Taum Sauk pumped storage plant
Encyclopedia
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
Ozarks approximately 90 miles (144.8 km) south of St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
near Lesterville, Missouri
Lesterville, Missouri
Lesterville, Missouri is an unincorporated community in southeast Missouri. It is located in Reynolds County on Routes 21, 49, and 72 near the Black River....
in Reynolds County
Reynolds County, Missouri
Reynolds County is a county located in the northwestern portion of the Ozark Foothills Region in Southeast Missouri in the United States. As of the 2000 U.S. Census, the county's population was 6,689. A 2008 estimate, however, showed the population to be 6,388. Its county seat is Centerville...
. The pumped-storage hydroelectric
Pumped-storage hydroelectricity
Pumped-storage hydroelectricity is a type of hydroelectric power generation used by some power plants for load balancing. The method stores energy in the form of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost off-peak electric power is used to run the pumps...
plant, operated by the AmerenUE
Ameren
Ameren Corporation was created December 31, 1997 by the merger of Missouri's Union Electric Company and the neighboring Central Illinois Public Service Company . It is now a holding company for several power companies and energy companies. The company is based in St...
electric company, was designed to help meet peak power demands during the day. Electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
s are 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 turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
s at river level are reversible, and at night the excess electricity available on the power grid is used to pump water back to the mountaintop.
The Taum Sauk plant is notable in that it is a pure pump-back operation – there is 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.
The plant was out of operation after the upper reservoir suffered a catastrophic failure on December 14, 2005, until the rebuilt and recertified structure started producing power again on April 21, 2010.
The new upper reservoir dam, rebuilt from the ground up, is the largest roller-compacted concrete
Roller-compacted concrete
Roller-compacted concrete or rolled concrete is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement. RCC is a mix of cement/fly ash, water, sand, aggregate...
dam in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. The plant was named an IEEE Milestone in 2005.
Size and location
The original upper reservoir had a capacity of 4350 acre.ft. The upper reservoir is 800 feet (243.8 m) above the hydroelectric plant, which gives it a greater head than that of Hoover DamHoover Dam
Hoover Dam, once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President...
. The two are connected by a 7000 feet (2,133.6 m) tunnel through the mountain.
This powerplant is a net consumer of electricity; the laws of thermodynamics
Laws of thermodynamics
The four laws of thermodynamics summarize its most important facts. They define fundamental physical quantities, such as temperature, energy, and entropy, in order to describe thermodynamic systems. They also describe the transfer of energy as heat and work in thermodynamic processes...
dictate that more power is consumed pumping the water up the mountain than is generated when it comes down. However, the plant is still economical to operate because the reservoir is filled at night when the electrical generation system is running at low-cost baseline capacity. As a way to store excess power until it is needed, it has been described by the utility as "the biggest battery that we have."
The Taum Sauk reservoir is atop Proffit Mountain, not Taum Sauk Mountain
Taum Sauk Mountain
Taum Sauk Mountain in the Saint Francois Mountains is the highest natural point in the U.S. state of Missouri, 1,772 feet above mean sea level.The topography of Taum Sauk is that of a somewhat flat ridge rather than a peak....
, which was often a source of confusion to visitors to the site when it was open to the public prior to the reservoir failure. Taum Sauk Mountain, the highest point in Missouri, is about five miles (8 km) east of Proffit Mountain and is home to a state park
State park
State parks are parks or other protected areas managed at the federated state level within those nations which use "state" as a political subdivision. State parks are typically established by a state to preserve a location on account of its natural beauty, historic interest, or recreational...
. The reservoir is plainly visible from the lookout tower on Taum Sauk Mountain. The upper reservoir is also visible from Route 21 north of Centerville.
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
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
/Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
unconformity
Unconformity
An unconformity is a buried erosion surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe...
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. A pumpback station had eventually been installed to collect and return leakage to the reservoir. From September 13, 2004 to November 15, 2004 Geo-Synthetics Inc. installed lining material to reduce leaksUpper reservoir breached
Black River (Arkansas)
The Black River is a tributary of the White River, about 300 mi long , in southeastern Missouri and northeastern Arkansas in the United States. Via the White River, it is part of the Mississippi River watershed...
