Months after a Napier wastewater pipe was damaged, contractors working to repair the problem are back at square one.

The pipe, belonging to Pan Pac Forest Products, was first flagged by a resident in September, who reported discolouration near the water's edge at Whirinaki Beach.

It was found to be seepage of treated wastewater from Pan Pac's wastewater treatment plant.

At that time, the Pan Pac Forest Products managing director, Doug Ducker, advised residents in a letter that a section of pipeline "has sustained some form of damage or deterioration with small amounts of wastewater escaping".

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It was occurring about 70 metres from Whirinaki Beach Rd rather than the usual 2.4 kilometres.

Towards the end of December, work on the pipe was expected to be completed "within the next few days" meaning early this month.

However, Hawke's Bay Regional Council group manager regulation Liz Lambert said she was advised on Thursday by Pan Pac that its first solution had failed, and it was now trying a different option.

She said the location of the pipe, both being in a "very active coastal area" as well as being buried underground had contributed to the delays.

"They have been working right from the time it started, but sometimes just the physical location of some of these pieces of infrastructure means that it is more difficult and it does take more time because you need more specialist equipment and materials."

They initially went about sealing the breakage from the inside, by "pouring concrete", but weather and sea conditions prevented the work for some time.

Despite eventually being able to get in, it ultimately did not work.

"Their approach now is they are going to look to insert a sleeve inside the pipe to seal it from inside," Lambert said.

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Lambert said they have been kept "fully informed" through out the process.

"Right from when the leakage was detected by Pan Pac, they let us know and one of our compliance officers has been liaising with them the whole time."

The mill began operating in 1973, at which time it had a short outfall pipe into the ocean and in 2017 the discharge pipeline was extended from 300m to 2.4km.

Lambert said they estimated it was between 2 and 5 per cent of the actual discharge that was leaking out.

"It is not a significant environmental risk but it doesn't look good because of the discolouration which is caused by the product in the discharge.

"They have fenced off either side of the pipe and put up warning signs."

The cost of the repairs were being met by Pan Pac, Lambert said.

Pan Pac's Ducker said there was frustration, from others and himself, about the time it has taken for them to find a solution. He asked for "tolerance" for a little while longer.

He said it was a very "complex" issue as the pipe was underwater at all times and required divers to gain access in near to no visibility.

He said investigative work for the latest option is currently being progressed. They hope this "semi-permenant" option will be completed within the next three months, but were hesitant in providing a fixed date.

However, Ducker said the "most likely outcome" will be that in the "medium to longer term look to affect a full replacement of that old section of pipeline given that it is now 47-years old".

"That would be a matter of putting a new pipeline out from the mill site to where the pipeline was fitted back in the end of 2017 (500m)."

He said the effulent is "fully treated to specification" and there was no reason for concerns from any party that they were discharging in a way they shouldn't.