During a drivers' meeting in August he was asked whether he could complete work that involved wading in sea water, and replied that water would damage his prosthetic leg, which would be expensive to replace.
Two weeks before being made redundant, he was told the work he had been employed for had dropped off.
However he saw Sepclean were advertising for a full-time driver for the same type of work.
On September 19 Mr Connell's employment was terminated.
Director Victoria Reid said he was dismissed because the company lost the contract for the sludge run he was working on.
Ms Reid said she considered whether Mr Connell could be redeployed to other work but felt his disability limited him too much. But another employee gave evidence that he was capable of doing other work, saying: "I worked with Ronan on a number of jobs which involved climbing ladders, going into ship's holds, changing of hoses on trucks and even emptying a septic tank ... Ronan was a hard worker and was able to complete any task I could do."
Evidence was given that losing his job caused Mr Connell to become depressed and short-tempered and drink too much.
The determination said he was "visibly upset and emotionally affected", and that he had suffered severe humiliation and loss of dignity.
The authority found the dismissal was not justifiable and that he was discriminated against on the basis of his disability, by not being considered for redeployment.
Because Mr Connell had undertaken casual work with Sepclean before signing an employment agreement, he had previously been employed by the company, and a 90-day probation could not apply.
The law also does not prevent an employee taking a grievance on the basis of discrimination during a 90-day trial.
Sepclean was ordered to pay $10,000 compensation, $2460 in lost wages and $528 in unpaid notice.
The company has branches in Nelson, Tasman, Canterbury and Marlborough.
