Taum Sauk Hydroelectric Power Station: Difference between revisions

Revision as of 03:10, 11 February 2006

Latest revision as of 14:38, 11 August 2025

(391 intermediate revisions by more than 100 users not shown)

Line 1:

{{Use American English|date=April 2023}}

{{current}}

{{Use mdy dates|date=April 2023}}

[[Image:TaumSaukUpperReservoir-Ameren.jpg|thumb|right|An aerial photo of the upper reservoir of the Taum Sauk plant. Source: Ameren]]

{{Infobox dam

[[Image:Taum Sauk Pumped Storage.jpg|thumb|right|Water stored in the upper reservoir is available for hydroelectric generation during times of peak demand.]]

| name = Taum Sauk Hydroelectric Power Station

[[Image:Taum Sauk power plant.jpg|thumb|right|The two generators are each capable of producing up to 225 MW of power.]]

| name_official =

The '''Taum Sauk pumped storage plant''' (which suffered a catastrophic failure [[December 14]], [[2005]]) is located in the [[St. Francois Mountains|St. Francois mountain]] region of the [[Missouri]] [[Ozarks]] approximately 90 miles (145 km) south of [[St. Louis, Missouri|St. Louis]] near [[Lesterville, Missouri]]. The [[Pumped-storage hydroelectricity|Pumped-storage hydroelectric]] plant, operated by the [[AmerenUE]] electric company, is designed to help meet peak power demands during the day. [[Electrical generator]]s are turned by water flowing from a [[reservoir (water)|reservoir]] on top of Proffit Mountain into a lower reservoir on the East Fork of the Black River. The generators and [[turbine]]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.

| image = UserKTrimble-AP Taum Sauk Reservoir UnderConstruction Nov 22 2009 crop1.jpg

| image_size =

| image_caption = The rebuilt upper reservoir of the Taum Sauk plant, nearing completion in this photo, is the largest [[roller-compacted concrete]] dam in North America.

| image_alt =

| location_map = Missouri

| location_map_size =

| location_map_caption =

| location_map_alt =

| coordinates = {{Coord|37|32|08|N|90|49|05|W|region:US-MO_type:landmark|display=inline,title}}

| country = United States

| ___location = [[St. Francois Mountains]], [[Missouri]]

| purpose = P

| status = O

| construction_began = {{start date|1960}}<ref name="rogers-overview">{{cite web |last1=Rogers |first1=J. David |last2=Watkins |first2=Conor M. |title=Overview of the Taum Sauk Pumped Storage Power Plant Upper Reservoir Failure, Reynolds County, MO |url=http://web.mst.edu/~rogersda/dams/2_43_Rogers.pdf |website=Web.MST.edu |access-date=December 27, 2016 }}</ref>

| opening = {{start date|1963|12|20}}, {{start date|2010|04|15}}<ref name="ameren">{{cite web |title=Taum Sauk Energy Center {{!}} Ameren Missouri |url=https://www.ameren.com/missouri/environment/hydroelectric/taum-sauk-information |website=Ameren.com |access-date=December 27, 2016 }}</ref><ref name="FERC staff report" />

| demolished =

| cost = {{Ubl|[[United States dollar|US$]]45.9 million (1963)|US$490 million rebuild (2010)}}

| builder =

| owner = [[Ameren|Ameren Missouri]] (previously AmerenUE, formerly [[Union Electric Company|Union Electric]])

| operator = Ameren Missouri

| dam_type = G

| dam_crosses =

| dam_height_foundation = {{convert|125|ft}}

| dam_height_thalweg =

| dam_length = {{convert|6800|ft}}<ref name="rogers-overview-brief">{{cite web|last1=Rogers|first1=J. David|last2=Watkins|first2=Conor|last3=Hoffman|first3=David J.|title=Overview and History of the Taum Sauk Pumped Storage Project|url=http://web.mst.edu/~rogersda/dams/taum-sauk/watkins-taum-sauk-gsa_branson-compressed.pdf|website=web.mst.edu|access-date=December 27, 2016}}</ref><ref name="witt-brief">{{cite web|last1=Witt|first1=Warren A.|title=Taum Sauk Pumped Storage Energy Center|url=https://www.efis.psc.mo.gov/mpsc/commoncomponents/viewdocument.asp?DocId=935962611|accessdate=December 29, 2016}}</ref>

