Only a quarter of a gasoline spill at a fuel depot in St George’s has been recovered seven months after the incident, government environmental watchdogs said today.

And traces of the leak have spread outside the Rubis site where the accident happened in March.

A government spokeswoman said: “Some of the more water-soluble components of the gasoline — that is dissolved plume — that have leached into the groundwater and are now dissolved within the groundwater show a slightly larger spread to just outside of the Rubis site area.”

But the Department of Environment and Natural Resources said the concentrations were “well within Bermuda’s standards and are generally demonstrating a downward change in concentration over time as the cleanup continues”.

One home nearest to the fuel depot has been provided with clean water for its swimming pool and toilets.

The department also downsized the extent of the spill.

It was feared 19,300 US gallons had leaked, but government today said the figure was 17,200 US gallons.

Experts said that bacteria in the ground and groundwater was expected to break down components of the gas and reduce the volume of contaminants further.

Rubis and Arcadis — brought in to help with cleanup efforts — have been “closely following” government guidelines on pollution clean-ups.

The department added: “These guidelines address the recovery of the spilt gasoline from the ground, monitoring the extent and level of pollution and reporting the information to the department at the level of detail and frequency that is stated in the guidelines.

A vapour extraction system is also working around the clock to clear away gas vapours using six monitoring wells.

The department added: “The vapour plume monitoring continues with twice daily measurements from 12 on-site wells and daily measurements from two off-site monitoring wells. The groundwater plume is also monitored monthly.”

The department said in April that notification of the leak “was late by approximately 24 hours according to the conditions of the operating licence under the Clean Air Act 1991”.

A spokeswoman said: “The department will address this reporting non-compliance in due course.”