People in Cambridge fear a new sewage works will create congestion chaos.
If approved, a new facility will be built on land between Fen Ditton and Horningsea, known as Honey Hill.
It will replace the existing plant in the north of Cambridge, to make room for 8000 new homes.
Anglian Water has said the relocation will not generate a significant impact on traffic in the area.
The proposals are currently being examined by the planning inspectorate.