| dam_elevation_crest = {{convert|1601|ft}}

| dam_width_crest = {{convert|25|ft}}

| dam_width_base = {{convert|150|ft}}

| dam_volume = {{convert|3,200,640|yd3}}<!-- needs final verification -->

| spillway_count = 1

| spillway_type = Broad crested weir

| spillway_capacity = {{convert|5358|ft3/s}}

| res_name =

| res_capacity_total = {{convert|4350|acre.ft}}<!-- needs refinement due to active/inactive capacity issues and the unclear actual current capacity of the UR --><ref>{{Cite web|url=https://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/proj-desc.asp|title=FERC: Taum Sauk Pumped Storage Project - Description|website=FERC.gov|accessdate=March 16, 2019|archive-date=January 20, 2019|archive-url=https://web.archive.org/web/20190120011419/https://ferc.gov/industries/hydropower/safety/projects/taum-sauk/proj-desc.asp|url-status=dead}}</ref>

| res_capacity_active =

| res_capacity_inactive =

| res_catchment =

| res_surface = {{convert|54.5|acres}}<!-- needs refinement? -->

| res_max_length =

| res_max_width =

| res_max_depth = {{convert|120|ft}}<!-- needs refinement? -->

| res_elevation = {{convert|1597|ft}}

| res_tidal_range =

| lower_dam_type = G

| lower_dam_crosses = [[Black River (Arkansas-Missouri)|East Fork Black River]]

| lower_dam_height_foundation = {{convert|60|ft}}

| lower_dam_height_thalweg = {{convert|55|ft}}

| lower_dam_length = {{convert|390|ft}}<!-- 360 feet according to one source -->

| lower_dam_elevation_crest = {{convert|750|ft}}

| lower_dam_width_crest =

| lower_dam_width_base = {{convert|75|ft}}

| lower_dam_volume =

| lower_spillway_count = 1

| lower_spillway_type = Ogee crest

| lower_spillway_capacity = {{convert|70,000|ft3/s}}

| lower_res_name = Lower Taum Sauk Lake

| lower_res_capacity_total = {{convert|6350|acre.ft}}<!-- needs refinement due to active/inactive capacity issues -->

| lower_res_capacity_active =

| lower_res_capacity_inactive =

| lower_res_catchment = {{convert|88|mi2}}

| lower_res_surface = {{convert|395|acres}}

| lower_res_max_length =

| lower_res_max_width =

| lower_res_max_depth =

| lower_res_elevation = {{convert|749.5|ft}}

| lower_res_tidal_range =

| plant_name = Power Station

| plant_coordinates = {{Coord|37|31|14|N|90|50|04|W|region:US-MO_type:landmark|display=inline}}

| plant_operator = Ameren Missouri

| plant_commission = {{start date|1963|12|20}}, {{start date|2010|04|15}}

| plant_decommission =

| plant_type = P

| plant_hydraulic_head = {{convert|860|ft}}<!-- needs refinement -->

| plant_turbines =

| plant_pumpgenerators = 2 × 225 MW reversible [[Francis turbine|Francis]] type

| plant_pumps =

| plant_capacity = 450<!-- needs refinement? -->

| plant_capacity_factor = 5–8%<ref name="rogers-overview" /><ref name="NHPRS">{{cite web |author1=Danes and Moore |title=National Hydroelectric Power Resources Study: Volume X |url=http://large.stanford.edu/courses/2014/ph240/galvan-lopez2/docs/IWR019-000001-000517.pdf |accessdate=August 31, 2017 |page=75 |date=November 1981 |quote=The utilization factor for the plant ranges from five to eight percent. This is relatively low when compared to the 20 percent utilization factors of other plants such as Blenheim-Gilboa and is due to the different operating philosophies and generation mix of various utilities. }}</ref><!-- needs refinement -->

| plant_efficiency = 70%<!-- needs refinement? -->

| plant_storage_hours = 8 hours (3600 MW·h)<!-- needs refinement! -->

| plant_annual_gen = -148<!-- EIA data, https://www.eia.gov/electricity/data/browser/#/plant/2108?freq=A&ctype=linechart&ltype=pin&pin=&maptype=0&linechart=ELEC.PLANT.GEN.2108-ALL-ALL.A&columnchart=ELEC.PLANT.GEN.2108-ALL-ALL.A - not cited inline because that would screw up automatic formatting -->

| plant_annual_gen_year = 2017

| website = [https://www.ameren.com/missouri/environment/hydroelectric/taum-sauk-information Taum Sauk Energy Center]

| extra =

}}

The '''Taum Sauk pumped storage plant''' is a [[power station]] in the [[St. Francois Mountains|St. Francois mountain]] region of [[Missouri]], United States about {{convert|90|mi}} south of [[St. Louis, Missouri|St. Louis]] near [[Lesterville, Missouri]], in [[Reynolds County, Missouri|Reynolds County]]. It is operated by [[Ameren|Ameren Missouri]].

The Taum Sauk plant is notable in that it is a pure pump-back operation &ndash; there is no natural primary flow available for generation, unlike most other [[Pumped storage hydroelectricity|pumped storage]] sites. It was among the largest such project when it was built. Construction of the Taum Sauk plant was begun 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 [[pumped-storage hydroelectricity|pumped-storage hydroelectric]] plant was constructed from 1960–1962 and was designed to help meet daytime peak electric power demand.<ref name="Rogers 2010">{{Cite journal |last1=Rogers |first1=J. David |last2=Watkins |first2=Conor M. |last3=Chung |first3=Jae-Won |date=August 1, 2010 |title=The 2005 Upper Taum Sauk Dam Failure: A Case History |url=https://web.mst.edu/~rogersda/dams/taum-sauk/Taum-Sauk-Dam-Failure-EG&G-Aug2010.pdf |journal=Environmental and Engineering Geoscience |volume=16 |issue=3 |doi=10.2113/gseegeosci.16.3.257 |issn=1078-7275 |pages=257–289 |bibcode=2010EEGeo..16..257R |access-date=March 30, 2018 }}</ref> It began operation in 1963. [[Electrical generator]]s are turned by water flowing from a [[reservoir (water)|reservoir]] on top of [[Proffit Mountain]] into a lower reservoir on the East Fork of the [[Black River (Arkansas–Missouri)|Black River]]. At night, excess electricity on the power grid is used to pump water back to the mountaintop.

The upper reservoir has a capacity of 4,350 acre-feet (5,366,000 m&sup3;). The upper reservoir is 800 feet (244 m) above the hydroelectric plant, which gives it a greater [[Head (hydraulic)|head]] than that of [[Hoover Dam]]. The two are connected by a 7000 ft (2100 m) tunnel through the mountain.

ThisThe powerplantTaum Sauk plant is an open-loop pure pumped operation: unlike some other [[Pumped storage hydroelectricity|pumped storage]] sites, there is no natural primary flow into the upper reservoir available for generation. It is therefore a net consumer of electricity; the [[laws of thermodynamics]] dictate that more power is consumedused pumpingto pump the water up the mountain than is generated when it comes down. However, the plant canis still be economical to operate &ndash;because the upper reservoir is filledrefilled at night, when the electrical generation system is running at low-cost baseline capacity,. andThis ability to store huge amounts of energy led its operator to call Taum Sauk "the powerbiggest used[[Battery for(electricity)|battery]] pumpthat we have".<ref>{{cite web |title=Ameren UE unveils a revamped Taum Sauk reservoir |url=http://www.stltoday.com/business/ameren-backue-unveils-a-revamped-taum-sauk-reservoir/article_82793909-97e7-5ce5-a59d-e1cc5d243e38.html would|website=StlToday.com otherwise|date=May 28, 2010 |access-date=January 8, 2017 }}</ref> An unusual feature is the upper reservoir which is constructed on a flat surface, requiring a dam around the beentire wastedperimeter.

On December 14, 2005, a catastrophic failure in the upper reservoir dam put the plant out of operation until it was rebuilt, recertified, and reopened on April 21, 2010.<ref name="ameren21apr10">{{cite web|url = http://ameren.mediaroom.com/index.php?s=43&item=805|title = AmerenUE's Taum Sauk Pumped Storage Plant Is Back Online|publisher = [[Ameren]]|date = April 21, 2010|access-date = April 22, 2010 |archive-url = https://web.archive.org/web/20110714064819/http://ameren.mediaroom.com/index.php?s=43&item=805|archive-date = July 14, 2011}}</ref> The new upper reservoir dam, rebuilt from the ground up, is the largest [[roller-compacted concrete]] dam in [[North America]].<ref name="hydroworld1">{{cite web|url = http://www.hydroworld.com/index/display/article-display/5145640941/articles/hrhrw/damsandcivilstructures/general/2009/12/u_-s__society_on_dams.html|title = U. S. Society on Dams holds annual meeting and conference in California|date = April 16, 2010|access-date = April 19, 2010|publisher = PennWell Corporation|website=HydroWorld.com}}</ref>

That the Taum Sauk reservoir (37d32m10s N, 90d49m05s W) is atop Proffit Mountain and not [[Taum Sauk Mountain]] (37d34m13s N, 90d43m40s 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. Visitors can 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 operates a museum highlighting the natural history of Missouri. The powerplant is frequently visited by geology students because of a striking example of [[Precambrian]]/[[Cambrian]] [[unconformity]] in the rock layers exposed by the plant's construction.

