calibrations, QC process and summary, daily checks, positional accuracy statements for all data sets collected, a statement indicating if the least squares adjustment passed or failed the Chi-Squared test at a 95% confidence level and the value of the reference variance, dates/times of field surveys, and list of control used.