The Project
The project involves construction of an industrial site on land previously used for farming. To improve the bearing strength and stability of the ground, a dense grid of wick drains and an 8-foot high surcharge would be placed.
Monitoring Requirements
Settlement plates were specified to monitor the progress of consolidation. Weekly surveys of the settlement plates would be required during placement of the fill, and bi-weekly surveys would be required for six months afterwards.
Implementation
GEO-Instruments suggested that automated monitoring would be more efficient and safer than fielding survey crews, given the size of the site, the number of settlement plates, and continuous movement of heavy machines.
However, automated optical monitoring would require bringing more equipment onto the site: two complete AMTS systems, two gravity-base towers, and large solar panels.
As an alternative, GEO-Instruments proposed using Locator One GNSS sensors. The open sky of the farm field was ideal for acquisition of satellite signals and the compact, self-contained sensors could be deployed quickly and more economically than the AMTS systems.
Another potential benefit of the Locator One sensors was their built-in a radar sensor that can report fill height as referenced to the sensor.
Measurements from the GNSS sensors would be presented in the usual way (both graphical and numerical) on a project website.
A satellite view with an overlay showing project boundaries and the planned locations for 29 settlement plates with GNSS sensors. The 30th sensor is located outside the construction area and serves as a reference.
Installation of settlement plate.
GEO used an RTK receiver to establish precise coordinates for each settlement plate.
Settlement plates were installed at the beginning of the project even while organic material was being removed.
GeoCloud website with a planview of the surcharged area. The planview shows current readings from each settlement plate.