Drilling of 137 bore holes has commenced in the Clovelly Park and Mitchell Park contamination zone today.
However, Shadow Environment Minister, Michelle Lensink, has expressed concerns over a number of cost and time blow-outs with the drilling.
Environment Minister Ian Hunter told a Parliamentary Estimates Committee in July that the testing regime would cost $668,000.
"The cost of the drilling has now blown out by $500,000 more than the original estimate and results of the testing will now not be known until December, despite residents first being told that results would be known in October," said Ms Lensink.
"Almost two months after residents were told that they would be evacuated, only one resident has been moved.
"This is just another unacceptable delay for the residents of Clovelly Park, who have experienced enough trauma already.
"Environment Minister Hunter must now tell residents why these delays and blow-outs have occurred.
"We have seen the Weatherill Labor Government mismanage this contamination issue from the very beginning.
"Sadly for local residents, it looks like this mismanagement is continuing.
"The Weatherill Labor Government needs to lift its game – residents of Clovelly Park and Mitchell Park deserve better."