====LeaksSize and lining==___location==

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]

{{stack|

====Upper reservoir breached====

[[File:Taum Sauk Pumped Storage.jpg|thumb|Water stored in the upper reservoir is used to generate electricity during peak demand]]

:''For more information see '''[[Taum Sauk Dam Failure]]'''''

[[File:Taum Sauk power plant.jpg|thumb|The two generators can each produce up to 225 MW of power]]

[[File:Taum Sauk upper reservoir full 2005.jpg|thumb|The original upper reservoir, full to within a few feet of the top of the parapet wall]]

}}

The upper reservoir can hold about {{Convert|1.5|e9USgal|acre.ft e6m3|abbr=off}} of water behind a wall nearly {{convert|100|ft}} tall.<ref name="facts-n-figures">{{cite web |url = https://www.ameren.com/missouri/environment/hydroelectric/taum-sauk-facts-and-figures |title = Taum Sauk Facts & Figures |access-date = November 18, 2017 |publisher = [[Ameren]] |archive-date = December 1, 2017 |archive-url = https://web.archive.org/web/20171201044036/https://www.ameren.com/missouri/environment/hydroelectric/taum-sauk-facts-and-figures |url-status = dead }}</ref> It sits {{convert|760|ft}} above the 450 [[Megawatt|MW]] hydroelectric plant, which gives it a greater [[Head (hydraulic)|head]] than that of [[Hoover Dam]]. The two are connected by a {{convert|7000|ft|adj=on}} tunnel bored through the mountain.

[[Image:Taum Sauk reservoir-FERC 12-22-05 01.jpg|thumb|right|A large section of the upper reservoir failed, draining over a billion gallons of water in less than half an hour.]]

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 m&sup3;) of water in twelve minutes and sending a 20 foot (7m) crest of water down the [[Black River (Arkansas)|Black River]]. According to AmerenUE, a computer software problem cause 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.

The Taum Sauk upper reservoir sits on ridge just below the summit of [[Proffit Mountain]], not [[Taum Sauk Mountain]], which is about {{convert|5|mi|0}} to the east. It is visible from [[Missouri Route 21|Route 21]] north of [[Centerville, Missouri|Centerville]] and from Route N approaching [[Johnson's Shut-ins State Park]] from the south.

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

Before the failure of the upper reservoir, visitors could drive to the top of Proffit Mountain and walk to an observation deck above the reservoir. Ameren operated a museum at the entrance gate highlighting the geologic and [[natural history]] of Missouri. The power plant 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.

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

==History==

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

===Site selection===

In 1953, the [[Union Electric Company]] began to look for a site on which to build a new pumped storage plant. By 1958, company officials had decided to focus on sites with at least {{convert|300|ft|-2}} of vertical head, which would allow them to use a smaller storage reservoir. Union Electric hired [[Sverdrup & Parcel|Sverdrup-Parcel & Associates]] to evaluate potential sites in the [[St. Francois Mountains]], which were chosen for their relative proximity to St. Louis (where Union Electric was based) and the favorably large elevation differentials (some approaching {{convert|1000|ft}}).

Sverdrup-Parcel & Associates intended to recommend [[Taum Sauk Mountain]] as the site, in part because it was the highest point in Missouri at {{convert|1752|ft}}, but strong political opposition to development of the scenic mountain (which was later incorporated into a state park) ruled it out. The nearby Proffit Mountain ended up being an excellent alternative thanks to its comparable elevation ({{convert|1720|ft}}, the 6th-highest point in Missouri), its close proximity to the [[Black River (Arkansas-Missouri)|East Fork of the Black River]], and the reasonably short distance of {{convert|27|mi}} to the existing power transmission grid.<ref name="Rogers 2010" />

No fatalities were reported. Jerry Toop, his wife and three children were swept away when the wall of water obliterated their home. Toop is the superintendent of [[Johnson's Shut-Ins State Park]] and [[Taum Sauk]] State Parks -- which make up Missouri's second largest state park ([[Lake of the Ozarks]] is larger). They survived with injuries and suffering from exposure however their problems were compounded by improper treatment by rescue workers for [[Hypothermia]] which resulted in severe burns. The children were treated for the problems in [[St. Louis]] and later released. An unknown number of homes and vehicles were flooded.

===Construction===

The dam of the lower reservoir held, trapping much of the deluge. If it had given way then towns downstream, including [[Lesterville, Missouri|Lesterville]] and [[Centerville, Missouri|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]

Construction on Taum Sauk began in 1960. The construction team consisted of Fruin-Colnon Construction and the Utah Construction and Mining Company. It went into operation in 1963 with two reversible pump-turbine units that could each generate {{convert|175|MW}} of power. It was not licensed by the US Federal Power Commission (the predecessor of the Federal Energy Regulatory Commission) because Union Electric contended that the FPC did not have jurisdiction over the non-navigable headwaters where the power station was constructed. In FPC v. Union Elec. Co., 381 U.S. 90 (1965), the United States Supreme Court held that the FPC did have jurisdiction and that Taum Sauk did require a FPC license. Although designed and built without federal supervision, a license was retroactively granted.<ref>{{Cite web | url=https://www.courtlistener.com/opinion/107050/fpc-v-union-elec-co/ | title=Federal Power Commission v. Union Electric Co., 381 U.S. 90 | year=1965}}</ref><ref>{{Cite web | url=https://www.mirrorpond.info/1997/09/ferc-abdication-of-jurisdiction/ | title=FERC’s abdication of jurisdiction over hydroelectric dams on nonnavigable rivers | archive-url=https://web.archive.org/web/20180718030631/https://www.mirrorpond.info/1997/09/ferc-abdication-of-jurisdiction/ | archive-date=July 18, 2018 }} FERC’s abdication of jurisdiction over hydroelectric dams on nonnavigable rivers, 27 Envtl. L. 741 (Fall 1997)</ref>

