Three diesel spills have occurred at the Ogden rail yard area since November, and one of them amounted to as much as 5,000 gallons of fuel, environmental officials said.
Jim Thiros, an environmental scientist with the Department Of Environmental Quality, said the two most recent spills in the rail area involved 50 to 200 gallons of diesel.But a leak on Nov. 18 could have amounted to 2,000 to 5,000 gallons of diesel at Fruit Express on 29th Street, according to an incident report filed with the state's Environmental Response and Remediation Division.
The leak wasn't reported for at least two weeks, even though environmental laws require all spills of toxic materials exceeding 25 gallons to be reported to EPA or state officials immediately, Thiros said.
He said the tank's contents also were not documented so it isn't known exactly how much diesel leaked out.
According to the DEQ incident report, the spill occurred when a fuel company filling an above-ground storage tank did not open the correct valve and the fuel traveled into lines that were no longer in service.
"We're calling it our mystery spill and estimating it at 2,000 gallons, although it could have been more," Thiros said.
Fruit Express is a subsidiary of Union Pacific, which is now working with the state to clean up the pollution.
Fruit Express was also the site of a leak of about 200 gallons of diesel on Dec. 14.
That leak was caused by a frozen line that spit out 200 gallons of diesel to the surface when it thawed.
The third diesel spill occurred Jan. 30, when 30 to 50 gallons of diesel were spilled during a refueling operation by Jardine Petroleum.
The contaminated soil from that spill has already been excavated, Thiros said.
Meanwhile, several sites in the train yard area, which stretches west of Wall Avenue between 21st Street and Riverdale Road, are being studied by the state and the Environmental Protection Agency.
In earlier days, petroleum and other wastes were commonly dumped directly onto the ground by the railroads.
Thiros said the state has put in 10 monitoring wells at various sites in the yard to provide more information about the extent of pollution there. State officials also plan to gather more soil samples.