Northern suburbs retailers fear plans by two rival national supermarket chains to set up shop within 1km of each other could threaten their survival.Plans to construct an Aldi supermarket in Woonona - next to the historic Bulli Court House and former Bulli Police Station buildings - have been unveiled only weeks after the proposal for a Woolworths supermarket at Bulli was placed on public exhibition.Comments on the Woolworths plan close on Friday, but so far only two submissions have been lodged, including one objection.They would be the first supermarkets in Woonona and Bulli and bring the number of supermarket proposals for the northern suburbs to four.A Coles supermarket was proposed in the Ambience complex at Fairy Meadow.That plan now appears uncertain after the Belmorgan company constructing the complex, SPV 7 Pty Ltd, was placed in the hands of a liquidator.A supermarket would also be part of Valad Property Group's proposed shopping centre in Corrimal, which is being assessed by Wollongong City Council. The development application for the two-storey Aldi supermarket and a retail shop at the corner of the Princes Hwy and Hopetoun St is on public exhibition until September 11.An existing car yard and two-storey Illawarra Retirement Trust building on the site will be demolished under the plan.The former Bulli Police Station and Bulli Court House, both of which have heritage status under Wollongong's Local Environmental Plan, are also part of the site and will be refurbished in the first stage of development.The owner of an historic Bulli business said some things should remain the same.''Personally, I think supermarkets rob towns of small businesses,'' he said.The operator of a Woonona fresh food business feared he would lose customers and believed most customers were swayed by price.''I don't think it will be good for the area. I would say long-term, a Woolworths or Aldi around here will flush out some of the little guys and make it harder for businesses.''Other businesses were more positive about the arrival of the big players.''I think it will be good for the community and will keep people in the town,'' Bruce Hawthorne, of Hawthornes Meats in Woonona, said.K&M Bakery owner Sharon Claridge agreed, saying: ''I don't think it will affect business or take our customers.''Aldi declined to comment on the proposal.