Race to get the oil using Archimedean screw pump New Zealand
TAURANGA A salvage crew back on the grounded Rena aims to remove the bulk of the fuel oil off the container ship over the next few days.
Heavy fuel recovery machinery will be lifted onto the platforms attached to the Rena today and an Archimedean screw pump will be inserted into the tank to extract the oil.
The cold oil has hardened to the consistency of Marmite, which is why the special type of screw pump is needed to get the oil out.
The Archimedean screw pump is normally used in the waste water industry to pump sewage that is full of solids mixed with the water.
Archimedes screw pumps are usually open from the top when used on land these would not be the case in these situation under water.
The Archimedean screw will have to be enclosed screw pump to stop the oil from escaping or leaking in the water,
I presume as I have not seen any images of the special Archimedean screw pump being used in the extraction of the oil
The six-strong crew were to resume pumping oil this morning after four small platforms were attached to the side of the stricken vessel.
The crew, operating from the platforms near the edge of the deck and using an Archimedes screw pump, will first work on the rear portside tank and hope to move 770 tonnes the bulk of the heavy fuel oil still on the ship to the waiting barge Awanuia.
‘‘If the weather stays fine, we will transfer the oil how long it takes, I don’t know,’’ said Bruce Anderson, Maritime New Zealand salvage unit manager.
‘‘We have to take it slowly and make sure things are set up properly.’’
The vessel’s power was off and the fuel was no longer hot it was a cold density like Marmite, and it had to be sucked from the tank into hoses attached to the Awanuia.
So far, 350 tonnes of the 1700 tonnes on board the Rena has escaped creating widespread pollution and distress along Western Bay beaches. Experts said the ship was relatively stable on the Astrolabe reef; however the structure of the ship was compromised.
Andrew Berry, of the Marine Pollution Response Service, said the two cracks on either side of the ship had joined, and there was now a large crack underneath the ship’s hull.
‘‘The ship is holding itself on the reef by its internal structure,’’ he said.
It was believed there were still 1346 tonnes of oil on board the vessel 770 tonnes in the port 5 tanks, 356 tonnes in the starboard 5 tank, which was under water and 220 tonnes in two settling tanks near the engine room.
Mr Anderson said thermal imaging had made ‘‘us confident that the oil is still in the tanks, and there has been no rupture to the one under water’’.
Six local tradesmen, four from Mount Maunganui Engineering and two from Tauranga Engineering Industries, worked through Thursday night to build the steel platforms, the size of a standard office desk.
The salvage crew, in full immersion suits and attached to a safety harness, will operate different pieces of equipment on each platform that has a handrail.
Mr Anderson said the Rena was sitting ‘‘quite nicely’’ on the Astrolabe Reef and it was becoming less likely that it would break up.
But if the rear part of the ship did split up, there was every chance that section could rest on the reef and ‘‘that’s good news for us’’ he said.
‘‘Once we got the fuel out, we will start working on (removing) the containers.’’
Mr Anderson said a light sheen hung around the Rena yesterday.
‘‘It’s not a large amount of oil. We think oil accumulated around the containers in the hold of the forward section or it came from the keel duct.’’
He said the Awanuia yesterday undertook a whole range of rehearsals
to remove the oil finding out how close it could get to the Rena and what the appropriate safety margins were.
‘‘It’s still a dangerous situation and we have to take precautionary measures,’’ Mr Anderson said.
MNZ said salvage company Svitzer was responsible for collecting the containers in the water.
Svitzer have reported they have identified 35 of the 88 that have fallen overboard.
A further 14 containers have been recovered.
So far a total of 376 tonnes of waste have been removed. Waste is then being trucked to Hamilton for safe disposal.
The waste is being collected by two companies working through a consented waste management plan. Potentially toxic waste from the containers is also being disposed of through the consented waste management process.
Because of the change in wind, training was being co-ordinated for teams based in the Eastern Bay of Plenty.
This would ensure the response is ready for oil grounding there, national on-scene commander Nick Quinn said.
Beach access is restricted between Mount Maunganui and Maketu Point, including the Maketu Estuary.
This is to minimise, as much as possible, further environmental damage.
Booms have also been put in place in Waipu Bay and Waikareao Estuary.
The Waipu Bay boom extends across the mouth of the inner harbour from the boat ramp to the Tauranga Bridge marina.
There are two booms in place in Waikareao Estuary near the Tauranga underwater club.
The booms are bright orange and will be visible during daylight hours.
People are also advised not to eat fin fish, shellfish or whitebait from affected areas, including the harbour.
Health warnings are being issued to prepare residents for worsening smells from the oil.
MNZ said the oil spillage on the beaches, combined with the current weather conditions, had produced a noticeable smell in some areas.
This smell is likely to diminish over a period of one or two hours from the time the oil reaches the beach.
Race to get the oil using Archimedean screw pump New Zealand
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