Taum Sauk pumped storage plant

The remains of the Taum Sauk pumped storage plant are located in the St. Francois mountain region of the Missouri Ozarks approximately 90 miles (145 km) south of St. Louis near Lesterville, Missouri. The pumped-storage hydroelectric plant, operated by the AmerenUE electric company, was designed to help meet peak power demands during the day. Electrical generators were turned by water flowing from a reservoir on top of Proffit Mountain into a lower reservoir on the East Fork of the Black River. The generators and turbines at river level were reversible, and at night the excess electricity available on the power grid was used to pump water back to the mountaintop. The upper reservoir suffered a catastrophic failure on December 14, 2005. As of April 2007 the plant remains out of commission, but Ameren has said they have submitted plans to rebuild the plant, with return to service in 2009. [ "AmerenUE plans to rebuild 408-MW Taum Sauk", pg. 4, Hydro Review, April 2007 Vol XXVI, Number 2, ISSN 0084-0385 ]

The Taum Sauk plant was notable in that it was a pure pump-back operation – there was no natural primary flow available for generation, unlike most other pumped storage sites. It was among the largest such projects when it was built. Construction of the Taum Sauk plant began in 1960 and operation began in 1963. The two original reversible pump-turbine units were each capable of generating 175 megawatts of power. They were upgraded in 1999 to units capable of 225 megawatts each.

ize and location

The upper reservoir had a capacity of 4,350 acre-feet (5,366,000 m³). The upper reservoir was 800 feet (244 m) above the hydroelectric plant, which gives it a greater head than that of Hoover Dam. The two were connected by a 7000 ft (2100 m) tunnel through the mountain.

This powerplant was a net consumer of electricity; the laws of thermodynamics dictate that more power is consumed pumping the water up the mountain than is generated when it comes down. However, the plant was still economical to operate – the reservoir was filled at night when the electrical generation system is running at baseline capacity, and the power used for pump-back would otherwise be wasted.

That the Taum Sauk reservoir remains (37°32'10" N, 90°49'05" W) are atop Proffit Mountain and not Taum Sauk Mountain (37°34'13" N, 90°43'40" W) is often a source of confusion to tourists seeking to visit the site. Taum Sauk Mountain, the highest point in Missouri, is about five miles (8 km) east of Proffit Mountain and hosts a state park, not a reservoir. The reservoir is plainly visible from the lookout tower on Taum Sauk Mountain adjacent to the state park. Before the failure of the upper Reservoir visitors could usually drive to the top of Proffit Mountain and walk a ramp to an observation deck at the top of the reservoir. At the entrance gate Ameren also operated a museum highlighting the natural history of Missouri. The powerplant was frequently visited by geology students because of a striking example of Precambrian/Cambrian unconformity in the rock layers exposed by the plant's construction.

Leaks and lining

There had been minor leaks in the reservoir since it was constructed. From September 13, 2004 to November 15, 2004 Geo-Synthetics Inc. installed lining material to reduce leaks. [http://www.geo-synthetics.com/taum_sauk.asp]

Upper reservoir breached

On the morning of December 14, 2005, a triangular section on the northwest side of the upper reservoir failed, releasing a billion gallons (4 million m³) of water in twelve minutes and sending a 20 foot (7m) crest of water down the Black River. According to AmerenUE, a computer software problem caused the reservoir to continue filling even though it was already at its normal level. The water overtopped the walls, leading to the failure at 5:12 a.m. In addition, preliminary indications are that minor leakage through the dam walls over a prolonged period, had carried away fine material in the walls, weakening the reservoir's holding walls. Piping ultimately creates voids in reservoir walls and causes reservoir walls to slump and fail. The failure of the reservoir occurred as the reservoir was being filled to capacity or may have possibly been overtopped.

There was no overflow spillway. A maximum fill level was reported to be convert|6|ft|m below the top. If the reservoir was filled in 16 hours and is 55 acres across, that would calculate to about convert|1|ft|m|abbr=on of water rise in 12 minutes. The reservoir would have overflowed in approximately 72 minutes, once the maximum level was exceeded. It was likely that the reservoir failed once water overflowed the reservoir as earthen levees will erode when overtopped.

The reservoir had been lined with a membrane in 2004 to minimize water leakage. It had been losing two feet of water for some time prior to the installation of the lining. The phenomenon of fine material being washed out of a reservoir structure is known as "piping". When piping occurs, the reservoir structure can settle in or slump, which means water may start flowing over its top – but that is because a weakened area in the reservoir has settled down

Periodic surveys are necessary at a reservoir to identify if leakage and "piping" is occurring.

No fatalities were reported. Jerry Toops, his wife and three children were swept away when the wall of water obliterated their home. Toops is the superintendent of Johnson's Shut-Ins State Park and Taum Sauk State Parks. They survived with injuries and suffering from exposure. The children were transported to a hospital in St. Louis and later released. One child was treated for severe burns which resulted from heat packs applied by rescue workers as treatment for hypothermia.

Low cloud levels prevented medical helicopters from flying to aid victims. It wasn't until the clouds cleared up that the helicopters could retrieve victims. Three victims, all children, were first taken to Farmington, then they were transported by ambulance to SSM Cardinal Glennon Children's Hospital in St. Louis. A spokesperson for the family has informed the media that they do not want the conditions of the children to be disseminated.

