It applied to the Otago Regional Council for renewal of its consent to discharge up to 3000cu m a day, about 200m downstream of the confluence with the Manuherikia River. Submissions close on Friday, May 29.
The district council's permit for 10 years expired at the start of this month. It is seeking the maximum term for its renewed permit.
The council's utility services manager, Peter Greenwood, said the council planned to install an ultraviolet treatment plant to further treat the wastewater before it was discharged.
"Although the faecal coliform count samples taken from the river now are well within water quality guidelines, UV treatment of the effluent will just add another level of extra treatment," Mr Greenwood said.
The council's long-term council community plan indicated it would spend more than $1 million on the UV treatment plant in the next two years.
Mr Greenwood said several of the council's discharge permits were up for renewal now, or had just been granted for further terms.
"What we've had to do is allow for growth, to look long term and ensure that we cater for growth 20 and 30 years into the future."
The report prepared by Simon Beale, of MWH New Zealand for the council's Alexandra application said the existing form of treatment was considered to be performing well and mostly complying with effluent quality and water quality standards.
Biological monitoring of the river in 2005 near the wastewater outfall concluded the discharge from the treatment plant at the time was having no measurable adverse effects on riverbed organisms, Mr Beale said.
