Later in the day Pampoukidis said he saw Wiremu smoking a joint and saw an empty packet of synthetic cannabis on the ground.
Pampoukidis said that he watched Wiremu walking down the road on the site and he was "swaying from left to right, walking real slow and did not look healthy to be on site."
Wiremu sat in the middle of the road and Pampoukidis said he heard Wiremu say he was "being a cone" and he was "mumbling and being vague."
Assistant project manager Sasha Phillips was called and Wiremu was stood down. She told him he was being dismissed under the 90-day trial period in his individual agreement.
However, the ERA found there was no valid 90-day trial period agreement in the contract Wiremu had signed.
The company conceded there had been no valid clause in the contract, but requested the ERA waived any remedies awarded to Wiremu because he had smoked synthetic cannabis on the job.
Wiremu maintained throughout the employment process he had not smoked any cannabis, synthetic or natural, while at work.
He said he had been seen holding a cigarette, not a joint, and he never saw any packet of synthetic cannabis on the site.
The company also sought a penalty against Wiremu at the ERA because he had breached his employment agreement by not taking responsibility for his safety on the site when he sat in the middle of the road.
David Appleton, Member of the Authority, said there had been no proper investigation into Pampoukidis' claim by the company, and there had been no written statements taken.
Phillips told the ERA she was relying on the 90-day trial period she believed was part of the employment agreement when she dismissed Wiremu. If she had been aware there was no such trial period in his contract she would have investigated the claim he had smoked synthetic cannabis further and asked for a drug test. Wiremu was therefore unjustifiably dismissed.
The ERA found he had lost earnings of $5,140 because of the unjustified dismissal and awarded him $2500 for his distress.
However, Wiremu's evidence at the ERA was deemed not credible, flippant and deliberately evasive. Appleton said on the balance of probabilities Wiremu had been smoking synthetic cannabis on site and therefore reduced the lost wages and compensation by 75 per cent, awarding Wiremu a final total of $1910.
View the decision from the ERA here: