Treading delicate waters

Treading delicate waters A hovercraft-based electromagnetic (EM) system has detected likely munitions at a location in the Caribbean previously used for target practice by the U.S. Navy. The area covers more than 200 acres of shallow coral reefs that had been excluded from a broader geophysical survey because of the potential for damaging the coral.

By using a hovercraft and a near zero draft sensor array, Tetra Tech was able to survey vulnerable areas previously inaccessible except by more expensive and less sensitive helicopter based geophysical systems.

The survey represents Phase 2 of a remedial investigation and feasibility study on one of several former defense sites in the Caribbean. The entire 1,030-acre site served as an impact range for aerial bombs, rockets, missiles, mortars and naval projectiles from 1903 until 1975.

Despite the challenges of wind, waves, hypersalinity and heat, Tetra Tech’s crew was able to collect accurate data because of the maneuverability of the hovercraft.

The team processed auxiliary sensor measurement data such as GPS locations using hydrographic survey software and merged it with the EM data using Tetra Tech-developed software. The merged data was imported into Oasis montaj for processing, target detection and further analysis with Geosoft’s UXO software extensions.  

Read the full story on Earth Explorer.

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