Rich Lister Shirley Costa – widow of the late fruit and veg king Frank Costa – has joined forces with developer James Dibble on plans to build nearly 10,000 housing lots as part of new $7.5 billion master-planned mini-city about an hour’s drive from Adelaide.

Costa Property Group, the family office of Ms Costa and Mr Dibble’s Grange Developments have snapped up a 909ha site within the proposed 1860-hectare Gifford Hill precinct near the rural town of Murray Bridge.