GREENS MP and environment spokeswoman Cate Faehrmann said she still had concerns that radioactive waste would end up at the Kemps Creek waste facility despite assurance from its operator.
During her visit at the SITA facility last week, Ms Faehrmann said she was told by SITA personnel that measures had been taken to detect radioactive waste that should not be taken to the site.
She added that the state government stated any waste over a radioactive threshold would be sent to a facility at Lidcombe.
However, she conceded she still had many unanswered questions about the storage of waste at Kemps Creek.
In September, the Champion reported that Premier Barry O'Farrell reneged on his 2010 promise to not make Sydney's south-west a dumping ground for the wealthier suburbs.
The government has assigned 5000 tonnes of "reclassified radioactive waste" from the old Hunters Hill uranium smelter to be dumped at the Elizabeth Drive facility.
This decision was made despite a feasibility review by Parsons Brinckerhoff that stated radioactive material was detected at varying concentrations across the Hunters Hill site, with one of the samples exceeding the level for restricted solid waste.
Opposition environment spokesman Luke Foley said the feasibility reportinto disposal options for the waste showed the government manipulated the data to avoid it being classified as radioactive.
In addition to the waste being stored locally, Mr Foley said the report also stated that a management and monitoring plan would need to be funded and implemented at the dumping site for the next 300 years.
Ms Faehrmann said: "I am also concerned that levels of radioactivity will be disguised by averaging out the levels of radioactivity across the soil, so I have requested additional information in this regard. I will continue to keep a very close eye on this situation."