Client Needs: An engineering firm was in the process of refurbishing a relatively small ferryboat terminal in the Northeast. In this process, an intact, massive (and potentially explosive) Rodman cannonball was unearthed by a backhoe. To provide worker safety, the work zone had to be surveyed for other unexploded ordnance (UXO).
Services Provided: Aqua Survey utilized their customized military-grade electromagnetic induction (EMI) metal detection electronics (marine and terrestrial platforms) to locate ferrous and non-ferrous objects within the work zone. None of the detected targets were UXO. EMI was used because of its ability to detect both ferrous and non-ferrous objects. UXO objects often have very little ferrous content and are often undetectable with a magnetometer.
Submerged UXO on or protruding from the surface can be detected by side scan sonar. Terrestrial UXO laying on the ground can often be detected by eye. However, when UXO is potentially fully embedded in the soil or sediment, invasive electronics, such as EMI, are required.
What If: The survey indicates the probability of more UXO?
What if Solution: Aqua Survey uses RTK-GPS (accuracy within a couple of inches) to identify all target locations. An Explosive Ordnance Disposal (EOD) team would evacuate all non-essential people from the area, reacquire the target and then carefully expose the object to determine if it is UXO or metal debris. If underwater, an Aqua Survey EMI-tipped jet probe would be used to aid in reacquisition. If it is UXO, the EOD team would determine the safest way to eliminate the risk, which could range from Blow in Place (BIP) to removal to be detonated in a safer environment or deactivating its fuse.