Nuna pad spill total rises to 170 barrels
The Alaska Department of Environmental Conservation’s Division of Spill Prevention and Response said Aug. 8 that the spill total at Caelus Natural Resources Alaska’s Nuna well NDST-2 has risen to some 170 barrels, approximately 4,200 gallons, 100 barrels, of diesel freeze product fluid, and 2,940 gallons, 70 barrels, of mineral oil.
When Caelus initially reported the spill on June 18 it estimated a release of 5 gallons of crude that escaped the well cellar and an unknown amount of crude contained in ice within the well cellar.
The division said that on July 7, after ice within the cellar had melted, Caelus reported removing 2,500 gallons of freeze protect fluid from the well cellar, a material similar to mineral oil.
On July 10 Caelus reported an estimated total of 2,900 gallons of freeze protect fluid had been removed from the well cellar and surrounding gravel pad.
In its Aug. 8 situation report the division said Caelus has now estimated the total to some 170 barrels, 100 barrels of freeze product fluid and 70 barrels of mineral oil.
The division said the cause was determined when gravel was removed from around the cellar and anti-buoyancy plugs in the bottom of the cellar were not in place, allowing water to fill the cellar and freeze, damaging the outer annulus valve and assembly on the well allowing the diesel and freeze protect fluid to escape.
The outer annulus valve and assembly were repaired, the division said, stopping the flow of fluids through the flange face.
Some 6,200 cubic yards of contaminated gravel have been removed. Oil had migrated under the drill site’s protective layer of gravel filled bags, the division said, with a small amount of oil impacting surrounding tundra. Contaminated water exterior to the drill site has been removed and a vacuum truck is standing by.
Caelus is continuing to remove contaminated gravel, the division said, with a vacuum truck and super sucker being used to remove standing fluids from the well cellar and do spot cleanup around the site.
At this time the release is only known to have impacted the well cellar, a portion of the gravel pad and a very small area of adjacent tundra, the division said.