Memo warned of dam danger

St. Louis Post-Dispatch; 1/15/2006; Jeffrey Tomich and Eric Hand; ST. LOUIS POST-DISPATCH

St. Louis Post-Dispatch

01-15-2006

Memo warned of dam danger
Byline: Jeffrey Tomich and Eric Hand; ST. LOUIS POST-DISPATCH
Edition: Third Edition
Section: News
Memo: Taum Sauk reservoir break

WHAT HAPPENED

The reservoir breached on Dec. 14, releasing a torrent of water that swept a family's home off its foundation.
WHAT THE E-MAIL REVEALED

Almost three months earlier, Ameren employees had observed water spilling over a reservoir wall.

---

A gush of water spilled over the northwest wall of the Taum Sauk reservoir in late September and led to warnings that more overflowing could lead to a collapse, according to an internal AmerenUE e-mail.

Less than three months later, the reservoir ruptured in the same spot, releasing more than a billion gallons of water that surged through Johnson's Shut-Ins State Park.

The Sept. 27 e-mail from Richard Cooper, superintendent of Ameren's Taum Sauk Hydroelectric Plant, said the overtopping two days earlier had washed away rock at the base of the reservoir wall. Eroded trenches were a foot deep in some areas.

Cooper's e-mail, sent to several Ameren supervisors, said employees described the incident as "Niagara Falls."

"Overflowing the upper reservoir is obviously an absolute 'NO- NO,'" Cooper's e-mail said, noting that it would "cause eventual failure ... Those kind of headlines we don't need."

On Dec. 14, the headlines became a reality. The reservoir atop Proffit Mountain breached just before 5:30 a.m., releasing the torrent of water that badly damaged Johnson's Shut-Ins and swept park superintendent Jerry Toops' home off its foundation, with his family still inside.

Toops' three children were briefly hospitalized but have since been released.

Ameren never reported the September incident to federal regulators, who now are seeking answers about it.

Company e-mails also show that the plant for months had problems accurately gauging water levels in the reservoir.

The internal e-mails and documents were given to the Post- Dispatch by Don Giljum, business manager for Operating Engineers Local 148, the union that represents Taum Sauk workers.

"Our operators were letting (Ameren managers) know that something was wrong," Giljum said in an interview.

The Federal Energy Regulatory Commission, which regulates Taum Sauk and is investigating its failure, wasn't aware of the Sept. 25 incident until a site visit last week, according to a letter issued to Ameren on Friday. The agency gave Ameren a week to respond.

Federal regulations require companies to report conditions affecting the safety of a project or its operation "as soon as practicable" after discovered.

Ameren spokeswoman Susan Gallagher said in an interview that the company didn't consider the incident "reportable." She said the company did take action in response, but declined to provide specifics, citing the ongoing FERC investigation.

Dam expert Charles Morris, a civil engineer at the University of Missouri at Rolla, said any previous overtopping at Taum Sauk should have set off red flags.

"That structure was not designed to be overtopped. Period. If it did so, (Ameren) should have gone berserk," Morris said. "If they knew about it, they were very negligent."

Trouble with instruments

The 55-acre Taum Sauk reservoir, near Lesterville, Mo., about 100 miles south of St. Louis, is the upper part of a pumped-storage plant designed to meet peak daytime electricity needs.

At night, when electricity demand is low, Ameren pumps water from a 370-acre lower reservoir to the upper reservoir. Generating turbines start during the day, draining the reservoir.

For decades, the upper reservoir leaked, forcing Ameren to install an impermeable liner in 2004. After the liner was installed, the utility had problems with reservoir instruments, which measure water depths and are supposed to trigger alarms if water levels rise too high, according to company e-mails.

One of the instruments, contained in pipes that ran down the interior of the reservoir, measured elevation by the pressure of the water column over it. It was having problems, according to an Oct. 7 e-mail written by Cooper, who scheduled divers to inspect it.

"This bend in the pipes gives us a false reading and causes the reservoir level to look lower than it actually is," Cooper wrote. "Until these pipes can be re-attached we are lowering the pumpback shutdown setpoint to 1594 down from 1596. We want to give ourselves enough cushion so that we won't pump over the reservoir walls."

Cooper did not return a phone message seeking comment.

At an elevation of 1,594 feet above sea level, employees thought the reservoir was within three feet of the crest, which is 1,597 feet.

But according to other Ameren data obtained by the Post- Dispatch, the instruments may have registered a 3-foot cushion that didn't exist.

The data show the reservoir reaching an elevation of 1,594 feet at 5:08 a.m. on the morning of the failure. Four minutes later, pumping stopped -- with water levels still at 1,594 feet. One minute after that, at 5:13 a.m., water levels dropped as the breach occurred.

On the day of the collapse, Ameren's chief executive, Gary Rainwater, said at a news conference that an instrumentation failure led to overpumping, then overtopping, of the reservoir.

The data show that Ameren had been pumping to the same level -- 1,594 feet -- six times in the two weeks prior to the failure.

"If (the levels) were consistently in error, then they overtopped previously -- all those other nights that they pumped it up to that level," Morris said.

Photographs taken by UM-Rolla engineer Dave Hoffman in the days after the failure suggest erosion around the rim of the dam prior to Dec. 14. Hoffman, a former state dam inspector who joined officials touring the area after the Taum Sauk breach, said it's difficult to date the eroded gullies. But several of his photographs show grass growing out of eroded areas -- a sign that overtopping had occurred well before Dec. 14.

Passing marks

The Federal Energy Regulatory Commission was responsible for inspecting Taum Sauk annually. The agency also required that an outside consultant hired by Ameren conduct a more thorough inspection of Taum Sauk every five years.

In a 2003 report, inspectors with a Chicago firm barely touched on the instrument problems, stating the instruments were "not well documented on drawings." Yet FERC gave Ameren passing marks, even though inspectors found settlement and shifting of concrete panels around the northwest part of the kidney-shaped reservoir.

"The operators were confident in the ability of the system to prevent overfilling the upper reservoir," the inspectors wrote.

Morris said FERC ought to have asked for more proof that the instruments worked.

"Their job is to find out if it works, not to take somebody's word for it," he said. "My reaction to that is FERC wasn't doing their job."

Also, Taum Sauk has never been monitored 24 hours a day. Most of Taum Sauk's instruments are connected wirelessly to Ameren control stations in St. Louis and Osage.

In fact, Taum Sauk managers recently won an electrical engineering award that marveled at the way the plant was run via "remote control."

That award was presented on Sept. 26, one day after employees discovered the "Niagara Falls" overtopping.

Illustrations/Photos:
PHOTO; GRAPHIC; MAP;
Caption: PHOTO - In a photo taken Dec. 15, grass grows in an eroded
area at the Taum Sauk reservoir -- a sign that overtopping had
occurred well before the dam failure on Dec. 14. Courtesy of Dave
Hoffman / University of Missouri at Rolla PHOTO - Damage to the
reservoir, near Lesterville in southeast Missouri, is seen on Dec.
14 after the breach that morning. More than a billion gallons of
water surged through Johnson's Shut-Ins State Park. The Associated
Press GRAPHIC - Previous overtopping? Post-Dispatch GRAPHIC - The
"Niagara Falls" memo Post-Dispatch MAP - Taum Sauk resevoir Post-
Dispatch

(Copyright (c) 2006 The Post-Dispatch)