Sonya Rockhouse's desire to fulfil a promise to killed son remains strong despite a delay to the re-entry of the Pike River mine drift.
Families had been eagerly awaiting Friday's scheduled entry, more than eight years after 29 men died in an explosion at the West Coast coal mine and since Minister Andrew Little confirmed in November an attempt would be made.
However, plans were suspended on Thursday when oxygen levels, which cause a fire, were detected in the mine during testing. A "tube fault" has been blamed, with one possibility being that a wild animal, such as a goat or possum, chewed on it. A ceremony at the mine still went ahead with the families group on Friday, with Little and Prime Minister Jacinda Ardern present.
Rockhouse's son Ben was among the victims, while another son, Daniel, survived the deadly blast.
Re-entry was close despite the delay, she believed. She had been unable to sleep for weeks thinking about it.
"On the 19th November 2010 my heart was ripped out. My middle and youngest sons went up the tunnel and only one came home. My youngest son, Ben, is still in the mine.
"I've promised him every day I will come for him and today [Friday] we are starting to fulfil this promise."
He would be running new tubes into the borehole to get new samples. A 3 per cent oxygen level was detected at bore hole 51, directly above the roof fall at 2.3km up the tunnel, on Wednesday
Agency chief operating officer Dinghy Pattinson said possible causes for the presence of oxygen at bore hole 51, directly above the roof fall at 2.3km up the tunnel, were cracks at the borehole or a leaking tube.
The gas monitoring tubes run from an office block, over the mountain, 4.5km through the bush and down the borehole.
Pattinson ruled out fresh air entering the tunnel at the portal. New tubes had been run and oxygen was not detected.
"I am confident that it is a tube fault," Pattinson said.
Testing would continue until any decision was made to re-enter, but he could not put a date on when that might be. He reiterated health and safety would not be compromised.
Rockhouse thanked late union leader Helen Kelly, who encouraged the families to seek a judicial review into the decision by WorkSafe to drop charges against mine boss Peter Whittall.
"We won with the court finding the decision made by WorkSafe unlawful," she said.
Kelly died in October 2016, before the final judgment.
She also thanked her "wee mate" Anna Osborne, who decided to block the mine access road in November to prevent the permanent sealing of the mine in November 2016. Osborne's husband Milton was among the victims.