Clearing the path of the Balticconnector from unexploded ordnances

A fortnight ago Baltic Connector dealt with a remnant from World War II: the seafloor of the Baltic Sea lies full of explosives that had not exploded in battle. After a clearance operation lasting from April 22nd to the 26th, the entire path of the Baltic Connector has now been cleared from unexploded ordnances, or UXO.

The Finnish and Estonian navies had already cleared a lot of UXO targets in the Baltic Connector pipeline’s path. However, in the boundary zone 3, earlier surveys had identified objects which had not yet been cleared. The targets were located in the middle of the Baltic Sea, where the Baltic Connector crosses the existing Nord Stream 1 pipeline. One of the targets was located only 210 metres from the existing gas pipe, making the operation a high risk one, and requiring the target be moved to a separate disposal site to be cleared.

The operation proved to be an excellent job for two of the most experienced navy explosive divers offering their services through Finnish Diving Support Oy. For this operation, they teamed up with two old colleagues from the navy, with whom they had already worked closely in very similar operations, as well as Loxus Technology Oy for Remotely Operated Vehicle (ROV) operations.

The ROV explorer played an important role in locating the targets, visual inspection, risk evaluation and determining the method to clear the target. The ROV was also used to test whether the target was explosive and to later verify whether the target had been successfully cleared.

Three types of targets were identified. An Artillery Shell Projectile about 0,5 metres long located 210 metres from the Nord Stream pipeline was safely brought to surface, where it was attached to charges and moved to a disposal site. A one-metre long torpedo or air-dropped mine, with up to 250 kilograms of explosive content, had a disposal charge placed next to it and was then detonated at the site. A smoke buoy, a canister of about 0,5 metres in diameter, was found not to be explosive and was carried on-board to be disposed of at a hazardous waste disposal site.

All objects were successfully located, identified and disposed. The operation was an important step to start offshore pipeline construction works in July of this year.

PAUGE

Paul Gerrits
Ramboll

Images:

Location

MS Örnen at departure 23.04

ROV explorer

RHIB vessel identifying coordinates of target and placing reference buoy

ROV crew lowering ROV explorer

Crew preparing charges for target R-5191 on 24.04

Target R-5191 observed by ROV

Evaluation of target R-5191 from ROV images and discussing disposal plan 24.04

Divers getting ready for clearing R-5187 on 24.04

Target R-5187, a smoke buoy, was hauled in on 24.04

Target R-6180 located on 26.04.

Target R-6180 hauling onto the RHIB vessel on 26.04.

Target R-6180 attached to disposal charge on 26.04.

ROV image of disposal site of R-5191 after disposal