If the residual oil remaining in the hull of a sunken tanker is not recovered, in case of sinking accident in nearby national cost, no salvage operation can be performed safely and the remaining-oil itself might lead to a catastrophic disaster at any time. Because of these above conditions, a proper remaining-oil recovery operation is necessary.
In this regard, this paper summarized the general remaining-oil recovery operation procedure and introduced the equipment used in such operations generally. Based on this basic information, this paper focused on the two remaining-oil recovery operations over sunken tankers that were performed under 70m or more in depth of water in Korea by studying the applied methodologies and techniques in these two oil recovery operations in order to compare and analyze the rapidity, safety, efficiency, economic feasibility and even more factors from various possible angles.
And on the basis of such study, this paper deducted a standard model of remaining-oil recovery operation procedure appropriate for domestic circumstances in Korea.
The standard model of remaining-oil recovery operation procedure obtained through this comparative study bears four stages which are ‘the Preparation’, ‘the Oil Recovery’, ‘the Tank Cleaning’ and ‘the Work Termination’. The later three stages are designed to be applied for an each cargo tank of sunken tanker.
During ‘the Preparation’, the operation method shall be decided on the basis of the pre-inspection result obtained from documentary surveys and work condition investigating on site. Following the Preparation, the selected recovery method shall be applied to ‘the Oil Recovery’ and ‘the Tank Cleaning’ work which comes alternately to each tanks. ‘The Work Termination’ step shall come when an internationally recognized independent surveyor is satisfied with the level of the ‘the Oil Recovery’ and ‘the Tank Cleaning’ operations. The Work Termination procedure is progressed by 2 steps which work performer checks out whether any remaining-oil exists by putting a short stick into the hole made on top side of each tank’s hull and opening up the toper part of the sunken tank such as hatch cover to confirm and declare of the clean tank. However, such ‘the Work Termination’ procedure in this paper is designed with flexibility which each checking steps shall be progressed through discussion amongst the ordering party, the work performer and the independent surveyor by reflecting the condition of the sunken tanker, the level of difficulty, the demand level of the ordering party and etc.