VMT Loses Power

On October 13, 2005, Alyeska experienced a total loss of electrical power at the Valdez Marine Terminal (VMT). The power outage lasted from 30 minutes to about three hours at the VMT except at the VTO (Valdez Terminal Office building) where power was out for longer due to human error. Alyeska asserts that power to critical systems such as the OCC (Operational Control Center) had been carried by uninterruptible power supplies (UPS) and that controllability of the incoming oil had never been compromised. Staff followed up with Power/Vapor personnel to discover the specifics associated with the power failure. The power failure occurred in the midst of planned maintenance of Alyeska's three main generators for the following purposes: (1) to remove one operating generator from the VMT's grid that was thought to have a serious problem, (2) to verify by testing that the steam valve on a second generator was working properly after an adjustment; and (3) to cut over the third generator from standby to carrying the critical loads.

A team of experts including manufacturer's representatives had been assembled on site to conduct the maintenance operations on October 13. Alyeska did not think that power would be lost; however, loss of power was viewed as a possibility. Consequently, some mitigating measures had been put in place (e.g. no tankers at berth) should power be lost. Alyeska's maintenance configuration contained a hidden fault, which caused protective devices to disconnect operating generators from their loads and the VMT lost electrical power. The two large emergency generators were started immediately but some delays in their being connected to their assigned loads occurred because parts of the VMT's electrical grid had been disconnected from each other in support of the planned maintenance.