"You deliberately made a decision to consume alcohol to the extent that you would not be fit for work on 26 April 2017 when you were required to attend and be in a fit state to carry out your duties safely," the letter said.
In her response, Chapman said she did not "deliberately" make the decision to consume alcohol to the point where she would be unfit to attend work the next day.
"It was my BIRTHDAY, and friends dropped by unannounced," she wrote in an email to her employers. "I had my official birthday party on the Monday night and wasn't expecting visitors on Tuesday, however, visitors I got.
"As the afternoon went on I realised it was going to be a long night and I believe I acted responsibly and respectfully by contacting management to let them know I wouldn't be fit for work.
"Would it have been wiser for [me] to call at 6am on the 26th and plead illness? I think if I had done that then I wouldn't be writing this letter now, but it wouldn't have been the honest thing to do in my opinion.
"It was not my intention to deliberately take the day off, the events were not planned and not expected, and again, I feel that contacting management on the 25th was the right and responsible thing to do."
In a follow-up email she criticised "management's constant quest in turning molehills into mountains" and the "go in for the kill mentality" as "rather disturbing and completely against Tassal's moral code in my opinion".
In response, Tassal told Chapman that the company did "not consider your response set out above acts to mitigate your actions but rather alarmingly demonstrates to us that you take no accountability for your actions but rather look to place blame onto Tassal's management".
"It is clear from your responses that at 4.46pm on 25 April 2017 you made a decision that you would continue long into the night drinking rather than make sure you are fit for work to fulfil your duties the next day," the second letter said.
"How you can state you did nothing untoward or that it was not a deliberate decision to take 26 April 2017 off is astonishing and your reason 'because it's my birthday' is [neither] a reasonable conclusion [nor] acts to mitigate your actions."
In submissions to the FWC, Tassal also pointed out Chapman had a previous warning for similar conduct.
In December last year, she left a voicemail on the company's phone line at 8:33pm.
"Hello, it's Avril," she said. "Um ... I won't be at work today. I am non compos mentis, which means I'm f***in' s***faced. I just found out my brother's got advanced lung cancer and I'm a bit upset about it all yeah. Sorry."
In his decision, FWC deputy president David Barclay concluded that although there was a "valid reason for the dismissal", the termination was "harsh". "The case is not dissimilar to the situation of an employee 'taking a sickie' without being ill," he wrote.
"Here the applicant 'took a sickie' in circumstances where she had voluntarily embarked upon a course of conduct that resulted in incapacity for work. The situation is perhaps made worse by the applicant's acknowledgment that she could have gone to bed early and been fit for work the next day."
As reinstatement was determined to be "inappropriate", Tassal was ordered to pay Chapman compensation of $8229. The "harsh" conduct, according to the FWC, arose from Tassal "misusing" the prior warning as a reason to proceed to termination rather than a "less severe sanction".
