Written by Rita Brown – 24/08/2016 5:59 am
A 17,000-tonne oil rig which ran aground in the Outer Hebrides which was successfully refloated is expected to arrive at a temporary location this morning.
The Transocean Winner drilling rig ran aground on Lewis two weeks ago was refloated at high tide in Dalmore Bay, near Carloway at around 10pm on Monday.
Two tug boats have been taking the rig on a 54-mile journey to Broad Bay at the other side of the island where experts will assess the damage.
The journey has taken longer than initially estimated with a travelling speed of 1-1.5 knots per hour.
The Maritime & Coastguard Agency has been conducting counter pollution flyover checks in the area to examine the water for any sign of discharge, sheen or pollution from the rig.
There was no pollution reported in the Dalmore Bay area, but a slight sheen was detected as the aircraft continued to follow the path of the rig.
The sheen is said to be associated with the ongoing pressurisation of tanks to maintain the rig’s stability, but a Brigg’s Marine and Environmental Services team is accompanying the tow and assisting by “breaking up the light sheen”.
A temporary exclusion zone remains in place at Dalmore Bay until the seabed has been checked for any debris or environmental impact.
Hugh Shaw, the Secretary of State’s representative for maritime salvage and intervention, said: “We are taking advantage of the favourable weather conditions following this big step forward, and we will continue to closely monitor the rig whilst it is under tow.
“Once everything is declared safe, I will be looking at releasing the exclusion zone in Dalmore Bay.
“I would like to offer my sincere thanks to the Western Isles Council and community for their patience and their gracious hospitality during this challenging and disruptive period.
“This salvage operation has required the united cooperation from so many different organisations who have spared no effort to ensure that this rig reaches safer waters.”
Eight anchors are being laid out in Broad Bay to hold the rig in place when it arrives.
Transocean will then begin the assessment process – which includes putting divers in the water – to look at the damage the rig has suffered; a process which could take until the middle of September.
The semi-submersible structure was blown ashore at Dalmore during a towing operation on Monday August 8. The towline between the rig and its tug was lost en route from Norway to Malta amid high winds and heavy seas in the early hours that day.
The rig grounded with 280 tonnes of diesel on board and two of its four fuel tanks were damaged in the incident.
It resulted in the loss of 53,000 litres of fuel, most of which is thought to have evaporated with no damage to the environment.
The remaining 200 tonnes of hydrocarbons, mainly diesel oil with small amounts of base oil and brine, were transferred from the rig to the supply vessel Olympic Orion at the weekend.
A 300m exclusion zone around the rig will remain in place while the salvage work continues.
There will also be a 1km exclusion zone while it is towed from Dalmore Bay to Broad Bay, on the east coast of Lewis, some 54 miles (87km) away.
The Marine Accident Investigation Branch is carrying out a probe into the grounding of the rig and will issue its findings at a later date.