Ongoing tests by Ampol following the oily water overflow at Kurnell in April have detected a carcinogen at levels slightly higher than the accepted threshold in three locations along Captain Cook Drive.
Ampol said it had reported and discussed the results with the Environment Protection Authority.
"We can confirm that there is very low health risk at the levels of Benzo(a)pyrene (BaP) detected," the company said in an update to the community.
"Additionally, BaP in soil won't cause harm if you do not come in direct contact with it and the affected areas were already covered or capped with soil as part of this remediation program.
"Capping with soil is a common, effective remediation approach.
"While detections of BaP are likely unrelated to the wastewater treatment plant overflow, and pose a very low health risk when capped, Ampol will revisit the locations to remove and replace BaP contaminated soil to ensure community peace of mind."
Ampol said, following the incident, a thorough round of water and soil sampling was undertaken in key public areas around Captain Cook Drive, Bridges Street, Marton Park and in the horse arena.
"These results were provided to the community on 19 April," the statement said.
"This initial sampling identified areas requiring remediation to remove impacted soils.
"Excavation of impacted soil is now progressing in 6 of 8 remediation work zones in public areas, with the remaining areas to commence over the coming weeks."
Ampol said, to ensure remediation was being delivered effectively, validation soil samples were being collected as excavation works were completed in accordance with EPA guidelines.
"A larger number of validation samples are being collected than required by these guidelines," the company said.
"This gives us a greater level of confidence in the success of the remediation.
"As the results of the validation sampling are returned, they are compared to the most relevant Australian health-based guidelines to understand if management or assessment of the site is needed in the future."
Ampol said 203 validation samples had been collected and assessed to date, with maps and summary tables of the results published on the company's website," the statement said.
"Soil samples taken to validate remediation zones are tested for groups of compounds that are known to be present in petroleum products, including diesel.
"For almost all these compounds, concentrations were below the health-based criteria.
"Given the high density of sampling, this outcome provides confidence in the quality of remediation work delivered to date."