Missouri, utility settle lawsuit over 408-MW Taum Sauk breach

Missouri utility AmerenUE said Nov. 28 it signed a settlement agreement with the state of Missouri in which AmerenUE will pay $177.35 million in compensation and remediation of the 2005 breach of the upper reservoir of the 408-MW Taum Sauk pumped-storage project.

Taum Sauk (No. 2277) has not operated since the reservoir’s ring dam breached Dec. 14, 2005, releasing 1.4 billion gallons of water down the Black River, injuring nine people, and damaging property, including Johnson’s Shut-Ins State Park.

A Missouri Public Service Commission investigation cited a failure of utility management for the breach. A civil suit brought in Reynolds County Circuit Court by the state attorney general sought costs, expenses, penalties, and damages from AmerenUE.

The settlement agreement was signed by the state attorney general’s office and conservation and natural resources officials. It is subject to approval by the Reynolds County Circuit Court.

In addition to cash payment to various state funds, the settlement includes extensive remediation and restoration already performed by AmerenUE and additional prospective remediation and restoration. It also includes addition of 46 miles of former Rock Island Railway right of way, owned Ameren affiliate Missouri Central Railroad, to the state’s 225-mile Katy Trail biking and hiking path.

�We needed no outside pressure to begin restoring the park, supporting the communities around the park, or cooperating with state and federal agencies to determine the root causes of this disaster,� AmerenUE President Thomas Voss said. �Now, AmerenUE can begin rebuilding this important plant for the benefit of the citizens of Missouri and those who live in the Taum Sauk area.�

AmerenUE: No costs to be covered by ratepayers

AmerenUE reiterated it will not attempt to recover from ratepayers any of the breach-related costs or compensation. It said insurance is expected to cover substantially all settlement costs and the costs of rebuilding the reservoir.

AmerenUE said Nov. 7 it hired joint venture Ozark Constructors LLC to rebuild the breached reservoir. (HNN 11/8/07) Ozark Constructors is a joint venture of Colorado-based heavy civil contractor ASI Constructors Inc. and St. Louis-based Fred Weber Inc., which works in mining, aggregate processing, and heavy civil construction.

The utility also selected Paul Rizzo Associates Inc. as engineer of record and project manager. Rizzo designed a roller-compacted-concrete replacement dam that has been approved by the Federal Energy Regulatory Commission. AmerenUE expects the plant to remain out of service through at least the fall of 2009.

The Missouri Public Service Commission staff issued a report Oct. 24 blaming utility management for the failure.

�The breach was entirely avoidable in that the company knew for over two months that the water level sensors were unreliable, as they had broken free from their anchoring system, but unaccountably failed to make repairs,� PSC staff said.

The reservoir was overtopped when pumps failed to shut off. Once overtopping began, erosion undercut the rockfill dam and soon formed a breach about 656 feet wide at the top of the dam and 496 feet at the base. The reservoir was emptied within 25 minutes.

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