. 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 in the original reservoir. A maximum fill level was reported to be 6 feet (1.8 m) below the top. If the reservoir was filled in 6 hours and is 55 acres (222,577.3 m²) across, that would calculate to about 1 ft (0.3048 m) 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. Where piping occurs a reservoir structure can settle in or slump, lowering the level at which it will be overtopped at the point of settling. Periodic surveys are necessary at a reservoir to identify if leakage and "piping" is occurring.
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.
No fatalities were caused by the failure. The superintendent of Johnson's Shut-Ins
Johnson's Shut-Ins State Park
Johnson's Shut-Ins State Park is a Missouri state park on the East Fork Black River consisting of in Reynolds County. The park is jointly administered with adjoining Taum Sauk Mountain State Park, and together the two parks cover in the St...
and Taum Sauk
Taum Sauk Mountain State Park
Taum Sauk Mountain State Park is located in the Saint Francois Mountains in the Missouri Ozarks. It is centered around Taum Sauk Mountain, the highest point in the state....
State Parks, Jerry Toops, his wife and three children were swept away when the wall of water obliterated their home. They survived, suffering from injuries and exposure. The children were transported to a hospital in St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
and later released. One child was treated for severe burns which resulted from heat packs applied by rescue workers as treatment for hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
.
The dam of the lower reservoir, which by design is able to hold much of the capacity of the upper reservoir, withstood the onslaught of the flood. By storing most of the deluge it spared towns downstream, including Lesterville
Lesterville, Missouri
Lesterville, Missouri is an unincorporated community in southeast Missouri. It is located in Reynolds County on Routes 21, 49, and 72 near the Black River....
and Centerville
Centerville, Missouri
Centerville is a city in Reynolds County, Missouri, along the West Fork of the Black River. The population was 171 at the 2000 census. It is the county seat of Reynolds County.-West Fork Lead Mine:...
, from a damaging flood. A voluntary evacuation order was issued for those areas, but there was no damage. The high water was stopped at Clearwater Lake
Clearwater Lake (Missouri)
Clearwater Lake is a reservoir on the Black River six miles from Piedmont, Missouri. The U.S. Army Corps of Engineers uses Clearwater for flood control in the White and lower Mississippi River Basins....
, the dam of which was not damaged by the rising waters.
Litigation and Investigations
FERC has fined Ameren $15 million pursuant to a settlement for the breach at Taum Sauk. This is the second highest fine ever levied by FERC, only outstripped by the fine and subsequent settlement against FPL regarding the 2008 Florida electricity blackout.The State of Missouri sued Ameren for Actual and Punitive Damages alleging Ameren was reckless in its operation of the plant.
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.
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.
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.
Reconstruction
Federal regulators approved Amerens plan to rebuild the reservoir, and construction began in late 2007. The rebuilt structure is made entirely of roller-compacted concreteRoller-compacted concrete
Roller-compacted concrete or rolled concrete is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement. RCC is a mix of cement/fly ash, water, sand, aggregate...
, unlike the earth-fill original. In addition to fill-detection instrumentation it incorporates a spillway to handle any overflow and a video system to monitor the water level. The $450 million cost of rebuilding the reservoir was covered mostly by insurance. The utility is prohibited from billing customers to recoup any of the cost.
Water was pumped into the rebuilt reservoir for the first time on February 27, 2010, and engineers monitored the response of the new structure as the water level was repeatedly raised and lowered. The final approval required from the FERC for “return to normal project operations” was received on April 1, 2010. The utility met the Missouri Public Service Commission’s in-service criteria for operations on April 15, and electricity was first generated from the new structure on April 21, 2010. The new dam was recognized by the U.S. Society on Dams
United States Society on Dams
The United States Society on Dams is a professional association that is dedicated to:* Advancing the knowledge of dam engineering, construction, planning, operation, performance, rehabilitation, decommissioning, maintenance, security and safety;...
with its "Award of Excellence in the Constructed Project".
Church Mountain reservoir
Federal Energy Regulatory Commission
The Federal Energy Regulatory Commission is the United States federal agency with jurisdiction over interstate electricity sales, wholesale electric rates, hydroelectric licensing, natural gas pricing, and oil pipeline rates...
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. However, Ameren refused the state's request for title to or a long-term lease on Church Mountain as part of its settlement for the damage it caused to Johnson's Shut-ins State Park. Environmentalists have condemned the settlement for failing to protect Church Mountain and the Taum Sauk Creek valley, leaving the company free to resurrect the second reservoir plan in the future.