At its completion, the Taum Sauk plant was by far the largest pumped storage plant in North America in a number of measures, and was considered a major milestone in the development of pumped storage technology. Its pump-turbines were the largest ever produced at the time of construction, it had an unusually high head (the highest in the US at the time, far surpassing all previous US pumped storage projects), a large storage capacity (it has been described as "the first of the large capacity pumped-storage stations to begin operation in the United States"<ref name="FERC rebuilding report">{{cite web|title=Rebuilding the Taum Sauk Pumped Storage Project's Upper Reservoir|url=https://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/p-2277.pdf|publisher=[[Federal Energy Regulatory Commission]]|accessdate=March 30, 2018|date=June 2007|archive-date=January 20, 2019|archive-url=https://web.archive.org/web/20190120014611/https://ferc.gov/industries/hydropower/safety/projects/taum-sauk/p-2277.pdf|url-status=dead}}</ref>), [[black start]] capability, and had the unique ability to be operated either remotely by remote human operators in off-site facilities located 90–120 miles away (at St. Louis or [[Bagnell Dam|Osage Power Plant/Bagnell Dam]]) or even fully automatically with zero human intervention.<ref name="rogers-overview" /> Taum Sauk was also the first pure pumped storage plant in the United States.<ref name="Rogers 2010" />

A memo from Richard Cooper, superintendent of Ameren’s Taum Sauk Hydroelectric Plant, indicated that the reservoir had a "Niagra Falls" style overflow on September 27 at the same spot that was breached. 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.

===Upgrades===

==Church Mountain reservoir==

The pump-turbine units were uprated in July 1972 from their initial rating of 175 MW each to 204 MW each, increasing the plant's overall rating from 350 MW to 408 MW.<ref name="FERC staff report">{{cite web|title=Report of Findings on the Overtopping and Embankment Breach of the Upper Dam - Taum Sauk Pumped Storage Project, FERC No. 2277|url=https://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/staff-rpt/full-rpt.pdf|publisher=[[Federal Energy Regulatory Commission]]|accessdate=March 30, 2018|date=April 28, 2006|archive-date=January 20, 2019|archive-url=https://web.archive.org/web/20190120011422/https://ferc.gov/industries/hydropower/safety/projects/taum-sauk/staff-rpt/full-rpt.pdf|url-status=dead}}</ref><ref name="FERC IPOC report">{{cite web|last1=Hendron|first1=Alfred J.|last2=Ehasz|first2=Joseph L.|last3=Paul|first3=Kermit|title=Taum Sauk Upper Dam Breach FERC No. P-2277 — Technical Reasons for the Breach of December 14, 2005 by FERC Independent Panel of Consultants (IPOC)|url=https://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/ipoc-rpt/full-rpt.pdf|publisher=[[Federal Energy Regulatory Commission]]|accessdate=March 30, 2018|date=May 24, 2006|archive-date=June 30, 2018|archive-url=https://web.archive.org/web/20180630100251/https://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/ipoc-rpt/full-rpt.pdf|url-status=dead}}</ref>

[[Image:Proffit to Taum Sauk.jpg|thumb|left|The lower reservoir for a Church Mountain plant would flood 400 acres (1.6 km&sup2;) of Taum Sauk Creek valley.]]

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 km&sup2;), and the lower reservoir would flood 400 acres (1.6 km&sup2;) 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 of 2001.

From 1998–1999, the turbine runners for both units were upgraded, resulting in improved flow rates and another power uprate to 225 MW per unit (450 MW total).<ref name="Correcting Trashrack Failure">{{cite news|last1=March|first1=Patrick|last2=Ratliff|first2=Matthew|last3=Kirchner|first3=Phillip|title=Sticky Wickets: Correcting Trashrack Failure at a Pumped-Storage Plant|url=https://www.hydroworld.com/articles/hr/print/volume-32/issue-6/departments/sticky-wickets-correcting-trashrack-failure-at-a-pumped-storage-plant.html|accessdate=March 30, 2018|work=www.hydroworld.com|date=July 16, 2013|archive-date=March 27, 2019|archive-url=https://web.archive.org/web/20190327085910/https://www.hydroworld.com/articles/hr/print/volume-32/issue-6/departments/sticky-wickets-correcting-trashrack-failure-at-a-pumped-storage-plant.html|url-status=dead}}</ref><ref name="FERC IPOC report" />

