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AmerenUE’s Taum Sauk Pumped Storage Plant Is Back Online
54.5-Acre New Upper Reservoir Is the Largest Roller-Compacted Concrete Dam in North America

AmerenUE announced today that its 440-megawatt Taum Sauk pumped storage hydroelectric plant is again generating electricity. The company received permission from the Federal Energy Regulatory Commission (FERC) to “return to normal project operations” on April 1, 2010. Additionally, on April 15th, UE met the Missouri Public Service Commission’s in-service criteria for operations.

“We are thrilled that Taum Sauk has returned to service to become a valuable generating plant for our customers and the State of Missouri,” said Warner Baxter, AmerenUE president and chief executive officer. “We also appreciate the tremendous support we have received from our key stakeholders in the community during our rebuilding of the upper reservoir and restoration activities at Johnson’s Shut-Ins State Park. In addition, I want to thank our employees and our partners for their dedication and completing this project with the highest of quality.”

Ozark Constructors, LLC, rebuilt the upper reservoir under the guidance of the project’s engineer of record, Paul C. Rizzo Associates, Inc. Ozark Constructors is a venture partnership formed by ASI Constructors, Inc., and St. Louis-based Fred Weber, Inc. Established in 1978, ASI, based in Pueblo West, CO, is a heavy civil contractor specializing exclusively in the construction and rehabilitation of dams, spillways and major water resources. Over its 40-year history, Fred Weber has grown from a small, family-owned business to a 1,650 employee-owned company with mining, aggregate processing and heavy civil construction expertise.

Following Paul C. Rizzo Associates design, the upper reservoir was built using roller-compacted concrete. Before concrete could be poured, workers removed the remaining walls of the old reservoir that breeched in December 2005, excavating to bedrock. Leveling concrete was placed initially and roller-compacted concrete—made in part with crushed rocks recycled from the old reservoir—was placed to form the walls of the new reservoir. The last concrete was poured in November 2009. On February 27, the first water was pumped into the new dam, effectively initiating the FERC-approved Upper Reservoir Refill Program.

The rebuilt upper reservoir includes many safety features, including:

• Dam Crest: A crest elevation is above the highest anticipated water surface and has a three and half foot parapet wall above the crest;

• Overflow Release Structure: In the unlikely event that all systems fail and the upper reservoir overflows, the overflow release structure would allow water to flow into Taum Sauk creek without damage to the RCC structure;

• Multiple independent lines of defense, including continuous video camera monitoring of the upper reservoir water levels to ensure that proper water levels are maintained in both the upper and lower reservoirs; and

• Separate instrumentation and monitoring systems that will be dedicated solely to dam safety.

• Finally, a drainage gallery exists that collects and constantly measures water to monitor the health of the structure year round.

“Dam safety and construction quality was our top priority in the rebuilding of the upper reservoir”, said Mark Birk, AmerenUE vice president, Power Operations. “Throughout our efforts, we worked closely with federal and state regulatory authorities to ensure that this project complied with all applicable standards for the safe operation of the plant and the upper reservoir.”

The project also has a significant economic impact on the area. A study conducted by the Center for Economic & Business Research at Southeast Missouri State University showed the rebuild would meaningfully contribute to economic growth in Missouri, benefiting especially Iron, Madison, Reynolds, St. Francois and Wayne Counties in southeast Missouri. In particular, this project created a significant number of jobs in the region. In total, approximately 1,000 employees were engaged at some point over the course of the project.

“Taum Sauk has been a significant part of the region’s economy since 1963 and will continue to be for many years to come,” said Baxter.

Consistent with its settlement with the State of Missouri and FERC, the company provided millions in funding to aid area communities, promote tourism and repair Johnson’s Shut-Ins. Providing support for the local community of Lesterville has remained a priority since the rebuilding began.

“AmerenUE has shown itself to be a good neighbor and responsible corporate citizen every day since the breech happened,” said Earlene Fox, superintendent of Lesterville R-IV School District. “They voluntarily elected to continue paying taxes even during the years that the plant was not generating electricity. UE proved that they care about this community and are here to stay.”

AmerenUE, founded in 1902, provides electric and gas service to approximately 1.2 million customers across central and eastern Missouri, including the greater St. Louis area. UE serves 57 Missouri counties and 500 towns. The company's electric rates are among the lowest in the nation. For more information, visit www.amerenue.com.

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Contacts: Tim Fox 314-554-4335, Michael West 314-554-2389