Canterbury ‘prepared’ for any major oil spill crisis

Press, 16 April 1980, Page 21

Canterbury ‘prepared’ for any major oil spill crisis

A coastal tanker bound for Lyttelton with 23,000 tonnes of heavy bunkering oil collides with a fishing boat in heavy fog in the Canterbury Bight. The trawler sinks, but not before holing the tanker, which starts to leak heavy oil into the sea. Survivors from the trawler are hauled aboard the tanker. A north-easterly wind springs up, and the spreading oil slick begins to drift towards the coast, helped by an onshore current. Christchurch’s beaches are threatened, and with them

the birdlife of the shoreline and the Avon-Heathcote Estuary. What is to be done? If effective action is not taken quickly the beaches of Pegasus Bay will soon be polluted with thick globs of tarry oil—just like the beaches of the English Channel after tanker accidents there. It has not happened here yet, but with coastal oil tankers plying to and from Lyttelton, and ocean-going tankers from the Persian Gulf sailing up the coast to Marsden Point from time to time, such a disaster is always on the cards.

By

GARRY ARTHUR

The Marine Division of the Ministry of Transport believes it is ready for such a spill. First on the scene would be its Christchurch regional marine officer, Mr Peter Williams, who would commandeer a helicopter or a launch to see the extent of the spill for himself. He would take an expert with him to take samples and identify the type of oil.

In command is the Marine Divison’s oil spills action committee. As it is a serious spill, Captain P. W. Johnson, the division’s nautical adviser on oil pollution, has flown down from Wellington to be the “on-scene controller.” He calls on other Government departments for help, including wildlife experts to rescue endangered or oil-covered birds, the Fire Service to provide' trained manpower, and the Ministry of Warks and Development for removal equipment. He can also call on the Oil industry’s own oil spills committee in Wellington for help. If the pollution is from volatile oils — petrol or deisel — they will do nothing. No effective measures have been devised for coping with vol* atile oils, so it would just be allowed to evaporate. But our spill is of the worst kind — heavy fuel oil. which does not lose much by evaporation. If the slick was drifting away from the toast, again nothing wotild be done. It would be left to break up and disappear out in the Pacific. But this slick is being drawn towards the coast by the action of wind and current.

Dispersal is the first

line of attack. In a store in Wordsworth Street, Sydenham, the division has three sets of spraying booms and 3000 gallons of Correxit 9527. Each spraying set is mounted on a four-wheel trailer ready for towing to the nearest embarkation point, or for being flown there in an Air Force C-130 Hercules.

This equipment has not been tried on an oil slick at sea (a “live” practice is prohibited by the laws against polluting the sea with oil) but Christchurch firemen have been trained to use it. They would be called out to Operate the spraying booms once they were installed on a tug, a fishing boat, or some other available vessel at Lyttelton. The dispersant acts by breaking the mass of oil into minute globules and stopping them from co-, alescing again into an oily mass. Bacteria and other organisms in the sea then have a better chance of dealing with them. The vessel would sail slowly through the oil slick, spraying the dispersant on each side. Christchurch’s 3000 gallons would disperse about 120 tonnes of oil, according to an estimate by Captain Johnson.

If that stockpile ran out, more could be sent by air from Auckland. That is where the main stockpile of oil pollution equipment is held, because of the greater likelihood of a major spill in the vicinity of the Marsden Point oil refinery at Whangarei.

The amount of dispersant held in Christchurch is considered “practical for what might' be expected.” Auckland

has a further 16,500 gallons and 13 sets of spraying equipment. Total stocks in New Zealand are enough, to deal with about 1000 tonnes Of oil, but this is being built up over

the next few years to deal with three times that amount.

