All workers heading out to the rig are required to undergo a breath alcohol test by transporter HNZ Global before they are helicoptered out.
At 9.33am Foster had an initial test and it detected alcohol.
At 9.35am he had his first screening test and it recorded 80mcg/L (micrograms per litre of breath).
Under HNZ's procedure that result would not stop a worker from boarding a flight out to the rig.
However, the person who tested Foster said he "smelt strongly of alcohol" and HNZ was asked to take another test.
Foster gave written consent for HNZ to perform a confirmation test (the third test) and this was taken at 9.55am.
The confirmation test gave an error reading and the machine was turned off. It then gave a reading of 110mcg/L.
Another machine was produced and it too gave a reading of 110mcg/L.
At 10.15am, a fifth test was undertaken by HNZ and recorded Foster's breath alcohol content as 70mcg/L.
He was told to "suit up" and get ready to travel out to the rig but shortly after that was informed he was not permitted to board.
He was then told The Drug Detection Agency (TDDA) would be arriving to take further tests.
At 11.07am TDDA performed an initial test which returned a 20mcg/L reading.
At 11.32am another test recorded a zero or "negative" result.
Despite the other results Modec chose to consider only the failed 110mcg/L reading.
After a series of meetings, Foster was dismissed on one month's notice for breaching Modec's zero-tolerance safety policies.
Foster said the dismissal was "substantively and procedurally unjustified" and sought reinstatement, compensation, lost wages and costs through the ERA.
His personal grievance claim alleged the confirmation test that Modec used to dismiss him should not have been taken according to Modec's own policy.
Foster said he had already passed the screening test at 9.35am with a reading of 80mcg/L.
Modec said Foster consented to this additional test but acknowledged there was some ambiguity regarding alcohol threshold levels.
On one hand Modec said anything that exceeded zero was prohibited but then defined a positive breath alcohol test in a safety-sensitive area as over 100mcg/L.
The ERA said a fair and reasonable employer could not impose a testing regime
with a corresponding sanction without first ensuring the standard is clear and certain.
Foster also questioned why under HNZ's testing regime his breath alcohol level had increased from 80mcg/L to 110mcg/L.
The ERA said there was no suggestion Foster consumed alcohol at the heliport and there was no explanation given as to why the level rose from 80mcg/L to 110mcg/L.
A 27 per cent increase in breath alcohol over a 20 minute period, particularly 12 hours after the event, was considerable the ERA said.
"I am not satisfied Modec obtained sufficient information as to whether the increase in Mr Foster's test results reflected an increasing impact of the effects of alcohol or some other physical response."
The ERA said that omission brought into question whether the confirmation test results in the circumstances they were taken were a reliable indicator of impairment.
The ERA found Modec should not have relied on the confirmation test result(s) of 110mcg/L because the results were obtained in breach of its procedure standards.
Despite calling on TDDA to do further tests, Modec did not treat the lower specialist results as conclusive and instead went with HNZ's test results.
"An employer is expected to act in accordance with its policies and a failure to do so is not the action of a fair and reasonable employer in all the circumstances," the ERA found.
Foster said he suffered hurt and humiliation at having to tell his daughter he could no longer afford to help her with accommodation costs when she was at university.
He also said his wife was distressed by the dismissal and felt some responsibility for the alcohol they shared on the Sunday night.
The ERA awarded Foster $21,505.13 in lost wages and $14,000 for hurt and humiliation.
