(IDEX Online) - De Beers Canada has been charged with an environmental breach after releasing almost 1,600 gallons of diesel at its former Snap Lake mine.The fine for such a breach Environmental Protection Act is from C$100,000 to C$4m.A report by De Beers blames human error for the spill. A worker forgot to close the tank's outlet valve, a court was told.The miner invested over $2.2bn in Snap Lake, Northwest Territories (pictured), its first mining project outside Africa.It had an expected 15-year life when it opened in July 2008, but was closed seven-and-a-half years later, after a decline in diamond prices and ongoing water problems at the mine.De Beers said it had since reviewed working procedures. The company is due to appear in court again on 28 September.