May, 1998: Equipment Experience from the 28000 tonne spill (October 1997) from the tanker “Evoikos” after a collision in the Singapore Strait.
By Chris Richards, Oil Spill Services Manager, Singapore Oil Spill Response Centre
Interesting to read the March, 1998 article regarding the performance of skimmers and booms – I would certainly agree that the information provided by manufacturers can be somewhat misleading (and perhaps meaningless) although in most cases probably not intentionally so. Perhaps there is a case for carrying out some realistic tests under controlled conditions – a repeatable simulation of conditions that are as realistic as possible using oils of known specifications.
Our own (Singapore Oil Spill Response Centre) experiences may be of interest, particularly of the response to the recent 28000 tonne spill (October 1997) from the tanker “Evoikos” after a collision in the Singapore Strait.
Several different types of skimmers were used in an attempt to recover the oil after it had been in the water for a few days – it had partly emulsified by then although it was fairly viscous oil even before it was spilt – 380 Fuel Oil.
The main problem with recovery was not so much with the skimmer’s ability to pick up the oil, rather the pump’s ability to drain the skimmer. All the pump types (including DOP 250 screw pumps) very quickly jammed up, having filled themselves with oil which then became virtually solid.
The only unit that worked and continued working successfully was our “ORCA” inductor unit – with its very large suction hose diameter and few moving parts it was capable of lifting the “oil” from the surface (with care and experience, without much water either) and drawing it into its internal tank – and then pumping it out again to temporary storage*1. Admittedly the weather conditions were very calm at the time allowing us to minimise the quantity of water picked up but nevertheless on this particular response the ORCA worked very well.
But as always, all spill responses are different and in other conditions it may not have been a success – definitely there remains a case of responses being supervised by experienced people who know (or at least have a fair idea) of what is likely to work under a particular set of circumstances and what will not. This also applies when equipment is being procured (by non-oil spill response organisations) for a specific purpose – far better to consult an unbiased opinion before spending considerable sums of money and maybe ending up with something that is not really suited for the intended purpose.
Oil Spill Services Manager
Singapore Oil Spill Response Centre
*1 We don’t know why Chris Richards decided to remove the oil first into the ORCA tank itself which contains only space for 14bbls, as per the OPA ’90 rules for having equipment on board to contain min 14 bbls of onboard spillage. If Chris Richards had used the ‘universal hatch cover’ and connected the system to a receiving hold of a barge, the ORCA could have pumped the crude oil directly into the barge’s tank resulting in, a much higher volume, non stop, up to the capacity of the barge.