VICTRACK will start two months of environmental testing work at the Horsham rail yards and on Mill Street on Monday.
Contractor BlueSphere Environmental will drill and install bores and collect soil and groundwater samples from 7am to 6pm each day.
The work comes in response to an Environment Protection Authority notice that requires investigation into potential clean-up at the site.
VicTrack received a clean-up notice for contamination of land and groundwater due to hydrocarbon storage and distribution at the site.
Fuel was historically unloaded at the site into pipelines via rail tankers.
The environmental works will investigate how this has affected the land.
Roads in the area will remain open during the testing, which will run until November 24.
Traffic signs will be in place on Mill Street some days.
Residents in the vicinity of the works will receive a postal letter from VicTrack with more information.