The province has again ordered the owners of a Gas Plus station in Bowness to clean up a leak from nearly two years ago. (CBC)

The province is once again ordering a clean-up of a contaminated gas station near the Bow River in northwest Calgary.

Nearly two years ago 9,000 litres of gasoline leaked from the Gas Plus station at 6336 Bowness Rd. N.W. , seeping into the ground.

The province issued an Environmental Protection Order against the business’s owners in December 2010, requiring the owners to dig up the site and remove soil contaminated with hydrocarbons.

But Gas Plus Inc. and Handel Transport appealed, claiming the order was biased and based on faulty science.

According to an order issued by Alberta Environment and Water Minister Diana McQueen on Thursday, the gas station’s owners must now confirm the location of all contaminated material and remove it within four months.

Early last year, three families living nearby were told by Alberta Health Services to leave their homes temporarily after air testing revealed high levels of benzene and other chemicals.  

The new Ministerial Order "supports the work of Alberta Health Services by broadening the indoor air quality sampling area to include more homes and businesses and ensuring that indoor air quality monitoring is carried out by an independent qualified professional," the province said in a release.