However, the approval again proved to be a contentious decision, with some councillors pushing for council to conduct its own independent economic study and a social impact study before making a decision.

Councillor Sara Murray said she wanted council to commission an independent economic study before any decision was made, as she was concerned not enough information had been provided to councillors on the development.

Cr Murray said she felt not enough was known about what sort of impact the development would have on Mittagong's surrounding towns, and whether the development at Mittagong it would alter Bowral's council-designated position as the retail centre of the Southern Highlands.

She said the Big W development would be the biggest development to come to council in the next 20 years, and she didn't want council to be "glib" in approving the development. Councillors' Larry Whipper and Jim Clark echoed similar concerns, with Cr Whipper also calling for a social impact study.

Cr Clark was suspicious about why his fellow councillors didn't want an economic study to take place, saying council needed to "do all our homework and make sure we make the right decision".