==External links==

{{Geolinks-US-streetscale|37.53611111|-90.81805556}}

Minor leaks in the reservoir led to the construction of a collection pond and pumpback station to collect and return leaked water to the reservoir. Later, to reduce leakage, Geo-Synthetics installed lining material in the reservoir itself from September 13 to November 15, 2004.<ref>{{cite web|url=http://www.geo-synthetics.com/taum_sauk.asp |title=AmerenUE Taum Sauk Reservoir Lining Project |accessdate=December 14, 2005 |url-status=dead |archiveurl=https://web.archive.org/web/20051023170913/http://www.geo-synthetics.com/taum_sauk.asp |archivedate=October 23, 2005 }}</ref>

[[Category:pumped storage plants]]

The plant was named an [[List of IEEE milestones|IEEE Milestone]] in October 2005, just months before the upper reservoir failed.<ref>{{cite web |url=http://www.ieeeghn.org/wiki/index.php/Milestones:Taum_Sauk_Pumped-Storage_Electric_Power_Plant,_1963 |title=Milestones:Taum Sauk Pumped-Storage Electric Power Plant, 1963 |author= |date= |work=IEEE Global History Network |publisher=IEEE |accessdate=August 4, 2011}}</ref> It was subsequently rededicated as an IEEE Milestone in 2010 after the new upper reservoir dam was completed.<ref name=IEEE_rededication />

=== 2005 upper reservoir failure ===

[[File:Taum Sauk reservoir-FERC 12-22-05 01.jpg|thumb|left|In 2005, a large section of the upper reservoir failed, draining over {{Convert|1|e9USgal|GL|abbr=off}} of water in less than half an hour.]]

[[File:Taum Sauk reservoir-FERC 12 22 05 02.jpg|thumb|left|A broad swath of dense forest was washed away and scoured to [[bedrock]] by the escaping flow.]]

[[File:Tscompare.jpg|thumb|left|Aerial photos show the upper reservoir before and after its failure.]]

At 5:12&nbsp;a.m. on December 14, 2005, the northwest side of the upper reservoir was overtopped when water continued to be pumped from the lower reservoir after the upper was full. This led to the catastrophic failure of a triangular section of the reservoir wall and the release of {{convert|1|e9USgal|m3|abbr=}} of water in 12 minutes. The sudden release sent a {{convert|20|ft|0|adj=on}} crest of water northwest of the reservoir about {{cvt|1.75|mi|0}} down the ridge to the East Fork of the [[Black River (Arkansas)|Black River]] inside the north upstream side of Johnson's Shut-Ins State Park. The river at the park is normally very shallow with rapids running over granite boulders. The flood destroyed many of the structures in the park and forced the closing of the trail connecting it to Taum Sauk Mountain.

A combination of design and construction flaws, continuing to operate the dam when the primary system for gauging the water level was known to be inaccurate (gauge pipes had become detached), moving the "failsafe" secondary gauging system above the actual height of the dam to avoid false positives, and operating the dam in an unsafe manner by routinely overfilling the reservoir caused the upper reservoir dam to overtop.<ref>{{Cite web | url=http://www.bpa.gov/power/PG/NW-HydroOperators-Forum/Materials/CaseStudyT-Sauk_Ehasz-Paul.pdf | title=Report On Technical Reasons for the Breach |archive-url=https://web.archive.org/web/20170623020725/http://www.bpa.gov/power/PG/NW-HydroOperators-Forum/Materials/CaseStudyT-Sauk_Ehasz-Paul.pdf |archive-date=June 23, 2017 }} Missouri University of Science & Technology: The 2005 Upper Taum Sauk Dam Failure:A Case History</ref><ref name="FERC staff report" /> There was no overflow spillway in the original reservoir.

A memo from Richard Cooper, superintendent of 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 one was killed by the failure. The superintendent of [[Johnson's Shut-Ins State Park|Johnson's Shut-Ins]] and [[Taum Sauk Mountain State Park|Taum Sauk]] 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, Missouri|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]].

