News

The City of Bentonville GPS Network was outdated, and monuments were being damaged by construction and development. Elevations were inconsistent and not on the established datum of NAVD88. CEI established five new monuments and recovered twenty-two monuments suitable for continued observations. Brian Ward with NOAA’s National Geodetic Survey (NGS) helped to establish the five new monuments to meet NGS Class II standards and aided in the Blue-Booking process for official NGS Survey Marks. Three GPS receivers were used to observe monuments simultaneously which enabled a solid network of connected vectors. A daisy chain plan allowed each monument to be observed twice, each observation lasted four hours. This was done to ensure tolerances of 0.03 meters. Three-foot holes were dug to allow for the 9/16” rod to be driven to refusal on the five new monuments, which proved to be the biggest challenge in the limestone encrusted earth. By utilizing OPUS Projects Software, the entire network can be updated with future datum changes with no additional field work necessary. The total cost of the project was $83K, which CEI was able to deliver under the contract amount of $115K.