Mobil's response to a Lyttelton Harbour fuel spill is being investigated as the regional council's harbour master voices concerns about how the oil giant reacted.
A landslide hit two of Mobil's tanks in Lyttelton during a storm on March 5, rupturing a tank with 1.2 million litres of jet fuel. Another tank with 91 octane petrol was dented but did not rupture.
Mobil's bund, or secondary containment backup, built for such incidents, should have held all 1.2 million litres after the rupture, but it failed and jet fuel spilled into nearby drains and the harbour.
The stench of fuel forced 19 homes to be evacuated and left 10 house boats inaccessible for more than four days.
A Press investigation into the oil spill found:
Fuel leaked into Lyttelton Harbour because there was no way to close up five holes in the bund.
The holes have since been concreted over. Workers at the site tried to make-shift bungs or corks to put in the holes using bits of tree branches brought down during the weather.
Photos and emails released under the Official Information Act show earthquake-repair work on parts of the bund. Fuel escaped through gaps in these repairs.
Environment Canterbury (ECan) and Worksafe New Zealand are investigating.
ECan on-scene commander for marine response and harbour master Jim Dilley told The Press he saw the fuel escaping from the gaps in the bund that had been repaired.
A Mobil official told him they were earthquake repair patch jobs, he said.
Dilley arrived on site about 4pm, more than two hours after the landslide. He said he watched men with a saw making makeshift bungs from trees.
"The chaps there had taken some of the trees which had broken in the storm, the branches, and were shaping them with tapered ends into make-shift bungs and started banging them in."
The bund had holes and there was no mechanism to close them, Dilley said. "I am surprised in a facility that is meant to keep liquid in, that there were these holes and no way of closing them."
Mobil did not answer questions from The Press on what the purpose of the holes were and why there was no way of closing them.
Dilley said he was taken around the bund by a Mobil official and noticed some fuel flowing out of the earthquake patch jobs.
The leaks were on the opposite side of the landslide more than 100 metres away. They were few and the incident was containable, he said.
There was no fuel in the harbour at that stage but he advised Mobil to block the drain next door to the bund with sandbags and clay.
Dilley then sent an email to several parties, including ECan chief executive Bill Bayfield, Maritime New Zealand, and Lyttelton Port Company boss Peter Davie.
He told them the bund "is holding" and if the other tank of 91 octane started leaking "there was remaining capacity in the bund" for it.
Within hours the situation had changed, Dilley said.
"I was called back 3am in the morning, four hours after I left, went down to the site again and a larger number of leaks were evident - they were everywhere in the bund wall.
"Jet fuel was actually evident on the surface of the land and this
was in a flowing state like small rivers . . . rivers of jet fuel moving away from the bund."
There was evidence of fuel in the harbour. The ECan team worked to stop the flow of fuel and water from the stormwater outlet into the harbour.
Another source, who was on site, told The Press ECan was forced to take over the land response.
ECan would usually only be responsible for the marine response.
The source said: "We [responders] were strongly suggesting courses of action to [Mobil] and when they weren't following up . . . ECan did them.
"That included blocking the drains, setting up collection points, pumping the gas from the bund, organising sucker trucks, making clay bunds to stop the flow from the bund, pumping that gas back into the bund and setting up collection tanks and pumping the fuel into those collection tanks," the source said.
Dilley said the ECan team was focused on stopping more fuel entering the harbour.
Mobil told The Press it responded quickly.
"The response required considerable resources with additional people and specialist expertise obtained from other Mobil facilities . . ."
Dilley said other tank farm operators from NZ Oil Services Ltd helped at the site.
They, not Mobil, provided a tank to hold the fuel being pumped from outside and inside the bund, he said.
After 36 hours, the ECan team began handing the reins over to Mobil officials.
- Fairfax Media