“That’s the sort of figure we’re thinking of,” says Captain Johnson. “If a ~ tanker spills 30,000 tonnes of oil, up to 60 per cent of it can evaporate off. That would be the case with white fuels, and with Maui condensate it would be about 80 per cent, leaving a .waxy material which is difficult to clear up.” Bunker oil is the nasty one according to Captain Johnson. A really big spill of heavy oil could take weeks or even months to clear up. Containment of the oil slick is crucial once it starts moving towards the coast. The wider it spreads, the harder it is to handle. To deal with this problem, the Marine Division has just taken delivery of a set of oil containment booms, based at Auckland for deployment by air or road around the country. They are plasticcovered canvas floats about 200 metres long. Alternatively, a chemical called Oilherder is on hand for spraying around the oil slick. It acts like a noose and stops the oil from spreading. Once restrained by the boom, or “corailed” by Oilherder, the oil will be sprayed with dispersant to

make it sink, or it will be skimmed off by the Marine Division’s hydraulically driven “gulper.” This is an 18 inch square oil skimmer which sucks the oil over a weir and pumps it

away to a barge or tanker. Meanwhile the crippled oil tanker is still laden with oil which must not be allowed to add to the growing slick on the surface of the sea. To unload it, the Marine Division has three large portable submersible pumps which can shift 200 to 250 tonnes of oil an hour. These, too, have to be flown down from Auckland.

To protect the off-load-ing barge or tanker, the division has •' three large pneumatic fenders, each 15ft by Bft. Firemen who have been trained to use the pumping equipment, would be flown to the spot by helicopter. In spite of all these efforts, the spill is so severe, so close to the coast, and wind and tide are so unfavourable, that large quantities of heavy oil are washed up on the beach at New Brighton. Before it hits the sand, a sprayer rolls along the beach coating the sand with a sealant to stop it soaking in. For two or three days nothing else is done. It looks terrible, and people get very angry, but .the 'Marine Division leaves the stuff alone to enable as much as possible to disappear into the atmosphere by evaporation. It will be easier to clean up when the “light ends,” as the volatile substances

are called, have evaporated.

Then begins the hard work. “Cleaning up On the beaches is a labour-in-tensive job,” Captain Johnson says. “We’d use shovels, rakes, and forks. Heavy machinery is likely to do more harm than good.”

Any oil that washes into salt marshes along the coast will be left alone, because of the key role played by the marshes in the food chain. It would simply be left to degrade naturally, which might take up to two years. Any attempt at recovering the oil might damage the food chain. Some of the slick drifts through the heads into Lyttelton Harbour, and becomes the Lyttelton Harbour Board’s problem. It sends out the pilot cutter, fitted with a machine to spray detergent on the oil. But Captain Jim Partington, the deputy harbourmaster, says the board could not cope with a big spill by itself. It would have to call on the Marine Division for help. Judging by what has happened at Lyttelton in the past, Captain Partington thinks a big spill highly unlikely. The worst danger is from ships illegally pumping out their bilges in the harbour, or from a pumping mistake. Bulk oil is pumped ashore through discharging arms, and spillage is unlikely. “There’s more chance of a spill from a ship that’s bunkering at the oil wharf,” Captain Partington says; “The oil coming aboard through a. line can overflow through an air vent on .to the deck if they are not careful.”

Lyttelton also has frequent visits from Persian Gulf tankers which make Lyttelton their first port of call after sailing round the bottom of the South Island. Lyttelton’s deep draft (37ft) enables tankers to discharge 6000 tons or so of oil to lighten them enough so that they can use shallower North Island ports. But Captain Partington says their cargoes are usually petrol, not crude oil.

Captain Johnson of the Marine Division keeps up to date with the latest news on oil pollution through the weekly oil spill intelligence report issued by the American Centre for Short-lived Phenomena.

Much new equipment has been developed in the. wake of major oil spills overseas, and Captain Johnson is contantly evaluating it. He is cautious, however, because different equipment is needed for different conditions.

Sawdust, for example, was used to mop up oil on the French coast after the Amoco Cadiz disaster. The sawdust mopped up the oil, but then they had no way of getting the oily sawdust off the water, and the pollution problem remained.

Evaluating and buying new equipment and materials, and training people to deal with oil pollution, costs a lot of money, but it is not a direct charge on the taxpayer. All shipping pays a levy (recently increased by 20 per cent) which goes into an oil pollution fund. This produces about $500,000 a year, and is designed to cover the' cost of clean-up operations if a spill occurs.