Trucking company Crawfords Freightlines had been storing ammonium nitrate at Sandgate since 2009, when the state government called an environmental audit of various chemical sites after the August 2011 leak of hexavalent chromium from Orica’s Kooragang Island factory.

The audit found Crawfords had Workcover permits to store up to 13,500tonnes at a time of the material, which is used to make the explosive for open-cut coalmining.

But it lacked the Department of Planning approval needed to store more than 2000tonnes at a time.

 Crawfords was ordered to limit its Sandgate stockpiles to 2000tonnes, which it has done ever since by having much of its ammonium nitrate stored elsewhere.

 In February last year, Newcastle City Council gave the company a year to gain the necessary government approvals or stop storing chemicals at the site.

 In documents on display until March 11 with the planning department, Crawfords said it usually handled about 75,000tonnes a year, with 21,000tonnes shipped from overseas to Sydney, 36,000tonnes shipped to Newcastle and the rest ‘‘as required’’ bought from Orica Kooragang Island.

Resuming its previous method of operation would take 10 laden semi-trailers a day off Newcastle’s streets.

‘‘Historically, ammonium nitrate from the port of Sydney was placed on trains... and delivered three times per week,’’ the company said.

‘‘Currently ... [the 800-tonne train loads] are delivered by rail to alternative storage facilities operated by Toll Group [at Carrington and Tomago], and delivered by road to the [Sandgate] site when storage becomes available.’’

A spokesman for Crawfords said the company had complied with the restrictions since they were introduced, but the double-handling was expensive.

He said approving the facility would maintain the jobs of 65 people who worked from the site.