Fire Wreaks Havoc With Dam Releases

A fire 60 miles north of Phoenix, Arizona wreaked havoc on transmission lines, which is causing problems with power generation and water releases at Glen Canyon Dam. Flows have been curtailed to enable Wilderness Adventures, the concessionaire offering below-the-dam tours, to move its boats to Lees Ferry to avoid damage from jet tube releases. The Bureau of Reclamation has asked for broadcast of the following alert:

From: Randall Peterson
Date: 6/25/2005 10:31:35 AM

A fire is currently burning under the two Glen Canyon - Pinnacle Peak Transmission Lines in the vicinity of Sunset Point which is approximately 60 miles north of Phoenix, Arizona. As of Friday, the fire had caused four trips of the two 345 kV transmission lines from Glen Canyon to Pinnacle Peak. The Pinnacle Peak Substation is near Phoenix, Arizona. The lines tripped out of service twice on Wednesday, once on Thursday and again on Friday. On each occasion generation at Glen Canyon was reduced over 200 MW, which reduced releases to the Colorado River. Except for Friday, the loss of the 345 kV transmission lines was short-lived varying between 20 minutes and an hour and twelve minutes with releases between 10,000 cfs and 11,500 cfs depending on the incident.

When the lines were reconnected to the plant, generation at Glen Canyon had to be reduced significantly in order to match phase angles and tie the generation station to the transmission system. This caused a reduction in releases, momentarily going below the minimum flow criteria of 5000 cfs before restoring flows to about 10,000 cfs and then ramping about 78 MW each hour until generation was raise to match the then current schedule. Friday's event was more serious as the lines tripped at about 2:45 PM, Mountain Standard Time and by 3:30 PM there was still no estimate from Western when the lines could be restored and by then river flows had dropped to about 3000 cfs. Not knowing when generation might be restored, Reclamation then operated the hollow jet valves to release 2000 cfs from the valves to complement 3000 cfs from the plant to maintain 5000 cfs minimum. At about 4:20 PM switching operation Western dropped all generating units in the plant off line. Consequently, releases at the hollow jet valves were increased to 5000 cfs. Releases to the river were maintained from the valves until about 5:00 PM when part of the transmission system was reestablished and generation could begin. By about 5:30 PM, generation was at 152 MW and releases at the plant was about 3670 cfs. As generation increased, releases from the plant and valves were correlated to maintain 5000 cfs in the river. At 6:00 PM generation was at 230 MW and releases were 9150 cfs.

On Saturday, between 8:30 - 9:00 AM, MDT, the line outage problems continued and Glen Canyon generation had dropped down to 50 MW. Releases are currently 3,200 cfs bypass and 1,800 cfs generation. Western hasn't been able to close the Flagstaff lines to resume normal generation. The river concessionaire Wilderness Adventures, is closed down. They have moved some boats and the remaining ones are getting hit hard by the bypass releases from the hollow jet valves. They have reported at least 13 boats have been damaged so far. ROD daytime releases are 8,000 cfs minimum - we are currently at 5,000 cfs. Ken Rice at the dam is working with Wilderness Adventures to see if they can move their boats to Lees Ferry. When that is accomplished, our [dam operators'] plan is to increase releases through the bypass tubes to meet the ROD daytime minimum of 8,000 cfs.