Two months after Housing South Australia said it would prioritise a relocation of Adelaide southern suburbs residents from a contamination zone, just one public housing tenant has moved out.
The government agency said eight tenants had opted to move away from Clovelly Park, but it was still negotiating with the residents of a further 14 properties.
About 1,400 residents and businesses in that suburb and neighbouring Mitchell Park had been told their properties were in a wider testing zone for the chemical trichloroethylene (TCE).
Drilling was to start on Wednesday as part of testing to establish the extent of soil and groundwater contamination in the area, the site of the former Mitsubishi car manufacturing plant and car parts maker Monroe.
Concerning levels of the industrial solvent detected in soil and air in three streets in Clovelly Park prompted a recommendation that about 30 public housing tenants move away.
Environment Protection Authority (EPA) manager Richard McLachlan said the testing would try to trace the source of TCE vapour and involve drilling 137 holes across the area.
"It's actually looking at houses in particular which we've got data already for and really trying to understand where the vapour is coming from, whether it's actually from the groundwater or whether it's actually from other sources from the soil," he said.
Clovelly Park and Mitchell Park have also experienced a 10 per cent drop in property values due to contaminated groundwater.