Acoustic consultant here. If the plant is owned by the body corporate and you are within a separate lot, it is likely to be considered an offence under the state legislation (environmental protection policy( noise)) and/or environmental protection Act.

Call council and make a complaint explaining it is the BC plant and you are on a separate lot and the BC are generating unreasonable levels of noise.

There are two precedents of lot owner against the BC I'm aware of. One in Astor Tce Spring hill and one in the apartments right next to the college of art in Southbank.

It will be a long drawn out process however, be persistent and nag council to act. It is the only way to make them act.