Steven Albert Blance was at the centre of a drug ring estimated to be dealing 1kg of methamphetamine a week in the north Wellington suburb of Tawa. (File photo)

​A senior Porirua Mongrel Mob member who dealt millions of dollars worth of methamphetamine has been jailed for 14 years and six months.

Steven Albert Blance, 48, was sentenced at the High Court in Wellington on Friday.

Blance ran a sophisticated operation from his fortified Housing NZ flat, sent up a drone to watch over the area, put a surveillance camera in trees, and had an electronic beam sensor on a carpad to alert him to visitors to his flat in Linden, a northern suburb of Wellington.

STUFF William Allan Berkland was sentenced on charges including dealing in methamphetamine. (File photo)

Over six months 15kg of methamphetamine went into the Tawa and Porirua community causing incalculable harm, prosecutor Emma Light said.

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Blance pleaded guilty to charges of supplying methamphetamine, having the drug for supply, conspiring to supply, possession of weapons and ammunition, and receiving a stolen Harley-Davidson motorcycle.

SUPPLIED/NZ POLICE Some of the cash found in the police raid at the end of their surveillance operation. (File photo)

He has to serve at least seven years and three months of the sentence of 14 years and six months' jail before he can be considered for parole.

William Allan Berkland, 46, sat just below Blance in the hierarchy of the drug operation. The judge said he accepted the description of Berkland as Blance's "right hand man".

Berkland was sentenced to 13 years and three months' jail and has to serve at least six years and three months before he is eligible for parole.

SUPPLIED/NZ POLICE Some of the $511,000 that was seized. (File photo)

Berkland pleaded guilty to charges of supplying methamphetamine, having the drug for supply and offering to supply it, conspiring to deal it, and also dealing the class B drug NBOMe, growing cannabis, having diazepam for supply, and having weapons and ammunition.

Justice David Collins said the Crown's case was that even more than 15 kg was dealt but sentencing proceeded on the identified amount.

When police raided properties linked to the investigation they found about 3kg of the drug which was tested and found to be 76 per cent pure, just under the 80 per cent possible highest purity, the judge said. Police also found $511,000 cash.

NZ POLICE One of the weapons seized in a massive raid in Porirua and Tawa on April 11, 2017.

Blance and Berkland both lived in Housing New Zealand flats a short walk from each other in Linden, which borders the suburb of Tawa.

It was estimated the pair supplied about 1kg of methamphetamine a week, bought in bulk from Auckland suppliers, the judge said.

Between October 2016 and April 2017 at least 15kg of methamphetamine was bought for $5.25 million. That amount netted at least $1.5m profit.

Hundreds of customers visited day and night to buy methamphetamine. Between February 20 and April 11, 2017, police recorded 700 visitors to Blance's flat.

Blance's lawyer, Liz Hall, said Blance was in bad health and had cognitive problems because of a traumatic head injury. He had done a lot of good helping others, and it had not all been about the drugs, she said.

Berkland's lawyer, Christopher Stevenson, said Berkland was a committed father, with relatively little criminal record. He held down jobs but after a series of unspecified unfortunate events, he lost hope and turned to using, and then dealing, methamphetamine.

Both men had a rousing farewell as they left the court to begin their sentences.

Detective Senior Sergeant Tim Leitch, head of the Wellington drugs and organised crime unit, was also at court for the sentencing. He said afterwards that the terms reflected the harm the two men had inflicted on the wider Porirua community.

"Steven Blance was recorded saying,'If they paid me $5000 a week I'd be happy and I wouldn't have to sell crack'."

"This short sentence perhaps best illustrates his level of arrogance and sense of self entitlement," Leitch said.

It had been an extremely challenging investigation but they collected powerful evidence that left the two with no option but to plead guilty.

"These offenders are career criminals who had little regard whatsoever for the harm they were causing in the community as they sold a kilogram, or $600,000 of methamphetamine, each and every week," Leitch said.