Teams of oil spill clean-up operators are continuing hunting down polluting pockets of heavy fuel oil nearly two months after an estimated 1.5 tonnes of the oil leaked into the harbour.

So far, the clean-up has cost the Bay of Plenty Regional Council $691,766.

Floating oil containment booms at $50 a metre deployed the bridge marina on Monday. Photo: Bruce Barnard.

A small hole in a spur line off the main under-wharf bunker line leaked the oil into the water on April 27.

It was blowing a northerly gale at the time and with an incoming tide the slick was carried from under the wharf, through the bridge marina and up the harbour to Maungatapu.

While the regional council was advised, little immediate action was taken. There was limited equipment available.

The emergency supplies of oil spill floating booms had not been replaced and were not available until the following day. Regional Council staff argued at the time that they would not have worked in the conditions anyway.

The Maungatapu beaches were cleaned up fairly quickly. The Tauranga Harbour Bridge Marina is taking a lot longer.

The oiled boats have been lifted and cleaned. Many of them cannot go back into their original berths because oil carried into the marina lodged into the gaps between the floats on the pontoons.

They discovered the oil worked its way into the seagrass growing between the floats, the pontoon sections. Each berth has to be boomed off in both directions and the gaps water blasted.

'Which took a long, long, time,” says Tauranga Bridge Marina manager Tony Arnold.

Because there's two knots of tide going in each direction, each berth has to be boomed off in both directions while the work was done.

The larger boats on A pier won't be going out of the water until they can go back in to their own berths. Many of the other boats from A B and C piers are squeezed onto temporary berths at the south end of the marina.

As of the end of May the hardstand operators Bridge Marina Travelift cleaned and returned 48 boats to the water, with about another 40 awaiting treatment.

Many of the boats are a simple lift, hold and wash, while the oilier ones can take two to three days.

'In most cases, the boats have been wiped or water blasted clean, cut and polished,” says Mobil Oil in a statement. Very few needed re-antifouling. Mobil is directly paying for the cleaning to expedite the process, rather than paying owners individually. While a thorough investigation is being conducted into the cause of the estimate 1.5 tonnes spill, it is too early to comment further," says the last Mobil statement.

There is no figure yet available on the cost of the clean-up. Claims are still being processed and work is continuing on affected areas and boats.

'We have been working very closely with our customers and continue to accommodate bunkering at the tanker berth as best we can. The bunker pipeline to the main wharf remains shutdown.

"We are working on a plan to reinstate the bunker pipeline, which will not be used until we have full confidence in its integrity. Unfortunately this is taking time, and we do not expect it to be operational for several weeks yet,” says the statement.