The dam of the lower reservoir held, trapping much of the deluge. If it had given way then towns downstream, including Lesterville and Centerville would have been in grave danger. A voluntary evacuation order was issued for those areas, but there was no damage. The high water was stopped at Clearwater Lake, the dam of which was not damaged by the rising waters. [http://www.stltoday.com/stltoday/news/stories.nsf/missouristatenews/story/0A4A827BA5C98DB2862570D7004F9A49?OpenDocument]

A memo from Richard Cooper, superintendent of Ameren’s Taum Sauk Hydroelectric Plant, indicated that the reservoir had a "Niagara Falls" style overflow on September 27 at the same spot that was breached, (caused by wave action related to winds from Hurricane Rita.) Another Cooper memo had also indicated that Cooper had warned that gauges used to monitor the water height in the reservoir were malfunctioning in October.

Litigation and Investigations

FERC has fined Ameren $15 million pursuant to a settlement for the breach at Taum Sauk. This is the highest fine ever levied by FERC.

The State of Missouri has sued Ameren for Actual and Punitive Damages alleging Ameren was reckless in its operation of the plant.

[http://ferc.gov/industries/hydropower/safety/projects/taum-sauk.asp FERC Taum Sauk Page - Reports, Charges and Settlement available here]

[http://www.ago.mo.gov/newsreleases/2006/121306b.htm Missouri Attorney General Press Release with link to Petition for lawsuit against Ameren for breach]

The Missouri Highway Patrol delivered a report of its criminal investigation to the Attorney General in June 2007 which "did not name any suspect" and the Attorney General made a statement that there would be no criminal charges. According to press reports, the report states that Ameren failed to provide the identity of the person who raised the gauges meant to prevent overtopping and also states that the gauges were moved before investigators were on the scene.

[http://www.stltoday.com/stltoday/news/stories.nsf/stlouiscitycounty/story/06323A30D4407520862572F4000BDE98?OpenDocument St. Louis Post Dispatch article ]

[http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/06-08-2007/0004604925&EDATE= Ameren Press Release]

KMOX radio in St. Louis reports that the EPA assisted by the U.S. Attorney's Office has begun an investigation into violations of the Clean Water Act and has requested the Highway Patrol's report.

[http://www.kmox.com/pages/603101.php?contentType=4&contentId=628667= Report on EPA Investigation]

The Public Service Commission reopened its investigation (based on the Highway Patrol report) and subsequently found the accident to be a failure of Ameren management, stating:

...the Commission can only conclude that the loss of the Taum Sauk plant was due to imprudence on the part of UE (Ameren's AmerenUE Subsidiary). UE was well-aware of the catastrophic results likely to occur if the UR (Upper Reservoir) was overtopped by over-pumping. UE knew, or should have known, that storing water against the parapet wall of a rockfill dam was “unprecedented.” UE knew,or should have known, that operating with a freeboard of only one or two feet left no margin for error and required particularly accurate control of the UR water level. Given that circumstance, UE’s decision to continue operating Taum Sauk after the discovery of the failure of the gauge piping anchoring system and the consequent unreliability of the piezometers upon which the UR control system was based is frankly beyond imprudent – it is reckless. UE also knew or should have known that the upper Warrick probes had been reset above the lowest point at the top of the UR." (PSC Report page 71, definitions of Acronyms added)

Ameren has 90 days from the date of the report to answer back to the PSC how it will meet the recommendations of the report, which include a whistle blower rule, changes in safety management structure, financial accounting for the rebuild of the upper reservoir, and single point of management for the rebuild.

[http://www.waterpowermagazine.com/story.asp?sectioncode=130&storyCode=2047683 Water Power Magazine on PSC Report]

[http://www.psc.mo.gov/electric/report%2010-24-07.pdf Link to PSC Report Full Text]

Church Mountain reservoir

In June, 2001, Ameren Development Corp, a subsidiary of Ameren Corporation, announced that it had filed for a permit from the Federal Energy Regulatory Commission in order to begin evaluating the construction of a much larger pump-back plant on neighboring Church Mountain. The upper reservoir of this 770 megawatt plant would be 130 acres (0.5 km²), and the lower reservoir would flood 400 acres (1.6 km²) of the scenic and environmentally significant Taum Sauk Creek valley. Resistance from a number of environmental groups, the Missouri governor's office, and the state's attorney general caused the company to conclude it was impossible to build the plant in both an environmentally friendly and cost-effective manner, and the permit application was withdrawn in August 2001.

Gallery of Taum Sauk Destruction

References

* Southeast Missourian (Cape Giradeau, MO): [http://www.semissourian.com/story/1131377.html Taum Sauk Reservoir fails]
* Ameren Press Releases [http://www.ameren.com/AboutUs/adc_newsfull.asp?NewsSeqID=449] , [http://www.ameren.com/AboutUs/adc_newsfull.asp?NewsSeqID=450]
* Daily Journal (Park Hills, Missouri): [http://www.mydjconnection.com/articles/2005/12/14/community/news1.txt Taum Sauk Dam Fails]
* National Weather Service, St. Louis Office: [http://www.crh.noaa.gov/lsx/?n=taumsaukdamfailure Taum Sauk Dam Failure]
* USGS Mid-Continent Geographic Science Center [http://mcmcweb.er.usgs.gov/mcgsc/taum_sauk_reservoir_photos122005.html]
* Johnson's Shut-Ins State Park damage update page [http://www.mostateparks.com/jshutinsdamage.htm]
* Ameren web pages on Taum Sauk and Johnson's Shut-ins restoration [http://www.ameren.com/taumsauk/]

External links

* [http://www.ameren.com/taumsauk/ Ameren website on Taum Sauk and Johnson's Shut-Ins restoration]
* [http://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/ipoc-rpt.asp FERC Independent Panel of Consultants (IPOC) Report, May 25, 2006]