Safety Incident Topic: Diesel spillage
Location Of Incident: Brisbane, Australia
Date Of Incident: 30th July, 2005
Brief Account Of Incident
On Saturday, July approx 80,000 litres of Diesel overflowed from one of two slops tanks. The slops tanks had a flaw in the high level alarm, whereby if one of the two tanks alarms activation (eg got wet) the other tank alarm would not work. The alarms were wired to operate as one not individually. This flaw was known but risk of both tanks filling at the same time deemed low. This was due to the relative inactivity of use and operational work around which was in place.
Prior to the incident one slops tank (WS 9996) had been filling during an interface between Jet and Diesel and had activated the high level alarm. This alarm was turn off and the other slops tank valve opened so WS 9996 could not be used. However as WS 9996 alarm probe was still wet the new slops tank (WS 9997) effectively had no working high level alarm.
Several previous incidents had occured with the operation of the slops tank resulting in two previous near misses and a HAZOP notation. The procedures for operation had been discussed at operators meeting.
The operator at the time forgot to close the slops valve after interface, allowing the next two transfer of product to bleed into both the Diesel tank and the open slops tank (WS9997) - with no active alarm and the operator not being aware he had left valve open. The tank filled approx 90,000 litre tank.
The operator did not return to the manifold until advised of the spill (some 2 1/2 hours) even with a change in transfer. This was a procedural breach. The operator did not consider the new transfer to be a risk as the same product was being transferred and could monitor from office.
Whilst the spill of 80,000 litres is serious it could be have been much worse as the transfer still had another 1/2 hour to go before the end of the transfer. The tanker driver only smelt the fumes and investigated to then see the spill. The spill escaped secondary containment and it was solely due to quick and early action of those involved that prevented the spill from migrating off site.
What Went wrong
The following root / system causes were identified as follows.
. poor judgement
. Inadequate leadership
. Inadequate enforcement of PSP
. Inadequate correction of prior hazard
. Inadequate assessment of needs and risks
. Inadequate identification of critical safe behaviours
. Inadequate audit / monitoring
The spill occurred because an individual had a memory/ perception failure and also failed to follow procedures. At the root of these failures is both an inability by management to recognise a circumstance where such a failure could occur, and failyre by leadership and staff to identify critical safe behaviours. There was an awareness of the high level alarm problems but a risk assessment found the risk 'LOW". A lack of formality in the risk assessment process.