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Hydro Review

Dam Safety & Security

Report card gives America's dams a "D" grade

A "report card" released in March by the American Society of Civil Engineers (ASCE) gives America's dams an overall grade of "D."

The study - called the 2013 Report Card for America's Infrastructure - is an analysis published by ASCE every four years. The document "depicts the condition and performance of the nation's infrastructure in the familiar form of a school report card," ASCE says, and includes grades for 16 different categories.

America's cumulative infrastructure grade point average is a D+, with $3.6 trillion of investments needed by 2020, the report says. The grade for dams is D.

Regarding dams, the average age of the 84,000 dams in the U.S. is 52 years old, the report card says.

According to ASCE, dams fitting the "high-hazard" category numbered nearly 14,000 in 2012, with 4,000 dams qualifying as "deficient" (including 2,000 classified as high-hazard). The Association of State Dam Safety Officials estimates that it will require an investment of $21 billion to repair these aging, yet critical, high-hazard dams.

As the study notes, the vast majority of America's dams are not regulated by the federal government, but instead rely on state dam safety programs for inspection. Many state programs lack sufficient resources and regulatory authority, however, leading ASCE to suggest the implementation of more national programs as a means of alleviating the problem.

The report card lists several solutions that could be used to raise the grade for dams, including:

- Reauthorizing the National Dam Safety Program by 2014 and fully funding the program for each year under the reauthorization;

- Establishing a national dam rehabilitation and repair funding program to cost share repairs to publicly owned, nonfederal high-hazard dams;

- Developing emergency action plans for every high-hazard dam by 2017; and

- Implementing a national public awareness campaign to educate individuals on the location and condition of dams in their area.

To view the report card in full, visit www.infrastructurereportcard.org.

Corps completes pile concrete work at Wolf Creek Dam

The U.S. Army Corps of Engineers' Nashville District poured concrete in March for the last pile of Wolf Creek Dam's seepage barrier wall as part of a dam safety improvement project. The seepage barrier wall was installed by Treviicos Soletanche JV.

The step marks the last and most critical part of the project, the Corps said, which was required to mitigate seepage through the karst geology deep in Wolf Creek Dam's foundation. The Corps identified the earthfill and concrete gravity dam as being critically near failure or having extremely high life or economic risk. Money to repair the dam was included in economic stimulus appropriations approved by Congress.

The pile is one of almost 1,200 that are about 3 feet in diameter and extend up to 2,775 into bedrock below the foundation of the embankment.

Pending a successful review, the Corps said it will raise the impounded Lake Cumberland about 20 feet from its current operating zone to 500 to 705 feet in elevation.

Wolf Creek Dam impounds water for a 270-MW hydropower project of the same name.

Reclamation begins dam safety evaluations at Clark Canyon Dam

The U.S. Department of Interior's Bureau of Reclamation will conduct an exploratory drilling program at Clark Canyon Dam in Montana as part of its ongoing dam safety analysis program.

Located at the head of the Beaverhead River in the southwestern part of the state, Clark Canyon Dam is an earthfill structure with a height of 147.5 feet, a crest length of 2,950 feet and a volume of almost 2 million cubic yards of material.

Reclamation's investigations at the 48-year-old structure include the drilling of a series of exploratory holes along the dam's east abutment that will be used to gather information on the foundation and overlying material.

Reclamation continuously inspects its dams as they age to determine that high standards of dam safety are being maintained.

Xcel installing warning sirens near 5.4-MW Menomonie project

Midwestern utility Xcel Energy began installing warning sirens on its hydroelectric projects along the Red Cedar River in late 2012 as a means to alert the nearby public if there was a dam failure or other catastrophic event that would endanger those downstream.

The solar-powered warning sirens will be attached to 55-foot-tall poles and installed in two locations downstream from the 5.4-MW Menomonie plant.

In the event of an emergency, the company says the sirens will emit a "whoop tone," then an audio recording with spoken instructions.

Xcel, which operates 19 hydro plants with a combined capacity of about 260 MW, previously installed similar sirens at other locations, including three downstream of the Trego project and nine downstream of the lower Chippewa River facilities.

GEI performs dam safety and management work in Colorado

GEI Consultants Inc. was awarded several contracts in January through its Denver office for geotechnical, environmental consulting and planning services related to the dam safety and operations in Colorado.

Included are updates to the U.S. Bureau of Indian Affairs' (BIA) dam safety handbook, rehabilitation design and construction at the Hodgson-Harris Dam reservoir rehabilitation project and a dam inundation map for Tucker Lake.

GEI said the objective of BIA's Safety of Dams Program Handbook is to implement a "risk-informed decision process" congruent with Interior's Public Protection Guidelines.

The updates will also incorporate current industry and BIA standards with policies and guidelines related to risk assessment, safety inspections, engineering evaluations, design and construction processes, permitting, emergency management, operation and maintenance, warning systems, dam security and training.

Meanwhile, the company's work at the Hodgson-Harris reservoir - located near Superior, Colo. - includes the restoration of the impounding dam. The rehabilitation project will allow the reservoir to store its historic water volume and also decrease the likelihood of dam failure.

Last, GEI has recently completed a dam inundation project map for Tucker Lake in Arvada, Colo. The lake is adjacent to Blunn Reservoir and Ralston Creek, with impounding dams on its north and south ends. GEI said it performed dam breach analyses and flood inundation for each of the drainage channels, assuming a "worst case" scenario for each dam.

The analyses, conducted for the Arvada Department of Public Works and Engineering, were performed in accordance with the Colorado Office of the State Engineer's Dam Safety Branch Guidelines for Dam Breach Analysis.

Colorado announces dam safety improvements at Beaver Creek

Colorado Parks and Wildlife will begin a two-year repair project to increase dam safety at Beaver Creek Reservoir this summer, allowing its 4,400-acre-foot reservoir to be filled again by mid-2015.

The reservoir is an important component in the overall water management system in the San Luis Valley, and its water is used for irrigation, recreation and wildlife habitat.

It has been drawn down to about half its capacity since problems with the 100-year old dam structure were discovered in 2010, the agency said.

The US$15 million project will be conducted in two stages, with the first beginning in July. This phase will see the dam's spillway rebuilt. Work is expected to be complete in December.

Next, Colorado Parks and Wildlife said it will build a new abutment support for the dam and make improvements to the outlet tunnel. This portion of the rehabilitation is expected to begin in April 2014 and be complete by the end of that year.

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