The flood continued downstream {{convert|4.3|miles}} on the East Fork of the Snake River to the dam on the river supplying the Lower Reservoir for plant. 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, Missouri|Lesterville]] and [[Centerville, Missouri|Centerville]], from a damaging flood. A voluntary evacuation order was issued for those areas, but there was no damage. The high water was totally stopped at [[Clearwater Lake (Missouri)|Clearwater Lake]] {{convert|29|miles}} below the Lower Reservoir, the dam of which was not damaged by the rising waters.<ref>[http://www.stltoday.com/stltoday/news/stories.nsf/missouristatenews/story/0A4A827BA5C98DB2862570D7004F9A49?OpenDocument Unknown]{{Dead link|date=June 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

====Litigation and investigations====

<!-- split into investigations section first, then litigations section after? Reason being the sheer volume of investigative work done. -->

The US [[Federal Energy Regulatory Commission]] (FERC) fined Ameren US$15 million pursuant to a settlement for the breach at Taum Sauk—a US$10 million civil penalty combined with the requirement to pay US$5 million into interest-bearing escrow in order to fund a variety of "project enhancements at or near the Taum Sauk project".<ref name="FERC settlement">{{cite web |title=AmerenUE agrees to pay $15 million - Settlement |url=https://www.ferc.gov/media/news-releases/2006/2006-4/10-02-06-agreement.pdf |publisher=[[Federal Energy Regulatory Commission]] |access-date=September 2, 2017 |archive-date=January 20, 2019 |archive-url=https://web.archive.org/web/20190120014611/https://ferc.gov/media/news-releases/2006/2006-4/10-02-06-agreement.pdf |url-status=dead }}</ref> The US$15 million fine was the largest fine in FERC's history, 30 times larger than the previous record fine of US$500,000.<ref name="Rogers 2010" />

The [[Government of Missouri|State of Missouri]] sued Ameren for "actual and punitive damages" alleging Ameren was reckless in its operation of the plant.<ref>{{cite web |title=Taum Sauk |url=http://ferc.gov/industries/hydropower/safety/projects/taum-sauk.asp |publisher=[[Federal Energy Regulatory Commission]] |access-date=December 18, 2006 |archive-date=July 19, 2012 |archive-url=https://archive.today/20120719192639/http://ferc.gov/industries/hydropower/safety/projects/taum-sauk.asp |url-status=dead }}</ref><ref>{{cite web |url=http://www.ago.mo.gov/newsreleases/2006/121306b.htm |title=Nixon Sues Ameren, Seeks Compensation and Punitive Damages for State for Taum Sauk Disaster |access-date=December 18, 2006 |archive-url=https://web.archive.org/web/20070626191607/http://www.ago.mo.gov/newsreleases/2006/121306b.htm |archive-date=June 26, 2007 }} Missouri Attorney General Press Release with link to Petition for lawsuit against Ameren for breach</ref>

In 2006, Ameren settled with the Toops family, stating it would pay restitution to the injured family while withholding the terms of the settlement.<ref>{{cite web | url=https://www.stlpr.org/delete1/2006-02-21/ameren-settles-with-family-swept-away-in-reservoir-failure | title=Ameren settles with family swept away in reservoir failure | date=February 21, 2006 }}</ref>

The [[Missouri Highway Patrol]] delivered a report of its criminal investigation to the [[Missouri 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.<ref>[http://www.stltoday.com/stltoday/news/stories.nsf/stlouiscitycounty/story/06323A30D4407520862572F4000BDE98?OpenDocument St. Louis Post Dispatch article]{{Dead link|date=June 2018 |bot=InternetArchiveBot |fix-attempted=yes}}</ref><ref>{{cite web | url=https://ameren.mediaroom.com/news-releases?item=345 | title=AmerenUE Disputes Statement From Dam Safety Official | date= June 6, 2007}} Ameren Press Release disputing press reports of tampering with evidence</ref>

KMOX radio in St. Louis reported that the [[US Environmental Protection Agency]] assisted by the US Attorney's Office for the [[Eastern District of Missouri]] had begun an investigation into violations of the [[Clean Water Act]] and has requested the Missouri Highway Patrol's report.<ref>{{Cite web | url=http://www.kmox.com/pages/603101.php?contentType=4&contentId=628667= | title=Report on EPA Investigation | website=www.kmox.com}}</ref>

The Missouri Public Service Commission (PSC) reopened its investigation and subsequently found the accident to be a failure of Ameren management, stating:

<blockquote>

...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 (nautical)|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 [[piezometer]]s 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)

</blockquote>

Ameren had 90 days from the date of the report to tell the PSC how it will meet the recommendations of the report, which include a [[whistleblower]] rule, changes in safety management structure, financial accounting for the rebuild of the upper reservoir, and single point of management for the rebuild.<ref>{{cite web |url=http://www.waterpowermagazine.com/story.asp?sectioncode%3D130%26storyCode%3D2047683 |title=International Water Power and Dam Construction |access-date=October 28, 2007 |archive-url=https://web.archive.org/web/20090916210531/http://www.waterpowermagazine.com/story.asp?sectioncode=130&storyCode=2047683 |archivedate=September 16, 2009 }} Water Power Magazine on PSC Report</ref><ref>{{cite web |url=http://www.psc.mo.gov/electric/report%2010-24-07.pdf |title=Link to PSC Report Full Text |access-date=October 28, 2007 |archive-url=https://web.archive.org/web/20080517165656/http://www.psc.mo.gov/electric/report%2010-24-07.pdf |archivedate=May 17, 2008 }}</ref>

