State environmental regulators are overseeing the response to two crude oil spills discovered in July at the Drift River tank farm on the west side of Cook Inlet.
The spills by Hilcorp Alaska's Cook Inlet Pipeline Co. were associated with over-pressurization of a 20-inch fill line, according to a report Tuesday from the Alaska Department of Environmental Conservation.
The company reported a spill on July 2, saying 14 gallons of crude oil had collected inside a valve box. One gallon spilled on the ground.
In the second spill, the company on July 29 reported a crude oil stain "at the surface of one of the buried 20-inch fill line blind flanges in the pipe corridor between Tanks 1 and 4," the agency said.
In the second spill, (Cook Inlet Pipeline) has estimated that 28 gallons spilled, based on the size of the surface stain, said Young Ha, Cook Inlet and Kodiak unit supervisor for the DEC.
But Ha said the number is subject to change based on further investigation.
The fill-line has been isolated and shut down, the report said. Oil that reached the ground following the first spill has been excavated. The agency will monitor cleanup activity of the second spill, as well as testing and activities associated with the line.
The agency also wants Cook Inlet Pipeline to "submit a plan that includes how they are going to identify any additional potential spills from the 20-inch fill line, remove the remaining crude oil in the line, test line integrity, and identify future plans for the line," the report said.