Three more parts of Sydney’s Rozelle Interchange project have been found to have been laid with mulch contaminated with bonded asbestos.

A traffic island a kilometre from Sydney’s Rozelle Parklands has become the latest place abestos-laden mulch has been discovered as authorities mull over the best way to clean up the mess.

The traffic light island at the far northern end of the Rozelle Interchange was identified late on Thursday, bringing to 17 the number of areas the contaminated material has been found scattered across the project area.

Two garden beds at the interchange’s operations centre in Rozelle were also found to have the bonded asbestos, the state transport authority said.

While low risk compared to friable asbestos, bonded asbestos can weaken and become potentially powderable as it ages and is exposed to the elements.

Authorities meanwhile are working through plans to remediate the ever-expanding exposure zone more than a fortnight since the alarm was first raised.

It emerged on Thursday concerns about the safety of the 10-hectare Rozelle Parkland, opened in December, were raised by a member of the public more than a week before it was closed.

Park operator Transport for NSW said the department became aware of the potential for contamination at the park on January 8 following an email to a general project inbox.

A spokesperson blamed minimal staffing over Christmas for the email not reaching the appropriate team until January 8 “when it was immediately actioned and the member of the public was contacted directly”.

Investigations began the next day with material taken for testing revealing asbestos in a landscaped area near a children’s playground.

The park was closed on January 10, and the local council and the public were informed later that morning.

In the week since, more than 110 samples of mulch in areas both accessible and inaccessible to the public have been tested, returning 17 results including the traffic light island at Victoria Road and Terry Street.

The area, near Iron Cove Bridge, has been fenced off from the public.

Further finds could be possible with the state transport authority continuing to test all areas associated with the interchange.

Project contractor John Holland CPB Joint Venture is due to deliver a draft remediation plan to the government imminently.

Transport for NSW said it would “work through” the plan to ensure it aligns with a clean-up notice issued by the NSW Environment Protection Authority.

That plan will be shared publicly once finalised.

-AAP