{{As of|2011|post=,}} Ameren was reported to have paid a total of close to US$200 million in settlements related to the 2005 breach.<ref name="stltoday-more-trouble">{{cite news|title=More trouble for Ameren Missouri's Taum Sauk hydroelectric plant|url=http://www.stltoday.com/business/local/more-trouble-for-ameren-missouri-s-taum-sauk-hydroelectric-plant/article_3e850e06-2ce1-11e1-b336-0019bb30f31a.html|access-date=January 8, 2017 |website=stltoday.com }}</ref><ref name="settlement-details">{{cite news |title=Settlement reached in Taum Sauk reservoir collapse |url=http://www.semissourian.com/story/1293845.html |access-date=January 8, 2017 |website=semissourian.com |date=November 28, 2007 }}</ref>

=== Reconstruction ===

[[File:TaumSaukReservoir underconstruction.jpg|thumb|Aerial photo shows reconstruction progress in late November 2009]]

[[File:Taum Sauk Reservoir from scour-089.jpg|thumb|The completed replacement reservoir, viewed from the scour created by the collapse of the original]]

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.<ref name="ameren21apr10" /> The new dam was recognized by the [[United States Society on Dams]] with its "Award of Excellence in the Constructed Project".<ref name="hydroworld1" /> On September 27, 2010, [[IEEE]] rededicated the plant as an [[List of IEEE Milestones|IEEE Milestone]].<ref name="IEEE_rededication">{{cite web |title=Taum Sauk Rededication |url=https://ewh.ieee.org/soc/pes/saintlouis/Newsletters/Taum%20Sauk%20rededication.htm |access-date=January 8, 2017 }}</ref>

==See also==

* [[List of hydroelectric power station failures]]

{{Portal bar|United States|Water|Renewable energy}}

==References==

{{reflist}}

==General references==

* Southeast Missourian (Cape Girardeau, Missouri): [https://web.archive.org/web/20061218034654/http://www.semissourian.com/story/1131377.html Taum Sauk Reservoir fails]

* Ameren Press Releases: [https://web.archive.org/web/20070310232900/http://www.ameren.com/AboutUs/adc_newsfull.asp?NewsSeqID=449 Media Release Detail], [https://web.archive.org/web/20070310232929/http://www.ameren.com/AboutUs/adc_newsfull.asp?NewsSeqID=450 Media Release Detail]

* Daily Journal (Park Hills, Missouri): [http://www.mydjconnection.com/articles/2005/12/14/community/news1.txt Taum Sauk Dam Fails] {{Webarchive|url=https://web.archive.org/web/20060924034209/http://www.mydjconnection.com/articles/2005/12/14/community/news1.txt |date=September 24, 2006 }}

* National Weather Service, St. Louis Office: [http://www.crh.noaa.gov/lsx/?n=taumsaukdamfailure Taum Sauk Dam Failure]

* [https://web.archive.org/web/20090324030052/http://mcgsc.usgs.gov/taum_sauk_reservoir_photos122005.html Photos] from the [[USGS]] Mid-Continent Geographic Science Center

* [https://web.archive.org/web/20061220003133/http://www.mostateparks.com/jshutinsdamage.htm Johnson's Shut-Ins State Park damage update page]

* Ameren web pages on [https://web.archive.org/web/20060209041219/http://www.ameren.com/taumsauk/ Taum Sauk and Johnson's Shut-ins restoration]

== External links ==

{{Commons category|Taum Sauk Reservoir breach}}

{{Commons category|Taum Sauk Hydroelectric Power Station}}

* [http://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/ipoc-rpt.asp FERC Independent Panel of Consultants (IPOC) Report, May 25, 2006] {{Webarchive|url=https://web.archive.org/web/20061207093204/http://www.ferc.gov/industries/hydropower/safety/projects/taum-sauk/ipoc-rpt.asp |date=December 7, 2006 }}

* [http://apps.ameren.com/hydroelectric/reports/taumsauk/ Ameren Missouri Taum Sauk Water Management Website] {{Webarchive|url=https://web.archive.org/web/20161227125903/http://apps.ameren.com/hydroelectric/reports/taumsauk/ |date=December 27, 2016 }}

{{Electricity generation}}

[[Category:Energy infrastructure completed in 1963]]

[[Category:1963 establishments in Missouri]]

[[Category:Hydroelectric power plants in Missouri]]

[[Category:Pumped-storage hydroelectric power stations in the United States]]

[[Category:Dam failures in the United States]]

[[Category:Disasters in Missouri]]

[[Category:Buildings and structures in Reynolds County, Missouri]]

[[Category:Roller-compacted concrete dams]]

[[Category:Dams in Missouri]]

[[Category:Black River (Arkansas–Missouri)]]