ANCHORAGE, AK -- August 12, 1996 -- Alyeska Pipeline Service Company reported today that less than ten gallons of crude oil was found Saturday on water contained in a concrete vault that houses Check Valve 29A. The check valve is located near mile 162 of the trans-Alaska pipeline, approximately 17 miles south of Pump Station 4. The crude oil caused a sheen on the water contained in the vault, and has been cleaned up. Crude oil did not escape the contained area. No additional oil appears to be leaking from the valve. Crews are monitoring the check valve until the source of the leak can be determined.

Light sheen was first noticed in the vault on Wednesday, August 7. An initial cleanup was conducted. When crews revisited the site on Saturday, August 10, the water contained a heavier sheen and was cleaned up. There does not appear to be any further leakage.

The buried concrete vault is approximately 14 x 22 feet and 14 feet deep. Access is through two manhole covers at ground level, and the check valve is near the bottom of the vault. The vault is not designed to be sealed, so water can seep into it. This water must be drained down to expose the valve and other equipment, and allow crews to investigate the site. Alyeska is working with regulatory agencies to ensure proper disposal of the water as the vault is drained. The water in the vault contains less than one part per million total hydrocarbons.

Check Valve 29A was installed near milepost 162 of the trans-Alaska pipeline in 1991, as part of the Atigun reroute project. It is one of three buried check valves located on the north side of Atigun Pass. All three are contained within concrete vaults.

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