The notices, which include three prohibition notices and one improvement notice, relate to the storage and treatment of flammable materials on the site as well as an incident involving a small fire during a refuelling activity.

The incident comes after the CFMEU notified WorkSafe of unsupported three metre deep excavation which had been discovered by the construction union during a site visit to the project in August. The safety breach occurred three months after another unsupported shallow trench collapsed onto a worker's legs after heavy rain in May.

The fire incident related to the ignition of fuel vapours as a generator was filled with petrol in close proximity to where grinding of a metal track weld was occurring. A small fire was quickly extinguished and there were no injuries to workers on the site.

Infringements totaling more than $14,000 was also issued to a subcontractor and the principal contractor involved on the project.

WorkSafe ACT said due to poor operational and site set up issues. Multiple types of flammable substances were being stored in the area of the welding areas in an "inappropriate manner".

Two of the prohibition notices have since been lifted following appropriate remediation action.

Work Safety commissioner Greg Jones said safety on the light rail project remained a key focus of WorkSafe ACT. He said the presence of inspectors would continue to increase on site. Three additional inspectors will start to support the project later this year.

"This is a project which is not only of great prominence but also complexity and safety must remain the overarching consideration of workers and project officers working on this project," he said.

"As we head into the busy end of year period my message to workers on this site, and others across the city, is not to rush to complete deadlines at the expense of safety.