JEFFERSON CITY-After water washed over the top of the Taum Sauk hydroelectric plant reservoir in September 2005, plant supervisors determined the water level gauges weren't accurate and attempted to correct them.
But a former Taum Sauk supervisor testified Tuesday that he never checked out the reservoir's separate emergency water sensors. Had that warning system worked properly, it could have prevented the reservoir from again overflowing and ultimately collapsing less than three months later.
The failure of the Taum Sauk reservoir sent more than 1 billion gallons of water rushing down a mountainside on Dec. 14, 2005, deluging Johnson's Shut-ins State Park and seriously injuring the park superintendent's family.
Jeffrey Scott, who then was in charge of the plant's power production and engineering, is the only on-site supervisor to testify before the Missouri Public Service as it investigates whether the reservoir failure was indicative of broader safety problems at St. Louis-based AmerenUE.
Scott was the No. 2 person at the southeast Missouri plant, which pumps water into a reservoir when electricity demand is low and then releases it to generate power when electricity prices rise. Plant superintendent Richard Cooper is ill and has been unable to testify before state utility regulators.
The PSC's investigation is one of at least four government inquiries. Ameren agreed to pay $15 million after an investigation by the Federal Energy Regulatory Commission. The state Highway Patrol also investigated, though Attorney General Jay Nixon decided to pursue only civil penalties, not criminal charges. The federal Environmental Protection Agency also is looking into the incident.
Concerns about the reservoir's water levels first arose Sept. 25, 2005, as high winds from the remnants of Hurricane Rita washed waves over the top of the wall and eroded a gravel road on the other side.
After that incident, Scott said he and Cooper drove to the top of the mountain and noticed that, regardless of the wind, the reservoir's water level appeared higher than it should.
Scott said they determined one of the three water level gauges was reporting readings about a foot different from the other two. So he altered the computer program to cancel the data from that third gauge, then added an additional four-tenths of a foot to the average water level shown by the other two sensors to try to make the readings match the actual water levels they had seen.
On Sept. 28, 2005, Scott received an e-mail message from Ameren engineer Tom Pierie asking whether the reservoir's emergency water-level sensors had picked up the high readings when water spilled over the top three days earlier. Those sensors are supposed to automatically shut down the power plant's pumps.
Scott testified he could not recall how — or whether — he responded to that e-mail.
Pressed by an attorney for the state on whether he had checked the emergency sensors after the overflow, Scott eventually responded: "Not to my recollection." Scott, who oversaw nine hydroelectric plant technicians, said there was no maintenance schedule for the emergency water-level sensors — called Warrick Probes — and no periodic checks on their condition.
In another e-mail to Cooper and Scott on Oct. 7, 2005, Pierie noted plans to install a third Warrick Probe at a lower level and wrote that the two existing ones were placed 7 inches and 4 inches from the top of the reservoir wall. He said that was intended to avoid emergency shutdowns from routine waves.
But that could have raised a red flag, because the probes were posted on a section of wall that was a foot higher than the wall's lowest point, meaning they were set so high as to essentially be ineffective.
At the time, "I don't know if anybody put two and two together when they got this e-mail," Scott said.
Under questioning by state attorneys and Public Service Commissioner Steve Gaw, Scott repeatedly said he could not recall details about events leading up to the 2005 reservoir collapse, including the reasoning for certain decisions and the specifics of conversations among Ameren personnel.
At one point, a frustrated Gaw reminded Scott he had taken an oath to tell the truth. Scott insisted he could not recall much, as nearly two years have passed.