Almost 800 odour reports have been made to Environmental Protection Authority by Brimbank and Melton residents this year.
An EPA spokesperson said there had been 776 reports this year until May 7.
Melton City Council said there had been 6600 objections over Boral’s expansion plans.
The EPA issued a Pollution Abatement Notice to Boral to complete remedial measures by May 12 to prevent offensive odours escaping beyond its boundaries.
It has investigated 16 times and undertaken 15 rounds of targeted odour surveillance since February 27.
A Pollution Abatement Notice was also issued on May 5 to Pinegro to modify its infrastructure, technology and management practices by July 9.
“We will continue to monitor these two operators and hold them to account on notice requirements, and we’ll track and report back to the community whether this results in a decrease in odour reporting,” EPA Manager Metro Richard Marks said.
He said callers may be required to swear an affidavit when reporting.
“This includes the time, duration, and location of where you were when you smelled the odour, the impact of the odour on you and your family, and correct contact details,” he said.
Residents can call the EPA Pollution Hotline on 1300 372 842.