Chevron New Zealand - the marketing company behind Caltex - tried unsuccessfully to find operators willing to replace the Cromwell site's underground tanks.
The tanks are more than 15 years old.
Chevron spokeswomen Sharon Buckland, of Auckland, said it was company policy for tanks to be replaced every 15 or so years, to ensure soil was not contaminated.
Ms Buckland said the existing operators of Cromwell's Caltex service station were given the opportunity to purchase new tanks, but declined.
Other potential operators approached by Chevron also declined, she said.
"The retailer doesn't think the demand is there to justify the cost of retanking, and we can't interest anyone else in doing it either," she said.
Ms Buckland said Chevron would not pay for replacement tanks, although it owned the land and building at Cromwell.
"The retail business has to support its own tanks," she said.
Ms Buckland said the tanks would be removed from the site as soon as a crew was able to do so, following the last day of operation on Friday.
Soil from the site would be tested, and removed if found to be contaminated.
"It's quite likely there will be some seepage after that length of time and, if soil is contaminated, we lift it out and take it away for safe disposal," she said.
Once the site was free of any contamination, it would be reinstated and sold, Ms Buckland said.
When contacted by the Otago Daily Times yesterday, existing co-operator Kaye Hancock, of Alexandra, referred comment to Chevron business manager Kevin Smith, who referred comment to Ms Buckland.
