As part of a beach suppletion project on the Romanian shores ADEDE executed a sonar- and magnetometry survey of the borrow area.
Romanian Navy Charts of the area showed a mine field crossing a section of the borrow area, reason why the Romanian authorities ordered a survey to be conducted under Navy supervision before dredging started. For centuries the Black Sea has been a logistical hub between the orient and the west and as such it is surrounded by rich settlements, outposts and most important ports and harbours.  As a rule trade routes and areas worth settling are targets in times of war and therefore worthwhile defending, negating and attacking. During both World Wars the Black Sea was a front line and top of that the it was in essence the border between opposing parties during the Cold War. Given that background there was always a high expectancy of sea mines and other ordnance deposits even without the forementioned chart.

chart clipping

Clipping of the chart showing the mine field against the rectangular borrow area.

anomaliesbs

The anomalies in the borrow area, top right corner as expected, center to right in the middle was an unexpected extra.

sssmijn

Sonar image of a sea mine and seat.

The survey consisted of a combined SSS and magnetometry survey in order to cancel out non-hazardous objects on the seabed prior to composing a target list. The magnetometers were towed behind an ROTV to enhance data acquisition quality. The data showed what was expected and an additional surprise. The anchors and seats of the charted mine field were in situ with two anomalies, likely to be mines, a bit further into the borrow area. The surprise was an additional line of anomalies consistent with a line of moored mines in the middle of the borrow area. The Romanian Navy EOD has inspected the anomalies and has taken suitable measures to ensure a safe working environment for the dredging company. All mines were identified as part of defensive lines of Romanian mines.

Towed side scan sonar

The towed side scan sonar is used for making images of the water bed, usually in deep water and large project areas.


Marine magnetometer

The G882 towed magnetometer system detects ferromagnetic anomalies on and under the sea bed.


Scanfish Katria ROTV

The ROTV is a towed semi-robotic vehicle which ensures a constant distance between sensors and target ensuring consistent data quality.