Developing offshore projects, such as wind farms, require where possible minimal operational constraints. The reasons behind this desired precision is both for technical and commercial/insurance purposes. However, the presence of geophysical contacts, some of which are potentially UXO, may hamper engineering design.
Depending on the stage of the project the effect will not only delay offshore operations but may have a much larger impact on the overall site design and effort to investigate these problematic geophysical contacts. This situation has been driven by a difficulty to discriminate between potential UXO and, for example, natural geological features. This is especially the case in areas of boulder fields and high magnetic background geology (e.g. outcropping igneous bedrock). However the problems can be even more significant around ports and other harbour facilities where man-made features hamper geophysical interpretation.
Robust discrimination of non-UXO from UXO is a very important step in marine UXO risk management. In many instances the desired performance level is not currently being reached by the wider industry. In Ordtek's experience many geophysical datasets fall below the accuracy criteria required to identify UXO, with some solutions being hardly any better than random estimation, often with an overreliance on fabricated “surrogate items”.
Ordtek set out to remove the inefficiencies in UXO detection and interpretation through processes that provably locate and identify UXO with high accuracy. The proposed solution is a marine based geophysical contact location and identification method using a technique for modelling and identifying objects using the basis of complex datasets. The solution fuses geophysics, geotechnical data and ordnance characteristics, and determines best algorithms/fit for each dataset. The techniques used include information theory, geophysics based modelling, signal processing modelling, and proprietary data from real bombs and mines. The challenge is to integrate these techniques and to determine the key information content, in order to extend the accuracy of predictive modelling.
The process has proved successful on some of the most challenging renewable developments across Europe. Ordtek have identified numerous items of UXO from geophysical datasets including German bombs and American mines.
On other projects where initial geophysical target grading had resulted in 1,000's of magnetic and side scan sonar anomalies across the site, being recommended for either investigation or avoidance, were reduced to a figure of less than 10% using Ordtek’s interrogation of geophysical contacts.