24 February 2015 Last updated at 14:27 GMT
Animal experts say the creatures, who look like giant seals and are known as sea cows, went into the pipe seeking warmth before getting trapped.
The rescue operation took the whole of Monday night.
All mammals, including a mother and her baby calf were eventually pulled from the pipe and are safe and well.

Richard Ratcliffe's wife, Nazanin Zaghari-Ratcliffe, was arrested in April while visiting family with their two-year-old daughter and is accused of seeking to "overthrow the regime".
Mr Ratcliffe has asked David Cameron to help, and says the Foreign Office is doing more "as this gets more serious".
His daughter is with family in Iran.
Mrs Zaghari-Ratcliffe, 37, of north London, works for the London-based Thomson Reuters Foundation charity.
She travelled to Iran on an Iranian passport with daughter Gabriella and was arrested at Tehran's Imam Khomeini Airport on 3 April and taken to Kerman in the south-east of the country.
Her family had expected her to be released last week, but a statement from the Islamic Revolutionary Guard Corps now claims she heads a "foreign-linked hostile network".
Mr Ratcliffe, who has been trying to get a visa to visit his wife, told BBC Radio 4 she had spent 45 days in solitary confinement and this had made her "very weak".
"When she came out she wasn't able to walk without blackouts and she had a problem with her hair falling out and she'd lost quite a lot of weight," he said.
Her condition improved during a spell living alongside other inmates and she was then told she would be released, Mr Ratcliffe said.
Mrs Zaghari-Ratcliffe left Kerman prison on 5 June but, instead of being released, her parents were told she was being moved to a different prison.
Mr Ratcliffe said the family then heard "nothing from her for a number of days", adding: "Last week we celebrated Gabriella's birthday and we had no idea where she was."
On Monday Mrs Zaghari-Ratcliffe called her parents to say she was in a prison in Tehran - and Mr Ratcliffe believes that may help her.
"Now she's in Tehran then, if nothing else, the Iranian authorities can look more seriously at what's going on and look at these crazy theories coming out from the provincial office," he said.
He said the reasons for the accusations against his wife were "not at all clear", but he believed they came from the Kerman branch of Iran's Revolutionary Guard - and in part they might be "justifying that they've held her for 70 days".
He said the accusations were not detailed but they suggested his wife was "in charge of this great network of media organisations and espionage agencies and that she and Gabriella are there running the whole thing".
He added: "It feels this is wrapped up in Iranian politics and different factions fighting and holding her as some sort of bargaining chip."
The Foreign Office said it was urgently seeking information on Mrs Zaghari-Ratcliffe's situation.
More than a dozen manatees who got stuck in a pipe in Florida have been rescued by firefighters.
[NEXT_CONCEPT]
The husband of a British-Iranian woman in jail in Iran says he hopes "senior intervention" from UK and Iranian authorities will lead to her release.